Prevalence and Antibiotic Resistance Patterns of Micro-organisms in Post-operative Wound Infections from the Surgical Floor of Mayo Hospital

: Surgical site infections (SSIs) remain a major cause of postoperative morbidity in low- and middle-income settings, with rising antimicrobial resistance complicating empirical management. Local data on pathogen profiles and resistance patterns are essential to guide effective therapy and infection control strategies. Objective: To determine the prevalence of surgical site infections and to characterise the microbiological spectrum and antibiotic resistance patterns of pathogens isolated from post-operative wound infections at a tertiary care hospital in Lahore, Pakistan. Methods: A cross-sectional study was conducted at the Surgical Tower of Mayo Hospital, Lahore, from January 2025 to July 2025. Consecutive patients with clinically suspected post-operative wound infections were enrolled. Wound swabs or pus aspirates were collected aseptically from 250 patients and processed using standard microbiological techniques. Isolates were identified by Gram staining and biochemical methods. Antibiotic susceptibility testing was performed using the Kirby–Bauer disc diffusion method in accordance with CLSI guidelines. Demographic and clinical data were recorded, and descriptive statistics were used to summarise prevalence, pathogen distribution, and susceptibility patterns. Results: Of 250 post-operative wound samples, 75 were culture-positive, yielding an SSI prevalence of 30.0%. Culture positivity was higher among males (58.6%) and urban residents (61.3%), with the greatest burden observed in patients aged 35–44 years (34.6%). General and orthopaedic surgeries accounted for the highest proportions of culture-positive infections. A total of 93 bacterial isolates were recovered, predominantly Gram-negative organisms, including Escherichia coli (23.6%), Klebsiella pneumoniae (19.4%), Pseudomonas aeruginosa (19.4%), and Acinetobacter baumannii (17.2%). Methicillin-resistant Staphylococcus aureus constituted 14.0% of isolates. High resistance to penicillins and cephalosporins was observed among Gram-negative pathogens, with reduced fluoroquinolone effectiveness. Carbapenems and amikacin demonstrated the highest activity against Gram-negative isolates, while vancomycin and linezolid remained effective against Gram-positive organisms, including MRSA. Conclusion: Post-operative wound infections at this tertiary care centre were frequent and predominantly caused by multidrug-resistant Gram-negative pathogens. The observed resistance patterns limit the utility of commonly used empirical antibiotics and underscore the need for routine culture-based diagnosis, local antibiogram-guided therapy, and strengthened antimicrobial stewardship and infection control measures in surgical settings