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Veröffentlichung Hygienisch-mikrobiologische Untersuchungen eines Fließgewässers (Weiße Elster) im Einzugsgebiet eines Badegewässers (Talsperre Pirk)(2016) Feuerpfeil, Irmgard; Hummel, Annette; Mehlis, Anika; Renner, PeterÜber einen Zeitraum von ca. zwei Jahren wurde die mikrobiologische Belastung eines Flusses im Einzugsgebiet einer Talsperre, die als Badegewässer genutzt wird, untersucht. Dieser Flussbereich ist Vorfluter für drei Kläranlagen. Untersucht wurden die Parameter E. coli, coliforme Bakterien, intestinale Enterokokken, Clostridium perfringens (C. perfringens), somatische Coliphagen, Campylobacter, Adenoviren, Cryptosporidium-Oocysten und Giardia-Cysten. Durch die Abflüsse der Kläranlagen und auch andere diffuse Einleitungen sowie Abschwemmungen von landwirtschaftlichen Nutzflächen ist die Belastung des Flusses mit Krankheitserregern hoch. Die Wasserqualität an der Badestelle der Talsperre hingegen ist gut, lediglich Adenovirus- DNA kommt manchmal in höheren Konzentrationen vor. Die Befunde sprechen für ein hohes Selbstreinigungspotenzial der Talsperre, insbesondere in ihrer vergleichsweise flachen Vorsperre.
Quelle: http://www.dwa.deVeröffentlichung A new approach to testing the efficacy of drinking water disinfectants(2018) Frohnert, Anne; Grunert, Andreas; Selinka, Hans-Christoph; Szewzyk, RegineNew disinfection procedures are being developed and proposed for use in drinking-water production. Authorising their use requires an effective test strategy that can simulate conditions in practice. For this purpose, we developed a test rig working in a flow-through mode similar to the disinfection procedures in waterworks, but under tightly defined conditions, including very short contact times. To quantify the influence of DOC, temperature and pH on the efficacy of two standard disinfectants, chlorine and chlorine dioxide, simulated use tests were systematically performed. This test rig enabled quantitative comparison of the reduction of four test organisms, two viruses and two bacteria, in response to disinfection. Chlorine was substantially more effective against Enterococcus faecium than chlorine dioxide whereas the latter was more effective against the bacteriophage MS2, especially at pH values of >7.5 at which chlorine efficacies already decline. Contrary to expectation, bacteria were not generally reduced more quickly than viruses. Overall, the results confirm a high efficacy of chlorine and chlorine dioxide, validating them as standard disinfectants for assessing the efficacy of new disinfectants. Furthermore, these data demonstrate that the test rig is an appropriate tool for testing new disinfectants as well as disinfection procedures.Veröffentlichung Biocide susceptibility and antimicrobial resistance of Escherichia coli isolated from swine feces, pork meat and humans in Germany(2023) Silva, David Attuy Vey da; Dieckmann, Ralf; Makarewicz, Oliwia; Al Dahouk, SaschaPhenotypic susceptibility testing of Escherichia (E.) coli is an essential tool to gain a better understanding of the potential impact of biocide selection pressure on antimicrobial resistance. We, therefore, determined the biocide and antimicrobial susceptibility of 216 extended-spectrum Î2-lactamase-producing (ESBL) and 177 non-ESBL E. coli isolated from swine feces, pork meat, voluntary donors and inpatients and evaluated associations between their susceptibilities. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of benzalkonium chloride, chlorhexidine digluconate (CHG), chlorocresol (PCMC), glutaraldehyde (GDA), isopropanol (IPA), octenidine dihydrochloride and sodium hypochlorite (NaOCl) showed unimodal distributions, indicating the absence of bacterial adaptation to biocides due to the acquisition of resistance mechanisms. Although MIC95 and MBC95 did not vary more than one doubling dilution step between isolates of porcine and human origin, significant differences in MIC and/or MBC distributions were identified for GDA, CHG, IPA, PCMC and NaOCl. Comparing non-ESBL and ESBL E. coli, significantly different MIC and/or MBC distributions were found for PCMC, CHG and GDA. Antimicrobial susceptibility testing revealed the highest frequency of resistant E. coli in the subpopulation isolated from inpatients. We observed significant but weakly positive correlations between biocide MICs and/or MBCs and antimicrobial MICs. In summary, our data indicate a rather moderate effect of biocide use on the susceptibility of E. coli to biocides and antimicrobials. © 2023 by the authors