Microbiology Flashcards
What is Tellulrite agar used to detect?
C. diphtheriae
What is Loeffler medium used to detect?
C. diphtheriae
What is lowenstein-Jensen agar used to detect?
Mycobacterium TB
How do you stain for H. pylori?
Silver Stain
How do you stain for Legionella?
Silver Stain
Where can you get listeria from?
Unpasteurized milk, deli meats or by vertical transmission/vaginal delivery
What is carbol fuschin?
Acid fast stain
What is the charcoal yeast extract with cysteine and iron?
Legionella
What is MacConkey agar used for?
Lactose fermenting (such as E.coli); will form pink colonies
What is EMB (eosin-methylene blue) agar used for?
E. coli (forms green metallic sheen)
What are the aerobes?
Nocardia, Pseudomonas, Mycobacterium
What are obligate intracellular pathogens?
Rickettsia, Chlamydia
What are the catalase positive organisms?
S. aureus, E.coli, Candida, Serratia, Pseudomonas, Aspergillus, Listeria, Burkholderia, Nocardia
How does Pertussis toxin work?
Increases cAMP b displaying Gi, impairing phagocytosis. Its an ADP-ribosylating toxin.
How does C. perfringens toxin work?
It is a phospholipase (lecithinase) that degrades cell membranes
Transformation vs Transduction?
Transformation: naked DNA transfer
Transduction: Generalized - lytic phage
Trasnduction: Specialized - lysogenic phage
What does Protein A do and what pathogen is it a virulence factor of?
Virulence factor of S. aureus. Binds Fc portion of IgG inhibiting complement activation and phagocytosis
If you get influenza infection, what pathogen can give you pneumonia after?
S. aureus (especially in elderly) or S. pneumo/Hib
What produces dextrans from glucose?
S. sanguis (viridans strep)
What are the toxins of S. pyogenes?
Exotoxin A and Streptolysin O
What is PYR Test positive?
S. pyogenes
What produces CAMP factor?
S. agalactiae
What causes subacute endocarditis following GI/GU procedures?
Group D enterococci
What encodes the diptheria toxin?
Beta-prophage
What else can diphtheria cause besides pharyngitis?
Myocarditis, arrhythmia, lymphadenopathy
What does Elek test do?
Tests for diphtheria toxin
What has metachromatic granules (blue and red)?
Diphtheria
What forms spores?
Bacillus (anthrax, cereus), clostridium, Coxiella burnetti
What else does C. perfringens cause besides gas gangrene?
Late onset food poisoning causing watery diarrhea; from undercooked meat
What looks like serpentine or medusa head?
Anthrax
What is the only gram positive bacteria to make endotoxin?
Listeria
Which bug causes spontaenous abortion?
Listeria
What cause vertebral osteomyelitis?
Myocbacterium TB (Pott’s Disease)
What is the prophylactic treatment of MAC?
Azithromycin
What does cord factor do?
Inhibits macrophage maturation and induces release of TNF-alpha
What do sulfatides (in TB) do?
inhibit phagolysosomal fusion
What does Lepromin test show?
Positive for tuberculoid due to Th1 response but negative for lepromatous due to Th2 response (no cell immunity)
What presents as hypopigmented hairless plaques with focal decreased sensation?
Tuberculoid Leprosy
What strain of Hib causes conjunctivitis, otitis media, bronchitis?
Nontypable
How do you treat Hib meningitis?
Ceftriaxone
How do you treat Hib mucosal infections?
Amoxicillin +/- clavulanate?
What do labs show for for legionella?
Hyponatremia
What is a non lactose fermenting gram negative rod that produces H2S?
Salmonella
What is a non lactose fermenting gram negative rod that does not produce H2S?
Shigella
What is the diagnosis? Travel to endemic area, faint rose colored spots on the abdomen, fever, abdominal pain, intestinal perforation.
Salmonella Typhi
How does Salmonella typhi cause a carrier state?
Remain in gallbladder
What enteric infection do you get from puppies’ feces?
Campylobacter of Yersinia
What is urease, oxidase, and catalase positive?
H. Pylori
Treatment for H. pylori?
PPI + clarithromycin + amoxicillin or metronidazole
What does leptospira cause?
Flu-like symptoms, jaundice, photophobia, conjunctival suffusion
Where do you get leptospira from?
Water contaminated with animal urine; seen among surfers and tropics?
What is Weil disease?
Severe form of Leptospirosis (jaundice, azotemia, fever, hemorrhage, anemia)
How do you treat Lyme Disease?
