Investigation of sensitivity and resistance to antibiotics and chemotherapeutics in E. coli strains isolated from animals bred in intensive farming conditions

Being an important pathogenic and indicator microorganism, E. coli has been included in all the resistance follow up programs worldwide. We carried out sampling on 42 cattle, pig and poultry farms. After sampling the material was delivered to the laboratories, where it was exposed to standard treatment and streaking by standard methods of microbiological diagnostics with the aim to isolate and identify E. coli strains. On the selected isolated E. coli strains an investigation of its sensitivity to a certain number of antimicrobial agents (ampicillin, tetracycline, chloramphenicol, streptomycin, neomycin and sulphametoxasol) was carried out. After obtaining the results from each farm for the three different animals categories (young healthy, young unhealthy, adult), 60 E. coli strains for eachcategori were isolated to be examined for sensitivity to 17 antibiotics and chemotherapeutics. The investigation included a total of 180 E. coli strains originating from cattle, pigs and poultry. For the investigation of isolated E. coli strains Mueller Hinton broth and agar, antibiogram tablets (Torlak, Belgrade) as well as discs by Becton Dickinson, BBL (USA) were used In isolated E. coli strains resistance to investigated antimicrobial agents was significantly different depending on the speciesage and health status of the animals. The majority of the isolated E. coli strains examined for 17 antibiotics and chemotherapeutics showed a resistance to 15, and sensitivity only to cephalosporines of the III generation and colistin.