Micro Flashcards
What is the causative organism of lymphogranuloma venereum?
Chlamydia trachomatis
How does a chancroid present?
Erythematous papule that rapidly turns into a pustule, and then a painful ulcer. The ulcer is 1-2 cm with a dermarcated boarder and is covered in a gray/yellow purulent exudate
What causes a chancroid ulcer?
Haemophilus ducreyi
What region do you find histoplasmosis in?
Central US; most frequently Ohio, Mississippi, Missouri river valleys
How does Coccidioides appear microscopically?
20-60 micrometer nonbudding spherules filled with endospores
Molluscum contagiosum is part of what virus family?
Poxvirus
What is the genome of the pox virus?
DsDNA, linear, enveloped and replicates in the cytoplasm with a DNA dependent RNA polymerase
An extracellular atypical fungus infecting patients with HIV?
Pneumocystis jirovecii
What do the granulomas look like of a person infected with Bartonella henelae?
Stellate granulomas with central necrosis and the organism
What causes cysticercosis?
Taenia solium
How does S aureus inhibit opsonization?
Protein A - binds Fc component of IgG
Skin scrapings from someone infected with HSV demonstrates what?
Intranuclear inclusion bodies
What family does RSV belong to?
Paramyxoviridae
How does one become infected with toxoplasma gondii?
Ingest the oocysts from cat feces or incompletely cooked lamb or pork
What does hantavirus cause? What is its mode of transmission?
Fatal respiratory illness; endemic to desert of SW US. Rodent droppings
Patient comes in contact with infected bird droppings and contracts and atypical pneumonia. What is the likely organism?
Chlamydophila psittaci
What does Rickettsia prowazekii cause?
Epidemic louse borne typhus
What do Cowdry type A inclusions look like?
Eosinophilic intranuclear viral inclusions
What is the classic triad of gestational toxoplasmosis?
Chorioretinitis, intracranial calcifications, encephalitis leading to hydrocephalus
What is the mechanism of cholera toxin?
Activating AC by ADP ribosylation of a GTP binding protein
What is the mechanism of exotoxin A? What organism produces it?
Pseudomonas aeruginosa; inhibits EF2 by ADP ribosylation
What kind of media do V vulnificus and parahaemolyticus grow on?
Alkaline media - TCBS
CMV is part of what virus family?
Herpesvirus family
What is erythema infectiosum?
Parvovirus B19 - slapped cheek fever
What is the mechanism causation of diarrhea due to cryptosporidiosis?
C parvum infects the brush border and causes direct lysis of the cells
Fungal infection that shows multiple tiny oval forms within macrophages on biopsy?
Histoplasmosis
During what stage of the bacterial life cycle do spores form?
Stationary phase - when cell growth ceases because of depletion of nutrients or accumulation of toxins
What is ecthyma grangrenosum? What causes it?
Black, necrotic center and a riased hemorrhagic ring outside; due to infection with P aeruginosa
What are common causes of septic abortion?
S aureus (very common), others: gram neg bacilli (E coli) and GBS
What generation is cefotaxime in?
3rg gen
Do third generation cephalosporins cover listeria?
No
Patient who recently underwent a genitourinary procedure has a UTI two days later. Gram stain shows gram + cocci in pairs and chains. Additionally, the organism is unable to convert nitrates to nitrites. What is the probable organism?
Enterococci - gamma hemolysis, PYR +, ability to grow in bile and 6.5% NaCl
How does RSV present?
Age <2 with antecedent nasal congestion/discharge and cough, following by wheezing/crackles and resp distress
