Monitoring of natural bathing waters in Slovenia includes the quantification of coliform bacteria and enterococci. Analysis of phenotypic and genotypic traits can be crucial to assess the potential pathogenicity of strains, the gene load associated with antimicrobial resistance in environmental waters and to identify the potential source of pollution. In the master thesis, we studied the occurrence of virulence genes and resistance to seven antimicrobial substances in E. coli strains in samples, isolated from waters and sediments, sampled monthly over a period of one year at 4 different locations. With ERIC-PCR method, we excluded clonal/related isolates from the same location on the same sampling day. In our analysis, we included 62 strains, which were classified into phylogenetic groups determined by Clermont, and the presence of 27 genes related to virulence factors was determined by the PCR method. The selected strains were tested for resistance to selected antimicrobial agents using the phenotypic method and genotyping for β-lactamases from the TEM, SHV, OXA and CTX-M groups, as well as plasmid-encoded resistance to fluoroquinolones (PMQR). Our results show that the
E. coli strains present in bathing waters are very diverse, from potentially pathogenic and multi- resistant to susceptible to antimicrobial substances without the presence of key virulence factors. Multiple resistant CTX-M positive strains and strains with the presence of several genes for virulence factors were isolated in the water samples of the Olympic rowing centre and the bathing area at Mala Zaka of Lake Bled in February, April and June. A potential pollution source, according to the phylogeny of isolates, time and location of sampling, is agricultural activity.
|
