Role Of Operating Theatre Environment In Causing Surgical Site Infections - One Year Longitudinal Study

Abstract

Introduction: Surgical site infections (SSIs) constitute a substantial part of surgical morbidity and mortality each year. Since air can act as a reservoir for microorganisms, airborne microbial concentration in the operating theatre (OT) needs to be studied for its role in the causation of SSIs. Objective: The present study was done to 1. Monitor operating theatre (OT) air for bacteria, and its relation with surgical site infections (SSIs) in patients operated in that particular OT. 2. Investigate the correlation between pre/ post operative antibiotic usage and antibiotic resistance in SSI isolates in relation to the patients’ condition. Methods: Elective clean and clean-contaminated surgeries were included. Only first surgical case of a day was sampled. Pre- and post-operative air sampling was conducted by settle plate (1/1/1) method. Patients were followed up. Three swabs from surgical incision site were taken and processed for aerobic and anaerobic pathogens as per standard guidelines. A modified medium, consisting of glucose broth and sodium polyanethol sulfonate was evaluated for increased aerobic culture yield. Results: 57 clean and 39 clean-contaminated surgeries were included. Staphylococcus aureus was found in six pre-op OT plates (6.25%) and ten post-op OT plates (10.42%), colony count of ten or more per plate. 87.5% of these isolates of Staph. aureus were susceptible to Cefoxitin, 50% to Erythromycin and 62.5% to Co-trimoxazole. 87.5% of the isolates were susceptible to Ciprofloxacin and 100% to Clindamycin. None of the isolates were susceptible to Penicillin. Two patients pertaining to these OTs developed SSIs. Both SSIs developed following clean-contaminated surgeries. They yielded Staphylococcus aureus from surgical incision site on follow up. These isolates were susceptible to Cefoxitin, Ciprofloxacin, Co-trimoxazole and Clindamycin. The isolates matched those obtained from the respective OT pre-operatively. There was no difference between culture results from moist swab and swab in the modified medium. No anaerobes were isolated. Conclusion: The study found 6-10% of contamination of OT air. The presence of pathogenic microorganisms in the OT air in significant numbers leads to a higher risk of SSI. Patients recovered without much morbidity as they received the drugs, post-operatively as per the antibiotic sensitivity report of the OT isolates. Surveillance of the OT environment is to be conducted vigilantly. The isolates thus obtained should be speciated and the antibiogram should be obtained to prevent post-operative infections