MICROBIOLOGY PART 2 Flashcards
Which Staph are resistant/sensitive to Novobiocin?
NOvobiocin—Saprophyticus is Resistant; Epidermidis is Sensitive.
“On the office’s “staph” retreat, there was NO StRESs.”
Which Strep are resistant/sensitive to Bacitracin and Optochin?
Optochin—Viridans is Resistant; Pneumoniae is Sensitive.
OVRPS (overpass).
Bacitracin—group B strep are Resistant; group A strep are Sensitive.
B-BRAS.
α-hemolytic bacteria
Form green ring around colonies on blood agar.
Include the following organisms: Streptococcus pneumoniae Viridans streptococci
β-hemolytic bacteria
Form clear area of hemolysis on blood agar. Include the following organisms:
Staphylococcus aureus Streptococcus pyogenes—group A strep )
Streptococcus agalactiae—group B strep
Listeria monocytogenes
Morphology and virulence factors of staphylococcus aureus
Gram-positive cocci in clusters
Protein A (virulence factor) binds Fc-IgG, inhibiting complement activation and phagocytosis.
“Staph make catalase because they have more “staff.”
Staphylococcus aureus Commonly colonizes ________.
the nose
Staphylococcus aureus causes
Inflammatory disease—skin infections, organ abscesses, pneumonia (often after influenza virus infection), endocarditis, and osteomyelitis
Toxin-mediated disease—toxic shock syndrome (TSST-1), scalded skin syndrome (exfoliative toxin), rapid-onset food poisoning (enterotoxins)
S. aureus food poisoning due to ingestion of preformed toxin –> short incubation period (2–6 hr). Enterotoxin is heat stable –> not destroyed by cooking.
Bad staph (aureus) make coagulase and toxins.” Forms fibrin clot around self abscess.
What is MRSA?
(methicillin-resistant S. aureus) infection—important cause of serious nosocomial and community-acquired infections; resistant to methicillin and nafcillin because of altered penicillinbinding protein
What is TSST (S. aerues)?
TSST is a superantigen that binds to MHC II and T-cell receptor, resulting in polyclonal T-cell activation. Presents as fever, vomiting, rash, desquamation, shock, end-organ failure. Use of vaginal or nasal tampons predisposes to toxic shock syndrome.
Staphylococcus epidermidis
Infects prosthetic devices and intravenous catheters by producing adherent biofilms. Component of normal skin flora; contaminates blood cultures. Novobiocin sensitive.
Staphylococcus saprophyticus
Second most common cause of uncomplicated UTI in young women (first is E. coli). Novobiocin resistant
Streptococcus pneumoniae causes
Most common cause of: Meningitis
Otitis media (in childhren) Pneumonia
Sinusitis
“S. pneumoniae MOPS are Most OPtochin Sensitive. “
Pneumococcus is associated with “rusty” sputum, sepsis in sickle cell anemia and splenectomy
Streptococcuss pneumonae morphology, virulence factors
Lancet-shaped, gram-positive diplococci A. Encapsulated. IgA protease.
No virulence without capsule.
Bile soluble (lysed by bile)
alfa - partial hemolysis (green)
Catalase + vs. Catalase -
+ = clusters –> Staphylococcus
- = chains –> Streptococcus
Viridans group streptococci
normal flora, causes, how to differentiate
Viridans streptococci are α-hemolytic. They are normal flora of the oropharynx and cause dental caries (Streptococcus mutans) and subacute bacterial endocarditis at damaged valves (S. sanguinis). Resistant to optochin, differentiating them from S. pneumoniae, which is α-hemolytic but is optochin sensitive
“Viridans group strep live in the mouth because they are not afraid of-the-chin (op-to-chin resistant).”
Streptococcus sanguinis
Sanguis = blood. There is lots of blood in the heart (endocarditis). S. sanguinis makes dextrans, which bind to fibrin-platelet aggregates on damaged heart valves.
Streptococcus pyogenes (group A) Causes..
