23-year trends indicate low rates of antimicrobial resistance inSalmonellaParatyphi A

AbstractBackgroundTyphoid and paratyphoid remain common bloodstream infections in areas with suboptimal water and sanitation infrastructure. Paratyphoid, caused bySalmonellaParatyphi A, is less prevalent than typhoid and its antimicrobial resistance (AMR) trends are less documented. Empirical treatment for paratyphoid is commonly based on the knowledge of susceptibility ofSalmonellaTyphi, which causes typhoid. Hence, with rising drug resistance inSalmonellaTyphi, last-line antibiotics like ceftriaxone and azithromycin are prescribed for both typhoid and paratyphoid. Here, we report 23-year AMR trends ofSalmonellaParatyphi A in Bangladesh.MethodsFrom 1999 to 2021, we conducted enteric fever surveillance in two major pediatric hospitals and three clinics in Dhaka, Bangladesh. Blood cultures were performed at the discretion of the treating physicians; cases were confirmed by culture, serological and biochemical tests. Antimicrobial susceptibility was determined following CLSI guidelines.ResultsOver 23 years, we identified 2,725 blood culture-confirmed paratyphoid cases. Over 97% of the isolates were susceptible to ampicillin, chloramphenicol, and cotrimoxazole, and no isolate was resistant to all three. No resistance to ceftriaxone was recorded, and >99% of the isolates were sensitive to azithromycin. A slight increase in minimum inhibitory concentration (MIC) is noticed for ceftriaxone but current average MIC is 32-fold lower than the resistance cut-off. Over 99%, of the isolates exhibited decreased susceptibility to ciprofloxacin.ConclusionsSalmonellaParatyphi A has remained susceptible to most antibiotics, unlikeSalmonellaTyphi, despite widespread usage of many antibiotics in Bangladesh. The data can guide evidence-based policy decisions for empirical treatment of paratyphoid fever.