Evaluation of the bactericidal efficacy of three different alcohol hand rubs against 57 clinical isolates of S. aureus
Introduction
Staphylococcus aureus causes significant morbidity and mortality in hospital intensive therapy units (ITUs).1 The most common mode of transmission of micro-organisms in the healthcare environment is via the hands of healthcare workers (HCWs).2, 3
Alcohol hand rubs (AHRs) were introduced in the healthcare environment as an alternative to hand washing for use when hands are physically clean. Their introduction resulted in much higher compliance rates and this has led to a reduction in infection rates.4, 5 There are many AHRs commercially available, each with a different formulation. Although these products all claim to kill a number of pathogenic micro-organisms, different efficacy test protocols are being used by manufacturers. These include methods such as EN1500, and EN12054 and EN1276, which measure efficacy against a small number of standard bacterial strains in suspension.6, 7, 8 For safety and ethical reasons, pathogenic micro-organisms cannot be tested on volunteers with EN1500, and suspension tests in particular may not be appropriate to measure the activity of such products since micro-organisms on skin are more difficult to kill than planktonic ones.9
As part of a surveillance programme for the effectiveness of hand disinfection measures in Welsh ITUs against meticillin-resistant Staphylococcus aureus (MRSA), the efficacy of three AHRs used in local ITUs was investigated using a common carrier test protocol. Parameters used in the methodology were based on observation of ITU staff to ensure that conditions in practice were reflected.
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Bacterial strains
Fifty-seven S. aureus isolates from positive blood cultures of clinically infected ITU patients between 2004 and 2006 were provided by two hospitals in Wales. Thirty-one isolates were MRSA and 26 meticillin-sensitive S. aureus (MSSA). S. aureus NCIMB 9518 was also used. Freezer stocks were stored at −80 °C and subcultured to working slopes, from which Tryptone soya agar slopes (TSA; Oxoid, Basingstoke, UK) were prepared for testing. Suspensions were prepared by washing the TSA slope
Observation of hand-sanitising practices in ITU
A summary of hand-sanitising observations is shown in Table I. One of the most important findings was the exposure time of the AHRs on hands, which was ≤15 s in both hospitals. However, it was observed that the majority of staff applied AHRs to the required areas of hands as stated in the hospital hand hygiene guidelines. These observations highlighted the importance of measuring the efficacy of AHRs using a short exposure time.
The volume of AHR delivered on the hand after the application of one
Discussion
The overall compliance in hand hygiene observed was high in hospital A and low in hospital B (Table I) when compared with other findings.11 Of great importance is the short exposure time observed for AHRs to be applied to the hands of HCWs and the variability in their application (Table I). The volume of AHR was found to be low compared with manufacturer's recommendation. The volume of AHR delivered on hand after the application of one pump varied between the different products as well as the
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Evaluation of the bactericidal efficacy of three different alcohol hand rubs against clinical isolates of Staphylococcus aureus using an ex vivo carrier test
2011, Journal of Hospital InfectionCitation Excerpt :This is likely to have reduced the evaporation time of the alcohol, although this AHR did not show any residual activity once evaporated. Cutan was not found to be more efficacious than the other AHRs following a 10 s contact time, which is similar to those used in practice.5 Clinical isolate 1 was found to be the most susceptible isolate, and isolate 2 was found to be the least susceptible isolate to the three AHRs in a previous study, with NCIMB 9518 being intermediate.5