Causes: Pyogenic—pharyngitis, cellulitis, impetigo Toxigenic—scarlet fever, toxic shock–like syndrome, necrotizing fasciitis Immunologic—rheumatic fever, acute glomerulonephritis
Impetigo more commonly precedes glomerulonephritis than pharyngitis.
“Pharyngitis can result in rheumatic “phever” and glomerulonephritis. “
Criteria for rheumatic fever
J♥NES criteria for rheumatic fever: Joints—polyarthritis ♥—carditis Nodules (subcutaneous) Erythema marginatum Sydenham chorea Pharyngitis can result in rheumatic “phever” and glomerulonephritis.
Scarlet fever criteria
Scarlet fever: scarlet rash with sandpaper-like texture, strawberry tongue, circumoral pallor.
Antibodies + Streptococcus pyogenes (group A)
Bacitracin sensitive.
Antibodies to M protein enhance host defenses against S. pyogenes but can give rise to rheumatic fever.
ASO titer detects recent S. pyogenes infection
Streptococcus agalactiae (group B) characteristics, normal flora, causes
B == Babies!
Bacitracin resistant, β-hemolytic, colonizes vagina; causes pneumonia, meningitis, and sepsis, mainly in babies.
When should you screen pregnant women for S. agalactiae? If +?
Screen pregnant women at 35–37 weeks.
Patients with culture receive intrapartum penicillin prophylaxis.
S. agalactiae produces ____ factor
Produces CAMP factor, which enlarges the area of hemolysis formed by S. aureus. (Note: CAMP stands for the authors of the test, not cyclic AMP.)
Hippurate test +
Enterococci (group D)
Enterococci (Enterococcus faecalis and E. faecium) are normal colonic flora that are penicillin G resistant and cause UTI, biliary tract infections, and subacute endocarditis (following GI/GU procedures).
Lancefield group D includes the enterococci and the nonenterococcal group D streptococci.
“Enterococci, hardier than nonenterococcal group D, can grow in 6.5% NaCl and bile (lab test).”
Entero = intestine,
faecalis = feces,
strepto = twisted (chains),
coccus = berry
Lancefield grouping
Lancefield grouping is based on differences in the C carbohydrate on the bacterial cell wall.
VRE
vancomycin-resistant enterococci) are an important cause of nosocomial infection.
Streptococcus bovis (group D)
Colonizes the gut. Can cause bacteremia and subacute endocarditis in colon cancer patients.
“Bovis in the blood = cancer in the colon”
Cornyebacterium diphtheriae
causes
Causes diphtheria via exotoxin encoded by β-prophage. Potent exotoxin inhibits protein synthesis via ADP-ribosylation of EF-2. Symptoms include pseudomembranous pharyngitis (grayish-white membrane A) with lymphadenopathy, myocarditis, and arrhythmias.
Coryne= clubshaped
Lab diagnosis of Cornyebacterium diphtheriae
Lab diagnosis based on gram-positive rods with metachromatic (blue and red) granules and Elek test for toxin.
Black colonies on cystine-tellurite agar.
Corynebacterium diphtheriae ABCDEFG
ABCDEFG: ADP-ribosylation Beta-prophage Corynebacterium Diphtheriae Elongation Factor 2 Granules
Vaccine for C. diphtheriae?
Toxoid vaccine prevents diphtheria.
Spores: bacterial
Some bacteria can form spores at the end of the stationary phase when nutrients are limited. Spores are highly resistant to heat and chemicals.
Have dipicolinic acid in their core. Have no metabolic activity.
How to kill spores?
Must autoclave to kill spores (as is done to surgical equipment) by steaming at 121°C for 15 minutes.
Spore-forming gram-positive bacteria found in soil
Bacillus anthracis, Clostridium perfringens, C. tetani
Other spore formers
B. cereus, C. botulinum, Coxiella burnetii.
Clostridia (with exotoxins)
Gram-positive, spore-forming, obligate anaerobic bacilli
C. tetani exotoxin and causes
Produces tetanospasmin, an exotoxin causing tetanus. Tetanus toxin (and botulinum toxin) are proteases that cleave releasing proteins for neurotransmitters.
