Impact of negative pressure system on microbiological air quality in a Central Sterile Supply Department

Objective: Guidelines recommend that the cleaning area in a Central Sterile Supply Department (CSSD) maintain a negative pressure of the environmental air, but how much this system can impact the contamination of the air by bioaerosols in the area is not known. The objective of this study was to assess the impact of negative pressure on CSSD by evaluating the microbiological air quality of this sector.

Methods: Microbiological air samples were collected in two CSSD in the same hospital: one with and one without a negative air pressure system. Outdoor air samples were collected as a comparative control. Andersen six-stage air sampler was used to obtain the microbiological air samples.

Results: The concentration of bioaerosols in the CSSD without negative pressure was 273.15 and 206.71 CFU/m³ , while in the CSSD with negative pressure the concentration of bioaerosols was 116.96 CFU/m³ and 131.10 CFU/m³ . The number of isolated colonies in the negative pressure CSSD was significantly lower (P = .01541).

Conclusion: The findings showed that the negative pressure system in the CSSD cleaning area contributed to the quantitative reduction in bioaerosols. However, the concentration of bioaerosols was lower than that established in the guideline for indoor air quality of many countries. Therefore, it cannot be concluded that CSSDs which do not have a negative pressure system in their cleaning area offer occupational risk.