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