Tetanus is tetanic paralysis (blocks glycine and GABA release [both are inhibitory neurotransmitters] from Renshaw cells in spinal cord). Causes spastic paralysis, trismus (lockjaw), and risus sardonicus.
C. botulinum exotoxin and causes
Produces a preformed, heat-labile toxin that inhibits ACh release at the neuromuscular junction, causing botulism. In adults, disease is caused by ingestion of preformed toxin. In babies, ingestion of spores in honey causes disease (floppy baby syndrome).
“Botulinum is from bad bottles of food and honey (causes a flaccid paralysis). “
C. perfringens exotoxin and causes
Produces α toxin (“lecithinase,” a phospholipase) that can cause myonecrosis (gas gangrene) and hemolysis.
“Perfringens perforates a gangrenous leg.”
Clostridia difficile exotoxin and causes
Produces 2 toxins. Toxin A, enterotoxin, binds to the brush border of the gut. Toxin B, cytotoxin, causes cytoskeletal disruption via actin depolymerization –> pseudomembranous colitis –>diarrhea. Often 2° to antibiotic use, especially clindamycin or ampicillin.
‘Difficile causes diarrhea”
How to diagnose C. difficile?
Diagnosed by detection of one or both toxins in stool.
Treatment for C. difficile?
metronidazole or oral vancomycin. For recurring cases, fecal transplant may prevent relapse.
Anthrax is caused by what bug
Caused by Bacillus anthracis, a gram-positive, spore-forming rod
morphology of B. anthracis and toxin
produces anthrax toxin. The only bacterium with a polypeptide capsule (contains d-glutamate).
Cutaneous anthrax vs. Pulmonary antrhraz
C: Boil-like lesion –> ulcer with black eschar ( right) (painless, necrotic) –> uncommonly progresses to bacteremia and death.
P: Inhalation of spores –> flu-like symptoms that rapidly progress to fever, pulmonary hemorrhage, mediastinitis, and shock.
Woolsorters’ disease—inhalation of spores from contaminated wood.
Bacillus cereus
Causes food poisoning. Spores survive cooking rice. Keeping rice warm results in germination of spores and enterotoxin formation.
Emetic type usually seen with rice and pasta.
Nausea and vomiting within 1–5 hr. Caused by cereulide, a preformed toxin. Diarrheal type causes watery, nonbloody diarrhea and GI pain within 8–18 hr.
Reheated rice syndrome.
Listeria monocytogenes transmission
Facultative intracellular microbe; acquired by ingestion of unpasteurized dairy products and deli meats, via transplacental transmission, or by vaginal transmission during birth.
Listeria monocytogenes morpholoy and virulence factors
Form “rocket tails” (via actin polymerization) that allow them to move through the cytoplasm and into the cell membrane, thereby avoiding antibody. Characteristic tumbling motility; is only gram-positive organism to produce LPS.
Listeria monocytogenes causes…
Can cause amnionitis, septicemia, and spontaneous abortion in pregnant women; granulomatosis infantiseptica; neonatal meningitis; meningitis in immunocompromised patients; mild gastroenteritis in healthy individuals.
Listeria monocytogenes treatment
Treatment: gastroenteritis usually self-limited; ampicillin in infants, immunocompromised patients, and the elderly in empirical treatment of meningitis.
Actinomyces
long branching filaments resembling fungi.
gram-positive anaerobe
not acid fast
Causes oral/facial abscesses that drain through sinus tracts, forms yellow “sulfur granules”
acintomyces normal flora
normal oral flora
actinomyces treatment
penicillin
nocardiaä
long, branching filaments resembling fungi.
gram-positive aerobe
acid fast(weak)
Causes pulmonary infections in immunocompromised and cutaneous infections after trauma in immunocompetent
Nocardia normal flora
found in soil
Nocardia treatment
treat with sulfonamides
Mycobacteria tuberculosis vs. kansasii vs. avium -intracellulare
Mycobacterium tuberculosis (TB, often resistant to multiple drugs). M. kansasii (pulmonary TB-like symptoms). M. avium–intracellulare (causes disseminated, non-TB disease in AIDS; often resistant to multiple drugs). .
