CHARACTERIZATION OF TETRACYCLINE-RESISTANT STAPHYLOCOOCUS AUREUS ISOLATED FROM BOVINE MASTITIS IN KHARTOUM STATE, SUDAN

Abstract

Thirty four strains of Staphylococcus aureus, isolated from mastitic
milk samples and the cow fences in Sudan were used for the polymerase
chain reaction (PCR) assay (arbitrary primed PCR), during the present study.
The PCR differentiated the isolates into 3 groups, of more than 90%
similarity within each. However all the isolates showed more than 70%
similarity with each other. Twenty seven (79.41%) of those isolates were
tetracycline and deoxocycline resistant. However all the isolates showed
susceptibility to minocycline. Plasmids (1-3) were detected in 30 (88.24%) of
Staphylococcus aureus isolates. The PCR products of the plasmid DNA and
Southern blot hybridization proved that the resistance was due to tet K gene.
Endonuclease restriction enzymes (Hind III), when used to cut the plasmid
DNA at the restriction site of tet K gene in tetracycline resistant S. aureus
isolates, differentiated the isolates carrying the tet K determinants into 4
groups. In one of them the tet K gene was found to be pST S14, while the
other three groups carried tet K gene from pT181. Amplification of all
products were analysed by electrophoresis in agrose gels (0.8-1.2%) and
detected by staining them with or without ethidium bromide.
The present study concluded that tet K gene is the common
responsible gene for transferring tetracycline resistance among the S. aureus
isolated from mastitis –infected cows in Sudan. Further detailed studies are
needed to evaluate and estimate the risk and role of antibiotics misuse in
veterinary practices