Antibiotic Resistance among Escherichia coli Isolates from Hospital Wastewater Compared to Community Wastewater

This study aimed to compare the antibiotic resistance levels of the indicator bacteria Escherichia coli in wastewater samples collected from two hospitals and two urban communities. Antimicrobial susceptibility testing was performed on 81 E. coli isolates (47 from hospitals and 34 from communities) using the disc diffusion method according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) methodology. Ten antibiotics from nine different classes were chosen. The strains isolated from the community wastewater, compared to those from the hospital wastewater, were not resistant to gentamicin (p = 0.03), but they showed a significantly higher susceptibility-increased exposure to ceftazidime (p = 0.001). Multidrug resistance was observed in 85.11% of the hospital wastewater isolates and 73.53% of the community isolates (p > 0.05). The frequency of the presumed carbapenemase-producing E. coli was higher among the community isolates (76.47% compared to 68.09%) (p > 0.05), whereas the frequency of the presumed extended-spectrum beta-lactamase (ESBL)-producing E. coli was higher among the hospital isolates (21.28% compared to 5.88%) (p > 0.05). The antibiotic resistance rates were high in both the hospital and community wastewaters, with very few significant differences between them, so the community outlet might be a source of resistant bacteria that is at least as important as the well-recognised hospitals.