4 Material und Umwelt
Filtern
Erscheinungsjahr
- 2023 (3) (entfernen)
Dokumenttyp
- Posterpräsentation (3) (entfernen)
Sprache
- Englisch (3) (entfernen)
Referierte Publikation
- nein (3)
Schlagworte
- Biocide (3) (entfernen)
Organisationseinheit der BAM
- 4.1 Biologische Materialschädigung und Referenzorganismen (3) (entfernen)
Background. Disinfection is an important mitigation strategy to control and prevent the spread of infections. Incomplete or incorrect usage of disinfection may promote evolution of resistance against disinfectants and antibiotics. Ideally, disinfection reduces the number of surviving bacteria and the chance for resistance evolution. Resistance describes the ability to grow in previously inhibitory concentrations of an antimicrobial, whereas tolerance is associated with enhanced survival of lethal doses. Individual bacteria from the same population can display considerable heterogeneity in their ability to survive treatment (i.e. tolerance) with antimicrobials, which can result in unexpected treatment failure.
Objective. In this study, we investigated six active substances of disinfectants, preservatives, and antiseptics against a population of E. coli to identify the presence of a tolerant subpopulation.
Methods. We performed time-kill experiments and analyzed the data with a mathematical model to statistically infer whether the data is best explained by the presence of a tolerant subpopulation.
Results. The analysis identified bimodal kill kinetics for benzalkonium chloride, didecyldimethylammonium chloride, and isopropanol. In contrast, kill kinetics by chlorhexidine, glutaraldehyde, and hydrogen peroxide were best explained by unimodal kill kinetics. These findings have implications for the risk of disinfection failure. In addition, we are currently performing adaptive laboratory evolution (ALE) experiments with the different disinfectants to investigate the potential consequences of tolerant sub-populations for the evolution of antimicrobial resistance and tolerance.
Background. Disinfection is an important mitigation strategy to control and prevent the spread of infections. Incomplete or incorrect usage of disinfection may promote evolution of resistance against disinfectants and antibiotics. Ideally, disinfection reduces the number of surviving bacteria and the chance for resistance evolution. Resistance describes the ability to grow in previously inhibitory concentrations of an antimicrobial, whereas tolerance is associated with enhanced survival of lethal doses. Individual bacteria from the same population can display considerable heterogeneity in their ability to survive treatment (i.e. tolerance) with antimicrobials, which can result in unexpected treatment failure.
Objective. In this study, we investigated six active substances of disinfectants, preservatives, and antiseptics against a population of E. coli to identify the presence of a tolerant subpopulation.
Methods. We performed time-kill experiments and analyzed the data with a mathematical model to statistically infer whether the data is best explained by the presence of a tolerant subpopulation.
Results. The analysis identified bimodal kill kinetics for benzalkonium chloride, didecyldimethylammonium chloride, and isopropanol. In contrast, kill kinetics by chlorhexidine, glutaraldehyde, and hydrogen peroxide were best explained by unimodal kill kinetics. These findings have implications for the risk of disinfection failure. In addition, we are currently performing adaptive laboratory evolution (ALE) experiments with the different disinfectants to investigate the potential consequences of tolerant sub-populations for the evolution of antimicrobial resistance and tolerance.
Biocides are used for a wide range of purposes, including disinfectants or preservatives. They play a major role in the prevention of microbial infections in healthcare and animal husbandry. The use of biocides often leads to the discharge of active biocidal substances into wastewater streams, causing the exposure of wastewater microbial communities to subinhibitory concentrations. In turn, it is known that wastewater treatment plants (WWTP) are hotspots for antibiotic resistant bacteria. Since similar mechanisms confer resistance to biocides and antibiotics, exposure to biocides can result in co-selection of antibiotic resistant bacteria in WWTP Here, we want to investigate co-selection processes of antibiotic resistance in natural WWTP microbial communities upon biocide exposure. Microbial communities were sampled at the WWTP Ruhleben in Berlin and characterized regarding their susceptibility against different clinically relevant antibiotics. To investigate the link between biocide exposure and antibiotic resistance, changes in the susceptibility level after exposure to environmentally relevant concentrations of the commonly used biocide didecyldimethylammonium chloride (DDAC) will be determined by enumerating resistant and non-resistant E. coli on selective plates with and without antibiotics and DDAC. In case of antibiotics, clinical breakpoint concentrations according to EUCAST will be used to discriminate between susceptible and resistant strains. In case of DDAC (and biocides in general), clinical breakpoints do not exist. Therefore, we determined a cut-off concentration at which the majority of naturally-occurring E. coli strains cannot grow anymore based on (I) the MIC (minimal inhibitory concentration) distribution, and (II) by plating wastewater communities onto selective indicator agar plates loaded with increasing DDAC concentration. Additionally, antibiotic cross-resistance will be determined by spotting single colonies, isolated from DDAC-selective plates onto antibiotic plates. The results of our experiments will help to determine selective concentrations and to estimate the risk of antibiotic co-selection and cross-resistance in microbial WWTP communities upon biocide exposure.