Water temperature as a factor in handwashing efficacy

Abstract

For many years, sanitarians have specified that the hands of food service workers should be washed and rinsed in warm or hot water to reduce the risk of cross‐contamination and disease transmission. In the food service environment, it has been suggested that handwashing with water at higher temperatures contributes to skin damage when frequent handwashing is necessitated, and that insistence on hot water usage is a deterrent to handwashing compliance. Separate handwashing studies involving different water temperatures and soap types (antibacterial versus non‐antibacterial) were performed. The ‘glove‐juice’ technique was employed for microbial recovery from hands in both studies. Initial work evaluated antimicrobial efficacy based on water temperature during normal handwashing with bland soap. Uninoculated, sterile menstrua (tryptic soy broth or hamburger meat) was used to study the effects of treatment temperatures (4.4°C, 12.8°C, 21.1°C, 35°C or 48.9°C) on the reduction of resident microflora, while Serratia marcescens‐inoculated menstrua was used to evaluate treatment effects on the reduction of transient contamination. Results of this first study indicated that water temperature exhibits no effect on transient or resident bacterial reduction during normal handwashing with bland soap. The follow‐up study examined the efficacy and skin irritation potential involving water temperatures with antimicrobial soaps. Hands of participants were contaminated with Escherichia coli inoculated ground beef, washed at one of two water temperatures (29°C or 43°C) using one of four highly active (USDA E2 equivalency) antibacterial soaps having different active ingredients (PCMX, Iodophor, Quat or Triclosan). Skin condition was recorded visually and with specialized instrumentation before and after repeated washing (12 times daily), measuring total moisture content, transepidermal water loss and erythema. Overall, the four soap products produced similar efficacy results. Although there were slight increases in Log10 reductions, visual skin irritation, loss of skin moisture content and transepidermal water loss at higher temperatures, results were not statistically significant for any parameter.

Quantifying the Effect of Hand Wash Duration, Soap Use, Ground Beef Debris, and Drying Methods on the Removal of Enterobacter aerogenes on Hands

“…Two separate studies, Michaels et al (26) and Courtenay et al (11), used inoculated ground beef as debris and found log reductions of an inoculated surrogate similar to those in our study. Michaels et al (26) reported a 1.5-to 2.5-log CFU reduction of Serratia marcescens, with a 15-s wash using antimicrobial soap; Courtenay et al (11) observed a 2.7-log reduction.…”

“…The FDA Model Food Code recommends washing hands for 20 s, under warm running water, with soap, and using either single-use towels or a forced air dryer to dry hands. Although the factors that influence hand washing effectiveness have been studied, these studies may not be comparable due to methodological differences (10) or statistical flaws (11,17,26). Evidence of the efficacy of air drying versus paper towel drying is contradictory.…”

“…Published research indicates that hand washes lasting longer than 20 s have little additional benefit but that washes for less than 10 s may not efficiently remove soil (26,30). A quick wash (5 s) without soap has been commonly observed in busy environments (6,15,35,41).…”

Effects of various hand hygiene regimes on removal and/or destruction ofEscherichia colion hands

“…2004), food service facilities (Paulson et al . 1999; Paulson 2000; Taylor 2000; Lane 2001; Michaels 2002; Michaels et al . 2002; Kerr et al .…”

Compendium of Veterinary Standard Precautions for Zoonotic Disease Prevention in Veterinary Personnel: National Association of State Public Health Veterinarians: Veterinary Infection Control Committee 2015

“…82 Water temperature has little effect on the removal of microorganisms from hands, but warm (as opposed to cold) water improves compliance. 88 Moisturizing soaps and lotions can preserve skin integrity and encourage adherence to hand hygiene protocols among veterinary staff. Dry, cracked skin is painful, indicates compromised skin integrity, and is more likely to be colonized with staphylococci and gram-negative organisms.…”