AN UPDATE ON CURRENT STATUS OF ANTIBIOTIC RESISTANCE IN SALMONELLA TYPHI: A RETROSPECTIVE ANALYSIS OF BLOOD CULTURE REPORTS FROM A TERTIARY CARE HOSPITAL

Background: Pakistan bears most of the burden of drug-resistant typhoid, challenging its healthcare systems with substantial cost. This study’s purpose is to investigate resistance in community-acquired salmonella typhi to guide its evidence-based empiric treatment. Methods: This study used retrospective data from the microbiology laboratory, Khyber Teaching Hospital, Peshawar (September 2022-March 2023). Data of routine diagnostic samples for typhoid was retrieved from the database. Kirby–Bauer disk diffusion method was employed to determine the sensitivity of S. Typhi against a panel of 21 selected antibiotic discs (not exclusively for each isolate). Results: Among 1742 suspected patients, 239 (13.92%) were positive for S. Typhi with 212/238 (89.1%), 227/233 (97.4%), and 196/239 (82.0%) isolates resistant to chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole, respectively. High resistance (88.0% to ciprofloxacin) was detected against fluoroquinolones. Third-generation cephalosporins also showed poor activity with 144/158 (91.1%) and 120/136 (88.2%) resistance towards ceftriaxone and cefixime, respectively, except for cefoperazone/sulbactam (2/123, 1.6%). Among 157 tested isolates, 3 (1.9%), 9 (5.7%), and 123 (78.3%) were labeled as non-resistant, MDR, and XDR strains, respectively. XDRs were less resistant to azithromycin (1/114), piperacillin/tazobactam (1/123), carbapenems (0/123), and tigecycline (0/123). Conclusion: XDR S. Typhi was observed as the dominant strain in Peshawar regions for which azithromycin is still the drug of choice. With emerging resistance, azithromycin safety should be ensured through antibiotic stewardship principles. An interesting finding was the enhanced activity of cefoperazone/sulbactam, suggesting future studies. Alternative options are expensive antibiotics which can be used as a last resort. Keywords: Typhoid, Antibiotic resistance, Extensive drug-resistant (XDR) S. Typhi, Pakistan.