Microbiology Flashcards
Asymptomatic bacteriuria: Diagnosis in catheterized urine.
Requires isolation of 10² colony-forming units per mL of the same species.
Only one sample is required.
Asymptomatic bacteriuria: Who needs treatment?
Those who are pregnant or who will undergo urological instrumentation.
UTI pathogen: Most common.
E. coli.
UTI pathogen: Older male with obstructive uropathy.
Enterococcus.
UTI pathogens: Culture-negative (3).
Mycoplasma hominis.
Ureaplasma urealyticum.
Chlamydia trachomatis.
UTI pathogen: Fungal.
Candida spp.
Hemorrhagic cystitis:
A. Pathogen.
B. Clinical background.
A. Adenovirus, esp. types 11 and 21.
B. Bone-marrow transplant.
Sensitivity and specificity of urine-dipstick tests:
A. Leukocyte esterase.
B. Nitrite.
A. SN: 70-95%; SP: 70%.
B. SN: 50%; SP: 95%.
Viral agents of diarrhea:
A. In winter.
B. Foodborne and infective with small inoculum.
A. Rotavirus.
B. Norwalk-like viruses.
Bacterial agents of diarrhea:
A. Traveler’s diarrhea.
B. Hemolytic-uremic syndrome.
A. Enterotoxigenic E. coli.
B. Enterohemorrhagic E. coli (O157:H7).
Enterohemorrhagic E. coli: Toxin.
Shiga toxin.
Salmonella bacteremia: Who is at risk (2)?
Those with sickle-cell disease or indwelling prostheses.
Bacterial enteritis: Leading agent in the U.S.
Campylobacter jejuni.
Campylobacter jejuni: Diseases other than enteritis.
Guillain-Barré syndrome.
Reactive arthritis.
Most virulent strain of Clostridium difficile:
A. Name.
B. Basis of virulence.
A. B1/NAP1/027.
B. Mutation in tcdC leads to increased production of toxins A and B.
Clostridium difficile: Reference method of testing for infection.
Cytotoxicity assay.
Clostridium difficile: Genes implicated in pathogenesis.
tcdA: Toxin A.
tcdB: Toxin B.
tcdC: Regulator of the toxins.
Another bacterial agent of antibiotic-associated colitis.
Klebsiella oxytoca.
Entamoeba histolytica: Preferred test.
Enzymatic immunoassay of stool.
Non-microscopic test for neutrophils in stool.
Stool lactoferrin.
Bacterial agents of pneumonia: Community-acquired, single most common.
Streptococcus pneumoniae.
Bacterial agents of pneumonia: In patients with COPD (3).
Haemophilus influenzae.
Moraxella catarrhalis.
Legionella pneumophila.
Bacterial agents of pneumonia: Alcoholics (3).
S. pneumoniae.
K. pneumoniae.
Gram-negative aerobic bacilli.
Bacterial agents of pneumonia: Bird handlers.
Chlamydophila psittaci.
Bacterial agents of pneumonia: Bronchiectasis (3).
Pseudomonas aeruginosa.
Burkholderia cepacia.
Staphylococcus aureus.
Bacterial agents of pneumonia: Atypical pneumonia.
Mycoplasma pneumoniae.
Chlamydophila pneumoniae.
Bacterial agents of pneumonia: Necrotizing (2).
S. aureus.
Ps. aeruginosa.
Bacterial agents of pneumonia: Hospital-acquired, single most common.
S. aureus.
Legionella pneumophila: Environmental associations (3).
Hot tubs.
Cooling towers.
Construction sites (dust).
Legionella pneumophila: Clinical manifestations (5).
High fever.
Hyponatremia.
Renal dysfunction.
Diarrhea.
Neurological abnormalities.
Coronaviruses that cause pneumonia (3).
SARS coronavirus.
NL63.
HKU1.
Human papillomaviruses that cause pneumonia.
K1, WU.
Hantavirus: Animal vector.
The deer mouse.
Hantavirus: Findings on peripheral smear (4).
Thrombocytopenia.
Neutrophilia without toxic granules.
Erythrocytosis.
Immunoblastic lymphocytosis.
Agents of endocarditis: Native valves (most common).
S. aureus.
Agents of endocarditis: Diseased valves, most common.
Streptococci, esp. viridans streptococci.
Agents of endocarditis: Prosthetic valves, very early, most common (3).
S. aureus.
S. epidermidis.
Gram-negative bacilli.
Agents of endocarditis: Prosthetic valves, early, most common (2).
S. epidermidis.
S. aureus.
Agents of endocarditis: Prosthetic valves, late, most common.
Streptococci.
Culture-negative endocarditis: Bacterial causes (5).
Coxiella burnetii.
Bartonella.
Legionella.
Chlamydia.
Tropheryma whippeli.
Culture-negative endocarditis: Noninfectious causes (3).
Libman-Sacks endocarditis.
Marantic endocarditis.
Carcinoid heart syndrome.
Culture-negative endocarditis: A third cause.
Previous antibiotic therapy.
Viral agents of encephalitis: Most common (2).
California encephalitis.
St. Louis encephalitis.
Viral agents of encephalitis: Herpesviridae (2).
HSV1, HHV6.
Amoebic agents of encephalitis (3).
Acanthamoeba spp.
Naegleria fowleri.
Balamuthia mandrillaris.
Agents of aseptic meningitis:
A. Most common.
B. Others (4).
A. Enteroviruses.
B. HSV-2, LCM virus, mumps virus, HIV.
Agents of aseptic meningitis: Seasonal variation.
Summer and fall: Enteroviruses.
Winter and spring: LCM virus.
Bacterial agents of meningitis: Neonates (3).
Group-B streptococci.
Gram-negative bacilli.
Listeria monocytogenes.
Bacterial agents of meningitis: Populations most affected by Listeria monocytogenes.
Neonates.
Elderly.
Immunocompromised.
Iron-overloaded.
Bacterial agents of meningitis: Infants, young children, young adults.
N. meningitidis.
S. pneumoniae.
H. influenzae.
Who is at highest risk of serious infections by N. meningitidis?
Those with a deficiency of C5-C9.
Bacterial agents of meningitis: Adults.
S. pneumoniae.
N. meningitidis.
Bacterial agents of meningitis: Southeast Asia.
Streptococcus suis.
HSV encephalitis: Unique findings in CSF (3).
Very high protein.
Blood.
Low glucose.
Most common agents of infections of prosthetic joints at:
A. Less than 3 months (2).
B. 3-24 months (2).
C. Beyond 24 months.
A. S. aureus, Gram-negative bacilli.
B. S. epidermidis, P. acnes.
C. S. epidermidis.
Infections of prosthetic valves: Cutoffs for leukocyte count and percentage of neutrophils in synovial fluid (2).
A. Knee: 1700/mL, >65% neutrophils.
B. Hip: 4200/mL, >80% neutrophils.
Severe sepsis: Definition.
Sepsis with organ dysfunction.
Septic shock: Definition.
Sepsis with refractory hypotension.
Sepsis vs. the systemic inflammatory-response syndrome: Theoretical difference.
SIRS is sepsis with no infectious source.
Sepsis vs. SIRS: Distinguishing test.
Procalcitonin: Elevated in sepsis.
Indicators of catheter-related sepsis (3).
Culture of catheter tip yields 5 times as many colonies as the blood culture.
Culture of catheter tip becomes positive at least 2 hours before the blood culture.
Cultures of catheter tip and blood yield the same organism.
Neonatal sepsis: Most common agents (2).
E. coli.
Group-B streptococci.
Agents of bacteremia in patients with colon cancer (2).
Streptococcus bovis.
Clostridium septicum.
Agent of fungal meningitis: Most common.
Cryptococcus.
Agent: Erythrasma.
Corynebacterium diphtheriae.
Agent: Juvenile periodontitis.
Aggregatibacter actinomycetemcomitans.
Agent: Glanders.
Burkholderia mallei.
Agent: Meliodosis.
Burkholderia pseudomallei.
Agent: Rocky Mountain spotted fever.
Rickettsia rickettsii.
Agents: Visceral larva migrans.
Toxocara canis, Toxocara cati.
Agent: Erysipelas.
Streptococcus pyogenes.
Agent: Erysipeloid.
Erysipelothrix rhusiopathiae.
Agent: Freshwater cellulitis.
Aeromonas hydrophilia.
Agent: Saltwater cellulitis.
Vibrio vulnificus.
Agent: Lymphogranuloma venereum.
Chlamydia trachomatis.
Agent: Acute epiglottitis.
Haemophylus influenzae.
Agents: Monoarticular arthritis (2).
Staphylococcus aureus.
Streptococci.
Agent: Arthritis in abusers of intravenous drugs.
Pseudomonas aeruginosa.
Agent: Polyarthritis in the sexually active.
Neisseria gonorrhoeae.
Agent: Croup.
Parainfluenza viruses 1-3.
Agents: Otitis media (3).
Streptococcus pneumoniae.
Haemophilus influenzae.
Moraxella catarrhalis.
Agent: Carrión’s disease.
Bartonella bacilliformis.
Agent: Verruga peruana.
Bartonella bacilliformis.
Agent: Uterine infection following septic abortion.
Clostridium perfringens.
Agent: Rat-bite fever.
Streptobacillus moniliformis.
Agent: Black piedra.
Piedraia hortae.
Agent: White piedra.
Trichosporon beigelii.
Agent: Tinea versicolor.
Malessezia furfur.
Agent: Tinea nigra.
Hortaea werneckii.
Agents: Chromoblastomycosis (3).
Phialophora verrucosa.
Cladophialophora spp.
Fonsecaea pedrosoi.
Agent: Lobomycosis.
Lacazia loboi.
Agents: Phaeohyphomycosis (3).
Phialophora verrucosa.
Exophiala jeanselmi.
Alterneria spp.
Agents: Eumyotic mycetoma (3).
Exophiala jeanselmi.
Madurella spp.
Pseudallescheria boydii.
Agents: Actinomycotic mycetoma (3).
Actinomyces spp.
Nocardia spp.
Streptomyces.
Agent: Rhinosporidiosis.
Rhinosporidium seeberi.
Agent: Rhinoscleroma.
Klebsiella rhinoscleromatis.
Agent: Roseola infantum (exanthem subitum).
HHV6.
Agent: Fifth disease.
Parvovirus B19.
Agent: African sleeping sickness.
Trypanosoma brucei.
Agent: Adiaspiromycosis.
Emmonsia parva.
Agent: Fungal otitis media.
Aspergillus niger.
Agent: Hand-foot-mouth disease.
Coxsackie A virus.
Agent: Viral myocarditis.
Coxsackie B virus.
Agent: Dog heartworm.
Dirofilaria immitis.
Agent: Tickborne encephalitis.
Tickborne-encephalitis virus.
Agent: Murine typhus.
Rickettsia typhi.
Agent: Epidemic typhus.
Rickettsia prowazekii.
Agent: Rickettsialpox.
Rickettsia akari.
Agent: Relapsing fever.
Borrelia recurrentis.
Agent: Trench fever.
Bartonella quintana.
Vector: Dog heartworm.
Anopheles spp.
Vectors: Lymphatic filariasis (2).
Anopheles spp.
Culex spp.
Vector: Yellow fever.
Aedes spp.
Vectors: Lyme disease (3).
Eastern U.S.: Ixodes scapularis.
Western U.S.: I. pacificus.
Europe: I. ricinus.
Vector: Babesia.
Ixodes spp.
Vector: Anaplasmosis.
Ixodes spp.
Diseases of which Amblyomma americanum is the vector (3).
Ehrichliosis.
Tularemia.
Southern tick-associated illness.
Dermacentor spp.: Diseases of which it is a vector (3).
Rocky Mountain spotted fever.
Tularemia.
Colorado tick fever.
Vector: Trachoma.
Musca sorbens.
Vector: Onchocercosis.
Simulium spp.
Vector: Rickettsialpox.
Mite.
Viral cytopathic effect: Tear-shaped cells.
Enteroviruses.
Viral cytopathic effect: Focal plaques in human diploid fibroblasts.
CMV.
Viral cytopathic effect: Grapelike clusters.
Adenoviruses.
Viral cytopathic effect: Syncytia.
Respiratory syncytial virus.
Viral cytopathic effect: Sweeping, with globular cells.
HSV-1, HSV-2.
Viral cytopathic effect: Minimal or none.
Influenza viruses.
Parainfluenza viruses.
Adenovirus infection: Histology.
Smudgy intranuclear inclusion.
CMV infection: Location of inclusions.
Nuclear and cytoplasmic.
Measles infection: Location of inclusions.
Cytoplasmic and nuclear.
RSV infection: Location of inclusions.
Cytoplasmic only.
DNA viruses: Those with envelopes.
Herpesviridae.
Hepadnaviridae.
Poxviridae.
DNA viruses: Those with single-stranded DNA.
Parvoviridae.
Bocavirus.
DNA viruses: Those with circular DNA.