Doxycycline or Ceftriaxone
What causes Francisella?
Ticks, rabbits, deer fly
How do you treat Rickettsial disease (rocky mountain etc)
Doxycycline
What bug do you get from cattle placenta and tick feces?
Coxiella Burnetti (Q fever aka pneumonia)
What has cytoplasmic inclusions seen on Giemsa?
Chlamydia
What grows on Eaton agar?
Mycoplasma (cholesterol enriched media)
What is a disc shaped yeast on methenamine silver stain?
Pneumocystis Jirovecii
What is a cigar shaped budding yeast?
Sporothrix schenkii
What is the treatment for entaemoba histolytica?
Metronidazole; Iodoquinol for asymptomatic
What causes bloody diarrhea, liver abscess with anchovy paste exudate, RUQ pain?
Entamoeba Histolytica
What is the classic triad of congenital toxoplasmosis?
Intracranial calcifications, chorioretinitis, hydrocephalus
How do you treat toxoplasmosis?
Sulfadiazine, pyrimethamine
What is the treatment for African sleeping sickness?
Suramin for blood borne disease; Melasoprol for CNS penetration
What is the treatment for Babesia?
Atovaquone + azithromycin
Which bugs cause dilated cardiomyopathy?
Coxsackie B and T. cruzi (Chagas Disease)
What is the treatment for T. cruzi?
Benzinidazole or nifurtimox
What disease is it if you see macrophages with amastigotes?
Leishmniasis
What is Leishmaniasis
Spiking fevers, hepatosplenomegaly, pancytopenia
What is associated with a strawberry cervix?
Trichomonas vaginalis
What do you treat Trichomonas with?
Metronidazole (both bacterial vaginosis and this is metronidazole)
What is the treatment for Strongyloides?
Ivermectin or albendazole
How do you treat enterobius, ascaris, and ancytoplasma/necator?
Pyrantel pamoate or bendazole
What is it if you see rhabtidiform larvae in stool?
Strongyloides
What are the symptoms of strongyloides?
Pruritc streak (larva currens), GI sx (diarrhea, vomiting, epigastric pain - may resemble peptic ulcer)
What bug is a snail the host of?
Schistosoma
What forms hyatid cysts in the liver?
Echinococcus
Which hepatitis virus causes risk of fulminant hepatitis in pregnancy women?
HEV
What bug do you get from shellfish?
HAV
Which two viruses are exceptions to this rule: all dsDNA and + RNA are infectious?
HBV, Poxvirus
What virus is an exception to this rule: all enveloped viruses acquire their envelopes from plasma membrane?
Herpesvirus: acquires envelopefrom nuclear membrane
What are the polyomaviruses?
JC and BK viruses
Which DNA virus is partially double stranded?
Hepadnavirus
Where do you get norovirus from?
Cruise ships, nursing homes, schools
Who gets rotavirus?
Children. It is the #1 cause of fatal diarrhea in children
What is the reservoir for yellow fever?
Monkeys or humans
What are the symptoms of yellow fever?
Jaundice, black vomitus, high fever
What is Pavlizumab?
It is a monoclonal antibody against F protein that prevents pneumonia caused by RSV in premature infants
How do paramyxoviruses cause infection?
They express F protein (surface protein) causing respiratory epithelial cells to fuse and form and multinucleated cells?
Which receptor does HIV bind early?
CCR5
Which receptor does HIV bind late?
CXCR4
Antibody to which of the HIV proteins crosses the placenta and creates a false positive result in the baby?
GP120
What causes hairy leukoplakia in AIDS patients?
EBV
What causes acid fast cysts in the stool?
Cryptosporidium
How do you differentiate superficial vascular proliferations in HIV caused by HHV-8 (Kaposi) from Bartonella henslae (bacillary angiomatosis)?
HHV-8 has lymphocytic infiltrate
B. henslae has neutrophilic infiltrate
What does P. jirovecii look like on imaging?
Ground glass appearance
How do you tell Haemophilus ducreyi and primary syphilis apart?
H. ducreyii you see a painFUL chancroid; primary syphilis you see a painLESS chancre.
What do you use for pneumocystis and pneumocystis plus toxoplasma (if severe) prophylaxis?
TMP- SMX
How does chloroquine work?
Blocks detoxification of heme into hemozoin
Which of the NRTI’s is a nucleotide instead of a nucleoside?
Tenofovir
Which NRTI for general HIV prophylaxis and transmission to baby?
Zidovudine
What is the toxicity of cephalosporins?
