Antimicrobial Resistance Genes in from Artificial Water Systems: Findings from a Two-Year Study.

BACKGROUND

species are the causative agent of Legionnaires' disease and, as ubiquitous waterborne bacteria, are prone to antimicrobial resistance gene (ARG) acquisition and dissemination due to the antimicrobial contamination of natural environments. Given the potential health risks associated with ARGs, it is crucial to assess their presence in the population.

METHODS

The ARGs and were detected in 348 samples, isolates, and DNA extracts using conventional PCR. In a subset of -positive isolates, azithromycin (AZT) MIC values were obtained using the EUCAST protocol and LpeAB activity was evaluated through an efflux pump inhibition assay.

RESULTS

The gene was found in 19% (66/348) of samples, with higher detection rates in the and sg1 subgroups, at 30% and 41%, respectively. A positive association between and sg1 was found. The MIC values of the -positive isolates ranged from 0.064 to 2 mg/L. LpeAB inhibition resulted in 2- and 4-fold MIC reductions in 10 of the 13 isolates analyzed. One sample each of and was found to possess the gene.

CONCLUSIONS

The gene is predominant in sg1. A few isolates with the gene exhibited MIC values below the EUCAST tentative highest MIC values for wild-type isolates. Expanding ARG monitoring in is essential to assess the public health risk of Legionnaires' disease.