Papillomaviridae.
Polyomaviridae.
DNA viruses: Families.
Adenoviridae. Bocavirus. Herpesviridae. Hepadnaviridae. Poxviridae. Parvoviridae. Papillomaviridae. Polyomaviridae.
RNA viruses: Helical.
Paramyxoviridae. Orthomyxoviridae. Rhabdoviridae. Bunyaviridae. Filoviridae. Deltavirus. Coronaviridae. Arenaviridae.
RNA viruses: Those with negative-sense RNA.
Paramyxoviridae. Orthomyxoviridae. Rhabdoviridae. Bunyaviridae. Filoviridae. Deltavirus. Arenaviridae.
RNA viruses: Which have double-stranded RNA?
Reoviridae.
RNA viruses: Which have circular RNA?
Bunyaviridae.
Arenaviridae.
Deltaviridae.
RNA viruses: Which have no envelope?
Astroviridae.
Picornaviridae.
Reoviridae.
Caliciviridae.
Herpes encephalitis: Classic gross finding.
Hemorrhagic necrosis of the anterior pole of both temporal lobes.
Neonatal herpes: Feared complications (3).
Encephalitis.
Chorioretinitis.
Sepsis.
HSV infection: Definitive method of diagnosis.
Cell culture.
Varicella: Risk factors for serious disseminated infection in adults (2).
Pregnancy.
Immunocompromise.
Varicella, congenital: Diagnosis (3).
Maternal history of infection, or
Characteristic skin lesions on neonate, or
Serological evidence of infection in neonate.
Varicella, congenital: Period of highest risk of transplacental infection.
During the third trimester.
Varicella: Reactivation syndromes.
Herpes zoster.
Ramsey Hunt syndrome.
Varicella: Time to cytopathic effect in culture.
About 2 weeks.
Varicella: Other diagnostic methods (3).
Serology (present of IgM or a 4-fold rise in IgG).
PCR.
DFA of skin scrapings.
Congenital CMV infection: Clinical manifestations (10).
Low birthweight.
Microcephaly.
Intracerebral calcifications.
Chorioretinitis.
Hepatosplenomegaly. Jaundice. Thrombocytopenia. Petechiae. Purpura.
Sensorineural hearing loss.
CMV colitis: Clinical presentation.
Can mimic exacerbation of idiopathic inflammatory bowel disease.
CMV infection: Antigen used in DFA.
pp65.
EBV: Associated neoplasms (7).
Burkitt's lymphoma. Hodgkin's lymphoma. Primary effusion lymphoma. Post-transplant lymphoproliferative disorder. Lymphomatoid granulomatosis. Oral hairy leukoplakia. Nasopharyngeal carcinoma.
EBV:
A. Cell that it infects.
B. Cell that proliferates in response to infection.
A. The B cell.
B. The CD8-positive T cell.
Duncan’s disease: Definition.
X-linked immunoproliferative disorder with predisposition to fulminant infection by EBV.
Duncan’s disease: Typical mechanism of death.
Hepatic necrosis.
Duncan’s disease: Abnormal gene.
SH2D1A, which encodes a subunit of the SLAP-associated protein.
Duncan’s disease: Immunological defect resulting from the abnormal gene.
Uncontrolled activation of T/NK cells during infection by EBV.
EBV serology: The basic tests (5).
Monospot.
IgM anti-VCA.
IgG anti-VCA.
IgG anti-EA.
Anti-EBNA.
EBV serology: Pattern in one who has never been infected.
All results are negative.
EBV serology: Early acute infection.
Positive: IgM and IgG anti-VCA.
Negative: IgG-anti-EA.
Monospot may be positive.
EBV serology: Acute infection.
Positive: IgM and IgG anti-VCA, anti-EA, Monospot.
Anti-EBNA may also be positive.
EBV serology: Convalescence.
Positive: IgG anti-VCA, anti-EA, anti-EBNA.
Negative: IgM anti-VCA, Monospot.
EBV serology: Remote infection.
Positive: Anti-EA, anti-EBNA.
Negative: IgM anti-VCA, Monospot.
IgG anti-VCA may be undetectable.
Monospot: How it works.
EBV induces heterophile antibodies that react with horse erythrocytes in the presence of guinea-pig kidney but not in the presence of bovine-erythrocyte stroma.
Monospot: Relevance of sensitivity to patient’s age.
Less sensitive in patients under age 4.
EBV: Antigen used in immunochemistry.
LMP1.
HHV6:
A. Disease.
B. Cell of latency.
A. Roseola infantum (exanthem subitum).
B. T cells.
HHV7:
A. Disease.
B. Cell of latency.
A. Roseola infantum.
B. Lymphocyte.
HHV8: Associated neoplasms (3).
Multicentric Castleman’s disease.
Primary effusion lymphoma.
Kaposi’s sarcoma.
HHV8: Antigen used in immunochemistry.
LANA1.
Types of adenovirus that cause
A. Respiratory infections.
B. Hemorrhagic cystitis.
C. Gastroenteritis in children.
A. 1-14 and 21.
B. 11 and 21.
C. 40 and 41.
Parvovirus B19: Histology.
Smudgy nuclear inclusions.
Bocavirus:
A. Definition.
B. How detected.
A. A respiratory virus.
B. By PCR only.
JC and BK viruses:
A. When acquired.
B. Clinical presentation of acute infection.
A. In childhood.
B. Asymptomatic.
Reactivation of JC virus:
A. Disease.
B. Affected cell.
C. Histology.
A. Progressive multifocal leukoencephalopathy.
B. Oligodendroglia.
C. Smudgy nuclear inclusions.
Reactivation of BK virus: Diseases (2).
Hemorrhagic cystitis.
Polyomaviral nephropathy.
Merkel-cell polyomavirus: Associated diseases (2).
Merkel-cell carcinoma.
CLL.
HPV types: Plantar wart.
1, 2.
HPV types: Common wart.
2, 1, 4.
HPV types: Plane wart.
3, 10.
HPV types: Oral focal epithelial hyperplasia.
13, 32.
HPV types: Epidermodysplasia verruciformis.
2, 3, 10, 5, 8.
Epidermodysplasia verruciformis:
A. Inheritance.
B. Time of expression.
C. Significance.
A. Autosomal recessive.
B. In the first decade.
C. May progress to SCC.
HPV types: Condyloma acuminatum.
6, 11.
HPV types: LSIL.
6, 11.
HPV types: HSIL (7).
16, 18, 31, 33, 35, 39, 45, others.
HPV types: Cervical adenocarcinoma.
16, 18.
HPV types: Bowenoid papulosis.
16, 18.
Recurrent respiratory papillomatosis: Types (2) and how they are acquired.
Adult: Sexual contact.
Juvenile: Passage through the birth canal.
Agents of bioterrorism: CDC category A (6).
Smallpox.
Hemorrhagic-fever viruses.
Bacillus anthracis.
Yersinia pestis.
Clostridium botulinum.
Francisella tularensis.
Hepatitis A: Incubation.
15-30 days.
The presence of HBsAg can mean what?
Acute hepatitis B.
Chronic carrier state.
Presence of HBeAg indicates what?
Active viral replication.
Presence of anti-HBc indicates what?
Exposure to HBV at some point in life.
Presence of anti-HBe means what?
Chronic carrier state without active viral replication.
Early serologic markers of HBV infection:
A. Order of appearance.
B. Relevance to clinical manifestations.
A. HBsAg, HBeAg, anti-HBc.
B. Emergence of antibodies coincides with appearance of symptoms.
Chronic hepatitis B: Definition.
Persistence of HBsAg for >6 months.
Population at greatest risk for chronic hepatitis B.
Neonatals infected transplacentally.
Rheumatological disease associated with chronic hepatitis B.
Polyarteritis nodosa.
When does HBV DNA become detectable in the serum?
Before HBsAg.
Chronic hepatitis B without detectable HBeAg:
A. Clinical significance.
B. Cause.
A. Can progress to fulminant hepatic failure.
B. Stop codon in C region or pre-C region of genome of HBV.
Replicative hepatitis B: Definition.
Presence of >10⁵ copies of HBV DNA per mL.
Expected serology: Resolved hepatitis B.
Anti-HBs.
Anti-HBc.
Expected serology: Immunization against HBV.
Anti-HBs only.
Expected serology: Acute hepatitis B.
HBsAg, IgM anti-HBc.
Expected serology: Chronic hepatitis B.
HBsAg, anti-HBc.
Hepatitis C: How many patients develop a chronic infection?
About 60%.
Hepatitis C: How many patients with chronic infection develop cirrhosis?
About 15%.
Hepatitis C: Extrahepatic manifestations.
Cryoglobulinemia with its attendant complications, e.g. anemia, glomerulonephritis.
Hepatitis C: Expected test results in a very early infection.
HCV RNA only.
Hepatitis C: Expected test results in acute infection.
HCV RNA.
Enzymatic immunoassay for anti-HCV.
RIBA.
Hepatitis C: Expected test results in chronic infection.
HCV RNA.
Enzymatic immunoassay for anti-HCV.
RIBA.
Hepatitis C: Expected test results in resolved infection.
Enzymatic immunoassay for anti-HCV.
RIBA.
Hepatitis C: What do these results mean?
EIA for anti-HCV: Positive.
RIBA: Negative.
HCV RNA: Negative.
False-positive result for anti-HCV.
Hepatitis C: Endpoint of antiviral therapy.
When HCV RNA has remained undetectable for >24 months after completion of therapy.
Hepatitis C genotypes:
A. Most common in the United States.
B. Most likely to develop resistance to antiviral therapy.
A. Genotype 1.
B. Genotype 1a.
Hepatitis E: Approximate mortality in pregnant women.
30%.
“Non-hepatitis” viruses that can cause hepatitis (6).
HSV1, HSV2.
VZV.
EBV.
CMV.
Yellow-fever virus.
Influenza A: Mechanism of antigenic drift bzw. antigenic shift.
Drift: Point mutations in genes for hemagglutinin or neuraminidase.
Shift: Genetic reassortment between strains.
Hemagglutinin: Role in pathogenesis of influenza.
Binds to sialic-acid-containing receptors on respiratory epithelial cells.
Hemagglutinin: Role in diagnosis.
The expression of hemagglutinin on infected cells is the basis of the hemadsorption test.
Rapid test for influenza:
A. Method.
B. Sensitivity.
C. Specificity.
A. Direct immunofluorescence.
B. 50-80%.
C. Highly specific.
Hemagglutinin inhibition: Uses.
Serologic diagnoses of infection.
Determination of viral subtype and strain.
Parainfluenza virus: How to diagnose infection (3).
PCR.
Immunofluorescence.
Hemadsorption.
Measles virus: Diseases (3).
Measles.
Atypical measles.
Subacute sclerosing panencephalitis.
Measles: Prodrome.
Cough, coryza, conjunctivitis.
Atypical measles: Typical patient.
Teenager who has received only one vaccination.
Subacute sclerosing panencephalitis:
A. Risk.
B. Period of incubation.
A. About 0.001%.
B. About 7 years.
Virus that can cause pancreatitis.
Mumps virus.
Respiratory syncytial virus:
A. Infectivity.
B. Host immunity.
A. Infects nearly all exposed children.
B. Short-lived; recurrent infection is the rule.
Respiratory syncytial virus: Detection (3).
PCR.
Immunofluorescence.
Cell culture.
Human metapneumovirus: Disease.
Lower respiratory infection.
Coxsackie A virus: Diseases.
Hand-foot-mouth disease.
Herpangina.
Coxsackie B virus: Diseases (3).
Myocarditis.
Pericarditis.
Epidemic pleurodynia.
Rhinovirus: Special condition of culture.
Incubation at 32 degrees.
Bunyaviridae: Examples (4).
Bunyavirus.
Hantavirus.
Nairovirus.
Rift Valley fever virus.
Rubella virus: Family.
Togaviridae.
Rubella during pregnancy:
A. When the fetus is most vulnerable.
B. How to prevent it.
A. During the first trimester.
B. Measure titers in women who intend to become pregnant.
Congenital rubella: Affected organs (3).
Ears: Sensorineural deafness.
Eyes: Cataracts, glaucoma, microphthalmia.
Heart: Patent ductus arteriosus.
Yellow fever: Histology (4).
Mid-zonal necrosis.
Microvesicular steatosis.
Apoptotic bodies.
No inflammation.
Flaviviridae: Examples (5).
Yellow-fever virus.
Dengue-fever virus.
St. Louis encephalitis virus.
West Nile virus.
Hepatitis C virus.
West Nile virus: Usual host.
Birds.
Rabies virus:
A. How does it get to the CNS?
B. How does it become transmissible to other animals?
A. Through retrograde fast axonal transport from the site of the bite.
B. It travels along the peripheral nerves to the salivary glands.
Rabies: Diagnostic histologic findings (2) and the location of each.
Negri bodies: Purkinje cells.
Babeș nodules: Microglia.
