Prevalência de resistência a antimicrobianos em isolados ...

Prevalência de resistência a antimicrobianos em isolados ambientais de Escherichia coli e enterococos
Abstract
Water is a scarce resource and essential to life that can be an important vehicle of
pathogenic enteric bacteria. Fecal matter is also a source of antimicrobial resistant
bacteria and contributes to its spread and their resistance genes into the environment and
among commensal communities and human and animal pathogenic bacteria. The
microbiological quality of water is monitored by the use of fecal indicator bacteria such
as Escherichia coli, enterococci and total microorganisms.
The main objective of this study has to determine the prevalence of ESBLs and AmpC
in environmental isolates of E. coli and also evaluate the prevalence of vancomycin-
resistant enterococci strains (VRE).from Douro river estuary and coastline of Oporto
city.
In the present study water samples were collected at four sites located in the Douro river
estuary and coastline between April and July. The detection and quantification of
biomarkers was performed by the filter membrane method. The susceptibility of strains
of E. coli and enterococci was tested by the disk diffusion method to various classes of
antimicrobials.
The higher microbial counts were determined between April and June in freshwater
samples. There were isolated 62 E. coli strains and 49 enterococci strains that showed
90,3% (56/62) and 83,7% (41/49) antimicrobial resistance, respectively. E.coli strains
showed higher frequencies of resistance to ampicillin (74,2%) and tetracycline (61,3%).
In these strains it was found phenotypes associated with multiple antimicrobial
resistance to at least three classes of antimicrobial agents in 56,5% (35/62) of the
isolates. It has been found that enterococci strains showed high resistance levels to
rifampicin (34,0%) and azithromycin (40,8%), and was detected the expression of
vancomycin resistance phenotype in 26,5% of the strains. We found a prevalence of
36,7% (18/49) of enterococci strains associated with multidrug resistance phenomens.
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