Increases nephrotoxicity of aminoglycosides, vitamkin K deficiency, hypersensitivity reactions
What is lepromin test positive for?
Tuberculoid leprosy because of Th1 response (would see IFN-gamma and IL-2 in induration)
What do you give for acute diphtheria?
Antitoxin (passive immunization) then give erythromycin/penicillin, DPT vaccine
How does Daptomycin work?
Membrane depolarization, inactivated by surfactant. Associated with CKP increase and myopathy
What is unique about spores?
They are heat resistant so you must autoclave
What causes noninflammatory diarrhea?
Cholera, Giardia, ETEC, S. aureus, B. cereus
What would you see in the stool if you had cholera?
Mucus and epithelial cells in stool
How do Nystatin and Amphotericin B work?
Create pores in cell membrane
What is Amphotericin B’s toxicity?
Arrhythmias (hypokalcemia, hypomagnesia), nephrotoxicity, anemia, IV phlebitis, fevers/chills
Is Aspergilloma colonizing or invasion?
Colonizing
How does Flyctosine work?
Inhibits DNA & RNA synthesis
How does Griseofulvin work?
Inhibits microtubule function
What does HCV progress to?
Chronic stable hepatitis
How does lyme disease present?
Facial nerve palsy, arthralgias, cardiac block, erythema migrans (annular rash with central clearing)
What organs does mumps cause inflammation in?
Pancreas, testes, parotid gland
What does anthrax look like on blood agar?
Nonhemolytic, rough gray colonies
What is the classic presentation of congenital syphilis?
Desquamating rash, cleft palate, rhinitis, RPR+
What else can ascaris cause besides intestinal infection?
Pneumonia; it posses one of the most potent allergens so cause type 1 hypersensitivity
What infections are CF patients most likely to get?
Pseudomonas
What is the diagnosis? Caseating granulomatous disease from ingestion of unpasteurized milk?
Brucella Abortis
What does Brucella abortis?
Abortions, endocarditis (aortic), mostly mild fevers
How does Fluconazole work?
Blocks lanosterol demethylase
What do you think of if you have HIV and see ring enhancing lesions?
Primary CNS lymphoma and to toxoplasma
What is the life cycle of strongyloides?
Get into feet from sand –> hematogenous spread to lungs –> coughed up and swallowed –> develop into adults –> lay eggs in intestinal mucosa –> hatch into rhabtidiform larvae –> excreted in stool
What is larva currens and what do you see it with?
It is pruritic, erythematos linear streaks on thighs and buttocks seen with strongyloides (due to larvae migrating away from perianal region)
How does diphtheria toxin work?
Inhibits protein synthesis via ADP ribosylation of EF-2
What virulence factor does E. coli use to cause meningitis and pneumonia?
K1 capsule
What virulence factor does E. coli use to cause pyelonephritis and cystitis?
Fimbriae
What does LPS endotoxin cause?
Septic shock
What part of LPS causes shock?
Lipid A
What do you give measles?
Vitamin A
What is a nonenterococcus group D bug?
S. bovis
What can you get enterococcus bacterial endocarditis?
GU instruments or cath
How does C. Diff toxin work?
Disrupts cytoskeleton via actin depolymerization
What is the MCC of infections associated with foreign bodies?
S. epidermis
What is the most likely organism if you have pneumonia, GI symptoms (diarrhea), high fever especially if neutrophisl but no bacteria?
Legionella
What do you get Legionella from?
Contaminated water exposure (cruise ships, recent travels, AC, hot tub)
What is ribavrin used for?
RSV and HCV
What should someone who develops septic shock or severe pulmonary disease from SW US be evaluated for?
Plague
Why is MRSA resistant to all beta lactams?
It has penicillin binding protein so drug can’t find it easily
How does acyclovir work?
Inhibits viral DNA synthesis by incorporating into viral DNA
Needs to be phosphorylated first (only in infected cells so few adverse effects)
What is the major pathogenesis of Salmonella and Shigella?
Mucosal invasion
What is a small focus of fibrotic tissue in TB?
Ghon complex (calcification is immune system walling off granuloma)
What is a cavitary lesion in TB?
Latent TB
What makes a cholera infection more likely?
PPI
What kills latent malaria infection with vivax and ovale?
Primaquin
What type of medium is Thayer Martin?
Selective
What does env in HIV make?
Glycosylated to make gp41 (invading) and gp120 (attaching)
When does T helper cell response to TB occur?
2-4 weeks after infection
What presents with prodrome, then agitation, disorientation, hydrophobia, hypersalivation, progressing to death or coma?
