Bacteriological Profile and Antibiotic Susceptibility Pattern of Pus Isolates in Surgical Site Infections: A Cross-Sectional Study

Abstract

Background: Surgical site infections (SSIs) are among the most common hospital-acquired infections, contributing to increased morbidity, prolonged hospital stays, and antimicrobial resistance. Understanding the local bacteriological spectrum and susceptibility pattern is essential for empirical therapy.

Objective: To isolate and identify bacterial pathogens from pus samples of surgical site infections and to determine their antibiotic susceptibility patterns as per CLSI 2012 guidelines.

Methods: This cross-sectional study was conducted on 210 pus samples collected from post-operative patients with clinically suspected SSIs. Culture and identification were performed using standard bacteriological techniques. Antibiotic susceptibility testing was carried out by the Kirby-Bauer disk diffusion method, and results interpreted using CLSI guidelines. Data were analyzed using descriptive statistics and chi-square test.

Results: Out of 210 samples, 172 (81.9%) were culture-positive. Staphylococcus aureus was the predominant isolate (41.3%), followed by Escherichia coli (22.1%) and Pseudomonas aeruginosa (14.5%). Methicillin resistance was found in 36% of S. aureus isolates. Gram-negative bacilli showed high resistance to ampicillin (84%) and ceftriaxone (66%). Amikacin and imipenem were the most effective agents. A statistically significant association was found between prior antibiotic use and multidrug resistance (p < 0.05).

Conclusion: S. aureus remains the leading cause of SSIs, with considerable methicillin resistance. Empirical therapy should be guided by local antibiogram data, and strict adherence to antimicrobial stewardship is recommended.

Keywords: Surgical site infection, Staphylococcus aureus, antibiotic resistance, pus culture