Question | Answer |
FTA-ABS, MTA-TP: to dx: | Syphilis |
catalase pos GNR, facultative intracellular parasite | Legionella |
Motile, oxidase-pos GNR +/- polysaccharide slime prodn, blue-green pus: | Pseudomonas |
Nonmotile facultative anaerobe GNR, contains endotoxic lipopolysaccharide, does not produce H2S: | Shigella |
large GNR, produces mucoid capsule on agar | Klebsiella |
Legionella will only grow on: | charcoal yeast extract agar w/iron & cysteine |
Mildly GN, fried egg colonial morphology on special media: | Mycoplasma pneumoniae |
Giant Multinucleated cells | Herpes virus (Genital) |
Tzank Smear | Herpes virus (Genital) |
Gram negative intracellular diplococci = | Gonorrhea |
bacterial meningitis: CSF | turbid to purulent; high pressure; high WBC w/segs; pro: 100-500; low glucose |
viral meningitis: CSF | normal pressure; WBC <1000 (lymph/mono); pro & glu normal |
granulomatous meningitis: CSF | high pro, low glu, lymphocytosis |
granulomatous meningitis: dx studies | Cx to dx but takes weeks; CT/MRI: enhancement of meninges, poss hydrocephalus |
brain abscess: dx studies | CT/MRI, then LP (CSF usu polymicrobial) |
Lymphocyte pleomorphism; heterophile Ab: | EBV |
Gram-positive encapsulated box-shaped rods in chains (box cars) = | B. anthracis |
Gram-neg pleomorphic bacillus = | B. pertussis |
CMV labs | lymphocytosis or leukopenia; intracytoplasmic inclusions (owl eyes) on tissue bx |
Orbital cellulitis | sinus xray & CT (soft tissue infiltration) |
Chronic sinusitis | MRI > CT for malig; CT > Waters view xray for sinus opacification |
HIV labs | +ELISA & Western blot; anemia, leukopenia, low pltateles, polyclonal hypergammaglobulinemia, high chol |
What are the 4 methods for diagnosis of HIV | Detect antibodies to the virus, detect viral p24 antigen, detect viral nucleic acid, culture HIV virus |
What is the most widely used method to diagnose HIV | Detection of antibody to HIV |
Most common cause of false positive tests for HIV in low risk pts | Recent immunization |
Initial screening for HIV = | EIA enzyme immunoassay (ELISA) |
What is the confirmatory test for HIV (done after the screening test) | Western blot or IFA (Immunofluorescence Assay) |
HIV requirement: | Patient must be informed of HIV testing; informed consent/ counseling no longer required nationally |
HIV Detuned testing | both sensitive & low-sensitivity tests; if only 1 is pos = recent infxn |
HIV p24 test | free antigen or bound antigen/Ab complexes; detectable 2-6 weeks post infection |
HIV p24 to dx: | viral Rx, neonatal infxn, detect HIV before seroconversion, dz progression |
HIV viral load | reflects Rx response better than CD4; detects transplacental transmission |
95% of HIV-infected patients test positive within: | 6 weeks of infection |
Counts predictive of risk fo opportunistic infection or malignancy in absence of HIV tx | CD4 <200 and CD4 lymph <14% |
Best test for dx of HIV before seroconversion and to monitor disease progression & response to tx | HIV viral load |
HIV-positive patients may also test positive for: | PPD, RPR, VDRL, CMV, toxyplasma IgG, hepatitis, Pap |
gold standard for imaging for acute sinusitis | CT |
EBV labs | Granulocytosis in first week, then lymphocytosis & many ATLs. +/- high AST/ALT & bili. Heterophile Ab pos within 4 weeks of onset. IgM rises & falls, IgG pos for life. |
Mumps labs | Serum IgM is diagnostic (may be delayed in immunized pt). May see high amylase, mild ARF. |
Rabies labs | DFA stain of bx / necropsy tissue (back of neck is 60-80% sensitive). RT-PCR or viral isolation from CSF/saliva also definitive |
SARS on CT | Ground glass opacities +/- focal consolidations |
SARS dx testing | RT-PCR for SARS-CoV in urine, stool (most likely pos), nasal secretions often neg early and variably positive by day 14. Serologies may be neg x3 weeks |
West Nile virus labs | IgM capture ELISA on serum/CSF. Acute & convalescent IgM titers may confirm acute infxn. PCR for blood donor screening. There is no vax. |
Anthrax diagnosis | Cx of skin lesion, blood, pleural fluid, CSF with box cars on microscopy. Widened mediastinum on CXR |
Campylobacter labs | Dark-field or phase contrast microscopy: GN, S-shaped or seagull-shaped bacteria |
Sigmoidoscopy shows punctate areas of ulceration and inflamed mucosa in infection with: | Shigella |