Bacteriology - Dx Flashcards
Bloodwork signs of inflammation
leukocytosis, neutrophilia w/ LS
when is a culture indicated?
if a definitive diagnosis changes treatment control and/or prognosis
empirical therapy if not
Important considerations to make when collecting a sample for C&S (4)
- specific location of infection
- sterile or normal flora
- when to sample (infective curve)
- collection technique
Why are fluid samples preferred over tissue > swab?
yields a much greater volume of sample
- when swabs must be used, use appropriate transport media + submit multiple swabs per site if possible
Which liquids are NEVER appropriate to suspend culture samples in?
- formalin
- alcohol
- EDTA
- heparin
What is the issue with swab collections?
- only hold ~0.05mL of fluid
- only pick up ~30% of bacteria
- can be difficult to extract bacteria off
- desiccate -> bacteria die
- exposed to air -> anaerobes die
indicated: mm, ears, uterus (guarded), cornea; when out of other options
when is the only time dry swabs are indicated?
PCR
What is the best transport media that covers aerobic, anaerobic, and fungal samples?
Amies media
evidence of inflammation on ytology +/-histopath
high protein, high cellularity/neutrophils, toxic changes, bacteria present
What is the preferred technique for fluid samples?
centesis
pros/cons to biopsy sample
Pros:
- can bypass NF (draining tracts)
- bacteria survive “longer” in tissues
- tissue may represent entire pathological process
Cons:
- invasive, expensive (sedation +/- anesthesia)
When taking blood culture samples, samples must be taken __?__ and kept at __?__ temperature.
- aseptically
- room
other RT samples: sus dermatophytes, CSF, joint fluid
What is the priority in sample transportation?
Deliver to the laboratory ASAP! - within 24h ideal
- prevent contamination, sample desiccation
- maintain viability of all organisms present
4 Point Rule when collecting from a sterile site
4 Point Rule = determining if detected organism = contamination or pathologic
1. sample collected correctly?
2. evidence of inflammation?
3. evidence of bacteria//organisms?
4. can these organisms cause disease?
When is empirical tx NEVER indicated?
- if suspected infection is in a difficult-to-treat site or has serious consequences
- animal is significantly compromised (very young, very old, seriously ill; co-morbidities)
- suspected bacterial pathogens do not have predicitable susceptibility pattern/or rapidly develop resistance
- suspected disease = reportable
- outbreak of disease (concern for contagion)
