Coliform bacteria, fabrics, and the environment.

Background: People come into contact with coliform bacteria at recreational sites. Previous research on bacteria adhering to fabrics and surfaces focused on the viability of clinically significant microbes, but did not examine the quantity of bacteria. This study examined the viability and quantity of coliform bacteria adhered to common fabrics.

Methods: The fabrics of 100% cotton, blended cotton, and silk were exposed to a mixture of environmental coliform isolates. Fabrics were incubated in the dark at 25°C or 37°C or in direct sunlight at room temperature for 30, 60, 90, and 120 days. The quantity and viability of the bacteria were determined by the Most Probable Number technique using Colilert reagent (IDEXX Laboratories, Westbrook, ME) and eosin methylene blue agar, respectively.

Results: The highest numbers of bacteria were detected for each type of fabric when stored in the dark at 25°C, whereas the lowest numbers of bacteria were detected when fabrics were stored in the dark at 37°C. Low numbers of bacteria were detected on silk and blended cotton exposed to sunlight at room temperature, but not 100% cotton.

Conclusion: It appears that coliform bacteria can survive on fabrics longer than previous studies have reported. Coliform bacteria survive better in the dark, at lower temperatures, and on fabrics that can retain moisture. These findings can be applied directly to the viability of bacteria on clothing and potential human exposure to fecal pathogens.