The emergence of extensively drug-resistant (XDR) Salmonella has raised concerns about the effectiveness of third-generation cephalosporins for empiric treatment. However, precise data on the burden of enteric fever and the prevalence of XDR Salmonella in different regions of Pakistan remain limited. This study aimed to determine the frequency of various Salmonella strains and specifically assess the prevalence of XDR Salmonella typhi and Salmonella paratyphi in Sindh. Between January and November 2023, a total of 7,900 blood and 18,000 urine cultures were processed. Positive cultures were identified using conventional biochemical tests, antisera, and, when needed, the Analytical Profile Index (API-20E). Antibiotic susceptibility testing (AST) was performed using the Kirby-Bauer disc diffusion method. Out of all samples, 134 blood and 29 urine cultures yielded Salmonella growth, with most cases occurring in males (61.9%) and school-aged children (61.3%). The most common strain was Salmonella typhi (82.2%), followed by S. paratyphi A (9.8%) and S. paratyphi C (7.3%), while S. paratyphi B was isolated from only one blood sample. Resistance was observed against first-line antibiotics and fluoroquinolones (69%) as well as third-generation cephalosporins (51%). None of the S. typhi, S. paratyphi A, or S. paratyphi C isolates showed resistance to azithromycin or meropenem, and all S. paratyphi A isolates remained sensitive to co-trimoxazole and cephalosporins. Although 49% of Salmonella isolates were sensitive to all tested antibiotics, a high proportion (42.9%) were found to be XDR in both blood and urine samples. In contrast, the frequency of multidrug-resistant (MDR) Salmonella was relatively low (7.9%). These findings highlight the persistence of the XDR Salmonella outbreak across Pakistan, underscoring the urgent need for effective surveillance and updated treatment strategies.
Khan et al. (Thu,) studied this question.