Prevalence and antimicrobial resistance profile of multi-drug resistant Salmonella Typhi isolated from blood at Khyber Pakhtunkhwa

Salmonella typhi is developing a high risk resistant to different antibiotics in last few years. A gradual change in antimicrobial susceptibility has led to serious challenges in treatment. Using antibiotics without first determining the sensitivity of the bacteria can lead to treatment failure. Hence bacterial isolation and susceptibility testing are essential for effective antibiotic therapy. A study was conducted from July 2022 to August 2023 to evaluate the prevalence of multi-drug resistant S. typhi in clinical samples and determine its susceptibility pattern in different districts of Khyber Pakhtunkhwa, Pakistan. A total of 1625 blood samples were collected from patients with symptoms of enteric fever in Peshawar, Mardan, Swat, and Dir. Out of 1625 samples, 341 isolates were identified as S. typhi through biochemical tests and PCR amplification of the fliC gene. Kirby Bauer's disc diffusion method was used to assess the antimicrobial activity using 11 different routinely used first-line and second-line antibiotics. Results showed that, the occurrence of S. typhi was 20.98 % in KP, appeared to be more prevalent in males (57.7%) than females (42.22%) while the age group ≤ 10 years had the highest infection rate of 54.25%. Seasonal analysis showed the highest occurrence of S. typhi in the summer season (38.41%). Peshawar had the highest prevalence of S. typhi (78.29%), followed by Dir (14.36%) and Mardan (7.03%). Antimicrobial susceptibility testing revealed that 90.71% of isolates were susceptible to Meropenem, while 71.83% were susceptible to Tetracycline. Higher resistance rates were observed for Ampicillin (77.40%), Sulfamethoxazole/trimethoprim (74.61%), Ceftriaxone (73.68%), and Erythromycin (71.52%). Significant portion of S. typhi isolates were identified as multi-drug resistant (71.94%) and extensively drug-resistant (22.38%). The study highlighted the high prevalence of multi-drug resistant S. typhi in Khyber Pakhtunkhwa and emphasize the need for effective surveillance and control measures to combat the spread of this pathogen