Volume 61 (2011) Issue: 2011 No#1

Investigation of the sensitivity of E. coli strains isolated from domestic animals to antibiotics and hemiotherapeutics in vitro

Author(s): Gavrović M, Ašanin Ružica, Mišić D, Jezdimirović Milanka, Žutić M

Keywords:animals, antibiotics, E. coli, resistance, sensitivity

Resistance to antibiotics is not a modern phenomenon. On the contrary, penicillin resistance in some bacterial strains developed quickly after its introduction into daily practice. At the same time some bacterial strains developed resistance to almost all known antibiotics, vancomycin included. Vancomycin was for a long time the only efficient antibiotic against staphylococcal infections. It is of special concern the fact that antibiotics are in everyday exploitation in agriculture and veterinary clinical practice which use them not only as a mean of therapeutic treatment, but as an additive in animal feedstuffs in order to promote growth and prevent bacterial infections. The same antibiotics are used in human medicine, which is a persistent problem. In such a way it is possible to develop resistance which can be transferred to human pathogenic bacteria via mobile genetic elements. The incidence of resistant bacterial strains increases year after year not only on a local level, but on a global scale, as well. Monitoring of the use of antibiotics and chemotherapeutics in the Republic of Serbia is not established as such, our intention was to study a number of bacteria isolated from cattle, pigs, poultry, dogs and cats. At this time we are presenting the results for pathogenic strains of E. coli in order to determine the use of antibiotics and chemotherapeutics of the old and new generations in domestic animals. E. coli sensitivity was investigated with the disc diffusion test for: ampicillin, amoxicillin with clavulanic acid, tetracycline, chloramphenicol, gentamicin, and ceftriaxon, sulphamethoxasole with trimethoprim, ciprofloxacin and florfenicol. E. coli strains resistant to three or more antibiotics were tested by means of agar dilution method for ciprofloxacin, tetracycline, chloramphenicol, gentamicin and amoxicillin with clavulanic acid by determination of the minimal inhibitory concentration (MIC). The tested E. coli strains resulted resistant to all antibiotics and chemotherapeutics with the exception of ceftriaxon and florfenicol. The highest resistance incidence (87.5%) was to tetracycline in E. coli strains isolated from pigs, 60% for E. coli strains isolated from cattle, 56% isolated from poultry and 20% originating from dogs. E. coli strains isolated from cats were sensitive to tetracycline. The highest incidence of ampicillin resistance was determined for E. coli strains originated from poultry (78%).