Antimicrobial Resistance Patterns and Prevalence of Salmonella Species in Blood Samples: Insights From a Tertiary Care Center in Nepal.

Abstract

Background: Typhoidal Salmonella infections remain a significant public health concern in low- and middle-income countries, with antimicrobial resistance (AMR) posing a major challenge. This study aimed to assess the prevalence and AMR patterns of Salmonella species in clinical samples from a tertiary care center in Nepal.

Methods: The study was conducted at the microbiology department in the country's largest public tertiary care hospital, TUTH, Nepal. A retrospective analysis was performed on 16,579 clinical specimens with culture-confirmed Salmonella isolates. Antimicrobial susceptibility testing was performed using the Kirby-Bauer disk diffusion method. Resistance and susceptibility trends were analyzed.

Results: Among 16,579 clinical samples analyzed, enteric fever was identified in 114 cases (0.7%). Of these, Salmonella Typhi accounted for 77.2%, while Salmonella Paratyphi comprised 22.8%. No multidrug resistance was observed, and all isolates were susceptible to third- and fourth-generation cephalosporins (e.g., cefixime, ceftriaxone, and cefepime) and β-lactamase inhibitors (e.g., piperacillin-tazobactam).Salmonella Paratyphi showed 100% sensitivity to ampicillin, amoxicillin, and cotrimoxazole, while susceptibility to chloramphenicol was high for both S. Typhi (88.9%) and S. Paratyphi (92.9%). Gentamicin exhibited comparatively lower sensitivity, with rates of 78.3% for S. Typhi and 80% for S. Paratyphi. Ciprofloxacin showed the lowest susceptibility, at 47.6% for S. Typhi and 60% for S. Paratyphi.

Conclusion: Our study identified a lower prevalence of culture-confirmed typhoidal Salmonella infections, with Salmonella Typhi predominating over Salmonella Paratyphi. High resistance to ciprofloxacin and gentamicin was observed, while susceptibility to ampicillin, chloramphenicol, and cotrimoxazole re-emerged, suggesting their potential for reintroduction in treatment. No multidrug resistance or resistance to third- and fourth-generation cephalosporins (e.g., cefixime, ceftriaxone, cefepime) and β-lactamase inhibitors (e.g., piperacillin-tazobactam) was noted, supporting their reliability for empirical therapy. These findings underscore the need for ongoing antimicrobial surveillance to guide effective treatment strategies.