Killing of fabric-associated bacteria in hospital laundry by low temperature washing

Hospitals using 71.1 C water for laundering consume vast amounts of energy. We studied whether washing at 22 C would result in fabric-associated between bacterial counts significantly different from those remaining after the high-temperature wash procedure in general use. Using a standard method to enumerate fabric-associated bacteria, we found that soiled sheets and terry cloth items were contaminated, respectively, with 10⁶ and 10⁸ cfu/100 cm² of fabric area, predominantly gram-negative rods (especially Enterobacteriaceae and Pseudomonadaceae). Staphylococcus species were the most common gram-positive organisms. A standard low-temperature washing cycle without laundry chemicals removed 3 log₁₀ of bacteria by agitation, dilution, and drainage. When low-temperature laundry chemicals were used, 3 log₁₀ of bacteria were killed after the bleach was added, and sheets and terry cloth items had postwash colony of 10¹-10² cfu/100 cm². Drying removed an additional 1-2 log₁₀ organisms. Bacterial counts and species from low and high-temperature washed fabrics were comparable. Low-temperature washing is therefore as effective as high-temperature washing for eliminating pathogenic bacteria from hospital laundry.