Rabies: How to diagnose histologically without doing a brain biopsy.
Biopsy of skin, including hair follicles.
Arenaviridae: Origin of name.
Incorporation of the host’s ribosomes imparts a sandy (granular) appearance.
Lymphocytic choriomeningitis virus:
A. Family.
B. Natural hosts.
A. Arenaviridae.
B. Rodents, esp. house mice and hamsters.
HTLV-1:
A. Transmission.
B. Affected cell.
A. Parenteral.
B. CD4-positive T lymphocyte.
HTLV-1:
A. Family.
B. Diagnosis of infection.
A. Retroviridae.
B. Screening ELISA, confirmatory western blot or PCR.
HTLV-1: Late sequelae of infection (2).
Tropical spastic paraparesis.
Adult T-cell leukemia/lymphoma.
Tropical spastic paraparesis: Histology.
Demyelination of the upper thoracic and lower cervical spinal cord.
Adult T-cell leukemia/lymphoma:
A. Lifetime risk.
B. Incubation.
A. About 5% for those infected before age 20.
B. 20-30 years.
Adult T-cell leukemia/lymphoma: Clinical presentation (3).
Jaundice.
Hepatosplenomegaly.
Weight loss.
Adult T-cell leukemia/lymphoma: Other possible clinical features (4).
Rash.
Increased thirst.
Hypercalcemia.
Increased circulating IL-2 receptors.
How long after infection does ___ become detectable?
A. anti-HIV antibody
B. p24 protein
A. 6-8 weeks.
B. 2-3 weeks.
Definition of a positive western blot for HIV.
Presence of band for any 2 of the following:
p24.
gp41.
gp120/160.
A western blot show bands but not in a combination that is considered positive.
A. Interpretation.
B. How to proceed.
A. Indeterminate.
B. If a repeat test at 6 months is indeterminate and there are no risk factors for HIV, then the result is called negative. If there are risk factors, then nucleic-acid testing must be done.
CD4 counts: Guidelines (2).
Measure the CD4 counts at consistent times of day.
Use age-specific reference intervals.
Preferred test for monitoring response to antiretroviral therapy.
HIV RNA.
Proviral DNA:
A. Definition.
B. Application.
A. DNA derived from viral RNA by reverse transcriptase.
B. May be used to confirm infection by HIV.
CD4 count: How often should it be performed?
Every 6 months while the disease is stable.
Viral load vs. CD4 count as predictors of outcomes.
Long term (10 years): Viral load is better.
Short term (6 months): CD4 count is better.
Viral load:
A. How reported.
B. Significant change.
A. As log units (for example, 1000 = 3 log units).
B. 0.5 log units.
Viral load: Relevance to HAART (2).
Viral load determines
- When to start HAART.
- The efficacy of HAART.
Use of HIV RNA to diagnose infection by HIV.
A positive result should be confirmed as soon as possible by ELISA and western blot.
Neonatal infection by HIV: Preferred test.
PCR for proviral DNA, although HIV RNA may be just as good.
Examination of stool for parasites: Number and timing of specimens.
Three specimens, at least 24 hours apart.
Fresh stool: When to examine for parasites.
Within an hour if possible; otherwise, preserve the stool in formalin or alcohol.
Parasites that may be missed by routine stains for ova and parasites (3).
Cryptosporidium.
Cyclospora cayetanensis.
Cystoisospora belli.
How to identify those parasites that may be missed by routine stains (2).
Modified stain for acid-fast bacilli.
Modified saffranin stain.
Culture medium: Free-living amoebae.
Tap-water agar on a bed of E. coli.
Culture medium: Leishmania and Trypanosoma.
Novy-MacNeal-Nicolle medium.
Culture medium: Trichomonas vaginalis.
Diamond’s medium.
Morphologically indistinguishable amoebae.
Entamoeba histolytica.
Entamoeba dispar (albeit without ingested RBCs).
Trophozoite of E. histolytica / E. dispar:
A. Size.
B. Motility.
A. 15-20 μm.
B. Unidirectional.
Trophozoite of E. histolytica / E. dispar:
A. Size and location of karyosome.
B. Distribution of chromatin.
A. Small and central.
B. Fine and even along the nuclear membrane.
Cyst of E. histolytica / E. dispar:
A. Number of nuclei.
B. Chromatoidal bars.
A. Never more than 4.
B. Rounded ends.
Trophozoite of Entamoeba coli.
A. Size.
B. Motility.
A. 20-25 μm.
B. Nondirectional.
Trophozoite of Entamoeba coli:
A. Size and location of karyosome.
B. Distribution of nuclear chromatin.
A. Large and eccentric.
B. Clumped along the nuclear membrane.
Cyst of Entamoeba coli.
A. Number of nuclei.
B. Chromatoidal bars.
A. Up to 8.
B. Frayed ends.
Trophozoite of Entamoeba hartmanni.
A. Size.
B. Motility.
A. 5-10 μm.
B. Nondirectional.
Trophozoite of Entamoeba hartmanni:
A. Size and location of karyosome.
B. Distribution of nuclear chromatin.
A. Small and central.
B. Fine and even along the nuclear membrane.
Cyst of Entamoeba hartmanni:
A. Number of nuclei.
B. Chromatoidal bars.
A. Never more than 4.
B. Rounded ends.
Entamoeba histolytica: A better method than morphology for detection in stool.
Enzymatic immunoassay.
Entamoeba histolytica: Most common location of ulcer.
Cecum.
Non-pathogenic amoebae (2).
Iodamoeba bütschlii.
Endolimax nana.
Endolimax nana: Distinguishing morphologic features (2).
Small size of trophozoite: 5-10 μm.
“Ball-in-socket” karyosome.
Iodamoeba bütschlii: Distinguishing morphologic features (2).
Large vacuole that takes up the iodine stain.
“Ball-in-socket” karyosome.
Pathogenic free-living amoebae: Major genera.
Acanthamoeba.
Naegleria.
Balamuthia.
Naegleria fowleri: Disease.
Primary amoebic meningoencephalitis.
Trophozoite of Naegleria fowleri:
A. Size.
B. Morphology of nucleus and karyosome.
A. 10-35 μm.
B. Small nucleus; large, dense, central karyosome.
Naegleria fowleri: Treatment of CSF specimens that may contain it.
Do not refrigerate.
Acanthamoeba spp. and Balamuthia mandrillaris:
A. Disease.
B. How they enter the body.
A. Granulomatous amoebic encephalitis.
B. Through skin or lungs.
Acanthamoeba spp. and Balamuthia mandrillaris: Histology.
Found around vessels.
Acanthamoeba spp.: Another disease.
Amoebic keratitis.
Trophozoite of Acanthamoeba spp.:
A. Nucleus.
B. Karyosome.
A. Small.
B. Large, central.
Cyst of Acanthamoeba:
A. Number of nuclei.
B. Size of karyosome.
C. Another distinguishing feature.
A. One.
B. Large.
C. Double wall.
Leading cause of protozoal diarrhea.
Giardia intestinalis.
Giardia intestinalis: Motility in wet preparation.
“Falling-leaf” motility.
Cyst of Giardia intestinalis:
A. Shape.
B. Nuclei.
A. Oval.
B. Four, arranged along a central axoneme.
Giardia intestinalis: Preferred method of identification.
Enzymatic immunoassay.
Chilomastix mensili: Disease.
None.
Chilomastix mensili: Differences from G. intestinalis (4).
Rotary motility.
No axoneme.
Lemon-shaped cyst.
Cyst has one nucleus.
Trophozoite of Dientamoeba fragilis: Distinguishing features (4).
Round.
Binucleate.
Each nucleus contains a central, “fractured” karyosome.
Internalized flagellum.
Cyst of Dientamoeba fragilis: Distinguishing feature.
No cyst form has been described.
Dientamoeba fragilis: Diseases (2).
Diarrhea.
Pruritus ani.
Dientamoeba fragilis: Concomitant pathogen.
Enterobius vermicularis.
Trichomonas vaginalis:
A. Number of nuclei.
B. Motility.
A. One.
B. Jerky and nondirectional.
Leishmania spp.:
A. Characteristic organelle.
B. Another genus of protozoans that possess this organelle.
A. Kinetoplast.
B. Trypanosoma.
Leishmania spp.: Genera of vectors (2).
The sandflies
− Phlebotomus.
− Lutzomyia.
Leishmania: Important species (4) and disease caused by each.
L. brasiliensis, L. mexicana: Cutaneous, mucocutaneous.
L. major, L. tropica: Cutaneous, visceral (also affects marrow).
Trypanosomes: Important species (2) and how to distinguish them.
T. cruzi: Large kinetoplast.
T. brucei: Small kinetoplast.
Trypanosomes: How best to find them in the peripheral blood.
Look in the buffy coat.
Chagas’ disease: Most common site of inoculation.
The face.
Romaña’s sign.
Periorbital and palpebral swelling as a sign of inoculation by the reduviid bug.
Trypanosoma brucei: Vector.
Glossina spp.
The one ciliated protozoon known to infect humans.
Balantidium coli.
Balantidium coli: Morphology of trophozoite (4).
Large: 100 μm.
Circumferential cilia.
Rod- or horseshoe-shaped macronucleus.
Micronucleus.
Microsporidia: Important genera (2).
Enterocytozoon.
Encephalitozoon.
Microsporidia: Where to find them on biopsies.
In the apical aspect of enterocytes.
Microsporidia: How to find them in stool samples.
Use a modified trichrome stain.
Cryptosporidium: Important species (2).
Cryptosporidium parvum.
Cryptosporidium hominis.
Cryptosporidium spp.: Where to look for them in a biopsy.
Attached to the brush border of enterocytes.
Cryptosporidium spp.: How to find them on a stool sample.
Use a modified acid-fast stain.
Cyclospora cayetanensis: Where to look for them on a biopsy.
Within the cytoplasm of enterocytes, where different developmental forms of the organism can be seen.
Cystoisospora belli: Distinction from C. cayetanensis (2).
Larger size: 25-30 μm rather than 8-10 μm.
Elliptical rather than circular.
Oocyst of Sarcocystis spp.:
A. Size.
B. Number of nuclei.
A. 15-20 μm.
B. Two.
Sarcocystis spp.: Affected tissues.
Muscle, intestine.
Sarcocystis spp.: Unique property that aids in identification.
Auto-fluorescence in ultraviolet light.
Toxoplasma gondii: Two forms.
Tachyzoite.
Bradyzoite.
Tachyzoite of Toxoplasma gondii: Size and shape.
3-5 μm; bow-shaped (τοξον); large, eccentric nucleus.
Toxoplasma gondii: How acquired (4).
Ingestion of cat feces.
Ingestion of infected meat.
Transfusion of blood; transplantation of tissues.
Transplacental transmission.
Toxoplasma gondii: Interpretation of IgG titers.
Very high or rising: Acute infection.
Low: Resolved infection.
Toxoplasma gondii: Effects on the fetus (2).
Early in gestation: Death.
Late: CNS disease.
Plasmodium spp.: Injected form.
The sporozoite.
Plasmodium spp.: Development in the hepatocyte.
Sporozoites develop into merozoites, which go on to infect erythrocytes.
Plasmodium spp.: Development in the erythrocyte.
Merozoites develop into trophozoites and then into schizonts and then into more merozoites. The merozoites burst out of the red cell and infect others.
Some merozoites develop into gametocytes.
Plasmodium spp.: What happens to the gametocytes?
They burst out of the erythrocyte and get ingested by the mosquito, along with red cells that contain trophozoites.
In the stomach of the mosquito, the gametocytes get fertilized and give rise to sporozoites.
Plasmodium spp.:
A. How long after inoculation do symptoms appear?
B. How long after inoculation do fever cycles begin?
A. About a week.
B. A few weeks.
Plasmodium spp.: Paroxysmal symptoms are associated with ___.
Intravascular hemolysis.
Tertian fever:
A. Definition.
B. Cause.
A. Fever spike every 48 hours.
B. Plasmodium vivax, ovale, falciparum.
Quartan fever:
A. Definition.
B. Cause.
A. Fever spike every 72 hours.
B. Plasmodium malariae.
Plasmodium: Species typically associated with the nephrotic syndrome.
Plasmodium malariae.
Plasmodium: Species most likely to affect the CNS.
Plasmodium falciparum.
Plasmodium: Species that causes “blackwater fever”.
Plasmodium falciparum.
Relapse of malaria:
A. Associated species.
B. Mechanism.
A. P. vivax, P. ovale.
B. Reinfection of erythrocytes by merozoites from the liver.
Plasmodium:
A. Species that infects young red cells.
B. Species that infects old red cells.
C. Species with no preference.
A. P. vivax, P. ovale.
B. P. malariae.
C. P. falciparum.
Plasmodium spp.: Fluorescent stains used in detection.
Acridine orange.
Rhodamine.
Plasmodium spp.: Best time to collect blood for examination.
Before the next fever spike.
Plasmodium falciparum: Morphology of the ring form (4).
