Trends in antimicrobial resistance amongst Salmonella Typhi in Bangladesh: a 24-year retrospective observational study (1999-2022)

BackgroundRising antimicrobial resistance (AMR) in Salmonella Typhi restricts typhoid treatment options, heightening concerns for pan-oral drug-resistant outbreaks. Bangladesh contemplates introducing typhoid conjugate vaccine (TCV) to address the typhoid burden and AMR. However, large-scale surveillance data on typhoid AMR in Bangladesh is scarce. ObjectiveThis study explores the AMR trends in Salmonella Typhi isolates from Bangladesh, drawing comparisons with antibiotic consumption to optimize antibiotic stewardship strategies for the country. MethodsOur typhoid fever surveillance included two pediatric hospitals and three private clinics in Dhaka, Bangladesh, spanning 1999 to 2022. Blood cultures were performed at physicians discretion; cases were confirmed by microbiological culture, serological, and biochemical tests. Antimicrobial susceptibility was determined following CLSI guidelines. National antibiotic consumption data for cotrimoxazole, ciprofloxacin, and azithromycin was obtained from IQVIA-MIDAS database for comparison. ResultsOur 24-year surveillance, encompassing 12,435 Salmonella Typhi cases, revealed declining trends in first-line drugs (amoxicillin, chloramphenicol, cotrimoxazole) and multidrug resistance (MDR; 38% to 17%, 1999-2022). Cotrimoxazole consumption dropped, 0.8 to 0.1 DDD/1000/day (1999-2020). Ciprofloxacin non-susceptibility persisted (>90%) with unchanged consumption (1.1-1.3 DDD/1000/day, 2002-2020). Low ceftriaxone resistance (<1%) was observed, with rising MIC (0.03 to 0.12 mg/L, 1999-2019). Azithromycin consumption increased (0.1 to 3.8 DDD/1000/day, 1999-2020), but resistance remained [&le;]4%. ConclusionOur study highlights declining MDR amongst Salmonella Typhi in Bangladesh, thus reintroducing first-line antimicrobials could work as an empirical treatment option for typhoid fever. Our analysis provides a baseline for monitoring the impact of future interventions, including the TCV, on typhoid burden and associated AMR.