Air sampling procedures to evaluate microbial contamination: A comparison between active and passive methods at high-risk areas in a Tertiary Care Hospital of Delhi

Abstract

Context: The microbial quality of air in the operation theatres (OTs) is a parameter which appreciably controls the healthcare-associated infections. However, there is currently no international consensus on the most suitable method to be used for air sampling or any set policy on how to achieve the total viable count (TVC) values although the optimum goals have been set. Aims: This study aims to evaluate the microbial air quality in different OTs of our tertiary care hospital at rest and inoperational by comparing active and passive air sampling. Settings and Design: The Department of Microbiology and all the OT rooms of UCMS and GTB Hospital, Delhi. There are 18 OT rooms. This was a cross-sectional, comparative study. Subjects and Methods: Five at rest samples (before the start of operation) and five inoperational samples (during operation) were collected from each of the 18 OTs by both active (using air sampler) and passive (gravity settle plate technique as per the 1/1/1 scheme) methods using five percent sheep blood agar in 9 cm petri plates. The number of personnel present inoperational was recorded, and the number of colony forming units on the petri dish was counted after incubation and compared. Statistical Analysis Used: As the data followed a non-normal distribution, non-parametric tests were applied. Wilcoxon signed rank test, Spearman's correlation coefficient, Simple linear regression and Independent sample t-test. Results: The total bioburden in the OTs exceeded the maximum acceptable limit value during both moments of sampling. There was a significant positive correlation in the TVC values obtained by active and passive sampling methods in the two moments. Conclusions: The present study demonstrates a comparability of results obtained by the two different sampling techniques at two sampling moments. However, authentication of this result necessitates additional studies. In the interim, it is promising to conclude that both methods can be used for universal scrutinising of air biocontamination.