A review of methods for the evaluation of handwashing efficacy

Repeat-exposure in vitro protocol to assess the risk of antimicrobial resistance (AMR) development from use of personal care products: Case study using an antibacterial liquid handwash

The global crisis we are facing with regard to antibiotic resistance has been largely attributed to the overuse and misuse of antibiotics in healthcare and agriculture. However, there is also growing global concern about cross-resistance between biocides and antibiotics. This has made clear the need for more research in this area along with easy-to-perform, but realistic, methods to characterise the potential risk associated with cross-resistance to antibiotics due to biocide use. The primary aim of this work was to develop a repeat-exposure method for predicting bacterial resistance to microbicides, including their cross-resistance to antibiotics. Realism is incorporated in the presented protocol through the use of relevant concentrations and contact times, validated neutralisers, appropriate test organisms and repeat-exposures. The protocol can be applied to formulated microbicides, as shown in the liquid handwash case study presented here. Five bacterial strains were included in the study: Staphylococcus aureus ATCC 6538, Pseudomonas aeruginosa ATCC 15442, Staphylococcus epidermidis ATCC 14990, Escherichia coli ATCC 10536 and Enterococcus hirae ATCC 10541. The protocol parameters used in the case study reflected a worst-case exposure scenario (in terms of contact time and concentration). The results demonstrated that repeated exposure to the liquid handwash would not be expected to lead to development of bacterial resistance or cross-resistance to antibiotics. It is envisaged that this protocol could be used by manufacturers of microbicidal formulations to assess whether repeated use of the test products would contribute to bacterial resistance development or cross-resistance to antibiotics.

Comparative Recovery of Serratia marcescens Using Bags versus Gloves as Described in ASTM E1174-21 Health Care Personnel Handwash Method

The ASTM E1174-21 Health Care Personnel Handwash method is prescribed by the U.S. Food and Drug Administration (FDA) to demonstrate the efficacy of antiseptic handwashing products. The standardized method allows for marker bacteria to be collected from the hands by using either a bag or a glove. Two recent studies utilizing the different collection methods testing the same product showed substantial differences in results. We sponsored two independent studies to compare the bag and glove collection methods following contamination with Serratia marcescens. Overall, there was no difference between collection methods for bacteria recovered (P = 0.603). The distribution of recovery for the bag method was slightly less variable than for the glove method. Statistical differences were observed within each lab based on the collection day. The day-to-day variability is critical to consider for future multiple-day studies. Additionally, hand size appears to impact recovery, especially for the glove method, with both small and medium hand sizes resulting in higher recovery than large and extralarge hand sizes (P = 0.015), whereas hand size did not impact recovery with the bag method (P = 0.315). While it appears that both the bag and glove methods can be used, our findings suggest that gloves may not be the best option for subjects with large to extra-large hands. Additional work looking at bacterial recovery following product treatment is warranted to understand the impact of large hands in the bag versus glove recovery method. IMPORTANCE Antiseptic hand wash products are evaluated using the standard ASTM E1174-21 to demonstrate their antibacterial efficacy. Often products are tested at multiple labs, and the need to understand variables that may play a role in the outcome of the study is important. This work allows us to evaluate the impact that the two collection methods, bags and gloves, have on bacteria recovery. If differences are observed, standardization to one method may be critical to ensure similar test results when planning studies at multiple labs.

Comparing the effectiveness of hand hygiene techniques in reducing the microbial load and covering hand surfaces in healthcare workers: Updated systematic review

BACKGROUND

This review, commissioned by the World Health Organization (WHO), examined the effectiveness of the WHO 6-step hand hygiene (HH) technique in reducing microbial load on hands and covering hand surfaces, and compared its effectiveness to other techniques.

METHODS

Medline, CINAHL, ProQuest, Web of Science, Mednar, and Google Scholar were searched for primary studies, published in English (1978-February 2021), evaluating the microbiological effectiveness or hand surface coverage of HH techniques in healthcare workers. Reviewers independently performed quality assessment using Cochrane tools. The protocol for the narrative review was registered (PROSPERO 2021: CRD42021236138).

RESULTS

Nine studies were included. Evidence demonstrated that the WHO technique reduced microbial load on hands. One study found the WHO technique more effective than the 3-step technique (P = .02), while another found no difference between these 2 techniques (P = .08). An adapted 3-step technique was more effective than the WHO technique in laboratory settings (P = .021), but not in clinical practice (P = .629). One study demonstrated that an adapted 6-step technique was more effective than the WHO technique (P = .001). Evidence was heterogeneous in application time, product, and volume. All studies were high risk of bias.

CONCLUSIONS

Eight studies found that the WHO 6-step technique reduced microbial load on healthcare workers' hands; but the studies were heterogeneous and further research is required to identify the most effective, yet feasible technique.

