PREDICTORS OF SURGICAL SITE INFECTION DESPITE APPROPRIATE ANTIBIOTIC PROPHYLAXIS: A RISK-BASED CLINICAL ANALYSIS

Abstract

Background: Although proper antibiotic prophylaxis is used for surgery, surgical site infection (SSI) is still a major postoperative problem indicating that there are patient-related, surgical, and microbial factors that remain associated with the risk of surgical site infection post-surgery.

Objective: To determine the association between patient, surgical and microbial parameters and the development of SSI in patients despite optimal antibiotic prophylaxis, and to describe the contribution of these parameters to the risk of postoperative infection.

Methods: The study was of analytical cross sectional type with prospective postoperative surveillance carried out from September 2025 to January 2026 at a tertiary care surgical hospital of Urban Region of Sindh. One hundred (100) adults who were undergoing eligible surgical procedures and were receiving appropriate antibiotic prophylaxis were evaluated. A structured proforma was filled with demographic, clinical, operative and prophylaxis-related data. CDC/NHSN criteria was used to assess SSI and microbiological identification and antimicrobial susceptibility testing of wound specimens was performed when clinically indicated. Descriptive statistics, chi-square/Fisher's exact tests, independent-samples t-test or Mann-Whitney U test, and multivariable logistic regression were used to analyze data.

Results: SSI was seen in 18 (18.0%) participants. Diabetes mellitus, obesity, anemia, and smoking were more frequent among patients with SSI. The presence of emergency surgery was associated with increased SSI (29.0% vs. 13.0%, p=0.047) and contaminated/dirty wound with even higher association (35.7% vs. 11.1%, p=0.003). Other factors associated with infection were also operative duration ≥120 minutes (28.6% vs. 10.0%, p=0.018). In the multivariable analysis, contaminated/dirty wounds was the most significantly associated factor with SSI (adjusted OR 4.12; 95% CI 1.48–11.46; p=0.007) followed by operative duration ≥120 minutes (adjusted OR 3.21; 95% CI 1.12–9.19; p=0.030). The most common organism isolated (38.9%) was Staphylococcus aureus.

Conclusion: There is no doubt that SSI was clinically significant even with proper prophylaxis. The significant residual risk factors were diabetes, emergency surgery, long operating time and contamination of the wound, which reinforces the need for a multi-faceted approach to prevention that includes patient optimization, careful surgical technique, wound management and specific surveillance.