Bacteriology

Question 1

When is empirical therapy indicated? Three answers.

Answer 1

(There is a proven efficacious treatment for your top differential, when waiting for c/s results, and when client cannot afford c/s)

Question 2

What are some instances where specific diagnosis of bacterial infections is needed?

Answer 2

(Animal is significantly compromised (very young/old, seriously ill), suspected infx in a difficult to treat site or a site with serious consequences (brain, joint, etc.), suspected bacterial pathogens with unpredictable susceptibility patterns or ones that rapidly develop resistance, poor responses to earlier therapy, outbreak of disease, and suspected dz is notifiable)

Question 3

When are swabs an acceptable sample?

Answer 3

(Mucus membranes, ears, uterine (if using guarded), conjunctiva, cornea, only when you can’t collect something better)

Question 4

(T/F) Fine needle aspirate samples are the preferred method for all bacteriology samples.

Answer 4

(T)

Question 5

What are cons of FNAs?

Answer 5

(Bacteria don’t live in them forever, especially anaerobes so get them to the lab asap)

Question 6

When you take an FNA, you should also perform a smear. What evidence would you be looking for to indicate bacterial infection?

Answer 6

(Lots of neutrophils = inflammation, toxic changes, bacteria either extra/intracellular)

Question 7

What is the purpose of removing the topmost layer of a punch biopsy sample prior to submission for bacteriology testing?

Answer 7

(Removes surface contamination)

Question 8

Do bacteria survive longer in FNA samples or tissue samples?

Answer 8

(Tissue samples)

Question 9

What are the pros and cons of free catch samples?

Answer 9

(Pros → cheap, may be the only way to collect a sample (i.e. GI tract), cons → will get normal flora contamination)

Question 10

Do you want blood to clot when taking blood culture samples?

Answer 10

(No)

Question 11

Can you use EDTA tubes for a blood culture?

Answer 11

(No EDTA has direct bacterial effect, use specific blood culture vials)

Question 12

Sepsis is usually associated with cyclical fevers where there are troughs and spikes, when should blood culture samples be taken in these patients?

Answer 12

(When they are in a fever spike, this usually corresponds to when there is a high number of bacteria in the blood)

Question 13

What are other sample types that you can use blood culture tubes for?

Answer 13

(Joint and CSF fluid)

Question 14

Should blood culture tubes be refrigerated?

Answer 14

(No, leave at room temp to allow bacteria to multiply, there shouldn’t be bacteria in these sites anyway so if there’s some, that’s significant enough and the actual number of them doesn’t matter)

Question 15

If you take a sample under the impression that there may be fungal involvement, should that sample be refrigerated or not?

Answer 15

(Not)

Question 16

If you are taking samples from a site with normal flora, what do you need to consider when you are looking at your interpretation?

Answer 16

(The bacteria found is not apart of the normal flora (but still have to be sure it can cause dz) OR the bacteria is apart of the normal flora but it has increased numbers and has the ability to cause the dz seen)

Question 17

What is the four point rule that should be applied to all samples/interpretations taken from sterile sites?

Answer 17

(Was the sample collected correctly, was there inflammation present on cytology, was there an organism present on cytology, and can the diagnosed organism cause THIS dz)

Question 18

There are two reasons that when suspecting Brucella canis infection, a culture alone cannot be relied on and serology should be performed, what are those two reasons?

Answer 18

(Brucella canis bacteremia is very cyclical and can easily be missed during sampling and it is uncommon for a dog to have Brucella antibodies since it is not a common dz nor vaccinated for so being antibody positive is highly indicative of infection)

Question 19

Why should you perform tests on urine in discospondylitis cases?

Answer 19

(A lot of disco cases start as UTIs then spread hematogenously)

Question 20

Though strangles cases can be treated empirically, why might further diagnostics be performed?

Answer 20

(Bc is it highly contagious and is also reportable in some states)

Question 21

(T/F) It would be a reasonable choice to sample nasal discharge with a swab in suspect strangles cases.

Answer 21

(T, Strep equi ssp equi is not normal flora in the nose so it is reasonable to say if your sample comes back as Strep ssp equi, it is causing dz)

Question 22

Do you need susceptibility testing in strangles cases?

Answer 22

(Depends on the animal, if able to give IV injections of susceptible drugs, no but if you need to give oral meds d/t temperament, yes)

Question 23

What four questions do you need to ask yourself when you sampled a site with normal flora and are considering the significance of a bacteria on your report?

Answer 23

(Was the sample collected correctly, is the organism a part of the normal flora, can this organism cause dz, and are there an excess number of this organism (if it is a part of normal flora))

Question 24

In the case of the calf with white, pasty diarrhea, it was unable to be determined if the E. coli cultured from the fecal sample was the cause of the clinical signs. If you suspected E. coli still, what further tests could you run to either confirm or deny your suspicion?

Answer 24

(Could run a PCR to look for toxin gene or could test for E. coli toxin in feces)