Abstract:Background: Rodriguez, Rizal, now the relocation site of the former Payatas landfill, faces environmental and public health challenges due to the presence of an unregulated open dumpsite near residential areas in Upper Sitio Pintor. Communities in this area rely on untreated water sources, including groundwater, which may harbor harmful bacteria such as Escherichia coli (E. coli). A known fecal coliform, E. coli, has the potential to develop antibiotic resistance in aquatic environments. This study aimed to detect the occurrence of E. coli in leachate, groundwater, and tap water near the dumpsite, describe the resistance profiles of antibiotic-resistant isolates, and compare resistance patterns across different antibiotic classes and water sources. Materials and Methods: A total of 58 water samples were collected in duplicates from 29 sampling sites: 13 from leachate, 13 from groundwater, and 3 from tap water. All samples were cultured for E. coli and subjected to antibiotic susceptibility testing using the Kirby-Bauer disk diffusion method. Descriptive statistics and Repeated Measures ANOVA were conducted using SPSS to compare resistance patterns across water sources. A P<0.05 was considered statistically significant. Results: E. coli was detected in 69.2% of leachate and 61.5% of groundwater samples, while all tap water samples tested negative. Leachate isolates showed the highest resistance to Penicillin (100%) and Aztreonam (44.4%), while groundwater isolates showed the highest resistance to Penicillin (87.5%) and Nitrofurantoin (68.8%). Significant differences in resistance were observed for Ceftriaxone (P=0.006) and Nitrofurantoin (P=0.003) across sources. Conclusions: This preliminary study highlights the presence of antibiotic-resistant E. coli in water sources near an open dumpsite. Results emphasize the need for improved water monitoring and waste management. Findings may guide future research and public health interventions on antibiotic resistance.
Keywords: Antimicrobial Resistance (AMR), antibiotic resistance, Escherichia coli, open dumpsite, leachate, groundwater
