RESUMEN
The objective of this work was to evaluate the antimicrobial resistant (AR) E. coli prevalence in recreational waters in Belgium and to assess the exposure risk for bathers. Nine stations were sampled during the 2021 bathing season. A total of 912 E. coli strains were isolated and tested by the disk diffusion method in accordance with EUCAST recommendations, including Extended-Spectrum Beta-Lactamase (ESBL) production. AR E. coli were counted at each bathing sites, 24% of strains were resistant to at least one antibiotic and 6% were Multi-Drug Resistant (MDR). A Multiple Antibiotic Resistance (MAR) index was calculated to compare the bathing sites. The Lesse river had the highest MAR index as well as the highest E. coli absolute abundance and the largest number of ESBL-producing E. coli. Conversely, the 3 lakes showed lower E. coli contamination levels and AR rates. A human health risk assessment of exposure to AR E. coli, based on the calculation of measured prevalence, was performed considering four different dose-response model scenarios. The human health risk (Pd) ranged from 10-9 to 0.183 (children). The exposure probabilities were low, except for scenario 3 (E. coli O157:H7), which is the most severe.
RESUMEN
The purpose of this work was to evaluate the level of antimicrobial resistant Escherichia coli isolates in freshwaters and hospital effluents in Belgium. The samples were collected from 24 locations along the Ourthe, Vesdre, Amblève and Meuse rivers and in the wastewater effluents of several hospitals. The sampling stations in rivers were classified according to the dominant land covers of the rivers (rural, urban and forest areas). Two sampling campaigns were organized in May and October 2019 to highlight a possible seasonal effect. A total of 938 E. coli strains were isolated on Chromogenic Selective Tryptone Bile X-glucuronide (TBX) and TBX supplemented with amoxicillin (TBX+AMX) media. Disk diffusion assays were performed following the EUCAST's recommendations to assess the antimicrobial resistance against 12 antibiotics. A total of 32·7% of strains were at least resistant to one antibiotic and 24·6% were multiple antimicrobial resistant strains on TBX. The highest resistance rates were found for ampicillin (AMP), amoxicillin coupled with clavulanic acid (AMC) and sulfamethoxazole/trimethoprim (SXT). The lowest resistance rates were observed for meropenem (MEM) and ertapenem (ETP), which are last resort antibiotics. No significant difference was observed between both campaigns for the resistance rate to antibiotics.
