PREVALENCE AND ANTIBIOGRAM OF SALMONELLA SPECIES ISOLATED FROM BLOOD SPECIMEN AT A TERTIARY CARE HOSPITAL

Background: This retrospective study aimed to evaluate the prevalence and antimicrobial susceptibility patterns of Salmonella species isolated from blood specimens at a tertiary care hospital between September 2022 and September 2024.

Methods: Blood culture was done by automated system (BacT/ALERT, Biomerieux). Identification, antibiotic susceptibility testing and MIC value were done with the help of Vitek-2 (Biomerieux System). AST is also done by Conventional method (Kirby-Bauers Disk diffusion) for some Antibiotics like Ampicillin, Azithromycin (only for S. Typhi) and Chloramphenicol. To confirm the serotype, we had performed slide agglutination test using specific antisera (Sifin diagnostics gmbh, Germany).

Results: A total of 2045 blood cultures were processed, yielding 90 isolates of Salmonella, including 73 (89.36%) Salmonella Typhi, 15 (16.67%) Salmonella Paratyphi A, and 2 (2.12%) Salmonella enterica. In our study out of total 90 isolates of Salmonella, 22 (24.45%) isolates are MDRO and 68 (75.55%) isolates are non-MDRO. Among these, Salmonella Typhi showed high susceptibility to amoxicillin/clavulanic acid (100%), ertapenem (100%), and meropenem (98.6%), with 0% susceptibility 64% intermediate & 36% resistance to ciprofloxacin. Salmonella Paratyphi A demonstrated 100% susceptibility to cefepime, ertapenem, imipenem, and colistin, but 0% susceptibility &100% resistance to ciprofloxacin. A notable decrease in susceptibility to fluoroquinolones, particularly ciprofloxacin, was observed. Third-generation cephalosporins, such as ceftriaxone, retained efficacy, showing 89% susceptibility for S. Typhi and 73.5% for S. Paratyphi A. Carbapenems and colistin were found effective for multidrug-resistant infections.

Conclusion: This study highlights increasing antimicrobial resistance in Salmonella Typhi and Salmonella Paratyphi A, with reduced effectiveness of ciprofloxacin, in both S. Typhi and S. Paratyphi A. Third-generation cephalosporins like ceftriaxone remain effective. Amoxicillin/clavulanic acid and piperacillin/tazobactam are good empirical choices, with de-escalation based on susceptibility testing. Carbapenems should be used cautiously in severe cases, and colistin is effective against multidrug-resistant strains. The findings stress the

need for continuous resistance monitoring and updated treatment guidelines to ensure appropriate antibiotic use and limit resistance.