Tap out: reducing waterborne Pseudomonas aeruginosa transmission in an intensive care unit.

BACKGROUND: Pseudomonas aeruginosa is a ubiquitous and important opportunistic pathogen in immunocompromised or critically ill patients. Nosocomial P. aeruginosa outbreaks have been associated with hospital water sources. AIM: To describe engineering interventions to minimize contamination of water outlets and the subsequent clinical impact. METHODS: New tap outlets were fitted at selected outlets across the intensive care unit (ICU). Laboratory testing demonstrated that, following artificial contamination with P. aeruginosa, these taps could be effectively decontaminated using a thermal washer-disinfector. Water samples were collected weekly from new outlets on the ICU over an eight-month period and tested for the enumeration of P. aeruginosa via membrane filtration. Surveillance of P. aeruginosa from clinical specimens was routinely undertaken. FINDINGS: Prior to the interventions, water sampling on ICU indicated that 30% of the outlets were positive for P. aeruginosa at any one time, and whole genome sequencing data suggested at least 30% transmission from water to patient. Since their installation, weekly sampling of the new tap outlets has been negative for P. aeruginosa, and the number of P. aeruginosa clinical isolates has fallen by 50%. CONCLUSION: Installation and maintenance of tap outlets free of P. aeruginosa can substantially reduce the number of P. aeruginosa clinical isolates in an ICU.

Assessment of the efficacy of a patient hand wipe: development of a test method.

BACKGROUND: Much attention has focused on hand decontamination for healthcare workers, but little attention has been paid to patient hand hygiene. Patients confined to bed are often unable to access handwashing facilities. They could use an alcohol hand rub, but these are not advised for soiled hands or social hand hygiene. One alternative is the use of a hand wipe. However, it is important to ascertain the effectiveness of hand wipes for removal of transient micro-organisms from the hands. AIM: To develop a method to assess the antimicrobial efficacy of hand wipes compared with handwashing, and thus determine if a hand wipe can be acceptable for patient hand hygiene. METHODS: The methodology was based on European Standards EN 1499 (2013) and EN 1500 (2013) as there is no standard for hand wipes. The hands of 20 healthy volunteers were contaminated artificially by immersion in Escherichia coli, and then sampled before and after the use of a reference soft soap or hand wipes for 60 s. The counts obtained were expressed as log10, and the log10 reductions were calculated. FINDINGS: The hand wipe with no antimicrobial agent (control wipe) was inferior to the soft soap. However, the antimicrobial hand wipe was statistically non-inferior to the soft soap. A log10 reduction of 3.54 was obtained for the soft soap, 2.46 for the control hand wipe, and 3.67 for the antimicrobial hand wipe. CONCLUSION: The evidence suggests that the antimicrobial hand wipe, when applied for 60 s, is at least as good as soap and water, representing an acceptable alternative to handwashing from a bactericidal perspective.

Comparison of the efficacy and drying times of liquid, gel and foam formats of alcohol-based hand rubs.

BACKGROUND: Hand rubs containing alcohols such as isopropanol (IPA) or ethanol (EtOH) are widely used for hygienic hand disinfection, and are presented in different formats (i.e. liquid, gel or foam). AIM: To determine if there is any difference in efficacy between these two active ingredients in the three formats. In addition, an assessment of the drying time was undertaken. Two non-commercial, 'standard' formulations were tested in each format: one containing 60% IPA, and the other containing 80% EtOH. METHODS: EN 1500 tests were performed with 20 volunteers to assess efficacy. The reference product was 2 x 3 mL of 60% IPA for 60 s, as described in EN 1500 (2013). The test products were 3 mL of liquid, gel or foam format; one full EN 1500 test was performed for each formulation (60% IPA and 80% EtOH). To assess drying time, two different volumes (1.5 and 3.0 mL) of the test formulations in liquid, gel or foam format were applied to the hands of 15 volunteers. Volunteers self-reported when their hands were dry; at the end of the test, the volunteers were asked to rate the time taken to dry on a three-point scale (too short, OK, too long). FINDINGS: This study found no difference in antibacterial efficacy attributable to formulation or format for the two 'standard' ABHR formulations, as assessed by EN 1500. When measured objectively, the EtOH-based formulations dried more rapidly than the IPA-based formulations, and for both formulations, gels took longer to dry than other formats. User perception of drying time broadly agreed with objective measurement. CONCLUSION: Given that there was no difference in efficacy and only moderate difference in drying time, it is proposed that ABHR in liquid, foam or gel format may be appropriate, provided that the specific product passes the required efficacy and safety standards.

