Source strength as a measurement to define the ability of clean air suits to reduce airborne contamination in operating rooms

Background: Surgical site infections after total hip and knee replacement are linked to the quality of the operating room (OR) air. Applying tight occlusive clothing, effective ventilation and correct working methods are key concepts to obtain low bacterial concentrations in the OR air. The dry penetration test referred to in European standard EN 13795-2:2019 is a screening method for materials used in surgical clothing. Source strength, defined as the dispersal of bacteria-carrying particles from persons during activity, is a functional test of clothing systems and has been calculated in a dispersal chamber and in ORs. Results from both tests can be used when comparing surgical clothing systems. Aim: This study relates results of dry penetration tests to source strength values for five surgical clothing systems available on the Swedish market. Methods: Experimental data are reported on the function of these products, expressed as source strength calculated from results in a dispersal chamber and in ORs during orthopaedic operations. Findings: All materials tested with dry penetration ≤50 colony-forming units (cfu) had source strength values <3 cfu/s for one person in the dispersal chamber, whereas the material of one product when laundered >50 times had source strength in the dispersal chamber of up to 8 cfu/s. Conclusion: The dry penetration test could predict the performance of clean air suits of the same design, but more studies are needed to obtain a more valid correlation. Requirements of source strength should be included in standards