Abstract

Fecal bacteria have been used for more than a century as indicators of fecal contamination in water. In recent years, the monitoring of somatic and F-specific coliphages has been gradually included in guidelines and regulations as an additional parameter to reinforce water safety. The Escherichia coli host strain CB390 was tailored to detect both somatic and F-specific coliphages in a single test. The efficacy of this strain for bacteriophage detection, previously evaluated in Western Europe and North America, was assessed here for the first time in South America. The detection of somatic and F-specific coliphages by the strain CB390, as well as by standardized methods, was performed in drinking and river water and municipal and abattoir wastewaters. No statistical difference was found in the numbers of total coliphages detected by strain CB390 and the sum of somatic and F-specific coliphages determined separately by the standardized ISO methods. The data presented here provide further validation of the effectiveness of the host strain E. coli CB390 for the detection of total coliphages in waters in a single test and demonstrate its suitability for application in upper-middle income countries of the Americas (World Bank category).

Highlights

  • The aptness of somatic and F-specific coliphages as indicators of viral and fecal contamination in water and food has been extensively studied, and the abundant scientific literature on this subject is covered in several reviews[1,2,3,4,5]

  • In this state of affairs, it could be advisable to assess the numbers of both phage types, using either the standardized methods to detect somatic and F-specific coliphages separately or a bacterial host strain capable of measuring both in a single test

  • The suitability of CB390 to detect total coliphages was assessed in Colombia (South America), a country that differs from previously studied areas in income level and climate

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Summary

Materials and Methods

Somatic and F-specific coliphages, bacteriophages infecting E. coli strain CB390 and E. coli, were analyzed from 48 samples of urban sewage, 84 samples of the Bogotá River collected in different sectors of the river with very different fecal contaminant loads, and 46 tap water samples of the Bogotá network. Somatic coliphages were quantified by enumerating plaque forming units (PFUs) in the E. coli host strain WG5 according to the ISO 10705-2 standard method[18]. F-specific coliphages were quantified by enumerating PFUs in strain WG49 of Salmonella enterica serovar typhimurium according to the ISO 10705-1 standard method[17]. Values of coliphages and E. coli concentrations in the drinking water, where the positive detection frequency was very low, were estimated by applying Thomas’ formula for the calculation of the most probable number for long series of data[35]

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