Exploring the Resistance Pattern of Salmonella Typhoidal Species

Background: Enteric fever/ typhoid, an infection caused by Salmonella enterica serovars: typhi and paratyphi, is continuously increasing with the emergence of antibiotic resistant Salmonella. According to WHO, an estimated 110,000 people die from it every year.
Objective: The primary objective of this study was to investigate the antibiotic susceptibility pattern of typhoidal Salmonella species in blood cultures of patients.
Methodology: This was a cross-sectional study, executed at Microbiology Laboratory (Diagnostic Centre), PAF Hospital Faisal Base Karachi, from August 2023 to March 2024. Salmonella typhi in all clinically suspected cases of typhoid fever was identified through conventional techniques following standard microbiological protocols. Assessment of antibiotic susceptibility was performed by Kirby-Bauer disk diffusion method.
Results: Out of 1178 blood samples culture 54 were gram positive bacteria, 193 were gram negative bacteria and 931 samples showed no growth. Among the gram-negative sample, 140 tested positive for Salmonella enterica typhoidal species. API 20E was used to further differentiate and identify the Salmonella species, 131 cases were Salmonella typhi and 9 paratyphi. Out of 140 Salmonella isolates, 77% (108) were resistant to ampicillin, 49.2% (69) to Ceftriaxone, 35% (49) to Sulfamethoxazole, and 47% (66) to Ciprofloxacin. Azithromycin and Meropenem remained sensitive in all 140 isolates of Salmonella typhoidal species.
Conclusion: This study identified the susceptibility profiles of Salmonella typhoidal species. Our findings underscore the importance of continuous surveillance and judious use of antibiotics to combat the emergence of antibiotic –resistant strains. Further research is warranted to continuously monitor and adapt treatment protocols in response to evolving resistance in Salmonella typhoidal species.

Gram positive bacteria, Gram negative bacteria, frequency, Salmonella typhi, E. coli.