Microbiological surveillance of operation theatres of a tertiary care hospital in Mizoram, north eastern part of India: 4 years retrospective analysis

Abstract

Healthcare associated infections are important cause of patient morbidity and mortality. Microbiological contamination of air and environment in the operation theatres (OTs) are major risk factor for surgical site and other hospital-associated infections. To identify bacterial colonization of surfaces, equipments and to determine the microbial contamination of air in the OTs of a tertiary care hospital in Lunglei, Mizoram which is in north eastern part of India. Four years (January 2016 – December 2020) retrospective analysis of a data obtained from routine microbiological surveillance of the OTs. Surface samples were taken with wet swabs from different sites and equipments, and Settle plate method for air in the OTs. Bacterial species were isolated and identified by conventional method. The colony forming unit (CFU) count/plate was expressed as CFU/m3 by Omeliansky formula. The culture positivity rate of surface swab samples was 6.4% (60/937). Bacillus spp. with 45 (67.16%) isolates was the most common baterial isolates. The bacterial CFU/m3 counts of air in the two OTs were in the range of 90 to 166 before fumigation. Staphylococcus aureus with 43(42.16%) was the predominant species obtained and the least common species obtained was Enterococcus faecalis with13 (12.74%). The bacterial CFU/m3 counts of air was one in both the OTs after fumigation. Settle plate method for air and swabbing technique for surfaces are proved to be valuable techniques in detecting the contamination level in our set up with limited resources.