Evaluation of a Newly Developed Vacuum Dried Microtiter Plate for Rapid Biocide Susceptibility Testing of Clinical Enterococcus faecium Isolates

Abstract

We investigated the suitability of a newly developed biocide susceptibility test system based on microtiter plates containing vacuum dried biocides as a fast and reliable screening method. The evaluated substances included the cationic biocides benzalkonium chloride (BAC), chlorhexidine dihydrochloride (CHX), cetylpyridinium chloride, didecyldimethylammonium chloride, and octenidine dihydrochloride. Testing a selection of Escherichia coli and enterococci, the biocide microtiter plates provided results comparable to those obtained from broth microdilution according to ISO 20776-1. Broad MIC ranges allowed for testing gram-positive and gram-negative species with the same plate design. In the second part of our study, we applied the established method to analyze the susceptibility of 90 clinical Enterococcus faecium isolates from a German university hospital, as previous studies have indicated a link between reduced susceptibility to substances such as CHX and BAC and vancomycin resistance. We therefore determined MIC and minimum bactericidal concentrations (MBC) for 48 non-clonal vancomycin susceptible and 42 non-clonal vancomycin resistant isolates, but MIC95 and MBC95 were quite similar in both groups. Our easy to handle and ready to use test system enables the routine surveillance of bacterial tolerance towards disinfectants in hospitals. As a result, hygiene measures can be adapted and nosocomial infections controlled despite increasing prevalence of antibiotic-resistant bacteria.

Bacterial sensitivity to chlorhexidine and povidone-iodine antiseptics over time: a systematic review and meta-analysis of human-derived data

“…Articles were published between 1976 and 2021, although the majority (95%) were published this century. The antiseptics used included five different CHX salts (digluconate 33 , 35 , 37 , 40 , 47 , 50 , 55 – 58 , 61 , 63 , 67 , 69 , 74 , 75 , 81 , 83 , 88 , 90 , 94 , 97 , 99 , 101 , 106 , 107 , 111 , 113 , gluconate 34 , 36 , 42 , 42 , 53 , 91 , 102 , 103 , 108 , 108 , 109 , 112 , dichlorohydrate 85 – 87 , diacetate 71 , 99 and dihydrochloride 96 ) and povidone-iodine 37 , 46 , 49 , 70 , 76 , 91 . In total, MBC data from 6218 microbes were extracted.…”

Current insights into the effects of cationic biocides exposure on Enterococcus spp.

“…have been described among diverse collections (Alotaibi et al, 2017;Ignak et al, 2017;Sobhanipoor et al, 2021). On the contrary, a decreased susceptibility in vancomycin-susceptible Enterococcus compared to vancomycin-resistant Enterococcus as well as no significant difference between the two groups has also been found for the biocides BC, CHX, DDAC or CPC (Baillie et al, 1992;Barry et al, 1999;Suller and Russell, 1999;Kõljalg et al, 2002;Braga et al, 2013;Roedel et al, 2020;Sobhanipoor et al, 2021). Such disparities among studies might be associated with the different methodologies used, various levels of previous exposure to CBs by the bacteria, or with other genetic or metabolic properties specific to each of the local bacterial populations studied.…”

Data_Sheet_1.PDF

“…have been described among diverse collections (Alotaibi et al, 2017;Ignak et al, 2017;Sobhanipoor et al, 2021). On the contrary, a decreased susceptibility in vancomycin-susceptible Enterococcus compared to vancomycin-resistant Enterococcus as well as no significant difference between the two groups has also been found for the biocides BC, CHX, DDAC or CPC (Baillie et al, 1992;Barry et al, 1999;Suller and Russell, 1999;Kõljalg et al, 2002;Braga et al, 2013;Roedel et al, 2020;Sobhanipoor et al, 2021). Such disparities among studies might be associated with the different methodologies used, various levels of previous exposure to CBs by the bacteria, or with other genetic or metabolic properties specific to each of the local bacterial populations studied.…”