Dose considerations for alcohol-based hand rubs.

BACKGROUND: Manufacturers' recommended dosages for alcohol-based hand rubs are typically determined by measuring product efficacy using a model protocol such as EN 1500; however, anecdotal reports and informal observation suggests that in many cases users self-titrate to much lower doses in real-world application. AIM: To examine the interdependence of alcohol-based hand-rub volume on in-vivo efficacy using the EN 1500 standard test method, on drying time on users' hands, and on their perceptions of acceptability. METHODS: Three formulations were studied using EN 1500 and a modification of this method. The modification used volumes ranging from 0.5 to 3.0 mL and 30 s application. Drying times were recorded and user acceptability was established using a three-point scale (too long, OK, or too short). Dying times were analysed in relation to hand surface area. FINDINGS: The drying time for all three products increased as a function of volume. The drying time displayed a positive association with volume and a negative association with hand surface area. The optimum volume for user acceptability was between 1.5 and 2 mL, yielding a drying time of between 20 and 30 s. CONCLUSION: Whereas EN 1500 is appropriate for establishing the efficacy of a hygienic hand-rub formulation compared to a benchmark, it does not reflect actual in-use conditions or the likely clinical effectiveness of the product. In particular, it fails to address the need to optimize the volume of application and user acceptability of the product.

Disinfectant wipes are appropriate to control microbial bioburden from surfaces: use of a new ASTM standard test protocol to demonstrate efficacy.

BACKGROUND: The use of disinfectant pre-soaked wipes (DPW) to decontaminate high-touch environmental surfaces (HTES) by wiping is becoming increasingly widespread in the healthcare environment. However, DPW are rarely tested using conditions simulating their field use, and the label claims of environmental surface disinfectants seldom include wiping action. AIM: To evaluate the new E2967-15 standard test specific to wipes, particularly their ability to decontaminate surfaces and to transfer acquired contamination to clean surfaces. METHODS: ASTM Standard E2967-15 was used by three independent laboratories to test the efficacy of five types of commercially available wipe products. All data generated were pulled together, and reproducibility and repeatability of the standard were measured. FINDINGS: All the commercial DPW tested achieved a >4log10 (>99.99%) reduction in colony-forming units (CFU) of Staphylococcus aureus and Acinetobacter baumanii with 10s of wiping, but only one DPW containing 0.5% accelerated H2O2 prevented the transfer of bacteria to another surface. CONCLUSION: This newly introduced standard method represents a significant advance in assessing DPW for microbial decontamination of HTES, and should greatly assist research and development, and in making more relevant and reliable claims on marketed DPW.

Development of a sporicidal test method for Clostridium difficile.

BACKGROUND: Disinfectants with claimed activity against Clostridium difficile must be evaluated to ensure efficacy against the spores that comprise an environmental source of patient infection. Unfortunately there is, at present, no generally accepted method for evaluating these disinfectants. In the absence of such a method, laboratories have to adapt protocols that were not designed for products used in medical environments and consequently may use inappropriate test organisms, exposure times, and pass criteria. AIM: To develop and evaluate a method for testing the activity of disinfectants against C. difficile spores using exposure times and pass criteria which are relevant to clinical application. METHODS: A Joint Working Party of the Healthcare Infection Society (HIS) and the Advisory Committee on Antimicrobial Resistance and Healthcare Associated Infections (ARHAI) of the Department of Health in England was assembled. The Working Party adapted a previously described enzyme-based method for spore purification (the Clospore method) using an exposure time of 5 min and a 5 log10 kill as a pass criterion. FINDINGS: Evaluation of the method by three laboratories demonstrated that the method is simple to follow and that the results are repeatable and reproducible. CONCLUSION: The method described by the Working Party produces a clean suspension with a high titre of spores. It is recommended that, for a disinfectant used in the environment, the product should demonstrate a 5 log10 reduction in 5 min under clean or dirty conditions to fulfil the requirements of the test.

The antibacterial activity and stability of acetic acid.

Acetic acid has been shown to have good antibacterial activity against micro-organisms such as Pseudomonas aeruginosa. This study examined the activity against a range of bacterial pathogens and also assessed any reduction in antibacterial activity due to evaporation or inactivation by organic material in dressings. Acetic acid was active at dilutions as low as 0.166% and the activity was not reduced by evaporation nor by inactivation by cotton swabs. Burn injuries are a major problem in countries with limited resources. Acetic acid is an ideal candidate for use in patients who are treated in those parts of the world.