PREVALENCE AND ANTIMICROBIAL RESISTANCE PATTERNS OF BACTERIAL ISOLATES FROM SURGICAL WOUND INFECTIONS IN A TERTIARY CARE HOSPITAL: A CROSS-SECTIONAL STUDY

Abstract

Background: Surgical site infections (SSIs) remain among the most frequent healthcare-associated infections worldwide and are increasingly complicated by antimicrobial resistance (AMR), particularly in resource-limited tertiary care settings. This study aimed to determine the prevalence of culture-positive surgical wound infections and characterize the antimicrobial resistance profiles of the causative bacterial isolates.

Methods: A hospital-based, prospective cross-sectional study was conducted over a 12-month period (January–December 2025) at the Department of Surgery and Microbiology, , a 500 -bed tertiary care teaching hospital Peshawar. Wound swabs/pus aspirates were collected aseptically from patients with clinically suspected SSI following the Centers for Disease Control and Prevention (CDC) surveillance definitions. Bacterial identification was performed using standard microbiological and biochemical methods (and/or an automated VITEK-2 system), and antimicrobial susceptibility testing (AST) was performed by the Kirby–Bauer disc diffusion method interpreted per current Clinical and Laboratory Standards Institute (CLSI) breakpoints. Multidrug resistance (MDR), extensive drug resistance (XDR), and pandrug resistance (PDR) were classified according to the Magiorakos et al. international consensus definitions. Data were analyzed using SPSS (version 26.0); categorical variables were expressed as frequencies/percentages, and associations were tested using the chi-square test, with p < 0.05 considered statistically significant.

Results: Of 850 surgical patients screened, 210 (24.7%) developed clinical signs of SSI, of which 158 (75.2%; 95% CI: 68.9–80.7%) were culture-positive, yielding 172 bacterial isolates (7.9% polymicrobial). Gram-negative bacteria predominated (108/172, 62.8%), led by Escherichia coli (19.8%), Klebsiella pneumoniae (16.3%), and Pseudomonas aeruginosa (14.0%); Staphylococcus aureus was the leading Gram-positive isolate (22.1%), of which 57.9% were methicillin-resistant (MRSA). High resistance was observed among Gram-negative isolates to ampicillin (88.9%), amoxicillin-clavulanate (74.1%), and ceftriaxone (65.7%), with comparatively preserved susceptibility to meropenem (91.7%) and colistin (97.2%). Gram-positive isolates showed high resistance to penicillin (90.6%) but retained near-universal susceptibility to vancomycin (98.4%) and linezolid (100%). Overall, 46.5% (80/172) of isolates met criteria for multidrug resistance, and 8.1% (14/172) were extensively drug-resistant.

Conclusion: Gram-negative organisms, particularly Enterobacterales and non-fermenters, are the predominant cause of surgical wound infections at this tertiary center, with a substantial burden of multidrug resistance. Carbapenems, colistin, vancomycin, and linezolid remain the most reliable empirical options, but their reserved use should be safeguarded through structured antimicrobial stewardship, periodic antibiogram updates, and strengthened infection-prevention practices.