Antibiotic Sensitivity Trends in Salmonella Blood Isolates: A Microbiological Perspective

Background: Enteric fever caused by Salmonella enterica serovars Typhi and Paratyphi remains a significant public health concern in endemic regions. The emergence of antimicrobial resistance, particularly to fluoroquinolones, has complicated treatment strategies and underscores the need for continuous regional surveillance to guide empirical therapy. Material and Methods: A laboratory-based retrospective study was conducted in the Department of Microbiology, Gujarat Cancer Society Medical College, Hospital and Research Centre (GCSMCH & RC), Ahmedabad, from January 2024 to August 2025. A total of 298 non-duplicate Salmonella isolates recovered from positive blood cultures were included. Identification was performed using standard biochemical methods and serological confirmation. Antimicrobial susceptibility testing was carried out using the Kirby–Bauer disc diffusion method on Mueller–Hinton agar in accordance with CLSI 2024 guidelines. Results: Among the 298 isolates, Salmonella Typhi was predominant (250; 83.89%), followed by Salmonella Paratyphi A (46; 15.43%) and Salmonella Paratyphi B (2; 0.67%). High susceptibility was observed to ceftriaxone (99.6%), cefotaxime (99.6%), ceftazidime (99.6%), cefixime (99.6%), cefepime (100%), cefoperazone–sulbactam (100%), and azithromycin (100%). Ciprofloxacin and levofloxacin demonstrated reduced susceptibility, with resistance rates of 4.69% respectively. Conclusion: The study highlights significant fluoroquinolone resistance among Salmonella blood isolates, limiting their role in empirical therapy. Sustained susceptibility to cephalosporins, β-lactam/β-lactamase inhibitor combinations, and azithromycin supports their continued use. Periodic antimicrobial surveillance is essential for optimizing treatment strategies for enteric fever.

Keywords: Salmonella Typhi, Salmonella Paratyphi, antimicrobial resistance, blood culture, enteric fever.