Bacteriological quality and resistance profile of escherichia coli in aquatic ecosystems surrounding the santa fe city, argentina

MARÍA JOSEFINA GONZALEZ; BÁRBARA GHIGLIONE; ROQUE FIGUEROA ESPINOSA; MILENA DROPPA

Texas

Congreso; AMS MICROBE; 2023

Natural surface waters are indispensable resources for developing life. Anthropogenic pressure on them produces adverse effects such as poor microbiological quality associated with the presence of antimicrobial-resistant microorganisms (AMR). According to the global report on AMR by the WHO, the emergence of multidrug-resistant E. coli is considered a threat to public health system, where resistance to third-generation cephalosporins (TGC), carbapenems, and colistin is of concern in human and animal medicine.This work evaluated the bacteriological quality, and the antibiotic resistance profile of E. coli recovered in aquatic ecosystems linked to Santa Fe City, Argentina. Four seasonal samplings (2021-2022) were carried out by taking water samples (W, n=58) and sediments (S, n=58) at 14 sites in Setúbal lake and the Santa Fe, Coronda, Salado, and Colastiné rivers. Sites were selected based on active human actions on them. Quantification of E. coli was assessed using plate counts with selective chromogenic medium. Identity of isolates was carried out by MALDI-TOF MS. Antibiotic susceptibility was determined according to CLSI (2022) guidelines and colistin resistance by agar-spot screening test.Concentration of E. coli ranged between 0-8000 CFU/100 ml for water samples and between 0-640000 CFU/100 ml for sediments. In all samples, the same quantification pattern was observed, with 5 out of 14 sites above guideline limits (EPA, PAHO, WHO) for water quality for the primary contact. These points coincide with the places of greatest anthropogenic activity. Even if E. coli were recovered in the four samplings, for the moment, the resistance profile has been assessed in 558 isolates corresponding to the first three seasonal samplings (W = 349, S = 209). Resistance to ampicillin (30.2% - 36.5% of the total isolates), tetracycline (24.3% - 30.2%), and trimethoprim-sulfamethoxazole (13.9% - 15.1%) was relatively common. A significant proportion of ciprofloxacin resistance (15%) was observed only in the winter sampling. MDR isolates were commonly detected. Finally, resistance to TGC (5.5 %) and colistin (9.5%) was reported in the isolates from the first two samplings (n=365). These preliminary AMR results in aquatic environments of the Middle Paraná river show the circulation of resistant E. coli, which could be favored by anthropogenic impact and environmental conditions. This has ecological and sanitary relevance since AMR strains can spread through these ecosystems with consequences for human health and environmental evolution.