Treatment of mycobacterium
Prophylactic treatment with azithromycin.
All mycobacteria are acid-fast organisms
TB symptoms and mechanism
TB symptoms include fever, night sweats, weight loss, and hemoptysis.
Cord factor in virulent strains inhibits macrophage maturation and induces release of TNF-α. Sulfatides (surface glycolipids) inhibit phagolysosomal fusion.
Primary tuberculosis
Infeccion with M. tuberculosis @ nonimmune host (usually child)–> Ghon complex (hilar nodes, hon focus usually in mid zone of lung)–>
Heals by fibrosis –> immunity and hypersensitivity –> tuberculin +
Proressive lung diesase (HIV, malnutrition) –> Death (rare)
Severe bacteremia –> Miliary tuberculosis –> Deah
Preallergic lymphatic or heatogenous dissemination –> Dormant tubercle bacilli in several organs –> Reactivation in adult life
Secondary tuberculosis
Infeccion with M. tubuerculosis partially immune hypersensitized host (usually adult)/ Reiinfeccion –>
Fibrocaseous cavitary lesion (usually upper lobes)
Extapulmonary tuberculosis
CNS (parenchymal tuberculoma or meningitis)
Vertebral body (Pott disease)
Lymphadenitis
Renal
GI
Adrenals
TB tests
PPD+ if current infection, past exposure, or BCG vaccinated. PPD- if no infection or anergic (steroids, malnutrition, immunocompromise) and in sarcoidosis.
Interferon-γ release assay (IGRA) is a more specific test; has fewer false positives from BCG vaccination.
Leprosy (Hansen disease) resevoir
in US…armaldillos
Leprosy bug
Caused by Mycobacterium leprae, an acid-fast bacillus that likes cool temperatures (infects skin and superficial nerves—“glove and stocking” loss of sensation) and cannot be grown in vitro
2 forms of Hansen disease
Lepromatous—presents diffusely over the skin , with leonine (lion-like) facies , and is communicable; characterized by low cell-mediated immunity with a humoral Th2 response.
“Lepromatous can be lethal.”
Tuberculoid—limited to a few hypoesthetic, hairless skin plaques; characterized by high cell-mediated immunity with a largely Th1 type immune response
Leprosy treatment
multidrug therapy consisting of dapsone and rifampin for 6 months for tuberculoid form; and dapsone, rifampin, and clofazimine for 2–5 years for lepromatous form.
Gram negative stain what color? and what types are divided into?
pink
diplococci,
coccoid rods,
rods,
oxidase + comma shaped
gram negative diploccocci: important pathogens + dividsions
maltose fermenter : N. meningitidis
maltose nonfermenter: N. gonorrhoeae
Gram -
“Coccoid” rods
Haemophilus influenzae (requires factors V and X)
Pasturella - animal bites
Brucella - crucellosis
Bordetella pertussis
Gram - Rods; importnat pathogens and divisions
lactose fermenters can be:
FAST (Kliebsiella, E. coli, Enterobacter)
SLOW (Citrobacter, Serratia, Others)
lactose nonfermenters can be:
OXIDASE - (Shigella, Salmonella, Proteus, Yersinia)
OXIDASE + (Pseudomonas)
Lactose-fermenting enteric bacteria
Grow pink colonies on MacConkey agar
Ej: Citrobacter, Klebsiella, E. coli, Enterobacter, and Serratia (weak fermenter).
Test with MacConKEE’S agar.
How does E.Coli ferment lactose?
). E. coli produces β-galactosidase, which breaks down lactose into glucose and galactose.
EMB agar
lactose fermenters grow as purple/ black colonies. E. coli grows purple colonies with a green sheen.
Penicillin and gram - negative bugs
Gram-negative bacilli are resistant to penicillin G but may be susceptible to penicillin derivatives such as ampicillin and amoxicillin. The gram-negative outer membrane layer inhibits entry of penicillin G and vancomycin.
Neisseria generalidades
Gram-negative diplococci.
Gonococci + Meningococci
Both ferment glucose and produce IgA proteases.
N. gonorrhoeae is often intracellular (within neutrophils)
MeninGococci ferment Maltose and Glucose.