Less than one third the diameter of the RBC.
Some may have 2 chromatin dots.
Appliqué forms may be seen.
Multiply infected red cells are common.
Plasmodium malariae: Morphology of the mature trophozoite (2).
Band and basket forms that do not fill the red cell.
Conspicuous hematin pigment.
Plasmodium spp.: Number of merozoites in the schizont.
P. vivax: 12-24.
P. ovale: 6-14.
P. malariae: 6-12.
P. falciparum: Schizont rarely seen in the blood.
Plasmodium malariae: Unique morphologic feature of the schizont.
Merozoites surround a large clump of hematin pigment.
Plasmodium: Species exhibiting Schüffner’s dots.
P. vivax.
P. ovale.
Plasmodium spp.: Appearance of hematin pigment.
P. malariae: Coarse.
All others: Fine.
How to distinguish Schüffner’s dots from hematin pigment.
Schüffner’s dots: Pale purple-pink.
Hematin pigment: Brown-black.
Plasmodium spp.: How many oil-immersion fields should be examined on a ___ smear?
A. Thick.
B. Thin.
A. At least 100.
B. At least 300.
Plasmodium falciparum: Name and appearance of unique inclusion in erythrocytes.
Maurer’s clefts: Round or comma-shaped red dots.
Plasmodial parasitosis:
A. Response to therapy.
B. Definition of severe parasitosis.
A. Initial increase precedes decrease.
B. Parasites in >2% of red cells.
Babesia spp.: Pigment found in erythrocytes.
None.
Babesia spp.: Interpretation of titers.
At least 1 to 1024: Active infection.
No more than 1 to 64: Remote infection.
Babesia spp.:
A. In North America.
B. In Europe.
A. Babesia microti.
B. Babesia divergens.
Babesiosis in the northeastern U.S.:
A. Vector.
B. Reservoirs.
A. Ixodes scapularis.
B. White-footed mouse, whitetail deer.
Babesiosis in Europe: Vector.
Ixodes ricinus.
Babesiosis: Clinical features.
Non-periodic fever.
Hemolysis.
Babesiosis: Risk factors for fatal disease (2).
Asplenia.
Immunocompromise.
Enterobius vermicularis: How to recognize it in tissue sections.
By its lateral alae.
Enterobius vermicularis: Shape of egg.
Oval, with one flat side.
Enterobius vermicularis: Residence of adult female.
Cecum and appendix.
Trichuris trichiura: Shape of egg.
Like a thick-walled barrel with a plug in each end.
Trichuris trichiura: Complication of infection in children.
Rectal prolapse.
Ascaris lumbricoides: Shape of egg.
Round to oval, bile-stained, with a thick, rough wall.
Ascaris lumbricoides: Life in human host.
Eggs get ingested.
Larvae cross mucosa to get carried in the blood to the lungs, whence they get expectorated and swallowed.
Adult worms infest the duodenum.
Ascaris lumbricoides: Complications of infestation (4).
Löffler’s syndrome.
Appendicitis.
Bowel obstruction.
Cholangitis.
Mouthparts of ___.
A. Necator americanus.
B. Ankylostoma duodenale.
A. Cutting plates.
B. “Teeth”.
Necator americanus and Ankylostoma duodenale: Egg.
Morula in a thin shell.
Hookworms: Life in human host.
Larvae enter through the skin, travel through the blood to the lungs, and get expectorated and swallowed.
Adults infest the duodenum.
Strongyloides stercoralis: Residence of adult females.
Intestinal crypts.
Strongyloides stercoralis: Egg.
Similar to that of the hookworms but not usually found in the stool.
Strongyloides stercoralis: Form found in the stool and how to recognize it.
Rhabditiform larva.
Similar to larvae of hookworms, but with shorter buccal cavity and a large genital primordium.
Strongyloides stercoralis: Simple diagnostics tests other than examination of stool (2).
String test.
Duodenal aspirate.
Strongyloides stercoralis: Life in human host.
Similar to that of hookworms.
Strongyloides stercoralis: Complications (2).
Auto-infection: Worms re-enter lungs from duodenum and get expectorated and swallowed.
Hyperinfection in the immunocompromised.
Bloodborne microfilariae: Main species (4).
Wuchereria bancrofti.
Brugia malayi.
Loa loa.
Mansonella perstans.
Bloodborne microfilariae: Which has no sheath?
Mansonella perstans.
Bloodborne microfilariae: Which species are
A. Diurnal.
B. Nocturnal.
C. Without preference.
A. Loa loa.
B. Wuchereria bancrofti, Brugia malayi.
C. Mansonella perstans.
Bloodborne microfilariae: Nuclei of tail.
No nuclei: W. bancrofti.
Two, discontinuous: B. malayi.
Continuous row: Loa loa, M. perstans.
Bloodborne microfilariae: Residence of adults.
Lymphatics: W. bancrofti, B. malayi.
Subcutis: Loa loa.
Subcutis and body cavities: M. perstans.
Bloodborne microfilariae: Vectors.
W. bancrofti, B. malayi: Mosquito.
Loa loa: Mango fly (Chrysops).
M. perstans: Biting midge (Culicoides).
Loa loa: Disease.
Transient migratory edema.
Onchocerca volvulus:
A. Vector.
B. Diagnosis of infestation.
A. Simulium blackfly.
B. Detection of worm in snips of skin.
Dirofilaria immitis:
A. Vector.
B. Histology.
A. Mosquito.
B. Degenerating worm in granuloma in lung or subcutis.
Toxocara spp.: Diseases (2).
Visceral larva migrans.
Ocular larva migrans.
Toxocara spp.: Clinical manifestations (3).
Hypereosinophilia.
Pneumonitis.
Hepatosplenomegaly.
Fasciolopsis buski:
A. How acquired.
B. Affected organ.
A. From the ingestion of freshwater plants.
B. Duodenum.
Fasciolopsis buski: Egg.
150 μm, thin shell, unshouldered operculum.
Fasciola hepatica:
A. How acquired.
B. Affected organ.
A. From the ingested of freshwater plants.
B. Liver, biliary tract.
Fasciola hepatica:
A. Egg.
B. Adult.
A. Indistinguishable from that of Fasciolopsis buski.
B. Cephalic cone.
Clonorchis sinensis:
A. How acquired.
B. Affected organ.
A. From the ingestion of undercooked freshwater fish.
B. Biliary tract.
Clonorchis sinensis:
A. Egg.
B. Adult.
A. 30 μm, shouldered operculum, abopercular knob.
B. Snoutlike cephalic region.
Paragonimus westermani:
A. How acquired.
B. Affected organs.
A. From the ingestion of undercooked crustaceans.
B. Lungs.
Paragonimus westermani: Egg.
90 μm, shouldered operculum, no abopercular knob.
Diphyllobothrium latum: Egg.
60 μm; flat, unshouldered operculum; abopercular knob.
Schistosomes:
A. How they enter the body.
B. Residence in the body.
A. The fork-tailed cercariae penetrate the skin.
B. Pelvic and mesenteric vessels.
Schistosomiasis: Stages of infection.
Acute: Immune complexes.
Chronic: Reaction to eggs in tissue.
Schistosoma mansonii: Affected organs.
Liver.
Colon (from infiltration of inferior mesenteric vessels).
Schistosoma japonicum: Affected organs.
Liver.
CNS (rarely).
Schistosoma haematobium: Affected organ.
Urinary bladder.
Schistosoma intercalatum: Affected organ.
Intestine.
Schistosomes: Distinguishing the species by their eggs.
S. haematobium: Terminal spine.
S. mansonii: Lateral spine.
S. japonicum: Small lateral knob; smaller and more spherical egg.
Taenia saginata: Trivial name.
Beef tapeworm.
Taenia saginata: Egg.
30-40 μm, thick wall with radial striations, 3 pairs of hooklets.
Taenia saginata:
A. Scolex.
B. Proglottid.
A. Four suckers, unarmed (i.e. without hooklets) rostellum.
B. Longer than wide; >13 lateral uterine branches.
Taenia saginata: Ingested form.
Encysted organisms (cysticerci).
The eggs of T. saginata are not infectious.
Taenia solium:
A. Trivial name.
B. Egg.
A. Pork tapeworm.
B. Indistinguishable from that of T. saginata.
Taenia solium:
A. Scolex.
B. Proglottid.
A. Four suckers, armed rostellum.
B. Longer than wide; <13 lateral uterine branches.
Cyst of Taenia solium:
A. Size.
B. Morphology.
A. 1 cm.
B. Double row of hooklets.
Taenia solium: How acquired (2).
By the ingestion of infected pork.
By the ingestion of eggs shed in feces.
Diphyllobothrium latum: Scolex.
Almond-shaped, with two longitudinal sucking grooves.
Diphyllobothrium latum: Proglottid.
Wider than long; uterus resembles rosette.
Hymenolepis nana: Egg.
Oval, 40-60 μm, with a polar thickenings and a double shell enclosing three pairs of hooklets.
Hymenolepis nana: How acquired (2).
By the accidental ingestion of infected beetles.
By person-to-person transmission.
Hymenolepis diminuta:
A. Trivial name.
B. How acquired.
A. Rat tapeworm.
B. By the ingestion of insect-contaminated food.
Hymenolepis diminuta: Egg.
Spherical, 60-80 μm, no polar thickenings.
Dipylidium caninum:
A. Egg.
B. Proglottid.
A. Similar to that of Hymenolepis diminuta, but occurring in packets of 5-15.
B. Two genital pores, one on each side.
Dipylidium caninum: Acquisition.
Ingestion of fleas that have fed on infected dogs and cats.
Echinococcus spp.: Cyst.
Contains protoscolices and hooklets.
Echinococcus spp.: Definitive host.
The dog.
Organisms that often infect someone already infected with ___.
A. Ascaris lumbricoides.
B. Enterobius vermicularis.
C. Babesia spp. (2).
D. HTLV.
A. Trichuris trichiura.
B. Dientamoeba fragilis.
C. Anaplasma phagocytophilum, Borrelia spp.
D. Strongyloides stercoralis.
Parasitosis that is worse with ___.
A. B-cell deficiency.
B. Splenectomy.
A. Giardiasis.
B. Babesiosis.
Usual fungal media:
A. Examples (3).
B. Conditions of incubation.
A. Sabouraud’s dextrose agar, inhibitory mold agar, brain-heart-infusion agar.
B. Four to six weeks at 25-30 degrees.
How does ___ inhibit the growth of bacteria?
A. Sabouraud’s dextrose agar.
B. Inhibitory mold agar.
C. Brain-heart-infusion agar.
A. Low pH, much dextrose.
B. Chloramphenicol.
C. Chloramphenicol and gentamicin.
Cycloheximide: Use in fungal media.
Excludes saprophytes but permits growth of most pathogenic fungi.
Cycloheximide: Pathogenic fungi that cannot grow in it.
Cryptococcus spp.
Many species of Candida.
Aspergillus spp.
Zygomycetes.
Cornmeal and potato-dextrose agars: Purpose.
Identification of fungal isolates by pigment and reproductive structures.
Agar with Tween 80: Purpose.
Identification of yeast isolates by their reproductive structures.
Agar with olive oil: Purpose.
Isolation and cultivation of Malassezia spp.
Birdseed (niger-seed) agar: Purpose.
To demonstrate phenol oxidase activity in Cryptococcus neoformans.
Yeasts vs. molds:
A. Macroscopic appearance of colony.
B. Temperature of growth.
A. Yeasts: creamy or mucoid; molds: fuzzy.
B. Yeasts: 37 degrees; molds: 25-30 degrees.
Macroscopic features of colonies of ___.
A. Hyaline septate molds.
B. Dematiaceous molds.
C. Zygomycetes.
A. White or colored surface; usually light reverse.
B. Dark surface and/or reverse (due to melanin).
C. Rapid growth.
Thermally dimorphic fungi: Medically important species (6).
Histoplasma capsulatum.
Blastomyces dermatitidis.
Coccidioides immitis.
Paracoccidioides brasiliensis.
Sporothrix schenckii.
Pencillium marneffi.
Histoplasma capsulatum:
A. Microscopy of yeast form.
B. Colony morphology.
A. 2-4 μm, narrow-based budding.
B. Cottony and white.
Histoplasma capsulatum:
A. Microconidia.
B. Macroconidia.
A. Small, smooth, tear-shaped.
B. Large, spiny, thick-walled.
Histoplasma capsulatum: Non-morphologic test for identification.
Assay for Histoplasma antigen in serum or urine.
Histoplasma capsulatum: Favorable condition of soil.
Rich in nitrogen from the feces of chickens and bats.
Histoplasma capsulatum: Affected organs (2).
Lungs.
Reticuloendothelial system in disseminated infections.
