Virulence associated factors in bacteria from water bodies in Belém, Pará, Brazil: bacteriological composition and threat to public health

Abstract

A lack of sewage treatment contaminates water bodies threatening human health by spreading waterborne gastroenteritis. This is a particular problem for developing countries, where the risks associated with surface water contamination remain largely unknown. To understand the risk associated with sewage contamination of water bodies, we evaluated the microbiological indicators of water quality and isolated bacterial strains from water bodies from the city of Belém, Pará, Brazil. The strains were identified by biochemical and serological tests and polymerase chain reactions (PCRs). The thermotolerant coliforms and Escherichia coli presented values above 1,000 (NMP/100 mL) biweekly from August 2012 to November 2015, without a significant statistical difference between sampling periods (Kruskal–Wallis p > 0.05). The water of the Tucunduba river presented contamination levels similar to those in a sewage pumping station (Dunn test p > 0.05). From 240 bacterial isolates, we identified 163 Vibrio cholerae, 8 Vibrio mimicus, 24 E. coli, and 5 Salmonella spp. The isolates of V. cholerae demonstrated N-acetylglucosamine (NAG) profile (Non-O1 and Non-O139) and 18 expressed the stn/sto gene. No E. coli was shown to be potentially pathogenic. The results revealed that water bodies in Belém were constantly contaminated by sewage and fecal microorganisms, including the potential circulation of pathogens in viable and cultivable form. HIGHLIGHTS Constant pollution of urban water bodies in Belém, North of Brazil.; Water body with bacteriological contamination index similar to sewage effluents.; Circulation of potential pathogens in their viable and cultivable form.; Vibrio cholerae NAG, with expression of important virulence genes in waterborne gastroenteritis.;

Keywords

• microbiological indicators
• pathogenic bacteria
• surface water
• water pollution