|Title:||Microbiological Air Sampling In Operating Theatres|
|Document ID:||Operational Circular OP 2023/06|
|Date of issue:||Thursday, 2 February 2006|
|Status:||NO LONGER APPLICABLE|
|Description:||While there is considerable evidence available to indicate that surgical site infections are a significant health risk to hospital patients, there is ongoing debate over the appropriate extent and frequency of microbiological surveillance of operating theatres.|
|Period of effect:||from 2 February 2006|
|Authorised by:||Dr John de Campo, Acting Director General, Department of Health, 20-Jan-2006|
|Print version:||View print version|
Microbiological Air Sampling In Operating Theatres
While there is considerable evidence available to indicate that surgical site infections are a significant health risk to hospital patients, there is ongoing debate over the appropriate extent and frequency of microbiological surveillance of operating theatres.
Exogenous infections of surgical wounds are caused predominantly by Staphylococcus aureus, and Staphylococcus epidermidis. S. aureus and S. epidermidis are shed into the environment by individual skin scales and, while healthy carriers have been found to shed few staphylococci, airborne contamination is inevitable owing to staff movement encountered during operating theatre activities. While there is evidence to indicate that most outbreaks are caused by heavy dispersers, every attempt should be made to minimise airborne transmission within operating theatres.
Health care facilities should implement proper design and ventilation of operating theatres as a means of controlling airborne contamination. Other strategies to prevent airborne microbial contaminants from entering surgical wounds should include:
There are no nationally agreed standards on when to undertake microbiological sampling in the operating theatre, or on the interpretation of sampling results. However, there is sufficient evidence to support the undertaking of microbiological air sampling:
Specialist microbiologist/infection control advice must be sought prior to undertaking air sampling in an operating theatre owing to the large number of factors that affect microbial air sampling results.
Types of Operating Theatres
Recommended Standards may vary between types of operating theatres. Design standards for operating rooms are defined in the Private Hospital Guidelines located at http://www.health.wa.gov.au/publications/
PLANNING FOR AIR SAMPLING
Health Care Workers should:
HOW TO AIR SAMPLE
There are several different types of air samplers available and the manufacturer’s instructions for use must be followed. If available, the preferred method is to use a sampler that can be turned on by a timer or remote control. Moreover, air samples should be taken after all the following conditions have been met:
The following process is recommended:
Any variation from the above operating theatre conditions should be noted on the laboratory request form as this information will influence interpretation of results.
RESULTS AND INTERPRETATION
Preliminary culture results are rarely available until after 24 hours incubation.
Aerobic cultures on non-selective medium should not exceed 35 colony-forming units (cfu) of bacteria and fungi per cubic metre of air for a conventional theatre and 1 cfu for an ultraclean theatre. These figures are not rigid standards and are intended as a guideline only. If the result exceeds these limits contact your Microbiologist/Infection Control Practitioner for interpretation and advice on further action.
Dr John de Campo
This circular last updated: Wednesday, 1 February 2006 at 3:38pm