Residual Viral and Bacterial Contamination of Surfaces after Cleaning and Disinfection

Abstract

c Environmental surfaces contaminated with pathogens can be sources of indirect transmission, and cleaning and disinfection are common interventions focused on reducing contamination levels. We determined the efficacy of cleaning and disinfection procedures for reducing contamination by noroviruses, rotavirus, poliovirus, parechovirus, adenovirus, influenza virus, Staphylococcus aureus, and Salmonella enterica from artificially contaminated stainless steel surfaces. After a single wipe with water, liquid soap, or 250-ppm free chlorine solution, the numbers of infective viruses and bacteria were reduced by 1 log 10 for poliovirus and close to 4 log 10 for influenza virus. There was no significant difference in residual contamination levels after wiping with water, liquid soap, or 250-ppm chlorine solution. When a single wipe with liquid soap was followed by a second wipe using 250-or 1,000-ppm chlorine, an extra 1-to 3-log 10 reduction was achieved, and except for rotavirus and norovirus genogroup I, no significant additional effect of 1,000 ppm compared to 250 ppm was found. A reduced correlation between reduction in PCR units (PCRU) and reduction in infectious particles suggests that at least part of the reduction achieved in the second step is due to inactivation instead of removal alone. We used data on infectious doses and transfer efficiencies to estimate a target level to which the residual contamination should be reduced and found that a single wipe with liquid soap followed by a wipe with 250-ppm free chlorine solution was sufficient to reduce the residual contamination to below the target level for most of the pathogens tested.

Controlling Hospital-Acquired Infection: Focus on the Role of the Environment and New Technologies for Decontamination

“…Two studies published in 2012 found that norovirus (human and MNV1 strains) could be substantially reduced on hard surfaces after wiping from one to six times using a range of inocula and material wipes (121,149). This supports the increasingly popular premise that physical removal could challenge routine use of disinfectants for controlling surface microbes (163,164) (Fig.…”

“…Detergent-based cleaning is not sufficient to eliminate norovirus from the environment (120). A recent in vitro study measured residual contamination of surfaces with norovirus after detergent cleaning with or without a disinfectant (121). The authors concluded that cleaning with liquid soap followed by a 1,000-ppm chlorine wipe generally produced the lowest level of persistent contamination.…”

“…The infectivity index of norovirus, however, meant that even the low levels achieved after a two-tier approach would still represent a risk for hand contact transmission. The authors suggested lengthening the contact time between chlorinated disinfectant and contaminated surfaces to a minimum of 5 min, since this reduced residual levels of virus to less than those capable of causing infection (121). Translating the results from this study to the clinical environment poses a challenge, since leaving disinfectants on surfaces for even 5 min in a busy ward may not be practical.…”

Dos and don’ts for hospital cleaning

“…There are increasing reports that suggest physical, rather than biocidal, removal of bioburden is key to the cleaning process [50][51][52][53][54][55][56][57][58]. This is not necessarily due to the fact that surface soil is known to impede microbiocidal activity of a disinfectant [59].…”

Sanitizer Efficacy against Murine Norovirus, a Surrogate for Human Norovirus, on Stainless Steel Surfaces when Using Three Application Methods

“…A recent study by Tuladhar et al (46) demonstrated improved removal and inactivation of noroviruses by using wipes soaked in 250 ppm chlorine after the surfaces had been wiped once with soap and water, suggesting a two-step cleaning/sanitizing procedure should also be adopted to maximize the effectiveness of sanitizing wipes. Another note of importance revealed by this study was that, while a direct correlation between the removal of the MNV-1 surrogate and removal of human norovirus from surfaces via wiping was difficult to discern, in fact MNV-1 appears to be somewhat more susceptible to degradation by the mechanical action of wiping alone (46). Future studies should consider this potential limitation of the MNV-1 surrogate.…”