Clinical microbiology

Question 1

Sterile sites in body

Answer 1

Genitourinary tract 
CNS
Cardiovascular/Circulatory system
Bone, joints 
Lower respiratory tract

Question 2

Lab diagnostics to identify pathogen

Answer 2

1) Microscopy
- E.g. Gram-stain, acid fast stain
2) Culture
3) Biochemistry
4) Serologic/Immunologic diagnostics
- E.g. Immunofluorescence, enzyme immunoassay, Western blot
5) MS / MALDI-TOF
6) Molecular/Nucleic acid based diagnostics
- E.g. PCR, nucleic acid probes

Question 3

Carry out AST for

Answer 3

1) Clinically significant isolates
2) Appropriately collected specimens
3) Possible resistance to primary therapeutic agents
4) Standard performance method & interpretive criteria available

Question 4

AST testing methods

Answer 4

1) Agar / Broth dilution method
2) Kirby-Bauer disk diffusion method
3) E-test

Question 5

Factors affecting in vivo activity of antibiotics

Answer 5

1) Ability of antibiotic to reach site of infection
2) Protein binding of drug
3) Patient’s immune system
4) Drug interactions
5) Some bacteria express enzymes that inhibit antibiotic in vivo
6) Drainage/Removal of infected foci

Question 6

Timeline

Answer 6

Day 1: Gram stain
Day 2: Culture bacteria
Day 3-4: Identify bacteria
Day 4: AST

Question 7

What is an antibiogram

Answer 7

Tabulates antimicrobial susceptibility of common bacterial isolates collected in hospital/institution

Question 8

Uses of antibiogram

Answer 8

Local resistance pattern
Monitor resistance trends over time
Guides selection of antibiotics in empiric therapy