Pharmacotherapy of Infectious Diseases and Antimicrobial Stewardship
What the exam tests
Infectious disease questions test empiric choice, PK/PD targets, culture interpretation, stewardship and locally relevant infections. Iraq's common problems include brucellosis, typhoid, tuberculosis, and multidrug-resistant Gram-negative infections in hospitalized patients.
Core rules
- Obtain cultures before the first antibiotic unless the patient is septic; then give antibiotics within one hour.
- Empiric therapy follows the local antibiogram, site, severity and allergy history; de-escalate when culture results return.
- Beta-lactams are time-dependent (fT>MIC); aminoglycosides and fluoroquinolones are concentration-dependent.
- Switch IV to oral when the patient is afebrile, hemodynamically stable and absorbing enteral feed.
- Document the indication and planned duration; shorter courses are preferred for many infections.
- Penicillin allergy labels are often inaccurate; use a structured history and challenge or delabel when appropriate.
Worked example
A 45-year-old farmer from a rural area presents with fever, sweats, arthralgia and sacroiliitis. Blood cultures grow Brucella melitensis. Treat with doxycycline 100 mg twice daily plus rifampicin 600–900 mg daily for six weeks, or doxycycline plus streptomycin for two to three weeks. Monotherapy is avoided because relapse is common.
Traps
Treating asymptomatic bacteriuria; using vancomycin for MRSA pneumonia without confirming the diagnosis; missing the need for source control; continuing antibiotics for a positive culture that represents colonization; forgetting rifampicin's CYP450 induction and orange discoloration of body fluids.