Abstract

ROJAS, Tomás et al. Biofilms formation and antimicrobial susceptibility among coliforms isolated in bottled drinking water in Carabobo, Venezuela. Bol Mal Salud Amb [online]. 2012, vol.52, n.1, pp.87-97. ISSN 1690-4648.

Pollution indicator bacteria such as heterotrophic bacteria, total and thermotolerant coliforms were quantified in bottled drinking water using standard method and membrane filter procedure. Biofilm formation and antimicrobial susceptibility (Kirby-Bauer method) were tested on sixty randomly selected coliform strains. Among 50 water samples, a large percentage (94) were found with heterotrophic bacteria levels above 100 CFU/mL, 46 % showed at least one CFU/100 mL of thermotolerant or total coliformes whereas 28 % and 30 % showed more than ten CFU/100 mL for both indicators. Coliform species found in higher proportion were, Klebsiella pneumoniae, Enterobacter cloacae, Enterobacter aerogenes, Escherichia coli and Klebsiella oxytoca. Using an "in vitro" assay for biofilms formation it was determined that between 75.8 y 79.2 % of total and thermotolerant coliforms, respectively, were found to be moderate or strong biofilm formers. There were no significant differences (P>0.05) between both groups regarding the capacity for biofilm formation. Most of the isolates were susceptible against the antibiotics tested and only two species showed unnatural resistance phenotypes. Multiresistance profiles, typical of strains associated with human clinical or veterinary activities were identified in one Enterobacter cloacae isolated (derepressed AmpC beta-lactamases) and one Escherichia coli strain was ampicilin resistant. This study suggests that the water sold in some plastic bottles in some urban areas near by Carabobo, Venezuela, may be a risk to health.

Keywords : Drinking Water; Coliforms; Biofilms; Antimicrobial susceptibility.