Antimicrobial surfaces and materials are frequently discussed as part of infection prevention bundles to reduce nosocomial infections. However, there is no evidence in the literature that antimicrobial gloves can prevent nosocomial infections. Due to the fact of frequent pathogen transmission occurring by the hands of medical staff [5, 9,10,11, 29] several manufacturers promote antimicrobial gloves based on different principles of action. Usually the potential antibacterial mode of action is confirmed by in vitro microbiological testing in accordance with ASTM D7907, a liquid based in vitro test that uses comfortable humidity and temperature, a large amount of contaminated liquid and unreallisticially long waiting periods.

In the recent years, it was demonstrated for solid surfaces that antimicrobial activity postulated by means of liquid-based in vitro testing is not representative for dry contamination typically observed on surfaces in hospitals [24, 25]. Therefore, results from liquid-based in vitro testing on flexible surfaces such as examination gloves should be critically reviewed. In patient care, gloves become invisibly contaminated by contact to patients and dry surfaces in the immediate environment. After contact with secretions and excretions of patients with visible contamination, an immediate change of gloves is recommended [6].

Therefore, the use of antimicrobial gloves in patient care would only make sense for longer periods of wear during activities without visible contamination with liquids and if the contamination of the gloves with microorganisms could be reduced immediately (hence in a contact time 3–5-s) [30]. Therefore, in the real world of patient care, gloves will thus never be exposed to the experimental conditions used in ASTM D7907. This finding is also supported by a current report of the VDI (The Association of German Engineers), which also confirms that it is not yet possible with normative methods to evaluate the contribution of antimicrobial products to the interruption of infection chains because their test design does not take into account practical application [17]. Therefore, in this study an alternative test method was established and gloves with antimicrobial activity detected in the ASTM D7907 test were examined.

The dry contamination with low organic load achieved in our experimental set up corresponds to realistic non visible contamination in patient care, which is why our test is basically suitable. In other studies, bacterial contamination of gloves after patient care ranged from 2 cfu/glove to > 30,000 cfu/glove or from 0 to more than 300 cfu per 5 fingertips, depending on the type and duration of patient contact and care, respectively [9,10,11]. These values are comparable to our range of 500–1500 CFU/glove on average measured in control gloves. The postulated antimicrobial gloves showed no activity at all for the Gram-negative species A. baumannii complex. However according to the manufacturer a reduction was also observed for Gram-negative bacteria using ASTM D7907 testing after 10 min. For the three different Gram-positive isolates tested, a marginal, not statistically significant reduction was found after 10 min waiting time with sufficient light intensity and was much lower compared to the reduction claimed by ASTM testing.

Because the activity is based on light according to the manufacturer's information, control experiments were carried out without light. The product's postulated antimicrobial activity is caused by a dye integrated into the outer layer of the gloves, which is said to act as a catalyst and generate the release of singlet oxygen in the presence of light. Singlet oxygen acts as a radical and attacks bacterial proteins and lipids, ultimately leading to cell death. Interestingly, the experiments without light showed a reduction of Gram-positive E. faecium after 10 min that was comparable to the LRV we have already seen with light. In this case observed differences in mean reduction were statistically significant (p < 0.05). However, the confidence interval is quite large and statistical significance can be assessed as insufficiently meaningful in the light of the professional background. Furthermore, the reduction was observed under dark conditions, so it may not be attributed to the claimed mode of action of the gloves, which is light-dependent. Instead, it could be assumed that the statistical significance is among others due to naturally occurring variations in the growth behaviour of microorganisms.

Also it was already shown that the glove material is an important factor influencing the bacterial transfer to and from a gloved hand [8]. Maybe the slight differences we observed in this study was due to a lower adherence of the bacteria to the glove material with the integrated dye instead of an active reduction.

Our study has some limitations which might be addressed in future research. Since only a specific batch of the manufacturer's antimicrobial gloves was studied, the statements in this study refer only to this batch. No general statement can be made at this time. This work also does not allow any general statements to be made about other gloves with postulated antimicrobial efficacy whose active principle is based on a different method.

In addition to the questionable effectiveness in practice, further aspects have to be considered when assessing the meaningfulness of such gloves. It should be mentioned that any disposable medical gloves must be removed after the end of an activity. Their change correlates with the indications for hand antisepsis [9]. This must always be done after the gloves have been removed, as all gloves do not provide complete protection against contamination of the hands through undetected perforations and also risk of contamination if the gloves are not removed properly. A deviation from this may be necessary in situations where frequent glove changes would have a relevant negative impact on the workflow. Here, disinfection of gloved hands would be conceivable. However, this would only make sense in the case of rapid, immediate effectiveness. A continuous reduction over a longer period of time by antimicrobial active ingredients cannot have a meaningful effect in this use. Moreover, the development of antimicrobial gloves with only (potential) efficacy against gram-positive pathogens should be discussed very critically, as the practical relevance is highly questionable. Furthermore, for reasons of sustainability, new gloves should only be developed if they are also biodegradable.