A 32-year-old man from Delhi presents with a 10-day history of sustained fever, headache, and abdominal pain. Blood culture grows Salmonella typhi sensitive to fluoroquinolones, third-generation cephalosporins, and azithromycin, but resistant to chloramphenicol and trimethoprim-sulfamethoxazole. What is the drug of choice for treatment of this enteric fever?

Explanation

## Drug of Choice for Enteric Fever — Resistance Patterns ### Current Treatment Landscape **Key Point:** In India, resistance patterns of Salmonella typhi have evolved dramatically over the past two decades. Multidrug-resistant (MDR) strains (resistant to chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole) are now endemic, necessitating a shift in first-line therapy. ### First-Line Options by Resistance Profile | Resistance Pattern | First-Line Drug | Alternative | Avoid | |---|---|---|---| | Susceptible to all | Chloramphenicol, ampicillin, or TMP-SMX | Fluoroquinolones | — | | MDR (resistant to above three) | Fluoroquinolone (ciprofloxacin) or 3rd-gen cephalosporin | Azithromycin | Chloramphenicol, ampicillin, TMP-SMX | | Fluoroquinolone-resistant (FQR) | 3rd-gen cephalosporin (ceftriaxone) or azithromycin | — | Fluoroquinolones | | Extensively drug-resistant (XDR) | Azithromycin or carbapenems | — | All above | ### Why Ciprofloxacin Here? **High-Yield:** The isolate in this case is **fluoroquinolone-sensitive** and **resistant to the older triple drugs** (chloramphenicol, TMP-SMX, ampicillin). Ciprofloxacin is the preferred fluoroquinolone for enteric fever because: 1. **Excellent intracellular penetration** — reaches macrophages where Salmonella resides 2. **Oral bioavailability** — allows step-down from IV therapy 3. **Rapid defervescence** — fever typically resolves within 3–5 days 4. **Standard dosing:** 500 mg orally twice daily for 5–7 days (or 400 mg IV twice daily if severe) **Clinical Pearl:** In uncomplicated enteric fever without complications (perforation, encephalopathy), fluoroquinolones are preferred over cephalosporins because they achieve better intracellular concentrations and shorter treatment duration (5–7 days vs. 7–14 days for cephalosporins). ### Rationale for Alternatives - **Ceftriaxone (3rd-gen cephalosporin):** Excellent choice for severe disease, complications, or fluoroquinolone resistance; requires longer duration (7–14 days) - **Azithromycin:** Reserved for fluoroquinolone-resistant or extensively drug-resistant strains **Mnemonic:** **FQMAC** — Fluoroquinolones, Macrolides (azithromycin), And Cephalosporins are the modern trilogy for resistant enteric fever. [cite:Harrison 21e Ch 155]