Week 13 (exam 4) Flashcards
What are the 5 distinct test types for genetic testing
direct examination
culture
antigen detection
nucleic acid amplification tests
serology
What color stain is gram-positive
blue/purple
What color stain is gram-negative
red/pink
Describe what cultures are
mainstay of microbiologic diagnosis
sensitive and specific
What is a negative aspect of cultures
only detect typical bacteria
- mycobacteria, fungi, parasites, and viruses must request appropriate tests
Where can cultures be taken from
multiple sites
- throats, nasal, cervical/urethral, wound, synovial fluids, tissue
What is culture sensitivity
determine the organism’s abx susceptibility
What does a urine culture sensitivity report contain
RIS
- r = resistant
- i = intermediate
- s = sensitive
What is an antigen detection test
rapid detection of infectious agents
What is a nucleic acid amplification test
detect difficult-to-grow or slow-growing organisms
What organisms does NA amplification detect
chlamydia, gonorrhea, HIV viral load, HSV encephalitis, MRSA, TB
Describe what an antistreptolysin O titer test is
blood test to measure antibodies against streptolysin O (a substance produced by group A strep)
used to detect if patient has had a recent infection by group A strep
An antistreptolysin O titer is used in diagnosis of
group A strep
What are the complications of antistreptolysin O titer
rheumatic fever, scarlet fever, glomerulonephritis
Antistreptolysin O titer uses serology to determine…
possible streptococcus disease
Antistreptolysin O titer present in serum…
1 week to 1 month post-infection onset
When do we order blood cultures
routine order on patients presenting with sepsis
What should you do to prevent specimen contamination when getting a blood culture
draw cultures 1st prior to any other tubes
obtain 2 culture specimens from 2 different sites 15 minutes apart
What is an indication for throat cultures
taken to diagnose bacterial, viral, gonococcal, candida phayngitis
Throat swabs are used to isolate which bacteria
streptococci
meningococci
gonococci
bordetella pertussis (nasopharyngeal swab)
corynebacterium diphtheria
What test is available to minimize antibiotic overuse
rapid strep screens
- rapid antigen detection test
- less sensitive than posterior pharynx swab
What is a urine culture and what do you need to make sure of
initially conducted as a urine dip or urinalysis
make sure it is a clean catch
What are the indications for cervical/urethral testing
patients with vaginal discharge, pelvic pain, urethritis, penile discharge
patients with STD risk
Compare and contrast wound cultures
aerobic
- with oxygen
- wounds closer to the surface
anaerobic
- without oxygen
- deeper wounds
How do you collect a wound culture
should “roll” swab
What are the types of indications for stool testing
stool culture
c. diff
ova and parasite
What are the indications for tuberculosis testing
Frequent close contact with someone who has a known infection
Have lived in a country where many people have TB
Work or live in a nursing home/health care facility, prison, or homeless shelter
Have HIV infection or poor immune system (on immunosuppressive drugs)
What do you use to diagnose tuberculosis
TB culture
Quantiferon GOLD test
- interferon-gamma release assay IGRA
What do we use since we are unable to make an acid-fast bacillus diagnosis with a positive AFB alone
need TB cultures
How is the procedure of an acid-fast bacillus done
done via sputum sample (same as TB)
How many blood tubes are used for a quantiferon gold test
4 tubes
Why do we use quantiferon gold test and not a culture
culture is the gold standard, IGRA is quicker and sensitive
If a quantiferon golf test is positive what do we do
order chest x-ray and cultures
What are other names for tuberculin skin testing
Mantoux test
PPD test
What shouldn’t you do after a tuberculin skin test
cover it up with a bandaid
Where do we find histoplasmosis
soil, bird, and bat droppings
What do we see on a CXR of histoplasmosis
miliary infiltrates
What is the gold standard for diagnosis of histoplasmosis
bone marrow culture
What do we see on a CXR of aspergillosis
fungus ball
What is the standard for HSV detection
culture
What dermatological finding is associated with measles (rubeola)
Koplik spots
How do we detect measles
Measles virus RNA revers transcription PCR-preferred method
What virus is associated with Mumps and how do we diagnose it
paramyxovirus
viral culture: saliva, throat, CSF, urine\
PCR: rapid diagnosis
Cytomegalovirus infects what
virus infects leukocytes
Parvovirus B19 is associated with what dermatological finding
erythema infectioussum
“slapped cheek appearance”
How do we diagnose Epstein-Barr virus (EBV)
diagnosed via heterophile Ab test
- “monospot”
How do we diagnose cryptococcus
diagnosed via CSF an serum testing
What is the bacteria that causes syphilis called
treponema pallidum
Compare and contrast the 2 groups of antibodies of syphilis
nontreponemal = reagin antibody
treponemal = antibodies directed towards treponema
What tests do we run for nontreponemal (syphilis)
RPR - rapid plasma reagin
VDRL: venereal disease research laboratory
What tests do we run for treponemal (syphilis)
fluorescent treponemal antibody absorption test (FTA-ABS)
- more accurate than RPR/VDRL
What do we see on KOH testing
budding yeast with hyphae