Histoplasma capsulatum var. duboisii:
A. Geographic distribution.
B. Affected organs.
A. Western and Central Africa.
B. Skin, bones, subcutis.
Histoplasma capsulatum var. duboisii:
A. Morphology in vitro.
B. Morphology in vivo.
A. Same as that of Histoplasma capsulatum var. capsulatum.
B. Yeast: 7-15 μm, narrow-based budding.
Blastomyces dermatitidis:
A. Microscopy of yeast form.
B. Colony morphology.
A. 8-15 μm, thick-walled, broad-based budding.
B. Cottony and white, turning tan with age.
Blastomyces dermatitidis: Conidia.
Single and smooth and borne on straight, delicate conidiophores that emerge directly from the hyphae (“lollipop conidia”).
Blastomyces dermatitidis:
A. Primary affected organs.
B. Organs affected in disseminated disease.
A. Lungs.
B. Skin, bones, mucous membranes.
Coccidioides immitis:
A. Size of spherule and of endospores.
B. Colony morphology.
A. 10-100 μm; 2-5 μm.
B. Moist, gray, and glabrous, turning cottony and white with maturity.
Coccidioides immitis: Microscopy of mold.
Hyphae and barrel-shaped arthroconidia alternating with empty cells.
Coccidioides immitis:
A. Primary affected organs.
B. Organs affected in disseminated disease.
A. Lungs.
B. Skin, bones.
Coccidioides: Another medically important species and its geographic distribution.
Coccidiodes posadosii: Southwestern United States, Mexico, Central America.
Paracoccidioides brasiliensis:
A. Microscopy of yeast.
B. Colony morphology.
A. 10-50 μm, circumferential budding.
B. White or tan; variable texture.
Paracoccidioides brasiliensis: Microscopy of mold form.
Smooth conidia borne on short, thick conidiophores that emerge directly from the hyphae.
Paracoccidiodes brasiliensis:
A. Primary affected organ.
B. Organs affected in disseminated disease (3).
A. Lungs.
B. Skin, mucous membranes, reticuloendothelial system.
Sporothrix schenckii:
A. Microscopy of yeast.
B. Colony morphology (mold).
A. 4-6 μm, cigar-shaped, narrow-based budding.
B. Moist, white to pale orange, turning brown with age.
Sporothrix schenckii: Microscopy of mold.
Clusters of microconidia borne on conidiophores.
Sporothrix schenckii:
A. Route of infection.
B. Affected organ.
A. Trauma.
B. Local lymphatics.
Penicillium marneffi:
A. Microscopy of yeast.
B. Colony morphology (mold).
A. 3-5 μm, ovoid, binary fission (no budding).
B. Powdery or velvety; white and becoming tan with age; red pigment surrounds colonies.
Penicillium marneffi: Microscopy of mold.
Brushlike clusters of phialides.
Penicillium marneffi: Endemicity.
Southeast Asia.
Aspergillus fumigatus: Color of colony (2).
Surface: Blue-green with a white apron.
Reverse: Light.
Aspergillus fumigatus: Microscopy.
Uniseriate phialides cover top ⅔ of the vesicle.
Phialides bear round conidia, 2-4 μm.
Aspergillus flavus: Color of colony (2).
Surface: Yellow-green to olive green.
Reverse: Light.
Aspergillus flavus: Microscopy.
Uniseriate or biseriate phialides cover whole vesicle.
Aspergillus niger: Color of colony (2).
Surface: Dark brown or black.
Reverse: Light.
Aspergillus niger: Microscopy.
Biseriate phialides cover whole vesicle; conidia are dark, round, and rough.
Aspergillus terreus: Color of colony (2).
A. Surface: Cinnamon brown.
B. Reverse: Yellow or orange.
Aspergillus terreus: Microscopy.
Biseriate phialides cover top ⅔ of vesicle; long chains of conidia.
Aspergillus spp.: Immunological test.
ELISA for galactomannan or for 1,3-β-glucan.
Infections caused by Aspergillus spp.:
A. In an immunocompetent host with cavitary lung disease.
B. In a host with atopy (2).
C. In an immunocompromised host (2).
A. Fungus ball.
B. Allergic sinonasal or bronchopulmonary aspergillosis.
C. Invasive sinonasal or bronchopulmonary aspergillosis.
Special clinical significance of
A. Aspergillus niger.
B. Aspergillus terreus.
A. Pulmonary infection leads to deposition of calcium oxalate in the tissues.
B. Resists amphotericin B.
Fusarium spp.: Infections.
Fungal keratitis.
Infections of burns.
Infections similar to those caused by Aspergillus spp.
Pseudallescheria boydii / Scedosporium boydii: Infections (3).
Fungal keratitis.
Eumycotic mycetoma.
Pneumonia after near-drowning.
Pseudallescheria boydii / Scedosporium boydii: Special clinical significance.
Resists amphotericin B.
Hyaline hyphomycetes with conidia in clusters: Genera (3).
Fusarium.
Acremonium.
Gliocladium.
Fusarium: Microscopy.
Canoe-shaped macroconidium contains 3-6 cells.
Acremonium: Microscopy.
“Diphtheroid” clusters of microconidia borne on threadlike conidiophores.
Gliocladium: Microscopy.
Resembles a mulberry (microconidia) held in the tips of four fingers (phialides).
Hyaline hyphomycetes with conidia in chains: Genera (3).
Penicillium.
Paecilomyces.
Scopulariopsis.
Penicillium: Microscopy.
Brushlike clusters of flask-shaped phialides bearing round conidia.
Paecilomyces: Microscopy.
Brushlike clusters of vase-shaped phialides bearing oval or spindle-shaped conidia.
Scopulariopsis: Microscopy.
Lemon-shaped microconidia that emerge one from another, forming chains.
Microconidia begin smooth but become spiny with maturity.
Hyaline hyphomycetes with single conidia: Genera (3).
Chrysosporium.
Sepedonium.
Beauveria.
Chrysosporium: Microscopy.
Resembles Blastomyces dermatitidis.
Sepedonium: Microscopy.
Resembles Histoplasma capsulatum.
Beauveria: Microscopy.
Geniculate conidiophores bear round or oval conidia.
Dermatophytes: Special biochemical property.
Resist cycloheximide.
Trichophyton rubrum: Colony.
Red reverse due to pigment.
Trichophyton rubrum: Microscopy.
Small, tear-shaped microconidia arranged on the hyphae like “birds on a wire”.
Trichophyton mentagrophytes: Microscopy.
Clusters of microconidia; spiral hyphae.
Trichophyton tonsurans: Microscopy.
Variable sizes and shapes of microconidia.
Microsporum canis: Morphology.
Fusiform macroconidium terminates in a knob and contains >6 cells.
Transverse septa.
Microsporum gypseum: Microscopy.
Elongated ovoid macroconidium has rounded end and contains no more than 6 cells.
Transverse septa.
Epidermophyton floccosum: Microscopy.
Smooth, club-shaped microconidia contain 2-6 cells and transverse septa.
Dematiaceous molds: Colony morphologies (3).
Dark surface and dark reverse.
Dark surface and light reverse.
Light surface and dark reverse.
Bipolaris: Microscopy.
Smooth, oval microconidia with transverse septa, arising from geniculate conidiophores.
Germ tubes may arise from each end of a macroconidium.
Drechslera: Microscopy.
Resembles Bipolaris, but the germ tubes arise from the sides of the macroconidia.
Exserohilum: Microscopy.
Macroconidia are long and narrow, resembling pea pods, and terminate in a nipplelike knob.
Helminthosporium: Microscopy.
Resembles a bottle brush, with side-by-side macroconidia arranged in whorls along the conidiophores.
Curvularia: Microscopy.
Transversely septate macroconidia are bent due to overgrowth of the central cell.
Alternaria: Microscopy.
Muriform conidium of which the pointed end is apposed to the blunt end of the next, forming a chain.
Ulocladium: Microscopy.
Oval muriform macroconidium borne on a geniculate conidiophore.
Stemphylium: Microscopy.
Oval muriform macroconidium borne on a straight conidiophore, resembling cotton candy on a stick.
Dematiaceous molds with yeastlike early growth: Genera (2).
Hortaea.
Exophiala.
Slow-growing dematiaceous fungi that are moldlike throughout their growth: Genera (2).
Pseudallescheria boydii.
Scedosporium prolificans.
Pseudallescheria boydii / Scedosporium boydii: Colony.
“House mouse gray” surface: Conidia are pigmented.
Light reverse: Hyphae are not pigmented.
Pseudallescheria boydii / Scedosporium boydii: Sexual structure.
Cleistothecium.
Pseudallescheria boydii / Scedosporium boydii: Alternative sexual form and its microscopy.
Graphium.
Conidiophores form a bundle (synnemata) resembling a sheaf of wheat.
Pseudallescheria boydii / Scedosporium boydii: Antiobiotic therapy.
Resists amphotericin B.
Usually responds to triazoles.
Scedosporium prolificans: Colony.
Dark surface and dark reverse.
Scedosporium prolificans: Sexual form.
None described.
Scedosporium prolificans: Microscopy.
Truncated round conidia in clusters borne on conidiophores that have a swollen base.
Scedosporium prolificans: Antibiotic therapy.
Resists amphotericin B, triazoles, and echinocandins.
Dematiaceous molds: Infections (3).
Chromoblastomycosis.
Eumycotic mycetoma.
Phaeohyphomycosis.
Chromoblastomycosis: Histology (3).
Pseudoepitheliomatous hyperplasia.
Pigmented hyphae.
Sclerotic (muriform) bodies.
Chromoblastomycosis: Route of infection.
Puncture wound.
Chromoblastomycosis: Genera (3).
Phialophora.
Fonsecaea.
Cladophialophora.
Eumycotic mycetoma: Histology.
Mold form granules within subcutaneous nodules.
Eumycotic mycetoma: Genera (3).
Exophiala.
Madurella.
Pseudallescheria.
Eumycotic mycetoma: Route of infection.
Puncture wound.
Rhizopus spp.:
A. Sporangia.
B. Sporangiophores.
A. Tend to collapse, forming umbrella shapes.
B. Nodal, unbranched; no apophysis.
Mucor spp.:
A. Sporangia.
B. Sporangiophores.
A. Globose.
B. No rhizoids; branched or unbranched; no apophysis.
Lichtheimia (Absidia) spp.:
A. Sporangia.
B. Sporangiophores.
A. Globose or mushroom-shaped.
B. Internodal, branched; conical apophysis.
Cunninghamella spp.
A. Sporangia.
B. Sporangiophores.
A. Sporangioles, each containing a single spore, are connected by the hairlike denticles to the columella.
B. Branched; terminate in a globose columella.
Chromagar: Uses.
Selection for yeasts.
Differentiation among yeasts based on colony color.
Germ-tube test: Purpose.
Presumptive identification of Candida albicans.
Germ-tube test: Procedure.
The yeast isolate is incubated in serum at 37 degrees for no more than 3 hours.
Production of true hyphae is a positive result.
Germ-tube test: True hypha vs. pseudohypha.
True hypha: No constriction between the hypha and the yeast cell.
Germ-tube test: Positive organisms (2).
Candida albicans.
Candida dublinensis.
Which yeast rapidly ferments trehalose?
Candida glabrata.
Candida albicans: Colony.
Produces filamentous radial extensions (“feet”).
Candida albicans: Microscopy.
Yeasts give rise to pseudohyphae that have blastoconidia at their septa and terminate in a chlamydospore.
Candida albicans: Appearance on Chromagar.
Green colonies.
Candida glabrata:
A. Growth.
B. Microscopy.
A. Slower than that of other candidae.
B. Yeasts only.
Candida glabrata: Antiobiotic therapy.
Sensitive to amphotericin B and to echinocandins.
Less sensitive to azoles.
Cryptococcus spp.:
A. Content of cell wall.
B. Microscopy.
C. Immunological test.
A. Melanin.
B. Yeasts only: 3-15 μm, narrow-based budding.
C. Capsular-polysaccharide antigen in CSF.
Phenol oxidase test:
A. Substrate.
B. Positive result.
C. Positive organism.
A. Caffeic acid (birdseed agar).
B. Brown colonies.
C. Cryptococcus neoformans.
Urease-positive yeasts: Genera (3).
Cryptococcus.
Rhodotorula.
Trichosporon.
Cryptococcus gattii:
A. Geography (2).
B. Botanical association.
A. Tropics, Pacific Northwest.
B. Eucalyptus tree.
Pneumocystis jiroveci: Colony.
Cannot be cultured in vitro.
Pneumocystis jiroveci: Chemical abnormality accompanying pneumonia.
High serum LDH.
Gram-positive vs. Gram-negative bacteria: Structure of cell.
Gram-positive: Thick peptidoglycan wall, no outer membrane.
Gram-negative: Thin peptidoglycan wall, outer membrane.
Active pigments in bacterial stains:
A. Gram stain (2).
B. Acid-fast stain.
A. Crystal violet, saffranin.
B. Carbolfuchsin.
Stains for acid-fast bacilli: Kinyoun method vs. Ziehl-Neelsen method.
Kinyoun method: No heat, more phenol.
