Conventional And Molecular Epidemioly Of Staphylococcus Aureus Isolates Originated From Human And Animals

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Mohamed, Wisal
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University of Khartoum
A total of 63 isolates were collected from different samples of human, cattle, sheep and camel gatherings in addition to one reference Staph. aureus strain. These isolates were subjected to phenotypic characterization using cultural, morphological, biological, biochemical and antibiotic susceptibility testing as well as to genotypic characterization using PCR. The antimicrobial susceptibility patterns of the isolates rmind by the single disk method using Muller-Hinton agar. The antibiotic sensitivity testing was performed for 50 out of the 63 Staph. aureus isolates against eight antimicrobial agents. The standard Staph. aureus was used to test the quality control. The frequencies of sensitive strains of animal origin were as follows: gentamicin 77.4%, erythromycin 70.9%, tobramycin 58%, followed by methicillin 51.6%, oxytetracycline 45.1%, cephalothin 32.5%, amoxycillin/ clavulunic acid 53.5%, and low sensitivity of penicillin 12.9%, where as the frequencies of sensitive strains of human origin to each drug were as follows: 15 gentamicin, 68.7%; tobramycin, 62.6%; erythormycine, 59.3%; cephalothin, 46.8%; oxytetracycline, 43.7%; methicillin, 31.2%; amoxicillin/clavulanic acid, 18.7%; penicillin, 9.%. The comparison of the overall sensitivity percentage of human and animal isolates revealed that all antibiotics were either equally or more effective for animal isolates than human ones. Representatives of the phenotypic clusters of Staph. aureus were subjected to genotypic analysis on the basis of coagulase gene polymorphism. The DNA was extracted from using two different boiling methods. The coagulase gene was amplified by PCR using a pair of olignucleotide nested primers. Amplification of coagulase gene among Sudanese strains of Staph. aureus revealed patterns with obvious polymorphism indicating genotypic variation. Given the specificity of the coagulase gene, the isolates were thus confirmed to be belong to the coagulase positive Staph. aurueus. The polymorphism of coagulase gene was authenticated and emphasized in the present study. Out of 31 PCR-amplification isolates, 21 produced a single band while 8 isolates produced two bands. The length of the amplicon ranged from 430 to 1000 bp. Amplicons of the 21 isolates were thus categorized as 670, 930, 950 and 1000 bp. The amplicons 930 bp were equivalent to the size band of the reference Staph. aureus strain.
108 Pages
Molecular Epidemioly,Staphylococcus,Human, Animals;Bacteriology Staphylococcus aureus;Collection ;clinical;environmental samples