Comparative Analysis Of Antibiotic Resistance And R-Plasmids Of Staphylococcus aureus Isolates From Human And Dog Samples

Bacterial resistance to antibiotics constitutes a major cause of failure in the treatment of bacterial infections. The genetic exchange of plasmids containing antibiotic resistant determinants between bacteria is believed to play a critical role in the evolution of antibiotics resistant bacteria and this has been shown in S. aureus. This study was therefore carried out to investigate the nature of plasmids that determine antibiotic resistance in Staphylococcus aureus isolates from man and animal. Thirty multiply drug resistant S. aureus isolates from a total of 147 apparently healthy humans and dogs, as well as from clinical cases were determined by antibiotic susceptibility test using the standard disc agar diffusion method. Plasmid isolation was carried out by the alkaline lysis method of Birnboim and Dolly. Electrophoresis as well as the transformation experiment was done.The result showed that no particular sensitivity pattern or plasmid profile  can be ascribed to either human or animal sources of isolates. Two isolates from a domestic dog and its owner (human) were observed to have identical plasmid profile and almost the same antibiogram. 23.130 kbp and 25.119 kbp plasmids that were responsible for amoxycilin resistance were transferred. In conclusion, the genetic basis of antibiotic resistance by S. aureus in our locality was found to be partly plasmid mediated. Plasmid analysis, in conjunction with the antibiogram is valuable in differentiating multiple resistant S. aureus.Furthermore, domestic pet animals were found to be reservoirs and potential risk factors in the transfer of multiply antibiotic resistant S. aureus and their R-plasmids to antibiotic susceptible S. aureus and other bacteria.