Viruses that form multinucleated giant cells (synctyia)
Come in 3's: MMR, & the 3 alpha-Herpesviruses (HSV-1, HSV-2, VZV)
How to diagnose Mycoplasma pneumoniae
Grows on Eaton's agar; no cell wall, so neither positive nor negative Gram staining. Cell membrane does contain cholesterol, though = the only one. "Fried-egg" colonies when grown on cholesterol-rich medium. Walking pneumonia = CXR looks worse than pt. High level of coldagglutinins (IgM Ab's): RBC's clump together when placed on ice.
2 bacteria with toxins that inactivate EF-2 (elongation factor -- messes up protein synthesis)
Corynebacterium diphtheriae, Pseudomonas
Only 1 gram-neg. "Nagging Pests Must Breathe": Nocardia, Pseudomonas, Mycobacterium, Bacillus
Detects Ab's against Rickettsia species, except for Q fever (Coxiella burnetti).
Only 1 gram-neg. "Can't Breathe Air": Clostridium, Bacteroides, Actinomyces.
Thrush (HIV/immunocomp, neonates, DM); diaper rash; vulvovaginitis (DM, antibiotics); endocarditis (IV drug users). Yeast w/pseudohyphae, but germ tube at 37C (remember, all the C fungi are yeast at some point).
1) Allergic bronchopulmonary aspergillosus. (IgE)
2) Fungus ball in lung cavity (mycetoma).
3) Invasive lung disease (immunocomp) -- often-asymptomatic pneumonia, but deadly.
Mold w/septate hyphae.
Yeast w/pseudohyphae. Chronic meningitis & pneumonia. India ink (not very sensitive), latex agglutination.
2nd most common malaria strain (remember FAVE). Cyclic fever, HA, hepatosplenomegaly/anemia.
Relapse, b/c dormant form (hypnozoite) lies in liver. Chloroquine-sensitive. Use primaquine for prophylaxis (they're protected from chloroquine in liver).
Most infectious (and common?). Induces knob formation on RBC's --> sequestration in microvasculature --> infarcts.
Malaria life cycle & resistance
Sporozoites infect & grow in liver --> trophozoites --> schizonts --> release lots of merozoites, which infect RBC's. Inside RBC's, whole life cycle repeats... merozoites released again (hemolysis). Some merozoites become gametocytes, which mosquito takes up for mating.
Resistance develops when ppl have different Duffy antigens (which malaria uses to bind to RBC's & get in).
Severe diarrhea in AIDS pts (mild in everyone else -- travel, daycare). The cysts are visible on acid-fast staining. (Other acid-fast stainers: the bacteria Mycobacterium & Nocardia, the great TB mimicker!)
Cat feces & meat contain cysts. Brain: birth defects in fetuses, abscesses in HIV pts (HA, focal neuro signs, retinitis --> blind). A baby might be fine, but then in 20's: reactivation --> retinitis --> blind.
Dysentery. More common in developing countries (cysts in water, fecal-to-oral). Bloody diarrhea (when trophozoites invade intestinal wall), liver abscess/RUQ pain... but most infections actually asymptomatic.
Foul play: Rapidly fatal meningoencephalitis. Ingest while swimming in fresh water (via cribiform plate).
Dirty contact lenses: keratitis --> blind
Tapeworms (mate in GI tract) + flukes.
Tapeworms: T.solium, D.latum, E.granuilosus
Flukes: Schistosoma, C.sinensis, P.westsermani
Nematode (roundworm) species where you eat the eggs
Enterobius, Ascaris, Trichinella spiralis, Toxocara canis (eggs in eggs)
Worm species where larvae penetrate your skin
Roundworms: Strongyloides, Necator americanus (hookworm)
If you eat tapeworm larvae, then brain cysts.
Nematode (roundworm) species transmitted by an insect vector
Onchocerca (female blackfly), Loa loa (deer, horse, & mango flies), Wuchereria bancrofti (female mosquito)
Pinworm. Ingest eggs (food, or fecal-to-oral) --> mature in gut --> eggs hatch at perianal opening
Giant roundworm. Ingest eggs --> intestinal infection. Kids can get malnutrition, gut obstruction... but many people infected w/o much disease.