Multidrug-resistant Escherichia coli from artesian well waters in Los Baos, Laguna, the Philippines

Due to the rising cost of commercial potable water, residents especially in rural areas increasingly rely on artesian well water, which is usually untreated and not regularly tested for potability. This could lead to a higher risk of ingestion of microorganisms exhibiting resistance to antibiotics. Thus, this study focused on detecting fecal coliforms specifically Escherichia coli from artesian well water samples from selected barangays [villages] (Bayog, Malinta, and Mayondon) in Los Baos, Laguna, the Philippines. Isolated E. coli were screened for antimicrobial resistance. Out of 30 water samples, eight were presumptively positive for coliforms, as determined using the multiple-tube fermentation method. Three out of eight samples (MY2-2, ML2-3, and ML2- 4) obtained E. coli isolates, as identified through phenotypic and molecular characterization. Using disk diffusion assay, resistance patterns were identified in the isolates for antibiotics cefoperazone, meropenem, ofloxacin, and trimethoprim sulfamethoxazole. Results revealed that MY2-2 was resistant to cefoperazone, meropenem, and trimethoprim sulfamethoxazole; ML2-3 was resistant to cefoperazone and meropenem, whereas ML2-4 was resistant to all four antibiotics. Polymerase chain reaction with primers detecting the TEM gene, which is a type of extended-spectrum beta-lactamase gene, showed that the isolates were resistant to ampicillin and penicillin. Results of phenotypic and molecular methods indicate that the isolates are multi-drug resistant. Based on household interviews, the artesian well water from which MY2-2 was isolated, was used for drinking by 10 households. Therefore, the local government units should regularly monitor artesian well water for microbiological quality, conduct education and information campaigns on the diseases that can be contracted from consuming unclean water, and ensure that potable water is accessible, especially for households with no access to purified water.