Gonococci ferment Glucose
Gonococci
no polysaccaride capsule
no maltose fermentation
no vaccine (due to rapid antigenic variation of pilus protiens)
sexually transmittted
Causes gonorrhea, septic arthritis, neonatal conjunctivitis, pelvic inflammatory disease (PID), and Fitz-Hugh–Curtis syndrome
Condoms prevent sexual transmission. Erythromycin ointment prevents neonatal transmission
Treatment: ceftriaxone + (azithromycin or doxycycline) for possible chlamydia coinfection
Meningococci
polysacaride capsule
maltose fermentation
vaccine (none for type B)
respiratory and oral secretion transmission
causes meningococcemia and meningitis, Waterhouse-Friderichsen syndrome
Rifampin, ciprofloxacin, or ceftriaxone prphylaxis in close contacts
tx: ceftriaxone or penicillin G
Haemophilus influenzae
Small gram-negative (coccobacillary) rod.
Aerosol transmission.
Most invasive disease caused by capsular type B.
Nontypeable strains cause mucosal infections (otitis media, conjunctivitis, bronchitis).
Produces IgA protease.
Culture on chocolate agar requires factors V (NAD+) and X (hematin) for growth; can also be grown with S. aureus, which provides factor V.
HaEMOPhilus causes Epiglottitis (“cherry red” in children)(thumprint sign), Meningitis, Otitis media, and Pneumonia.
Treat mucosal infections with amoxicillin +/- clavulanate. Treat meningitis with ceftriaxone. Rifampin prophylaxis in close contacts
Does not cause the flu (influenza virus does).
Vaccine for haemophilus influenzae
Vaccine contains type B capsular polysaccharide (polyribosylribitol phosphate) conjugated to diphtheria toxoid or other protein. Given between 2 and 18 months of age.
Legionella pneumopila
Gram-negative rod. Gram stains poorly—use silver stain. Grow on charcoal yeast extract culture with iron and cysteine. Detected clinically by presence of antigen in urine. Aerosol transmission from environmental water source habitat (e.g., air conditioning systems, hot water tanks). No person-toperson transmission. Treatment: macrolide or quinolone.
Legionnaires’ disease = severe pneumonia, fever, GI and CNS symptoms.
Pontiac fever = mild flu-like syndrome.
Lab show hyponatremia
“Think of a French legionnaire (soldier) with his silver helmet, sitting around a campfire (charcoal) with his iron dagger—he is no sissy (cysteine).”
Pseudomonas aeruginosa
Aerobic gram-negative rod.
Non-lactose fermenting, oxidase +.
Produces pyocyanin (blue-green pigment); has a grape-like odor. Water source.
Produces endotoxin (fever, shock) and exotoxin A (inactivates EF-2).
PSEUDOmonas is associated with wound and burn infections, Pneumonia (especially in cystic fibrosis), Sepsis, External otitis (swimmer’s ear), UTI, Drug use and Diabetic Osteomyelitis, and hot tub folliculitis.
Malignant otitis externa in diabetics.
Ecthyma gangrenosum—rapidly progressive, necrotic cutaneous lesions caused by Pseudomonas bacteremia. Typically seen in immunocompromised patients.
Treatment: aminoglycoside plus extendedspectrum penicillin (e.g., piperacillin, ticarcillin, cefepime, imipenem, meropenem).
Think Pseudomonas in burn victims.
Chronic pneumonia in cystic fibrosis patients is associated with biofilm.
E. coli virulence factors
fimbriae—cystitis and pyelonephritis; K capsule—pneumonia, neonatal meningitis; LPS endotoxin—septic shock.
EIEC
Microbe invades intestinal mucosa and causes necrosis and inflammation. Clinical manifestations similar to Shigella
INVASIVE, dysentery
ETEC
Produces heat-labile and heat-stable enteroToxins. No inflammation or invasion.
TRAVELERS DIARRHEA (watery)
EPEC
No toxin produced. Adheres to apical surface, flattens villi, prevents absorption.
diarrea usually in children (Pediatrics).
