Quinolone-resistant Escherichia coli isolated from birds of prey in Portugal are genetically distinct from those isolated from water environments and gulls in Portugal, Spain and Sweden.

The influence of geographic distribution and type of habitat on the molecular epidemiology of ciprofloxacin resistant Escherichia coli was investigated. Ciprofloxacin resistant E. coli from wastewater, urban water with faecal contamination and faeces of gulls, pigeons and birds of prey, from Portugal, Spain and Sweden were compared based on multi-locus sequence typing (MLST) and quinolone resistance genetic determinants. Multi-locus sequence typing allowed the differentiation of E. coli lineages associated with birds of prey from those inhabiting gulls and waters. E. coli lineages of clinical relevance, such as the complex ST131, were detected in wastewater, streams and gulls in Portugal, Spain and Sweden. Quinolone resistance was due to gyrA and parC mutations, although distinct mutations were detected in birds of prey and in wastewater, streams and gulls isolates. These differences were correlated with specific MLST lineages, suggesting resistance inheritance. Among the plasmid-mediated quinolone resistance genes, only aac(6')-ib-cr and qnrS were detected in wastewater, streams and gulls isolates, but not in birds of prey. The horizontal transfer of the gene aac(6')-ib-cr could be inferred from its occurrence in different MLST lineages.

Vancomycin resistant enterococci: from the hospital effluent to the urban wastewater treatment plant.

Vancomycin is an important antibiotic to treat serious nosocomial enterococci infections. Human activities, in particular those related with clinical practices performed in hospitals, can potentiate the transfer and selection of clinically-relevant resistant bacteria such as vancomycin resistant enterococci (VRE). Indeed, previous studies demonstrated the occurrence of VRE in urban wastewater treatment plants and related environments (e.g. sewage, rivers). In this study, the occurrence of VRE in a hospital effluent and in the receiving urban wastewater treatment plant was investigated. Vancomycin and ciprofloxacin resistant bacteria occurred in the hospital effluent and in raw municipal inflow at densities of 10(3) to 10(2) CFU mL(-1), being significantly more prevalent in the hospital effluent than in the urban wastewater. Most of the VRE isolated from the hospital effluent belonged to the species Enterococcus faecalis and Enterococcus faecium and presented multidrug-resistance phenotypes to ciprofloxacin, tetracycline, erythromycin, and high-level gentamicin. The same pattern was observed in clinical isolates and in enterococci isolated from the final effluent of the urban wastewater treatment plant. These results show that hospital effluents discharged into urban wastewater treatment plants may be a relevant source of resistance spread to the environment.