[Antibiotic resistance patterns of enterococci isolated from estuarine waters]

The introduction of antibiotic-resistant bacteria to the environment, affects its hygienic-sanitary quality. The objective of this work is to study the prevalence and the antibiotic resistance patterns of enterococci species isolated from Bahía Blanca estuarine waters. One hundred and three isolates were biochemically identified as Enterococcus spp. The diffusion technique was implemented, by using disks of: vancomycin (Van 30 microg), gentamicin (GenH 120 microg), streptomycin (StrH 300 microg), teicoplanin (T 30 microg), ampicillin (Am 10 microg) and ciprofloxacin (CIP 5 microg) according to the Clinical and Laboratory Standards Institute. Seven Enterococcus species were identified, being Enterococcus faecium and Enterococcus faecalis the most frequent. High level resistance to aminoglycosides was shown by 1.9% of the enterococci whereas 12.6% of the isolates were resistant to CIP. No isolates showed simultaneous resistance to StrH and GenH. Neither resistance to glycopeptides nor to Am was detected. Thirty four per cent of the isolates exhibited susceptibility to all antibiotics tested. Surveillance studies on antimicrobial resistance are usually based upon microorganisms isolated from clinical samples. The findings of this work constitute relevant data for the control of resistant strains, which were believed to be circumscribed to the hospital environment, but are also widespread in the natural sites.