Diagnostic Bacteriology

Question 1

When are specific diagnosis of bacterial infections needed?

Answer 1

When the animal is significantly compromised
-they are very young, very old or seriously ill
-the suspected infection is in a difficult to treat site or a site with serious consequences
-when the suspected pathogen does not have a predictable susceptibility pattern or rapidly develops resistance
-poor response to earlier therapy
-outbreak of disease/notifiable disease

Question 2

What do you need to figure out before taking a sample for C/S testing?

Answer 2

1. The specific location of the infection
2. Whether the site is sterile or if it is a site with normal flora
3. When to sample
4. What technique to use

Question 3

What is the problem with swabs?

Answer 3

You often dont get enough material, bacteria can adhere to them and not go into the media, they can dry out causing bacteria to die, and they are often used where they shouldnt be

Question 4

What are the 2 main indications for gaurded swabs?

Answer 4

Intrauterine and nasopharyngeal samples

Question 5

Describe the pros and cons of fine needle aspirates.

Answer 5

Pros: preferred for almost all samples, easier for collecting sample using sterile technique, easier to get more material, cheap and easy to use

Cons: bacteria dont live in them forever, particularly anaerobes

Question 6

What are the pros and cons to biopsy/surgical sample?

Answer 6

Pros: may be needed to bypass normal flora, bacteria can survive longer in tissues, tissues may represent the entire pathologic process

Cons: invasive, need sedation or anesthetic, more expensive, if long delay should process or add to transport media/transport vials

Question 7

What are the pros and cons of free catch samples?

Answer 7

Pros: cheap, may be only way to collect sample

Cons: will get contamination with normal flora

Question 8

How to take blood culture samples?

Answer 8

There are low levels of circulating bacteria in blood so you want a medium that is anticoagulatory and will encourage bacterial growth

Question 9

What are the major goals when transporting samples?

Answer 9

Prevent contamination, maintain viability of all organisms present, maintain ratios of bacteria as in clinical sample if mixed infection
-beware of sample drying, exposure to noxious environment, excessive time delays
-deliver to lab asap, deliver in appropriate containers, keep cool, and use appropriate transfer media