Antibiotic Resistance and Extended-Spectrum Beta-Lactamase Production of Escherichia coli Isolated from Irrigation Waters in Selected Urban Farms in Metro Manila, Philippines

Pierangeli Vital,Windell Rivera,Ma Dimasupil,Iñigo Santos,Cielo Paraoan,Enrico Zara,Joseth Abello

doi:10.3390/w10050548

Abstract

Highly-polluted surface waters are increasingly used for irrigation in different agricultural settings because they have high nutrient content and are readily available. However, studies showed that they are reservoirs for the emergence and dissemination of antibiotic-resistant bacteria in the environment. In this study, the resistance of 212 Escherichia coli isolates from irrigation water, soil, and vegetables in selected urban farms in Metro Manila, Philippines was evaluated. Results showed that antibiotic resistance was more prevalent in water (67.3%) compared to soil (56.4%) and vegetable (61.5%) isolates. Resistance to tetracycline was the highest among water (45.6%) and vegetable (42.3%) isolates while ampicillin resistance was the highest among soil isolates (33.3%). Multidrug-resistant (MDR) isolates were also observed and they were more prevalent in water (25.3%) compared to soil (2.8%) and vegetable (8.4%) isolates. Interestingly, there are patterns of antibiotic resistance that were common to isolates from different samples. Extended-spectrum beta-lactamase production (ESBL) was also investigated and genes were observed to be present in 13 isolates. This provides circumstantial evidence that highly-polluted surface waters harbor antibiotic-resistant and MDR E. coli that may be potentially transferred to primary production environments during their application for irrigation purposes.

Highlights

Agricultural productivity heavily relies on the use of irrigation water in irrigating agricultural plants, applying fertilizers and pesticides, and processing of farm products
The present study aims to evaluate the resistance of 212 E. coli isolates from irrigation water, soil, and vegetables in selected urban farms in Metro Manila, Philippines against nine commonly-used antibiotics and to ascertain the patterns of antibiotic resistance among the isolates
A total of 212 culture-positive E. coli consisting of 147 irrigation water, 39 soil, and 26 vegetable isolates were obtained from 190 water, soil, and vegetable samples

Summary

Introduction

Agricultural productivity heavily relies on the use of irrigation water in irrigating agricultural plants, applying fertilizers and pesticides, and processing of farm products. Surface waters are practical to use because of their availability and high nutrient content, they can be a potential source of fecal contaminants and pathogenic microorganisms that may be transferred to farm products, such as fresh produce, during irrigation [1,2,3]. One group of β-lactamase enzymes, the extended spectrum β-lactamases (ESBLs), produced by Escherichia coli, is of particular significance. These are able to target a wider range of antibiotics and plasmids that contain genes for ESBLs which often carry genes for resistance to various other antibiotics [10,11,12]

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Discussion

Conclusion