Hospital-acquired infections (HAIs) can be an important cause for morbidity and potentially mortality. There is increasing concern for the role of multi-drug resistant (MDR) organisms in HAIs. Surfaces, including stethoscopes, could act as fomites; however, there is no current consensus on decontamination protocols. Furthermore, there is increasing concern regarding the development of bacterial resistance to topically applied antiseptic agents, leading to evaluation of innovative decontamination methods.

The purposes of this project were to evaluate the type of bacterial contamination of stethoscopes in a referral hospital setting and to compare the effectiveness of three decontamination protocols.

This study was prospective and interventional. Based upon available information, a sample size of thirty stethoscopes per group was calculated to be adequate to determine differences between protocols. Three decontamination protocols were used in a crossover design across a six-week period. Decontamination protocols included 70% isopropyl alcohol, a quaternary ammonium/biguanide disinfectant (Anistel) and exposure to UV light (253.7 nm). For each, the diaphragm membrane of each stethoscope was sampled using a sterile cotton-tipped swab moistened in PBS before and after. Colony numbers were determined, and bacterial identification was performed. Between collection time points, stethoscopes were in regular clinical circulation.

For group comparisons, delta-change values in colony counts were determined for each stethoscope. Differences between groups were analysed using a non-parametric analysis of variance (Kruskal-Wallis test). Where differences were returned between groups, post-hoc analysis with Dunn's multiple comparisons method was performed to identify where differences occurred.

A variety of bacterial types were cultured across the course of the study. No MDR bacteria were isolated. There was no difference between delta change values when comparisons were made between decontamination protocols (p=0.07).

In this referral setting, stethoscope contamination with MDR bacteria was not present. There was no difference between groups regarding expected reductions in bacterial colony counts. UV light appeared equivalent to other topical solutions in reducing contamination rates of stethoscopes.

Disclosures

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