Microbiological Surveillance of Air Quality in Cardiac Operation Theatres: Comparison of the Conventional Settle Plate Technique vs Use of an Air Sampling Device.

Introduction: Surgical site infections (SSIs) after cardiac surgery poses a serious challenge. The foremost reason for contamination in operating rooms (OR) is airborne. Effective surveillance by air sampling or settle techniques is crucial in maintenance of air quality in cardiac OR.

Methodology: The air quality of two different cardiac OR (adult and pediatric) with laminar air flow system and HEPA filters in place was studied with an aim to compare the plate and air sampling technique. Sampling was done both passive and actively using a Surface Air System air sampler. Muller Hinton Agar plates incubated at 36 °C were used, and total viable count assessment was calculated using Koch's sedimentation method.

Results: Colony-forming unit (CFU) counts showed significant differences at various time points in both adult and pediatric OR. The settle plate as compared to the air sampling device correlated but showed lesser CFUs across pre, mid, and postsurgical periods (P < 0.05). The adult cardiac OR had significantly higher bioload than pediatric OR (P < 0.05). The results suggested that both the technique was good for air quality monitoring in OR.

Conclusion: The study compares the two-sampling technique in adult and pediatric cardiac OR, finding higher levels of bioload in adult ORs possibly due to more personnel and longer surgeries. Although settle plates offer basic contamination assessment, air samplers detect specific events efficiently. Using either air sampler or settle plate technique for microbial surveillance in cardiac ORs is suggested for monitoring and prevention of SSI.