Antibiogram profile of bacteria distributed along the Philippine General Hospital (PGH) – wastewater treatment facility (WWTF) – Manila Bay (MB) Wastewater Continuum

Abstract

he Philippine General Hospital (PGH) is considered as the largest hospital in the country with a bed capacity of 1,500. This facility lacks a primary inhouse treatment system for its wastes and diverts discharge straight to a treatment facility, allowing the wastewater from the hospital to join other domestic and industrial wastewater from the city and be treated accordingly by an off-sourced wastewater treatment facility. Inadequate handling of healthcare wastes may cause various hazards, leading to a spread of infectious diseases or genes linked to antimicrobial resistance. This study determined the distribution and antibiogram profile of cultivable, heterotrophic bacteria along the previously mentioned wastewater continuum. Wastewater samples from the effluent of PGH, influent and effluent of a wastewater treatment facility and the discharge point into the Manila Bay were obtained and serially plated, and three most abundant species per site were then isolated and subjected to downstream experiments. The identification of bacteria and their antibiogram profiles was done by the Department of Laboratories of the Philippine General Hospital, using the VITEK 2 Compact machine and disk diffusion assay with Clinical and Laboratory Standards (CLSI) breakpoints. From the eight samples of each sampling site, the total plate counts were 9875, 18330, 18240 and 440 CFU for the PGH effluent, WWTF influent, WWTF effluent and discharge point respectively for the first sampling date. For the second sampling date, the total plate counts were 10300, 10880, 8120 and 1440 CFU for the PGH effluent, WWTF influent, WWTF effluent and discharge point respectively.. All the identified bacteria showed resistance to at least one antibiotic tested in the study. Among these, Achromobacter xylosoxidans, Enterobacter cloacae, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas oleovorans and Sphingomonas paucimobilis were found to be multiresistant, all being against to three or more antimicrobial classes. Our findings suggest possible threats from the presence of antibiotic resistance genes occurring in wastewater effluents.A more extensive study on the distribution and dynamics not just of antibiotic resistant (AR) bacteria but more importantly AR genes must follow this investigation focusing on healthcare wastewater.