Evaluation of the bactericidal efficacy of three different alcohol hand rubs against 57 clinical isolates of S. aureus

We tested the efficacy of three alcohol hand rubs (AHRs) used in two local Welsh intensive therapy units (ITUs) against Staphylococcus aureus. The test protocol was based on a carrier test and parameters (concentration, contact time) were chosen following observation of hand-sanitising practices in the ITUs. Following AHR exposure, surviving bacteria were enumerated using a standard plate count method plus a Bioscreen C Microbial Growth Analyser. The AHRs demonstrated variable efficacy against the clinical isolates: the mean log(10) reduction after 10 s exposure to Soft Care Med H5, Cutan and Guest Medical AHRs was 2.67, 0.696 and 1.96, respectively, and after 30 s exposure was 4.58, 1.74 and 3.60, respectively. Since the average time taken by healthcare workers (HCWs) to rub AHR onto their hands was 11 s and 15 s at the two hospitals, the efficacy of these AHRs may be significantly limited against the S. aureus isolates under the conditions observed in practice. In addition, differences observed in log(10) reduction in bacterial number post-exposure using the Bioscreen compared to the plate count method provided evidence that S. aureus may be able to recover following Guest Medical AHR treatment within 2 min exposure, whereas after 5 min exposure bacterial damage caused by the AHR was irreversible. Although the introduction of AHRs improved hand hygiene compliance among HCWs, our observations highlighted that contact time is an important factor to ensure the efficacy of these products.