Shaw et al. (2018) reported that the hospital operating room (OR) is a special department requiring a relatively clean environment, and the microbial content in the operating room is an external factor affecting the infection rate of the surgical site. The purpose of this study is to use active sampling methods to assess the number of microbial colonies in the operating room during use, and to determine the factors affecting air pollution in the tertiary referral medical center.

The study was conducted in a medical center with 28 operating rooms with 3000 beds in northern Taiwan. The impact air sampler was used to detect the number of microbial colonies in the air during the period from May to August 2015, and to collect information on the characteristics of procedures related to the operation and the characteristics of the surgical environment (environmental and personnel related factors).

A total of 250 air samples were collected during the surgical operation. The average number of bacterial colonies in the operating room was 78±47cfu/m3. The average number of colonies in transplant surgery was the highest (123±60cfu/m3), followed by pediatric surgery (115±30.3cfu/m3). A total of 25 samples (10%) were found to cause pathogens, and coagulase-negative staphylococci (n=12, 4.8%) were the most common pathogens. After controlling for potential confounding factors through multiple regression analysis, the surgical stage was significantly correlated with the number of bacterial colonies (r = 0.346, p <0.001).

In addition, the independent factors affecting the number of bacterial colonies depend on the type of surgery (29.85cfu/m3, 95% confidence interval 1.28-58.42, p=0.041), and the surgical site (20.19cfu/m3, 95% confidence interval 8.24-32.14, p=0.001), the number of people in the operating room (4.93 cfu/m3, 95% confidence interval 1.47-8.38, p=0.005), surgical staging (36.5 cfu/m3, 95% confidence interval 24.76-48.25, p<0.001) And indoor temperature (9.4 cfu/m3, 95% confidence interval 1.61-17.18, p=0.018).

The researchers concluded that with a well-controlled ventilation system, the average number of microbial colonies obtained through active sampling during different periods of use in the operating room was low. The number of people in the operating room and their range of activities are key factors that affect the number of microbial colonies in the air in the operating room. Researchers suggest that when performing complicated operations with a large number of participants, the number of air changes in the operating room should be increased. A well-controlled ventilation system and infection control procedures related to the environment and surgical operations are extremely important to reduce the number of microbial colonies in the air.