Evaluating children's handwashing in schools: an integrative review of indicative measures and measurement tools

Children are a key target of handwashing interventions as washing hands reduces the spread of disease and reliance on antibiotics. While there is guidance for evaluating handwashing with adults in other settings, this is lacking for children in schools. An integrative review of 65 studies where handwashing was measured in schools was conducted to establish which indicative measures (what is measured to evaluate the processes and/or impacts of, handwashing) and measurement tools (data collection instruments) have been applied to evaluate handwashing in schools, and under what circumstances. Further analysis highlighted different challenges when seeking to apply such measures and tools in schools, as opposed to other settings. It was concluded that indicative measures, and measurement tools need to be appropriate to the organizational setting, the study participants, and research objectives. A summative analysis of relevant considerations is presented.

3M Petrifilm Lactic Acid Bacteria Count Plate Is a Reliable Tool for Enumerating Lactic Acid Bacteria in Bacon

ABSTRACT

This study aimed to evaluate the behavior of Petrifilm Lactic Acid Bacteria Count Plates (PLAB) as an alternative methodology to enumerate lactic acid bacteria (LAB) in bacon. Bacon samples (n = 40) were obtained from retail sale, 10-fold diluted with buffered peptone water (BPW, 0.2% [w/v]) and Letheen broth, and subjected to LAB enumeration according to four protocols: (i) de Man Rogosa Sharpe (MRS) agar, pH 5.7, 30°C; (ii) MRS, pH 5.7, 30°C, anaerobiosis; (iii) all-purpose Tween agar (APT), 25°C; and (iv) PLAB, 30°C. Colonies were enumerated at 24, 48, and 72 h, and the results expressed as log CFU per gram for comparison by analysis of variance and regression (P < 0.05). Furthermore, colonies were randomly selected and characterized as LAB (Gram staining and catalase). Mean LAB counts from MRS and PLAB did not present significant differences independently of incubation time or diluent (P > 0.05), whereas counts in APT with BPW after 24 h were significantly lower (P < 0.05). PLAB counts with BPW (24, 48, and 72 h) presented significant correlation with MRS (r ranging from 0.87 to 0.89; in anaerobiosis, r ranging from 0.94 to 0.95) and APT (r ranging from 0.84 to 0.86). With Letheen broth, PLAB (24, 48, and 72 h) presented significant correlation with MRS (r ranging from 0.92 to 0.94; in anaerobiosis, r ranging from 0.93 to 0.96) and APT (r ranging from 0.77 to 0.79). In total, 1,032 colonies (97%) from 1,063 colonies were characterized as LAB. Thus, PLAB can be considered as an alternative tool for enumerating LAB in bacon, with reliable results even after 24 h of incubation.

HIGHLIGHTS

Design, Fabrication, and Testing of a Novel Surgical Handwashing Machine

Background. Surgical hand scrub is strongly recommended as an essential measure to reduce surgical site infections (SSIs). SSI results in morbidity and additional cost. Micropunctures may occur on surgical gloves during operation, thus hand scrub cannot be omitted in any condition. Generally speaking, the adequacy of hand scrub is decided by the surgeon. Only occasionally, surveillance of hygienic status of hands is performed after scrub. Therefore, the potential exists that suboptimal handwash leads to SSIs. There are standards for preoperative handwash, but all of them are operator dependent, and continuous surveillance is actually impossible. One solution is to omit the role of surgeon in handwashing. This can be achieved by designing a standard procedure, performed mechanically by a machine, considering the detailed requirements of hygienic surgical hand scrub. The goal of this study was to develop a procedure that works on the design, fabrication, and trial of a new handwashing machine, for surgical hand scrub. Methods. A machine with a reciprocal spraying mechanism was designed that covers from the fingertips up to the elbow. Various combinations of staged irrigations with antiseptic solutions and water were to be programmed and implemented. Clinical experiments were performed several times with different handwashing programs, and swabs were taken from the skin surface and creases. Results. There was no microbial growth after 72 hours with any handwashing program. Conclusion. The preliminary experiments with this new handwashing machine show promising results for its application in surgical hand scrub.

