Microbio 2 Flashcards
How do neonates contract toxoplasmosis? What should pregnant women do to avoid congenital toxoplasmosis? Triad of ssx?
Transplacental transmission, w/in the first 6 months of pregnancy (in utero). Pregnant women shouldn’t handle cat litter in case of Toxoplasma in the cat feces.
>Triad: hydrocephalus, intracranial calcifications, choreoretinitis
Infectious mononucleosis.
MCC? SSx? Monospot test result?
> MCC: EBV
Pharyngitis, lymphadenopathy, atypical lymphocytes, splenomegaly.
Monospot (+) – serum heterophile antibodies agglutinate w/ RBCs of an unrelated species.
Heterophile antibody-negative mononucleosis-like syndrome.
MCC? SSx? How to contract? Monospot test result?
> MCC: CMV
Pneumonia, retinitis; Less commonly involves pharyngitis, lymphadenopathy vs. EBV-mono.
Can acquire w/ transfusion of leukocyte-laden blood products (infects leukocytes); also congenital, transplantation, sex, saliva, urine
Monospot (-)
An HIV patient w/ multiple ring-enhancing CNS lesions most likely has what?
1) Toxoplasmosis – don’t need pet exposure, can be transmitted thru contaminated foods; immunocompetents.
2) Primary CNS lymphoma – diffuse large-cell NHL of B-cell origin, EBV in almost all cases.
C. neoformans
[Transmission route, Dses]
Present in soil, bird droppings – transmitted via respi route (lungs).
Can cause meningoencephalitis, lung dse (pneumonia-like).
C. neoformans
[Stains]
> India ink: capsule shows as an unstained zone.
Mucicarmine: capsule stains red.
Methenamine silver: stains yeast cells (round cells w/ narrow-based buds).
V. cholera.
What media? Infectious dose?
Highly alkaline selective media: Thiosulfate-citrate-bile salts-sucrose (TCBS) agar
Acid-sensitive –> must survive acid pH of stomach to colonize SI –> 10^6 - 10^10 organisms
Neurocysticercosis.
Pathogenesis?
Ingest eggs of T. solium – embryos penetrate wall of small intestine – hematogenous spread to tissues (brain) – form cysticerci (fluid filled larval cysts surrounding invaginated scolex).
Which microbes only need a SMALL infectious dose to cause disease?
Shigella: 10 organisms
C. jejuni: 500
E. histolytica: 1-10
G. lamblia: 1-10
Which microbes need a LARGE infectious dose to cause disease?
Salmonella, Vibrio, C. perfringens, E. coli
10^4 - 10^8 (10^10)
Erythema infectiosum (Fifth disease) [Px, SSx]
Parvovirus B19, benign childhood illness.
>Replicate in erythrocyte precursors in bone marrow – blood group P antigen (“globoside”), the cell receptor for parvovirus B19.
>Nonspecific prodrome – erythematous rash on cheeks (“slapped cheek”) – lacy, reticular rash over trunk, extremities.
What is the most common lab finding associated w/ Legionella that can’t be found in other causes of pneumonia?
Hyponatremia.
>Inappropriate ADH secretion and/or renal tubulointerstitial nephritis impairing Na reabsorption