Rabies
What do you get rabies from?
Bats, raccoon, skunk bites
What transmits campylobacter?
Cattle, sheep, dogs, chicken
What has granular eosinophilic appearance resembling ground glass?
HBV (HBsAg in hepatocellular cytoplasm)
What is the host for schistosoma?
Snail
What does parvovirus cause in adults?
RA like symptoms
What is the diagnosis? Dysphagia, diplopia, dysphonia.
Botulinum
Why does HDV need HBV?
For coating of viral particles
What does MAC grow at?
41deg and has more widespread involvement in body
How does HBV replicate?
Produces positive RNA template from DNA template but DNA progeny
What is the only DNA viruses in the hepatitis family?
HBV
Why is there no vaccine to HCV?
Huge antigenic variation
What is one way CMV be transmitted?
Blood transfusions
What is an indurated genital ulcer?
Gumma (from syphilis)
What type of hypersensitivity does TB damage through?
Type 4
How do you tell if someone has risk for chronic HepB
HbeAg and HbsAg positive
How doe shigella invade the GI tract?
By first gaining access to M cells
What do you use to treat most coagulase negative straph?
Vancomycin
What is this: progency has capsid of one and genome of another but no change in genome so next generation of virions revert back to normal.
Phenotyping mixing
What do gram negative organisms that ferment lactose look like on agar?
Pink on MacConkey
What are the segmented viruses?
BOAR: bunya, orthomyxo, arena, reo
What has one large polypeptide that is cleaved by proteases into functional viral proteins?
Picronavirus
How does tetanus toxin infect?
Wound –> motor neurons –> spinal cord
How do you prevent HSV reactivation?
Daily valaycyclovir. Acyclovir during 1st episode is just for that episode (it doesn’t affect latent)
How does HCV have so much genetic variability?
3-5 exonuclease
What has cutaneous black eschar?
Antrhax
What has black eschar from the nose?
Mucormycosis
What is pustular skin lesions that form thick scabs?
Impetigo
If you do gastric biopsy and put in urea solution. If it turns pink then what does that mean?
Positive urea test indicative of H. pylori (urease converts urea to ammonia)
What would isoniazid monotherapy in TB result in?
Selective survival of bacterial cells secondary to gene mutation (either of catalase peroxidase enzyme or binding site of isoniazid)
What can be cultured at refrigeration temperatures and is beta hemolytic?
Listeria
What is most useful for making a tetanus diagnosis?
History and physical (there is no serum toxin assay)
What is the MC outcome of hepatitis infection?
Complete resolution
Which E. coli does not ferment sorbitol on MacConkey agar?
EHEC
What are the MCC of intraabdominal infections?
B. fragilis, E. coli
What causes abscess around appendix?
B. fragilis
How can HAV be killed?
Boiling, chlorination, bleach, formalin
What most likely happened if baby is born and gets oral thrush, interstitial pneumonia, and lymphopenia?
Mom transmitted HIV to baby
What do you treat Giardia with?
Metronidazole
What causes disulfiram like reaction with alcohol?
Metronidazole
What presents with intensely pruritic rash (excoriation with small crusted red papules) worse at night and on hands/palms?
Scabies
What is raltegavir?
Integrase inhibitor: prevents viral DNA integration and therefore inability to synthesize mRNA
Why do you use primaquine for vivax and ovale?
To kill hypnozoites (those inside hepatocytes)
Why do hepatocytes get destroyed when HBsAg present?
Viral antigens displayed on cell surface stimulate cytotoxic CTLs
What else besides BPH can also have difficulty starting a stream and maintaining?
Diabetic neuropathy leading to overflow incontinence
What causes liver abscess?
Echinococcus, Entameoba
What are councilman bodies a result of?
These eosinophilic globules are a result of hepatocyte apoptosis
What is reassortment?
When viruses with segmented genomes exchange segments. Responsible for influenza pandemics
What has trophozoites with phagocytosed RBC or cysts in stool?
Entamoeba histolytica
What is CMV colitis?
Common cause of colitis in immunocormpromised.
Reactivation of CMV after retinitis in HIV: GI sx, colonoscopy shows erythema, erosions, ulcerations.
Biopsy shows large cells with large ovioid nuclei containing basophilic depossits (intranuclear inclusions)
What would the HSV DNA of three different vesicular lesions look like?
The same!
What does Hep B infection lead to?
Most completely resolve
How do you kill anaerobic spores?
Autoclave (exposure to steam at 121 celsius for 15 minutes)