Fite’s stain for acid-fast bacilli:
A. Method.
B. Purpose.
A. Use of a weaker decolorizer.
B. Identification of Nocardia spp. and certain protozoa.
Stains for acid-fast bacilli: Fluorescent stain.
Auramine-rhodamine.
Buffered charcoal−yeast extract agar:
A. Other contents (2).
B. Purpose of charcoal.
C. Purpose of agar.
A. Iron, cysteine.
B. To bind inhibitors of growth.
C. Recovery of Legionella spp.
Mueller-Hinton agar: Purpose.
Testing for sensitivity to antimicrobials.
Thioglycolate broth: Purpose.
Cultivation of bacteria with little or no tolerance for oxygen.
MacConkey agar: Inhibitors (2).
Crystal violet.
Bile salts.
Eosin−methylene blue agar: Inhibitors.
Aniline dyes.
Campy-BAP: Inhibitors.
Antimicrobials to which campylobacters are naturally resistant.
Hektoen enteric agar: Inhibitors (3).
Bile salts.
Acid fuchsin.
Bromthymol blue.
Hektoen enteric agar: Purpose.
Recovery of Salmonella and Shigella spp.
Salmonella-Shigella agar: Inhibitors (3).
Bile salts.
Sodium citrate.
Brilliant green.
Selenite broth:
A. Inhibitor.
B. Purpose.
A. Sodium selenite.
B. Recovery and cultivation of Salmonella spp.
TCBS agar:
A. Contents.
B. Purpose.
A. Thiosulfate, citrate, bile salt, sucrose.
B. Recovery of vibriones.
Cefsulodin-irgasan-novobiocin agar: Purpose.
Recovery of yersiniae.
CNA agar:
A. Inhibitors.
B. Purpose.
A. Colistin, nalidixic acid.
B. Recovery of steptococci and cultivation of them according to hemolysis.
Lim broth: Purpose.
Recovery of group-B streptococci.
Regan-Lowe medium: Purpose.
Recovery of Bordetella spp.
Thayer-Martin agar:
A. Inhibitors.
B. Purpose.
A. Vancomycin, colistin, nystatin, SMX.
B. Recovery of neisseriae from nonsterile sites.
MacConkey agar: Use as a differential medium.
Fermenters of lactose: Pink or red colonies.
Others: Translucent colonies.
EMB agar: Use as a differential medium.
Fermenters of lactose: Green or purple-black colonies.
Others: Translucent colonies.
Hektoen enteric agar: Use as a differential medium.
Fermenters of lactose and/or sucrose: Yellow or orange colonies.
Producers of H₂S: Black colonies.
Others: Translucent colonies.
Salmonella-Shigella agar: Use as a differential medium.
Fermenters of lactose: Pink or red colonies.
Producers of H₂S: Black colonies.
Others: Translucent colonies.
TCBS agar: Use as a differential medium.
Fermenters of sucrose: Yellow colonies.
Others: Translucent colonies.
CIN agar: Use as a differential medium.
Fermenters of mannitol: Colorless colonies with a red center (“bullseyes”).
Others: Translucent colonies.
Bacteria that grow best at 25-30 degrees (3).
Yersinia enterocolitica.
Pseudomonas fluorescens.
Pseudomonas putida.
Campylobacters that cause diarrhea: Optimal temperature for growth.
42 degrees.
Listeria: Effect of temperature (3).
37 degrees: Optimal for growth.
25 degrees: Motility.
4 degrees: Can still multiply.
Catalase test: Possible confounder.
Blood agar: Red blood cells have inherent catalase activity.
Catalase: Genera of positive bacteria (4).
Staphylococcus.
Listeria.
Bacillus.
Campylobacter.
Tube-based coagulase test: Timing.
Must be read at 4 hours and at 24 hours.
Slide-based coagulase test:
A. Advantage.
B. Disadvantage.
C. Reason for the disadvantage.
A. Faster than the tube-based test.
B. Many false positives and false negatives.
C. Detects clumping factor but not free coagulase.
Novobiocin: Purpose.
To distinguish Staphylococcus saprophyticus (resistant) from other coagulase-negative staphylococci.
Optochin:
A. How to recognize it.
B. Purpose.
A. It is the P disk.
B. To distinguish Streptococcus pneumoniae (sensitive) from viridans streptococci.
CAMP test: Biochemical basis.
CAMP factor potentiates staphylococcal β-hemolysin.
CAMP test: Procedure.
The isolate is streaked at right angles to the streak of Staphylococcus aureus.
CAMP test: Positive results (2).
Group-B streptococci: Arrowhead at the junction of the streaks.
Listeria: Rectangle.
PYR test: Positive result.
Red color due to hydrolysis of PYR.
PYR test: Positive organisms (3).
Streptococcus pyogenes.
Enterococci.
Staphylococcus lugdunensis.
Bile-esculin test:
A. Procedure.
B. Positive result.
A. Incubation of an inoculated bile-esculin slant for 24 hours.
B. Black color due to hydrolysis of esculin.
Bile-esculin test: Positive organisms (2).
Enterococci.
Streptococcus bovis.
Oxidase test:
A. Reagent.
B. Positive result.
A. p-Phenylenediamine.
B. Blue color.
Oxidase test: Positive bacteria (6).
Capnocytophaga.
Legionella.
Moraxella.
Neisseria.
Pasteurella, Pseudomonas.
Curved Gram-negative rods.
Indole test: Mechanism of a positive result.
Pink color due to deamination of tryptophan to produce indole.
Indole test: Positive organisms (2).
Escherichia coli.
Pasteurella spp.
Others.
Rapid-urease test:
A. Positive result.
B. Positive organisms (2).
A. Change from yellow to pink.
B. Helicobacter pylori, Proteus spp.
β-Glucuronidase test:
A. Positive result.
B. Positive bacteria.
A. Fluorescence in ultraviolet light.
B. E. coli; streptococci of the anginosus group.
Hippurate test:
A. Reagent.
B. Positive result.
A. Ninhydrin.
B. Purple-blue color.
Hippurate test: Positive bacteria (5).
Group-B streptococci.
Listeria monocytogenes.
Legionella pneumophila.
Garderella vaginalis.
Campylobacter jejuni.
Lysozyme test:
A. Positive result.
B. Positive bacteria.
A. Growth in lysozyme broth.
B. Nocardia spp.
Methicillin-resistant Staphylococcus aureus:
A. Gene.
B. Protein.
A. mecA.
B. PBP2A.
MRSA: Identification (3).
Disk-diffusion method using cefoxitin disk.
DNA hybridization for mecA.
Latex agglutination for PBP2A.
MRSA: Detection in a nasal swab (2).
Culture.
PCR.
Carriage of Streptococcus pneumoniae:
A. Population.
B. Site.
A. Children.
B. Oropharynx.
Carriage of Clostridium difficile:
A. Population.
B. Site.
A. Infants.
B. Colon.
Carriage of Neisseria meningitidis: Site.
Oropharynx.
Staphylococcus lugdunensis:
A. Normal habitat.
B. Diseases.
A. Skin.
B. Similar to those causes by Staphylococcus aureus.
Staphylococcus lugdunensis:
A. Coagulase.
B. Other biochemical tests (2).
A. Negative but may be falsely positive with the slide-based method.
B. Positive: PYR, ornithine decarboxylase.
Streptococcus pyogenes:
A. Biochemical tests (2).
B. Lancefield group.
C. Hemolysis on blood agar.
A. Hydrolyzes PYR, sensitive to bacitracin.
B. A.
C. β.
Streptococcus pyogenes: Immunological complications of infection (3).
Acute rheumatic fever.
Post-streptococcal glomerulonephritis.
Pediatric autoimmune neuropsychiatric disorders.
Jones’ criteria for acute rheumatic fever: Major.
Subcutaneous nodules.
Pharyngitis.
Erythema marginatum.
Carditis.
Chorea.
Jones’ criteria for acute rheumatic fever: Minor.
Fever.
Arthralgia.
Prolonged PR interval.
Elevated ESR and/or CRP.
Jones’ criteria for acute rheumatic fever: How many must be met?
Two major criteria or one major criterion and two minor criteria.
Use of antibiotics to prevent complications of infection by Streptococcus pyogenes (2).
May prevent rheumatic heart disease.
Does not prevent glomerulonephritis.
Group-B streptococci:
A. Species.
B. Hemolysis on blood agar.
A. Streptococcus agalactiae.
B. β.
Group-B streptococci: Biochemical tests (2).
CAMP positive.
Hydrolyzes hippurate.
Screening of pregnant females for Group-B streptococci:
A. When?
B. Sample for collection.
A. At 35-37 weeks of gestation.
B. The same swab is used to collect from the vagina and the rectum.
Laboratory testing of pregnant females for Group-B streptococci:
A. Required initial step.
B. Methods (2).
A. Incubation in enrichment broth.
B. Culture, PCR.
Streptococcus pneumoniae:
A. Hemolysis of blood agar.
B. Biochemical test.
A. α.
B. Sensitive to optochin.
Viridans streptococci:
A. Hemolysis on blood agar.
B. Biochemical test.
C. Microscopy.
A. α.
B. Resists optochin.
C. Long chains.
Viridans streptococcus: Groups (4).
Streptococcus mitis.
Streptococcus mutans.
Streptococcus salivarius.
Streptococcus anginosus.
Streptococcus mitis group: Diseases (2).
Endocarditis
− Native valves.
− Prosthetic valves (late).
Streptococcus mutans group: Diseases (2).
Dental caries.
Endocarditis.
Streptococcus salivarius group: Diseases (2).
Bacteremia.
Endocarditis.
Streptococcus anginosus:
A. Disease.
B. Representative species.
A. Abscesses.
B. Streptococcus intermedius.
Enterococci:
A. Type of hemolysis.
B. Lancefield group.
A. None.
B. D.
Enterococci: Biochemical properties (3).
Hydrolysis of PYR.
Hydrolysis of esculin in bile.
Growth in 6.5% NaCl.
Enterococci that are naturally resistance to vancomycin:
A. Species (2).
B. Mechanism.
A. E. casseliflavus, E. gallinarum.
B. vanC.
Enterococcus faecium: Mechanisms of resistance to vancomycin (3).
vanA.
vanB.
vanD.
Enterococcus faecium: Mechanism of resistance to penicillin.
Altered penicillin-binding proteins.
Enterococcus faecium also resists which other classes of antibiotics (5)?
Cephalosporins.
Carbapenems.
Aminopenicillins.
Methicillin et al.
Ticarcillin et al.
Streptococcus bovis group:
A. Type of hemolysis.
B. Lancefield group.
A. None.
B. D.
Streptococcus bovis group: Biochemical properties (3).
Does not hydrolyze PYR.
Does not grow in 6.5% NaCl.
Hydrolyzes esculin in bile.
Association of Streptococcus bovis group with malignancy:
A. What malignancy?
B. What species?
A. Colon cancer.
B. S. gallolyticus subsp. gallolyticus.
Veillonella spp.: Significance (2).
Normal mucosal flora.
Participates in polymicrobial infections.
Neisseria spp.:
A. Requirement for incubation.
B. Biochemical property.
A. CO₂-rich environment.
B. Oxidase positive.
Neisseria spp.: Culture media (3).
Thayer-Martin agar.
Martin-Lewis agar.
New York City agar.
Neisseria gonorrhoeae: Percentage of infected individuals who are asymptomatic (2).
Males: 10%.
Females: 50%.
Neisseria gonorrhoeae infection in males: Complication of ascending infection.
Acute epididymis.
Neisseria gonorrhoeae infection in females:
A. Clinical manifestations.
B. Complication of ascending infection.
A. Pruritus, discharge, urethritis.
B. Pelvic inflammatory disease.
Neisseria gonorrhoeae: Complications of disseminated infection (2).
Purulent arthritis.
Fitz-Hugh-Curtis syndrome.
Serotypes of Neisseria meningitidis:
A. Basis.
B. Most important in the U.S.
C. Relevance to vaccination.
A. Capsular polysaccharide.
B. B, C, Y.
C. Serogroup B is not represented in the tetravalent vaccine.
Moraxella catarrhalis:
A. Growth on blood agar.
B. Biochemical test.
A. Grows well and produces “hockey puck” colonies.
B. Oxidase positive.
Moraxella catarrhalis: Diseases.
Pneumonia in smokers (COPD exacerbation).
Otitis media in children.
Kingella kingae:
A. Hemolysis.
B. Microscopy.
C. Diseases (4).
A. β.
B. Coccobacilli in pairs or short chains.
C. Endocarditis in adults; septic arthritis, osteomyelitis, and occult bacteremia in children.
Clostridium spp.: Basic characteristics (2).
Anaerobic spore-formers.
