Discuss the factors that may affect your choice of antimicrobial agent in a critically ill septic patient, giving examples where relevant.
Patient Factors
Organism
Site of infection
Organ dysfunction
Toxicity
Drug interactions
Non anti-microbial effects of antimicrobial
Hospital factors
Route of administration
Cost
Bactericidal vs bacteriostatic
Theoretical benefit from bactericidal drugs. Controversial whether there is a clinical benefit
Additional comments:
Candidates were not expected to provide long lists of antimicrobial agents but to mention some examples where relevant. Overall, the question was poorly answered with superficial answers showing a lack of depth of understanding of the topic. Some wrote about dosing and dose adjustment but not about the choice of antimicrobial agent. Some candidates included key phrases e.g., “time dependent killing” without any demonstration of understanding of how that concept affected the choice of antibiotic.
This vaguely worded broad question was answered poorly. This is not because the trainees were unaware of the influence of susceptibilities or drug interactions on antibiotic choice, but because they could not guess what exactly the examiners wanted from them.
The tabulated answer below was largely derived from an article by Surbhi et al (2011) from the Mayo Clinic Proceedings.
Factors | Discussion and examples | |
Disease specifics | Travel history |
|
Occupational exposure |
|
|
Recreational exposure |
|
|
Recent antimicrobial use |
|
|
Empiric vs. definitive |
|
|
Urgency and timing |
|
|
Reliability of cultures |
|
|
Host factors | Clearance |
|
Age |
|
|
Genetic variation |
|
|
Pregnancy and lactation |
|
|
Immunocomptence |
|
|
Allergies |
|
|
Organism factors | Susceptibility |
|
Biology |
|
|
Source control |
|
|
Duration of therapy |
|
|
Assessment of response |
|
|
Drug factors | Cost |
|
Toxicity |
|
|
Bioavailability |
|
|
Site penetration |
|
|
Bactericidal vs bacteriostatic |
|
|
Synergistic combination |
|
LONGACRE, AB. "Factors influencing the choice of antibiotics in therapy." The New Orleans medical and surgical journal 103.4 (1950): 160-167.
Leekha, Surbhi, Christine L. Terrell, and Randall S. Edson. "General principles of antimicrobial therapy." Mayo Clinic Proceedings. Vol. 86. No. 2. Elsevier, 2011.