Survival of Enterococcus faecium , Staphylococcus aureus and Pseudomonas aeruginosa on cotton

The aim of this study was to evaluate the survival of three challenge bacteria stored at 25℃, 5℃, and 50℃ up to 21 days on 100% cotton textile swatches. The survival of each chosen challenge bacteria was determined by the classical phenotype colony counting method through growth on selective media, and the molecular method of detecting Staphylococcus aureus-, Enterococcus faecium-, and Pseudomonas aeruginosa-specific DNA. E. faecium proved to be the most persistent chosen challenge bacteria at all three chosen storage temperatures. Both E. faecium and S. aureus survived on textile swatches up to 21 days at 25℃ at the highest inoculum. E. faecium and P. aeruginosa persisted at 50℃ only up to 9 and 3 days, respectively. All challenge bacteria survived on textile swatches at 5℃ ( E. faecium 12 days, P. aeruginosa and S. aureus less than 6 days). The results of survival at lower initial inoculum were lower and less dependent on temperature. Dehydration phenomena or fluctuation in relative humidity in the refrigerator at 5℃ possibly explains lower survival than at room temperature. Positive results for the detection of E. faecium- and P. aeruginosa-specific DNA were found for some samples with negative results for classical phenotype counting methods, perhaps owing to the fact that the bacterial cells, due to adverse environmental conditions, reached a viable, but noncultivable (VBNC) state, or that the extracellular DNA fragments persisted on the textiles. Survival of the challenge bacteria for more than 3 days regardless of temperature proves that hospital textiles as an inanimate surface should not be neglected as one of the possible vectors for transmission of pathogens causing healthcare associated infections.