Spread of bacteria on surfaces when cleaning with microfibre cloths

SummaryThe impact of environmental contamination on nosocomial cross-transmission is mostly unresolved and in Danish hospitals assessment of cleaning is based on visible criteria only. The use of premoistened microfibre cloths and the 16-side method have been introduced into Danish hospitals because of economic and ergonomic advantages but they have not been evaluated for applicability in hospital cleaning. Our hypothesis was that this method may spread bacteria. A surface was contaminated with bacteria (4 cfu/bacteria/cm2), and cleaned with a premoistened microfibre cloth folded to 16-side use. Each of 15 sterile surfaces was cleaned with a new side of the microfibre cloth; imprints were made and the experiment repeated 12 times. After cleaning, the contaminated surface imprints of microfibre cloths showed a median of 45.5 cfu/plate for E. faecalis and 2.5 cfu/plate for B. cereus. Median values from imprints from cloth sides 2–16 were between 1 and 12 cfu/plate for E. faecalis and 0 cfu/plate for B. cereus. Imprints of the contaminated surfaces were a median of 45.5 cfu/plate for E. faecalis, giving a reduction of 5.6-fold. For B. cereus the median value was 0 cfu/plate. The surface numbers 2–16 had median values between 0.5 and 7.5 for E. faecalis, which was spread to 11–15 of the 15 sterile surfaces (P < 0.01). B. cereus was found in six out of 180 imprints on surfaces 2–16, all with 1 cfu/plate (non-significant). The implication is that although there was an overall reduction in bacterial counts on the contaminated surface, bacteria were spread to subsequently cleaned surfaces.