Microbial Quality and Safety of Sushi Prepared with Gloved or Bare Hands: Food Handlers' Impact on Retail Food Hygiene and Safety

Food handlers play an important role in retail food hygiene and safety. This study was conducted to better understand the impact of food handlers on the microbiological quality and safety of sushi and ingredients handled by gloved and bare hands. At retail premises, food handlers were asked to prepare a batch of sushi with raw fish followed by a batch of sushi with cooked ingredients. Food (sushi and ready-to-eat ingredients), hand, and glove samples were collected for analysis of overall microorganisms (standard plate counts) and targeted foodborne bacteria: Staphylococcus aureus, Bacillus cereus, Escherichia coli, Salmonella, and Listeria monocytogenes. Results suggested that cross-contamination was more prevalent at premises where bare hands were used to prepare sushi. When bare hands were used, significantly higher standard plate counts were obtained from samples of cooked rice (2.3 to 4.9 log CFU/g) and sushi (2.8 to 6.9 log CFU/g) and the prevalence of S. aureus in samples was higher on food (21.7%, 28 of 129 samples) and hands (30%, 18 of 60 samples) ( P < 0.05). Glove changing in combination with hand washing minimized cross-contamination during sushi preparation as indicated by the lower prevalence of S. aureus (0%, 0 of 28 samples) and total targeted foodborne bacteria (3.6%, 1 of 28 samples) on the gloves of food handlers who changed gloves and washed their hands compared with those handlers who did not don new gloves. Repeated use of dishcloths could be a cause of cross-contamination, and the prevalence of total targeted foodborne bacteria was significantly higher on hands dried with dishcloths (64.7%, 11 of 17 samples) than on hands dried with paper towels (12.5%, 1 of 8 samples) ( P < 0.05). The prevalences of B. cereus, L. monocytogenes, and Salmonella in the 356 food samples were 5.1% (18 samples), 0.8% (3 samples), and 0%, respectively. Improvements to hand washing, hand drying, and glove changing practices are needed to lower the occurrence of cross-contamination during sushi preparation.

An assessment of food safety information provision for UK chemotherapy patients to reduce the risk of foodborne infection

OBJECTIVES

Given the increased risk of foodborne infection to cancer patients receiving chemotherapy treatment, and the risk of listeriosis reportedly five-times greater to this immunocompromised patient group, there is a need to ensure the implementation of domestic food safety practices among chemotherapy patients and their family caregivers. However, information regarding the adequacy of resources to inform and enable patients to implement domestic food safety practices to reduce the risk of foodborne infection is limited. Consequently, this study aimed to evaluate the provision of food safety information available to UK chemotherapy patients.

STUDY DESIGN

In-depth semi-structured interviews and content analysis of online patient information resources.

METHODS

Interviews with patients and family caregivers (n = 15) were conducted to explore food-related experiences during chemotherapy treatment. Online food-related information resources for chemotherapy patients (n = 45) were obtained from 35 of 154 National Health Service chemotherapy providers in England, Scotland, and Wales, the Department of Health (DoH) and three of 184 identified UK cancer charities. Identified food-related information resources were reviewed using a content-analysis approach to assess the inclusion of food safety information for chemotherapy patients.

RESULTS

In-depth interviews established that many patients indicated awareness of immunosuppression during treatment. Although patients reported practicing caution to reduce the risk of communicable diseases by avoiding crowded spaces/public transport, food safety was reported to be of minimal concern during treatment and the risk of foodborne infection was often underestimated. The review of online food-related patient information resources established that many resources failed to highlight the increased risk of foodborne infection and emphasize the importance of food safety for patients during chemotherapy treatment. Considerable information gaps exist, particularly in relation to listeriosis prevention practices. Cumulatively, information was inconsistent, insufficient, and varied between resources.

CONCLUSION

The study has identified the need for an effective, standardized food safety resource specifically targeting chemotherapy patients and family caregivers. Such intervention is essential to assist efforts in reducing the risks associated with foodborne infection among chemotherapy patients.

Handwashing, but how? Microbial effectiveness of existing handwashing practices in high-density suburbs of Harare, Zimbabwe

BACKGROUND

Consistent domestic hand hygiene can reduce diarrhea-related morbidity and mortality and the spread of other communicable diseases. However, it remains uncertain which technique of handwashing is most effective and practicable during everyday life. The goal of this study is to determine how the handwashing technique, as performed in the daily life by the participants of this case study in Harare, Zimbabwe, influences microbial handwashing effectiveness.

METHODS

Handwashing technique of 173 primary caregivers was observed in their homes and hand rinse samples were collected before and after handwashing. Samples were analyzed for Escherichia coli and total coliform concentrations. Generalized linear models were used to predict fecal hand contamination after washing from observed handwashing technique.

RESULTS

Cleaning under fingernails, scrubbing the fingertips, using soap, and drying hands through rubbing on clothes or a clean towel statistically significantly reduced E coli contamination of hands after washing. Tap use, scrubbing fingertips, and rubbing hands on clothes to dry them statistically significantly reduced total coliform contamination.

CONCLUSIONS

Recommendations for effective and practicable domestic handwashing in Harare, Zimbabwe, should include performing specific handscrubbing steps (ie, cleaning under the fingernails and rubbing the fingertips), and soap and tap use. This calls for further research to develop behavior change interventions that explicitly promote effective handwashing technique at critical times.