Diagnostic Methods for Bacterial Infections

Question 1

fastidious

Answer 1

difficult to grow

Question 2

Should PCR or culture be used for fastidious organisms?

Answer 2

PCR

Question 3

When to culture?

Answer 3

obvious gross lesion, easily accessible (ex: ear, feces, etc)

Question 4

16S

Answer 4

for bacterial PCR

Question 5

18S

Answer 5

for fungal PCR

Question 6

Should you isolate an organism from culture for antimicrobial susceptibility testing?

Answer 6

yes

Question 7

MALDI-TOF

Answer 7

mass spectrophotometry used to identify organisms following isolation

Question 8

Other ways to identify organisms besides direct ID

Answer 8

detect toxins produced by an organism, detect biochemical changes, look at characteristic lesions, etc

Question 9

Peak Antibody Titers

Answer 9

occur 2-3 weeks post-infection

Question 10

convalescent

Answer 10

recovering [from illness]

Question 11

What immunoglobulin would you want to detect to look for a current infection versus an earlier exposure or late infection?

Answer 11

IgM (vs IgG)

Question 12

S/P

Answer 12

sample to positive ratio

Question 13

Why use S/P with ELISA?

Answer 13

controls for minor variations in assay with time, temperature, etc. (normalizes the values)

Question 14

Test commonly used for surveillance?

Answer 14

ELISA

Question 15

select agent

Answer 15

biological agents and toxins that have been determined to have the potential to pose a severe threat

Question 16

Is an ELISA good to test one patient?

Answer 16

nah, 96 well plates cost money to run

Question 17

Agglutination reactions

Answer 17

good for detecting Brucella and Leptospira Ab titers

Question 18

Limitation(s) of IFA?

Answer 18

require a secondary host species specific antibody (anti-IgM or IgG), possible autofluorescence from tissues

Question 19

Agar Gel Immunodiffusion Pro and Con

Answer 19

very specific but very slow and expensive

Question 20

Cell Mediated Immune Responses to Determine Infectious Status of an Animal

Answer 20

Caudal fold tests for Mycobacterium bovis
Comparative cervical tuberculin test
Gamma-interferon responses

(honestly more often used with viruses)