Clostridium perfringens:
A. Microscopy.
B. Growth on blood agar.
C. Preliminary identification.
A. Gram-positive “boxcar-shaped” rods in short chains.
B. Double zone of β hemolysis.
C. Demonstration of lecithinase activity.
Clostridium septicum:
A. Colony morphology.
B. Disease.
A. Forms swarms rather than colonies.
B. Bacteremia secondary to GI disease, esp. colon cancer.
Clostridium botulinum: Diagnosis of disease.
Identification of toxin in serum, stool, vomitus, or food.
Clostridium tetani: Diagnosis of disease.
Based on clinical findings.
Clostridium difficile:
A. Preferred culture medium.
B. Condition of culture.
A. Cycloserine-cefoxitin-fructose-egg yolk agar.
B. Strictly anaerobic.
Clostridium difficile: Colony morphology.
Yellow, ground-glass appearance; fluorescence in ultraviolet light.
Clostridium difficile:
A. Odor of culture.
B. Microscopy.
A. “Horse manure”.
B. Thin, uniform bacilli with subterminal or free spores.
Clostridium difficile: Traditional method of detection of production of toxin.
Cytotoxicity culture.
Clostridium difficile: Current method of detection of production of toxin.
Molecular tests for the genes for toxins A and B.
Clostridium difficile: ELISA tests.
ELISA for glutamate dehydrogenase in stool (more sensitive).
ELISA for toxins A and B in stool.
Clostridium difficile: Virulent type.
B1/NAP1/027.
Clostridium difficile: Roles of PCR.
Detection of tcdA and tcdB.
Detection of tcdC in B1/NAP1/027.
Actinomyces spp.:
A. Important difference from Clostridium spp.
B. Important differences from Nocardia spp.
A. Actinomyces spp. form no spores.
B. Actinomyces spp. are anaerobic and are not acid fast.
Actinomyces israelii: Colony morphology.
“Molar tooth”.
Actinomyces israelii: Diseases (4).
Actinomycoses.
Cervicofacial: Trauma, surgery.
Thoracic: Aspiration.
Intraabdominal: Appendicitis, diverticulitis, surgery.
Female genital tract: IUD.
Propionibacterium acnes: Disease.
Infection of foreign bodies such as prosthetic joints.
Bacillus spp. vs. Clostridium spp.
Bacteria of both genera form spores.
Bacillus spp. are aerobic.
Bacillus spp.: Additional properties (2).
Motile (except B. anthracis).
Catalase positive.
Bacillus spp.: Medium for testing for motility.
Semisolid medium (liquid media are unsafe).
Bacillus anthracis: Properties of colonies (3).
“Medusa head”.
Tenacious.
Non-hemolytic.
Inhalational anthrax: Radiological finding.
Widened mediastinum due to hemorrhagic mediastinitis.
Bacillus cereus:
A. Location of spores.
B. Colony morphology (2).
C. Motility.
A. Subterminal.
B. β-Hemolytic, not tenacious.
C. Motile.
Bacillus cereus:
A. Distinctive biochemical property.
B. Oxygen tolerance.
A. Produces lecithinase.
B. Facultatively anaerobic.
Bacillus cereus: Diseases (2).
Food poisoning.
Serious infections in those with a weak immune system or a shunt.
Listeria monocytogenes: Similarities to group-B streptococci (5).
Morphology on Gram stain.
CAMP positive.
Hydrolyzes hippurate.
Vague β hemolysis.
Infects neonates.
Listeria monocytogenes: Important biochemical difference from group-B streptococci.
Listeria monocytogenes is catalase positive.
Listeria monocytogenes: Motility in wet mounts.
Tumbling.
Best demonstrated at 20-25 degrees.
Listeria monocytogenes: Motility in a motility tube.
Makes umbrella shape.
Diseases caused by Listeria monocytogenes:
A. Pregnant women (2).
B. Fetuses.
A. Flulike illness, bacteremia.
B. Chorioamnionitis.
Diseases caused by Listeria monocytogenes:
A. Neonates (3).
B. Immunocompromised (2).
A. Sepsis, meningitis, abscesses.
B. Sepsis, meningitis.
Erysipelothrix rhusiopathiae: Microscopy.
Coccobacilli occurring individually or in short chains.
Non-branching filaments.
Erysipelothrix rhusiopathiae: Motility.
Nonmotile.
Erysipelothrix rhusiopathiae: Biochemical properties.
Catalase negative.
Produces H₂S.
Erysipelothrix rhusiopathiae: Antibiosis.
Inherently resists vancomycin.
Erysipelothrix rhusiopathiae: How the infection is acquired.
Erysipeloid is acquired through exposure of a wound to animals that carry the bacterium.
Nocardia spp.:
A. Microscopy.
B. Staining.
A. Branching, beaded filaments.
B. Weakly acid fast (with Fite’s stain).
Nocardia: Properties of colonies (3).
Chalky white, turning orange-pink with maturity.
“Musty basement” odor.
Nocardia spp.: Diseases (3).
Actinomycotic mycetoma.
Invasive pulmonary infection.
Disseminated infection that can involve the CNS.
Rhodococcus equi: Microscopy.
Gram-positive cocci, coccobacilli, or coryneform rods.
Rhodococcus equi: Staining (2).
Positive: AFB stain (modified).
Often found within histiocytes.
Rhodococcus equi:
A. Colony morphology.
B. Diseases.
A. Salmon-colored, slimy.
B. Opportunistic infections, esp. pulmonary.
Corynebacterium diphtheriae: Growth on agar.
Grows well on blood agar, but Tinsale agar is better for isolation.
Cornyebacterium diphtheriae: Appearance on selective agar.
Brown-black colonies on modified Tinsdale agar due to reduction of tellurite to Te.
Tropheryma whippeli:
A. Habitat.
B. Risk factor for infection.
A. Ubiquitous.
B. Selective immune deficiency.
Tropheryma whippeli:
A. Epidemiology of infection.
B. Staining.
A. Affects mainly older men.
B. Positive for PAS, negative for AFB.
Bacteroides fragilis:
A. Antibiosis.
B. Colony morphology.
A. Produces β-lactamases.
B. Small and shiny on blood agar.
Bacteroides fragilis: Gram-stain morphology.
Variable.
“Safety pin” staining of organisms grown in liquid media.
Porphyomonas: Color of colonies.
Brown-black in natural light.
Brick-red fluorescence in ultraviolet light.
Porphyromonas: Oxygen tolerance.
Anaerobic.
Fusobacterium: Infections (2).
Tonsillitis with thrombophlebitis of the internal jugular vein.
Placental infections.
Enterobacteriaceae: Risk factors for nasopharyngeal carriage (3).
Hospitalization.
Uncontrolled diabetes mellitus.
Chronic alcoholism.
Lipopolysaccharide: Major components (2).
Lipid A.
O antigen.
Escherichieae: Genera.
Escherichia.
Shigella.
Klebsielleae: Genera.
Klebsiella.
Enterobacter.
Serratia.
Hafnia.
Pantoea.
Proteeae: Genera.
Proteus.
Morganella.
Providencia.
Enterobacteriaceae: Tribes that contain only one genus (4).
Salmonelleae.
Citrobactereae.
Edwardsielleae.
Yersinieae.
Enterobacteriaceae: Strong fermenters of lactose.
Escherichia coli.
Enterobacter spp.
Klebsiella spp.
Enterobacteriaceae: Producers of H₂S.
Salmonella.
Edwardsiella.
Citrobacter.
Proteus.
Enterobacteriaceae: Strong producers of urease.
Proteus.
Morganella.
Providencia rettgeri.
Enterobacteriaceae: Nonmotile members at 37 degrees.
Shigella.
Klebsiella.
Yersinia (motile at 22 degrees).
Enterobacteriaceae: Producers of a positive Voges-Proskauer reaction.
The Klebsielleae.
Enterobacteriaceae: Producers of phenylalanine deaminase.
The Proteeae.
KIA/TSI slants: Contents (4).
Sugars.
Peptides.
Iron.
Phenol red.
KIA/TSI slants: Sugars.
KIA: Lactose and glucose at 10 : 1.
TSI: Lactose and sucrose at 10 : 1.
KIA/TSI slants: pH at which phenol red changes color.
6.8 (to yellow).
KIA/TSI slants: When interpreted.
At 24 hours.
KIA/TSI slants: Alkaline/alkaline.
Nonfermenters of glucose (i.e. non-Enterobacteriaceae).
Pseudomonas, others.
KIA/TSI slants: Alkaline/acid with black precipitate.
Fermenters of glucose but not of lactose that produce H₂S.
Salmonella, Proteus, Edwardsiella, Citrobacter.
KIA/TSI slants: Alkaline/acid with no precipitate.
Fermenters of glucose but not of lactose that produce no H₂S.
Shigella, Serratia, Morganella, Providencia, Yersinia.
KIA/TSI slants: Acid/acid.
Strong fermenters of lactose.
Escherichia coli, Enterobacter, Klebsiella.
KIA/TSI slants: Purpose of the peptides.
To detect nonfermenters of lactose. At first, fermentation of glucose turns all of the agar yellow. However, when the glucose is used up, oxidative metabolism of the peptides (which are in the slant, where the oxygen is) begins, which turns the slant back to red.
Enterobacteriaceae: Indole positive (5).
Escherichia coli.
Edwardsiella tarda.
Klebsiella oxytoca.
Citrobacter koseri.
The Proteeae.
Escherichia coli O157:H7: Identification on a culture plate.
Does not ferment sorbitol on sorbitol-MacConkey agar.
Traveler’s diarrhea: Mechanism.
Enterotoxigenic E. coli produces “choleralike” toxins.
Enteroinvasive Escherichia coli: Properties (4).
Similar to Shigella, EIEC
− Causes dysentery.
− Produces T3SS, similar to shigatoxin.
− Does not ferment lactose.
− Is nonmotile.
Enteropathogenic E. coli: Properties.
Causes a disease that resembles shigellosis but does not produce a shigatoxin-like substance.
Enteroaggregative E. coli: Diseases (2).
Infantile diarrhea in poor countries.
Chronic refractory diarrhea in HIV patients.
Salmonella: Causes of bacteremia.
S. typhi.
S. paratyphi.
S. choleraesuis.
Salmonella: Causes of typhoid fever.
S. typhi.
S. paratyphi.
Typhoid fever:
A. Affected parenteral organs.
B. Role of gallbladder.
A. Reticuloendothelial cells of liver, spleen, gallbladder.
B. Serves as source of continual reinfection of bowel.
Shigella: Most important pathogens.
United States: Shigella sonnei.
Poor countries: Shigella flexneri.
Shigella: Species that can cause the hemolytic-uremic syndrome.
Shigella dysenteriae.
Shigella: Species that can cause reactive arthritis.
Shigella flexneri.
Klebsiella: Important pathogens (3).
Klebsiella pneumoniae: Pneumonia.
Klebsiella oxytoca: Neonatal sepsis.
Klebsiella rhinoscleromatis: Rhinoscleroma.
Yersinia: Medium and temperature of isolation.
CIN agar at room temperature.
Yersinia: Natural history.
Zoonotic organism that only accidentally infects humans.
Yersinia: Important pathogens (3).
Yersinia enterocolitica: Transfusion-related sepsis.
Yersinia pestis: Plague.
Yersinia pseudotuberculosis: Necrotizing granulomas.
Enterobacteriaceae vs. other enteric Gram-negative bacteria.
The latter may be oxidase positive.
Vibrio cholerae: Identification (2).
Culture: Yellow colonies on TCBS agar.
String test.
Vibrio cholerae: Classification.
O1: Cause of most cases of cholera.
Non-O1.
Vibrio parahaemolyticus:
A. Identification.
B. Diseases (2).
A. Culture: Green colonies on TCBS agar.
B. Foodborne illness, esp. in Japan; wound infections associated with seawater.
Vibrio vulnificus:
A. Habitat.
B. Diseases.
A. Seawater containing little salt, as in the Gulf of Mexico.
B. Foodborne illness with vomiting and diarrhea; wound infections associated with seawater.
Aeromonas and Plesiomonas:
A. Habitats.
B. Clinical significance.
A. Fresh water (including hospital sources); brackish water (such as aquaria).
B. Isolation in the stool may not indicate infection.
“Non-enteric” Gram-negative bacilli: Definition.
Those that grow on MacConkey agar but do not ferment glucose.
Pseudomonas aeruginosa:
A. Motility.
B. Hemolysis.
C. Temperature of growth.
A. Uses a polar flagellum.
B. β (often).
C. Grows well at 42 degrees.
“Fastidious” Gram-negative bacteria: Definition.
Those that form pinpoint colonies on enriched media but none at all on MacConkey agar.
Francisella tularensis:
A. Culture.
B. Biochemistry.
A. Requires cysteine and cystine.
B. Oxidase negative, urease negative; produces β-lactamases.
Brucella: Culture (2).
Chocolate agar in a CO₂-rich environment.
Routine media with a long incubation.
Brucella: Important pathogens.
Brucella abortus: Cattle.
Brucella melitensis: Sheep, goats.
Brucella suis: Swine.
