When is empirical therapy indicated?
when high level of efficacy for proven treatments (uncomplicated cystitis, pyoderma, cat bite abscesses, kennel cough)
when waiting for c/s results
when client cannot afford c/s
What 3 criteria should you base empirical treatment on?
- likely bacteria to cause the present dz
- likely antimicrobial sensitivity pattern of the present bacteria
- other factors – site of infection, cost of antibiotic, ease of administration, etc.
T/F: you should always get a definitive diagnosis in practice
false – only required if it wil change your disease control recommendations or prognosis for the patient.
when is definitive diagnosis required? (6 indications)
- animal is significantly compromised
- suspected infection is in a difficult-to-treat site or has serious consequences (bone, joint, brain, etc.)
- suspected bacteria do not have predictable susceptibility
- poor response to previous therapy
- outbreak of disease and concern for contagion
- suspected disease is notifiable
why are swabs not the best diagnostic sampling method?
- often do not collect enough material – atleast do 2
- bacteria can adhere to them and dry out or not transfer to culture media
- bacteria are exposed to air, so obligate anaerobes would die
- sometimes people collect from sites they shouldnt (ie draining tracts)
what is the only diagnostic test indication for dry swabs?
PCR ONLY
never bacteriology because the bacteria dry out.
For what locations are swabs acceptable?
- Mucous membranes
- ears
- uterine
- conjunctiva
- cornea
what are the components of the 4-point rule for interpretation of samples collected from sterile sites?
- was the sample collected correctly?
- is inflammation present
- are there organisms present?
- can those organisms cause the present disease?
what are the 2 rules for interpreting samples collected from sites with normal flora?
- If the organisms are a part of the NF, are they in excess #?
- if the organisms are not a part of the NF, can they cause the current disease?
T/F: cytological results can provide a presumptive diagnosis in some cases.
true
what organism is often diagnosed by cytology alone?
fungi (exs. blasto and malessezia)
T/F: you can send off samples for c/s that you collected from a draining tract because there may be a joint infection and it is imperative you determine the pathogen and treat quickly.
false do NOT collect samples for c/s from draining tracts. if a joint infection is suspected, it is recommended that you collect from the area of true infection.
how do you collect a sample from a tendon sheath?
sterile prep of the area
then ultrasound-guided FNA
T/F: FNA is a preferred technique for all samples.
true
its an easy technique, cheap, and you get more material.
the only downside is that bacteria dont live in them forever, especially anaerobes.
what type of container are you going to put an FNA sample in to transport it to the lab?
sterile container and slides
what 3 things can you determine with an FNA aspirate that could give you information about the presence/absence of inflammation and/or infection?
- protein
- cell count estimate (TNCC)
- types of cells
what 3 things on cytology are suggestive of bacterial ifnection?
- PMNs
- bacterial cells (extracellular or intracellular)
- toxic changes
How does your diagnostic test choice change between a case of superficial pyoderma versus deep pyoderma?
superificial can tested using sticky tape test or swabbed because this is NOT a sterile area. It can also be treated empirically because of this.
deep pyoderma requires biopsy
what diagnostic test is best to diagnose deep pyoderma?
punch biopsy
clean skin, take punch biopsy, remove top layer of skin with sterile scalpel blade, send bottom layer for culture and biopsy.
what are the major “pros” to biopsy/surgical samples?
- may be needed to bypass normal flora (draining tracts)
- bacteria survive longer in tissues
- tissues can represent the entire pathological process.
what are the major “cons” to biopsy/surgical samples?
- invasive (sedation or anesthesia)
- expensive
- if long delay, you must add transport media or use transport vials
what type of samples would you collect in a calf that is systemically affected (fever, high RR and HR) and has diarrhea?
- blood culture for PCR
- fecal culture or PCR
why is a free-catch feces sample for culture an appropriate diagnostic for a calf with diarrhea?
free catch samples are cheap and easy to obtain
you can get contamination, but if you suspect pathogens causing disease that would NOT be a part of the normal flora (such as salmonella), then it is an ideal test.
This goes for urine as well.
should blood be clotted for cultures?
no. so do not use purple tops because they contain EDTA.