EHEC
O157:H7 is the most common serotype. Produces Shiga-like toxin that causes Hemolytic-uremic syndrome (triad of anemia, thrombocytopenia, and acute renal failure). Also called STEC (Shiga toxin–producing E. coli).
Microthrombi form on endothelium damaged by toxin –> mechanical hemolysis (schistocytes formed) and decreases renal blood flow; microthrombi consume platelets
–>thrombocytopenia.
Dysentery (toxin alone causes necrosis and inflammation).
Does not ferment sorbitol (distinguishes it from other E. coli).
Kliebsiella
An intestinal flora that causes lobar pneumonia in alcoholics and diabetics when aspirated. Very mucoid colonies caused by abundant polysaccharide capsules. Red “currant jelly” sputum. Also cause of nosocomial UTIs.
4 A’s of Kliebsiella
Aspiration pneumonia Abscess in lungs and liver
Alcoholics
di-A-betics
Salmonella
have flagella (salmon swim)
disseminate hematogenously
many animal resevoirs
produce hydrogen sulfide
antibiotics may prolong fecal excretion of organism
invades intestinal mucosa and causes a monocytic response
can cause bloody diarrhea
does not ferment lactose
Salmonella typhi
Causes typhoid fever. Found only in humans. Characterized by rose spots on the abdomen, fever, headache, and diarrhea. Can remain in gallbladder and cause a carrier state.
Shigella
No flagella
cell to cell transmision, no hematogenous spread
resevoires = humans and primates
does not produce hydrogen sulfide
antibiotics shorten duration of fecal excretion of organism
invades intestinal mucosa and causes PMN infiltration
often causes bloody diarrhea
does not ferment lactose
Campylobacter jejuni
Major cause of bloody diarrhea, especially in children. Fecal-oral transmission through foods such as poultry, meat, unpasteurized milk. Comma or S-shaped, oxidase +, grows at 42°C (“Campylobacter likes the hot campfire”). Common antecedent to Guillain-Barré syndrome and reactive arthritis.
Vibrio cholerae
Produces profuse rice-water diarrhea via enterotoxin that permanently activates Gs,
INCREASES cAMP. Comma shaped, oxidase +, grows in alkaline media. Endemic to developing countries.
Prompt oral rehydration is necessary.
Yersinia enterocolitica
Usually transmitted from pet feces (e.g., puppies), contaminated milk, or pork. Causes mesenteric adenitis that can mimic Crohn disease or appendicitis.
Helibacter pylori
Causes gastritis and peptic ulcers (especially duodenal).
Risk factor for peptic ulcer, gastric adenocarcinoma and lymphoma. Curved gram-negative rod that is catalase, oxidase, and urease + (can use urea breath test or fecal antigen test for diagnosis).
Creates alkaline environment. Most common initial treatment is triple therapy: proton pump inhibitor + clarithromycin + either amoxicillin or metronidazole.
Spirochetes
The spirochetes are spiral-shaped bacteria with axial filaments and include Borrelia (big size), Leptospira, and Treponema.
Only Borrelia can be visualized using aniline dyes (Wright or Giemsa stain) in light microscopy.
Treponema is visualized by dark-field microscopy.
“BLT; B is Big”
Leptospira interrogans
Found in water contaminated with animal urine, causes leptospirosis: flu-like symptoms, jaundice, photophobia with conjunctival suffusion (erythema without exudate). Prevalent among surfers and in tropics (i.e., Hawaii
Weil disease
Weil disease
e (icterohemorrhagic leptospirosis)—severe form with jaundice and azotemia from liver and kidney dysfunction; fever, hemorrhage, and anemia.
@Leptospira interrogans
Lyme disease
Caused by Borrelia burgdorferi, which is transmitted by the tick Ixodes (also vector for Babesia). Natural reservoir is the mouse. Mice are important to tick life cycle.
Common in northeastern United States.
Initial symptoms—erythema chronicum migrans , flu-like symptoms, +/- facial nerve palsy.
Later symptoms—monoarthritis (large joints) and migratory polyarthritis, cardiac (AV nodal block), neurologic (encephalopathy, facial nerve palsy, polyneuropathy).
