Trends of Antimicrobial Resistance in Typhoidal Strains of Salmonella in a Tertiary Care Hospital in Pakistan

Introduction: Enteric fever or typhoid fever is a major public health issue affecting greater than 27 million individuals globally and is responsible for greater than 200,000 deaths per year. Due to the extensive overuse of antimicrobials, the world is moving toward a pre-antibiotic era. The emergence and transmission of antibiotic-resistant Salmonella species are a global threat and a serious concern in developing countries such as Pakistan. This study aimed to determine the trends in antimicrobial resistance (AMR) of typhoidal strains of Salmonella in a tertiary care hospital in Pakistan. Materials and Methods: It was a descriptive, cross-sectional study conducted in the pathology department of Sharif City Hospital, Lahore, after approval by the ethical committee of the institution. A total of 50 blood culture specimens positive for Salmonella typhi and Salmonella paratyphi from January 2019 to March 2020 were included by the non-probability consecutive sampling technique. The samples were processed by conventional bacteriological methods for isolation and identification. The antimicrobial susceptibility testing was done by the Kirby-Bauer disc diffusion method as recommended by the Clinical and Laboratory Standard Institute (CLSI). The statistical package for social sciences (SPSS, IBM Corp., Armonk, NY) version 25 was used for data entry and analysis. Results: Among the first-line drugs (ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole), 70% of strains were resistant, and only 30% strains were sensitive to them. Among the cephalosporins, 52% strains were sensitive to ceftriaxone, and 48% strains were sensitive to ceftazidime, cefotaxime, and cefepime. Twenty-four percent of strains were sensitive to ciprofloxacin. Only 50% of strains were sensitive to ampicillin-sulbactam, and 92% of strains were sensitive to piperacillin-tazobactam. All the strains were 100% sensitive to imipenem and meropenem; 96% of strains were sensitive to co-amoxiclav, doxycycline, and azithromycin. The frequency of multidrug-resistant (MDR) and extensively drug-resistant (XDR) Salmonella species was 16% and 54%. Conclusion: The increasing frequency of MDR and XDR Salmonella species in Pakistan is a major concern. A significant percentage of the typhoidal strains of Salmonella is resistant to the first-line (16%) and second-line (54%) antibiotics. Carbapenems and azithromycin are the last resort of therapy in such cases.