Brucella: Acquisition of infection.
Ingestion of unpasteurized dairy products.
Working with or slaughtering farm animals.
Brucellosis: Clinical triad.
Lymphadenopathy.
Hepatosplenomegaly.
Malodorous perspiration.
Brucella: Affected organs (3).
Heart: Endocarditis, a main cause of death.
Liver: Granulomatous hepatitis.
Fetus: Spontaneous abortion.
Bordetella: Required nutrients (3).
Nicotinic acid, cysteine, methionine.
Does not require X factor or V factor.
Bordetella: Other conditions for culture (4).
Bordet-Gengou or Regan-Lowe agar.
Supplemental CO₂.
35 degrees.
Incubation for 2-4 days.
Pasteurella: Biochemical properties (3).
Catalase positive.
Indole positive.
Oxidase positive.
Legionella: Gram stain.
Invisible.
Legionella: Detection other than culture (2).
Direct immunofluorescence.
Latex agglutination.
Legionella: Prevalent serogroup.
Serogroup 1.
Campylobacter jejuni:
A. Conditions of culture.
B. Biochemical properties (3).
A. Campy-BAP at 42 degrees.
B. Oxidase positive, catalase positive, hippurate hydrolysis.
Capnocytophaga canimorsus: Conditions of culture (2).
Supplemental CO₂.
May not be isolable from blood using routine media.
Capnocytophaga canimorsus: Biochemical properties (2).
Catalase positive.
Oxidase positive.
Streptobacillus moniliformis:
A. Appearance in culture.
B. Appearance on Gram stain.
A. “Puffball” colonies in thioglycolate broth.
B. Gram-variable tangled filaments with swellings.
Haemophilus species: Requirements for X factor and V factor.
All species require V factor except H. ducreyi, which requires X factor only.
H. influenzae, H. haemolyticus, and H. aegypti require both factors.
Haemophilus species: Hemolytic ones.
H. haemolyticus, H. parahaemolyticus, and H. aegypti.
“HACEK” bacteria:
Aggregatibacter aphrophilus.
Aggregatibacter actinomycetemcomitans.
Cardiobacterium hominis.
Eikenella corrodens.
Kingella kingae.
Helicobacter pylori: Properties of serologic test (2).
IgG anti-Helicobacter pylori
− Becomes detectable 4 weeks after infection.
− Remains elevated for weeks after successful treatment.
Helicobacter pylori: Uses of the urea breath test (2).
To diagnose infection.
To confirm eradication.
Helicobacter pylori: Uses of the test for stool antigen (2).
Same as for the urea breath test.
Helicobacter pylori: When to test for eradication.
4-12 weeks after completion of treatment.
Coxiella burnetii:
A. Classification.
B. Growth in vivo.
C. Microscopy.
A. γ-Proteobacteria.
B. Obligate intracellular parasite.
C. Pleomorphic Gram-negative coccobacilli.
Coxiella burnetii: Acquisition of infection.
Through exposure to the urine, feces, or birthing fluids of farm animals.
Acute Q fever:
A. Presentation.
B. Mortality.
C. Frequent cause of death.
A. Nonspecific.
B. 1-2%.
C. Myocarditis.
Acute Q fever: Sites of characteristic granulomas.
Liver, bone marrow.
Chronic Q fever:
A. Sites of infection.
B. Mortality.
A. Heart (endocarditis), blood vessels (endovasculitis), bones, joints.
B. High.
Q fever: Clinical setting of recrudescence.
Pregnancy.
Q fever: Diagnosis (2).
Serology.
PCR on infected tissue.
Treponema pallidum subsp. pallidum:
A. Oxygen tolerance.
B. Motility.
A. Microaerophilic.
B. Flexing.
Syphilis: Average period of incubation.
3 weeks.
Primary stage of venereal syphilis:
A. Symptom.
B. Duration.
C. Possible immunological complication.
A. Chancre.
B. 1-8 weeks.
C. Jarisch-Herxheimer reaction.
Secondary stage of venereal syphilis: Organ-specific manifestations (5).
Condylomata lata.
Hepatitis.
Arthritis.
Rash.
Meningitis, aseptic.
Secondary stage of venereal syphilis: Possible immunological complications.
Jarisch-Herxheimer reaction.
Immune-complex-mediated glomerulonephritis.
Tertiary stage of venereal syphilis: Affected sites.
Nervous system.
Cardiovascular system.
Bones and skin: Gummata.
Venereal syphilis: Common histologic findings.
In all stages:
− Obliterative endarteritis.
− Plasmacytic infiltrate.
Treponema pallidum subsp. pallidum: Direct visualization (4).
Darkfield microscopy.
Direct immunofluorescence.
Immunohistochemistry.
Silver stains.
Syphilis: Types of test (5).
Treponemal: Syphilis IgG, FTA-ABS, TP-PA.
Nontreponemal: VDRL, RPR.
Syphilis: Reliability of tests over time.
Nontreponemal antibodies tend to wane.
Treponemal antibodies persist indefinitely.
Syphilis: Use of tests.
Diagnosis of infection: Syphilis IgG.
Confirmation of active disease: Nontreponemal test.
Diseases caused by
A. Treponema pallidum subsp. pertenue.
B. Treponema pallidum subsp. endemicum.
C. Treponema carateum.
A. Yaws.
B. Endemic (nonvenereal) syphilis.
C. Pinta.
Borreliae: Morphology and motility.
Loosely coiled; corkscrew-like.
Lyme disease: Bacterial agents by region (3).
North America: Borrelia burgdorferi.
Europe: B. afzelii, B. garinii.
Lyme disease: Distribution in the United States.
Northeast.
Upper Midwest.
Northern California and Oregon.
Lyme disease in North America:
A. Reservoir.
B. Vectors.
A. White-footed mouse.
B. Ixodes scapularis, Ixodes pacificus.
Lyme disease: Stages.
Early: Erythema migrans.
Second: Palsy of the facial nerve; atrioventricular block.
Third: Arthropathy.
Lyme disease: Diagnosis.
Serology.
Borrelia burgdorferi: Common co-infecting organisms.
Babesia spp.
Anaplasma phagocytophilum.
Leptospira interrogans: Morphology.
Tightly coiled, with hooked ends.
Leptospirosis:
A. Clinical triad.
B. Routes of infection.
C. Usual host.
A. Meningitis, nephritis, hepatitis.
B. Conjunctivae, skin.
C. The rat.
Leptospirosis:
A. Area of highest incidence in the United States.
B. Diagnosis.
A. Hawaii.
B. Serology.
Intestinal spirochetosis: Organism.
Brachyspira aalborgi.
Chlamydia trachomatis: Neonatal infections (3).
Inclusion-body conjunctivitis.
Pneumonia.
Otitis.
Chlamydia trachomatis: Diagnosis (2).
Gold standard: Demonstration of McCoy cells in culture.
Current method: Nucleic-acid amplification.
Cause of
A. Psittacosis.
B. Atypical pneumonia.
A. Chlamydophila psittaci.
B. Chlamydophila pneumoniae.
Cause of
A. Lymphogranuloma venereum.
B. Granuloma inguinale.
A. Chlamydia trachomatis.
B. Calymmatobacterium granulomatis.
Rocky Mountain spotted fever:
A. Cause.
B. Area of highest incidence in the United States.
C. Vector.
A. Rickettsia rickettsiae.
B. The Southeast.
C. Dermacentor variabilis, the American dog tick.
Rocky Mountain spotted fever: Triad of early infection.
Fever.
Severe headache.
Centripetal rash beginning at wrists and ankles.
Rocky Mountain spotted fever: Later manifestations (3).
Renal failure.
Disseminated intravascular coagulation.
CNS disease.
Rocky Mountain spotted fever: Risk factor for fulminant disease.
Glucose-6-phosphate dehydrogenase deficiency.
Cause of
A. Human monocytoid ehrlichiosis.
B. Human granulocytic anaplasmosis.
A. Ehrlichia chafeensis.
B. Anaplasma phagocytophilum.
Ehrlichia/Anaplasma: Microscopy.
Modulae within intracellular vacuoles.
Cause and vector
A. Trench fever.
B. Oroya fever / verruga peruana.
A. Bartonella quintana; human body louse.
B. Bartonella bacilliformis; Lutzomyia spp.
Bartonella henselae: Diseases.
Cat-scratch disease.
Bacillary angiomatosis.
Bacillary angiomatosis: Affected organs (3).
Lymph nodes.
Skin.
Viscera.
Mycoplasma pneumoniae: Significance in transfusion medicine.
Can induce cold agglutinins against the I antigen.
Mycoplasma hominis:
A. Disease.
B. Colony morphology.
A. Non-gonococcal urethritis.
B. “Fried eggs”.
Mycobacteria: Stains (2).
Stains for acid-fast bacilli.
Auramine-rhodamine fluorochromes.
Value of mycobacterial culture (3).
Gold standard.
More sensitive than nucleic-acid amplification.
Required for testing for sensitivity to antibiotics.
Mycobacteria: Preferred growth medium.
Broth, typically Middlebrook broth.
Mycobacteria: Molecular methods of identification (2).
Nucleic-acid amplification.
Multiplex PCR.
Mycobacteria: Traditional methods of identification.
Rate of growth: Rapid or slow.
Pigmentation: Photochromogen, scotochromogen, non-chromogenic.
Biochemical reactions.
Mycobacteria that infect the lung (5).
M. tuberculosis.
M. avium complex.
M. kansasii.
M. xenopi.
M. abscessus.
Mycobacteria that infect lymph nodes (4).
M. tuberculosis.
M. avium complex.
M. scrofulaceum.
M. haemophilum.
Mycobacteria that infect skin and soft tissues (6).
M. abscessus.
M. fortuitum.
M. chelonae.
M. marinum.
M. ulcerans.
M. haemophilum.
Mycobacteria that infect the gastrointestinal tract (2).
M. tuberculosis.
M. avium complex.
Mycobacterium tuberculosis:
A. Rate of growth.
B. Colony morphology.
C. Preferred temperature.
A. Slow.
B. Flat, dry, white, wrinkled.
C. 37 degrees.
Mycobacterium tuberculosis:
A. Presence of cord factor.
B. Pigmentation.
A. Forms cords in broth.
B. Non-chromogenic.
Mycobacterium tuberculosis complex: Members.
M. tuberculosis.
M. canettii.
M. africanum.
M. microti.
M. bovis.
Mycobacterium tuberculosis: Possible outcomes of primary infection (3).
Spontaneous eradication.
Resolution (latency), with tubercles.
Active infection.
Tuberculosis: Tests of pleural fluid (4).
Smear.
Culture.
Nucleic-acid amplification.
Adenosine deaminase.
Tuberculosis: How to collect a sample in one who cannot produce adequate sputum.
Obtain a gastric aspirate.
Tuberculin skin test: Causes of a positive result (4).
Active tuberculosis.
Latent tuberculosis.
Infection with non-TB mycobacteria.
BCG vaccination.
Tuberculin skin test: Frequent cause of false negative.
Anergy in the immunocompromised.
Newer immunological test for tuberculosis: How it works.
T lymphocytes release much IFN-γ when exposed to ESAT-6 and CFP-10 in vitro.
Mycobacterium avium complex: Affected populations.
Immunocompromised.
Immunocompetent.
Mycobacterium avium complex: Classical cases of infection in the immunocompetent (3).
Cavitary lung disease of the upper lobe, mimicking tuberculosis, in a heavy smoker.
Weak cough in an elderly woman (Lady Windermere syndrome).
Hypersensitivity reaction from a hot tub.
Mycobacterium avium complex: Characteristics of culture (2).
Slow growth.
May or may be pigmented.
Scrofula: Leading cause in the United States.
Mycobacterium avium complex.
Mycobacterium kansasii:
A. Type of infection.
B. Factors that predispose to infection (2).
C. Culture (2).
A. Resembles tuberculosis.
B. Immunosuppression; preexisting lung disease.
C. Slow-growing; photochromogenic.
Mycobacterium marinum: Habitat.
Fresh water or seawater.
Mycobacterium ulcerans: Disease.
Buruli ulcer.
Mycobacteria: Rapid growers.
M. chelonae.
M. fortuitum.
M. abscessus.
Mycobacteria: Non-photochromogens.
M. paratuberculosis.
M. avium complex.
M. terrae.
M. triviale.
M. shimoidae.
Mycobacteria: Photochromogens.
M. kansasii.
M. marinum.
M. asiaticum.
M. simiae.
Mycobacteria: Scotochromogens.
M. scrofulaceum.
M. szulgai.
M. xenopi.
M. celatum.
M. gordonae.
M. flavescens.
Mycobacterium leprae:
A. Culture.
B. Best stain.
A. Cannot be cultured in vitro.
B. Fite’s stain.
Asymptomatic bacteriuria: Diagnosis in voided urine (2).
Requires isolation of at least 10⁵ colony-forming units per mL of the same species.
In females, two consecutive samples are needed.