Treatment: doxycycline,ceftriaxone
“FAKE a key Lyme Pie:
Facial nerve palsy (typically bilateral), arthritis, Kardiac block, Erythema migrans (“ bulls eye”)”
Syphillis is caused by
spirochete Treponema pallidum
Treatment of Syphilis
Penicillin G
Priary syphylis
Localized disease presenting with painless chancre
If available, use dark-field microscopy to visualize treponemes in fluid from chancre
. Serologic testing: VDRL/RPR (non-specifc), confirm diagnosis with specific test (e.g., FTA-ABS).
Secondary syphilis
Disseminated disease with constitutional symptoms, maculopapular rash (palms and soles), condylomata lata (also confirmable with dark-field microscopy).
Serologic testing: VDRL/RPR (non-specific), confirm diagnosis with specific test (e.g., FTA-ABS).
Secondary syphilis = Systemic. Latent syphilis (+ serology without symptoms) follows.
Terciary syphilis
Gummas (chronic granulomas), aortitis (vasa vasorum destruction), neurosyphilis (tabes dorsalis, “general paresis”), Argyll Robertson pupil.
Signs: broad-based ataxia, + Romberg, Charcot joint, stroke without hypertension. For neurosyphilis: test spinal fluid with VDRL or RPR.
Congenital syphilis
Saber shins, saddle nose, CN VIII deafness, Hutchinson teeth, mulberry molars. To prevent, treat mother early in pregnancy, as placental transmission typically occurs after first trimester.
Argyll Robertson pupil
Argyll Robertson pupil constricts with accommodation but is not reactive to light. Associated with 3° syphilis.
“Prostitute pupil” - acommodates but does not react
VDRL false positives
VDRL detects nonspecific antibody that reacts with beef cardiolipin. Inexpensive, widely available test for syphilis, quantitative, sensitive but not specific. Many false positives, including viral infection (e.g., mononucleosis [EBV], hepatitis), some drugs, and SLE.
“VDRL”
Viruses (mono, hepatitis), Drugs, Rheumatic fever, Lupus and Leprosy
Jarisch-Herxheimer reaction
Flu-like syndrome after antibiotics are started—due to killed bacteria releasing pyrogens.
Zoonosis
infectious disease transmitted between animals and humans
Gardnerella vaginalis
pleomorphic, gram-variable rod that is involved in vaginosis. Presents as a gray vaginal discharge with a fishy smell; nonpainful (vs. vaginitis). Associated with sexual activity, but not sexually transmitted. Bacterial vaginosis is also characterized by overgrowth of certain anaerobic bacteria in vagina. Clue cells, or vaginal epithelial cells covered with Gardnerella bacteria, are visible under the microscope (arrow) A.
Treatment: metronidazole or (to treat anaerobic bacteria) clindamycin.
Anaplasma spp.
causes anaplasmosis
transmitted by Ixodes ticks that live on deer and mice
Bartonella spp.
Cat scratch disease, bacillary angiomatosis
Transmitted through cat scratch
Borrelia burgdorferi
Lyme disease transmitted by Ixodes ticks that live on deer and mice
Borrelia recurrentis
Relapsing fever transmitted by Louse (recurrent due to variable surface antigens)
Brucella spp.
