Agricultural and municipal waste water as a source of antibiotic-resistant enterococci

Abstract

The occurrence of enterococci in different waste waters from two cattle farms in south and north Moravia and sewage treatment plant of the University of Veterinary and Pharmaceutical Sciences Brno, Czech Republic was investigated. Resistance and/or sensitivity of selected isolates was tested to various antibiotics. The samples were collected in the course of two years (1999-2000). The total counts of enterococci varied from 103 to 105 colony-forming units (CFU) per ml. Among 100 isolated strains 60 strains were identified as Enterococcus faecalis, 10 as Ent. durans as well as Ent. hirae, 8 strains were allotted to Ent. faecium, 5 to Ent. mundtii, 3 to Ent. gallinarum, 2 to Ent. casseliflavus, one strain was identified as Enterococcus spp. and one strain was not specified as enterococcus. The susceptibility to antibiotics was tested by both, the agar disk diffusion method and the microdilution method. The majority of enterococci (95%) was resistant to more than one antibiotic tested, especially to clindamycin, penicillin, cephalotin, ofloxacin and tetracycline. No vancomycin-resistant strain was found. Our results confirm that agricultural and municipal waste waters might be an important source of antibiotic-resistant enterococci.