CLOTHING IN LAMINAR-FLOW OPERATING-THEATERS

Bacterial shedding, wound contamination and clinical-infection rates i n clean wounds are influenced by operating-theatre dress. The aim of t his study was to clarify the relative contribution of hats, masks and clothing to the control of wound contamination in both ultraclean (enc losed vertical laminar-flow) and conventional (plenum ventilated) airf low theatres. Personnel wore varying combinations of dress in both typ es of theatre. Colony forming units (cfus) were measured on settle pla tes at head and waist height, and in the air by a centrifugal air samp ler. Bacterial counts in conventional theatres were consistently high and were not significantly influenced by theatre dress. There was a 22 -fold increase in cfus on settle plates at waist height when neither h at nor mask were worn, a 15-fold increase when a hat but no mask was w orn and a fourfold increase with a mask but no hat in vertical laminar airflow enclosures, although air sample counts remained low. When bal loon-cotton clothing was worn, rather than cuffed polyester with micro filament barrier-fabric gowns, cfu counts rose by a factor of six. The bacterial inoculum in conventionally ventilated theatres, or in ultra clean theatres if hat or mask are omitted or balloon-cotton clothing w orn, is theoretically sufficient to infect a prosthetic arthroplasty. Theatre-air sampling alone does not reflect local contamination when a surgeon stands over a wound in a vertical laminar-flow enclosure, and both hats and masks are an important part of dress in such environmen ts.