Brucellosis/undulant fever
transmitted through unpasteurized dairy
Campylobacter
bloody diarrhea
transmitted by puppies, livestock (fecal-oral, ingestion of undercooked meat)
Chlamydophila psittaci
Psittacosis
transmitted by parrots and other birds
oxiella burnetii
Q fevere transmitted by aerosols of cattle/sheep amniotic fluid
Ehrlichia chaffeensis
Ehrlichiosis transmitted by lone star ticks
francisella tularensis
tularemia trasnmitted by ticks, rabbits, deer fly
leptospiral spp
causes leptospirosis transmitted through animal urine
mycobacterium leprae
causes leprosy and is transmitted by humans with lepromatous leprosy and rarely by armadillos
Pasteurella multocida
causes cellulitis, oseomyelitus and trasnmited by animal bite, cats, dogs
Rickettsia prowaseii
causes epidemic typhus transmitted by lous
rickettsia rickettsii
causes rocky mountain spotted fever transmitted by dermacentor ticks
rickettsia typhi
causes endemic typhus transmitted by fleas
yersinia pestis
caused the plague
transmitted by fleas (rats and prairie dogas are resevoirs)
treatment for all rickettsial diseases and vector-borne illnesses
doxycycline
rash common rickettsial diseases and vector-borne illness
rocy mountain spotted fecer and typhus
rash rare ricettsial diseases and vector-borne illness
Ehrlichiosis
Anaplasmosis
Q fever
Rocky mountain spotted fever
Rickettsia rickettsii, vector is tick. Despite its name, disease occurs primarily in the South Atlantic states, especially North Carolina. Rash typically starts at wrists and ankles and then spreads to trunk, palms, and soles A. Rickettsiae are obligate intracellular organisms that need CoA and NAD+ because they cannot synthesize ATP.
Classic triad—headache, fever, rash (vasculitis).
Palms and soles rash is seen
Palms and soles rash is seen in Coxsackievirus A infection (hand, foot, and mouth disease), Rocky Mountain spotted fever, and 2° Syphilis (you drive CARS using your palms and soles
Typhus
Endemic (fleas)—R. typhi. Epidemic (human body louse)—R. prowazekii. Rash starts centrally and spreads out, sparing palms and soles.
“Rickettsii on the wRists, Typhus on the Trunk”
Ehrilchiosis
Ehrlichia; vector is tick. Monocytes with morulae (berry-like inclusions) in cytoplasm
Anaplasmosis
Anaplasma, vector is tick. Granulocytes with morulae in cytoplasm.
Q fever
Coxiella burnetii; no arthropod vector. Tick feces and cattle placenta release spores that are inhaled as aerosols. Presents as pneumonia.
Q fever is Queer because it has no rash or vector and its causative organism can survive outside in its endospore form. Not in the Rickettsia genus, but closely related.
Chlamydiae
Chlamydiae cannot make their own ATP. They are obligate intracellular organisms that cause mucosal infections.
2 forms: Elementary body (small, dense) is “Enfectious” and Enters cell via Endocytosis; transforms into reticulate body.
Reticulate body Replicates in cell by fission; reorganizes into elementary bodies.
Chlamydia trachomatis causes reactive arthritis (Reiter syndrome), follicular conjunctivitis A, nongonococcal urethritis, and PID.
C. pneumoniae and C. psittaci cause atypical pneumonia; transmitted by aerosol.
Treatment: azithromycin (favored because onetime treatment) or doxycycline
Chlamys = cloack (IC)
Chlamydophila psittaci = notable for an avian resevoir
Lab diagnosis: cytoplasmic inclusions seen on Giemsa or fluorescent antibody–stained smear. The chlamydial cell wall is unusual in that it lacks muramic acid.
Types A, B, and C of Chlamydia trachomatis
Chronic infection, cause blindness due to follicular conjunctivitis in Africa.
ABC = Africa/Blindness/Chronic infection.
Types D-K of Chlamydia trachomatis
Urethritis/PID, ectopic pregnancy, neonatal pneumonia (staccato cough), neonatal conjunctivitis.
everything else
Neonatal disease can be acquired during passage through infected birth canal.
Types L1, L2, and L3 of chlamydia trachomatis
Lymphogranuloma venereum—small, painless ulcers on genitals swollen, painful inguinal lymph nodes that ulcerate (“buboes”). Treat with doxycycline.
Mycoplasma pneumoniae
Classic cause of atypical “walking” pneumonia (insidious onset, headache, nonproductive cough, patchy or diffuse interstitial infiltrate). X-ray looks worse than patient. High titer of cold agglutinins (IgM), which can agglutinate or lyse RBCs. Grown on Eaton agar.
Treatment: macrolide, doxycycline, or fluoroquinolone (penicillin ineffective since Mycoplasma have no cell wall).
No cell wall. Not seen on Gram stain. Bacterial membrane contains sterols for stability. Mycoplasmal pneumonia is more common in patients
