Airborne transmission is one of the routes responsible for the spreading of disease for nosocomial infections [1]. Airborne transmission occurs when infectious agents are carried in the suspended air. Nosocomial infections are also known as hospital-acquired infections. It is an infection that was acquired in the hospital environment, which is not present during the time the patient was admitted [2]. The study of microbial in the indoor air of the hospital is important because it will give more understanding about the bioburden of the airborne microbes in the hospital environment. The hospital is where the patients are treated; hence may influence the health of patients to either recovering or acquiring infections that can lead to death.

Hospital is an important indoor environment responsible for the spread of air pathogens. It serves as a reservoir of pathogens. Individuals can be infected with a number of microorganisms, and then these pathogens are potentially transmitted to other individuals, including patients, hospital workers, and even visitors. Besides, the hospital is referred to as red as a special public place. Moreover, the number of people in the hospital is much higher compared to other public places [2]. In addition to that, one of the areas in the hospital that has a high risk of nosocomial infections among patients in the Operation Theatre (OT) room [3]. This is because the OT room is a place where all the surgeries are conducted. The patients are potentially exposed to the OT environments that may harbor many microbes such as Pseudomonas aeruginosa, Bacillus spp., Acinetobacter baumannii, Micrococcus spp. and methicillin-resistant Staphylococcus aureus (MRSA), which are the major pathogens associated with nosocomial infections [4]. Nosocomial infections in surgical patients are 38%, while Hospital-Acquired Infections (HAI) is ranged between 13% to 40%, respectively, in Italy, Europe, and the United States of America [5].

Surgical Site Infection (SSI) is the second most common infectious complication after urinary tract infection following cesarean section delivery [6]. They reported that in total, 18.8% of their study participants who were among patients undergoing cesarean section developed SSI. Approximately 20-30% of surgical infections are caused by Staphylococcus aureus [7]. Another previous study conducted at Hospital USM (HUSM) in 2015 reported that among 220 patients, the sample collected showed that almost 11.8% incidence was found to be surgical site infections [8].

The OT should be a clean and sterile place from microbes and dust. However, during the study period, the OT was in the process of renovation. Thus, it is hypothesized that renovation may emit foreign particles within the OT room and cause the air in the OT to be contaminated. The foreign particle may lead to nosocomial infections among the patients that already have a weak immune system due to the disease itself, causing them to be highly at risk of SSI. The renovation was conducted for six months; however, the OT was still under operation for surgeries. It is postulated that the microbial level in the indoor air will also be affected due to the renovations. As the effect of the hospital’s indoor air quality to humans is significant, hence it is important to conduct this preliminary study in determining the microbial contamination level at the OT. Moreover, there are limited studies that focused on indoor airborne microbial conducted in hospitals in Malaysia.

This is a cross-sectional study design in isolating bacteria in the OT of a teaching hospital. This study involved sample collection at eight Operation Rooms (ORs) and two corridors from September 2018 to January 2019, in which there was a renovation activity happening in the OT. Sampling was conducted thrice, which was repeated every two months.

Bacteria isolated that can be found in this study were Bacillus spp., Micrococcus spp. and Staphylococcus spp. These three types of bacteria were the most frequently isolated bacteria in all ORs and corridors. Sapkota et al. [9] observed that Staphylococcus spp., Micrococcus spp., Bacillus spp., Pseudomonas aeruginosa and Acinetobacter baumannii were the most common organisms detected in healthcare facilities.

Bacillus spp., Micrococcus spp. and Staphylococcus spp. can be transmitted from person-to-person and from air-to-people. Thus, Micrococcus spp. and Bacillus spp. were common bacteria in the environment, especially in OT [10]. Moreover, Bacillus spp. also contain spores that enable them to survive for a long period of time in the environment. Moreover, Staphylococcus spp. was usually associated with various diseases such as urinary tract infection and skin infection [11].

There were three types of bacteria isolated in this study, which were Bacillus spp., Micrococcus spp. and Staphylococcus spp. Although the bacteria identified and presence was low in percentage, but there was a chance that it can cause surgical site infection to the patients. Therefore, microbial level monitoring was very important and needs to be conducted as prevention measures.

Recommendation to maintain or reduce bioaerosol level in the OT can be made by strengthening surveillance of the hygiene in the OT. This can be achieved by making sure the ventilation systems provided in the OT was well checked so that it can generate adequate ventilation to reduce microbial in the air of OT. In addition to that, it was improving a hygiene procedure such as sweeping, regular cleaning, and disinfection of the hospital appliances in all health care settings before and after surgery was done. Overcrowding in the OT should also be avoided in the OTs because crowded places can increase the chances of infectious disease. Lastly, more effort is needed to improve the OT hygienic condition and recommendation by giving awareness and educational knowledge on how to reduce the hazard of airborne transmission, which was potentially pathogenic microorganism that can cause nosocomial infection toward the patients.

It is also suggested that in the future, the study can be done by using a swab sampling method for hospital appliances that are placed in the OT. It is also recommended that additional measurements such as the ventilation rate and fungal load were conducted, then further checking on the strains to be performed using the Polymerase Chain Reaction.