Journal of Water Resource and Protection, 2013, 5, 1117-1126 Published Online November 2013 (http://www.scirp.org/journal/jwarp) http://dx.doi.org/10.4236/jwarp.2013.511117 Open Access JWARP Presence of Multidrug-Resistant E. coli, Enterococcus spp. and Salmonella spp. in Lakes and Fountains of Porto, Portugal Carlos E. Flores 1,2* , Luís Loureiro 3 , Lucinda J. Bessa 4 , Paulo Martins da Costa 1,4 1 ICBAS-Abel Salazar Biomedical Sciences Institute, University of Porto, Porto, Portugal 2 Faculty of Sciences (FCUP), University of Porto, Porto, Portugal 3 Tulane University, School of Public Health and Tropical Medicine, New Orleans, USA 4 CIIMAR-Interdisciplinary Center for Marine and Environmental Research, University of Porto, Porto, Portugal Email: * carloseduardof1990@gmail.com Received September 8, 2013; revised October 11, 2013; accepted November 6, 2013 Copyright © 2013 Carlos E. Flores et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT Urban lakes and fountains provide recreational activities that could facilitate the contact between humans, animals and biological agents. The objective of this work was to assess the water quality and safety of 17 lakes and 13 fountains in the city of Porto (Portugal), by detecting the presence of Escherichia coli, enterococci and Salmonella spp., and analyz- ing their antimicrobial resistance. The mean number of E. coli colony forming units (CFU) was higher, both in lakes (2.67 × 10 3 CFU/100 ml) and fountains (3.52 × 10 2 CFU/100 ml), in comparison to enterococci counts: 5.60 × 10 2 and 4.10 × 10 CFU/100 ml, respectively. By screening a set of 26 multidrug-resistant E. coli (including seven ESBL-pro- ducing isolates) for virulence genes, we found strains carrying the fimH, chuA, cvaC, cnf1, hlyA, TSPE4.C2 and yjaA genes. Phylogenetic analyses have shown that the majority of E. coli strains belong to groups A and B1. Salmonella spp. was found in two lake water samples. Generally, the fecal contamination was notorious and worrisome, requiring pre- ventive measures to minimize the negative impacts on human health. Finding the contamination source is definitely im- portant so that interventions can be more effective. Keywords: Antimicrobial Resistance; Enterococcus spp.; Escherichia coli; Salmonella spp.; Fountains; Lakes 1. Introduction Recreational and decorative use of water can have im- portant effects on health and well-being. Presently, in se- veral cities, lakes and fountains are mainly used for these purposes. However, the contamination of urban lakes and fountains with fecal material can turn these water spots into potential hazards for public health. The presence of total coliforms, fecal coliforms and Escherichia coli is indicators of fecal pollution and commonly used to ana- lyze the safety and quality of water supplies and recrea- tional water [1,2]. E. coli belongs to the family of Enterobacteriaceae and is a common inhabitant of the gastrointestinal tract of humans and animals, and can be easily spread through water contaminated with fecal material. As a genetically diverse group, most strains of E. coli are harmless com- mensals, but others are capable of causing either intesti- nal or extra-intestinal (ExPEC isolates) disease, due to the existence of virulence genes in their genome or plasmids [3]. According to Clermont et al. [4], the analysis of vi- rulence genes contributes to the classification of E. coli into phylogenetic groups. The most virulent strains be- long to the phylogenetic group B2, with a minority of strains belonging to group D. Most of the commensal strains are included in group A and B1 [5]. Enterococci are also present in the normal gut of ani- mals and humans, and have been used as a water quality indicator in many countries. Presently, the genus Ente- rococcus comprises 51 validly published species [6]. How- ever, Enterococcus faecium and Enterococcus fecalis are the most prevalent species in animal feces and commonly used as indicators of fecal pollution [7,8]. In general, due to the difficulty associated with the di- rect isolation of pathogens from water samples, indica- tors of fecal pollution may denounce the presence of pa- thogenic microorganisms (such as salmonella) in water * Corresponding author.