Fresh faecal samples were collected with sterile swab sticks and conveyed promptly to the Department of Microbiology Laboratory (OAU) for microbiological analysis. Isolation and identification of S. aureus isolates The swab stick was inserted into a test tube containing 3 ml of sterile nutrient broth (Biolab, supplied by Merck, Johannesburg, South Africa), swirled Inhibitor Library research buy briefly to discharge the contents into the medium, and the culture was incubated at 37°C overnight. Thereafter, a loopful was
streaked on mannitol salt agar (MSA) (Biolab, supplied by Merck, Johannesburg, South Africa) and incubated at 37°C for 48 hours. Preliminary identification of S. aureus was based on positive Gram stain, and positive results for catalase, coagulase (tube method) and DNase tests. The procedure described previously  was employed for DNA
isolation. In summary, a single colony was suspended to a McFarland 1.0 standard in 100 μl of TE buffer (10 mM Tris, 1 mM EDTA, pH 8.0) with 10 U of achromopeptidase (Wako Chemical, Co. Ltd.), and the suspension was incubated at 55°C for 10 min. The supernatant was used as crude DNA for PCR. Molecular identification and confirmation of the isolates was based on sequencing analysis of the hsp60 gene as previously reported . PCR products were sequenced by using a Big Dye Terminator (version 3.1) cycle sequencing kit (Applied Biosystems, Foster City, CA) with an ABI Prism 3100 genetic analyzer (Applied Biosystems). Antibiotic susceptibility testing The susceptibility testing of the isolates to 11 antibiotics was performed using selleckchem the disk diffusion method and the following antibiotics were tested: penicillin (10 units), oxacillin (1 μg), cefoxitin (30 μg), erythromycin (15 μg), clindamycin (2 μg), tetracycline (30 μg), ciprofloxacin (5 μg), chloramphenicol (30 μg), fusidic
acid (10 μg) gentamicin (10 μg) and mupirocin (5 μg and 200 μg). S. aureus ATCC 25923 was the control Mirabegron strain for the susceptibility testing. The result was interpreted as resistant or susceptible based on the interpretative standard according to the Clinical Laboratory Standards Institute (CLSI) manual for bacterial isolates from animals . Interpretative zone diameter for resistance and susceptibility breakpoints to fusidic acid and mupirocin which are not stated in the CLSI guidelines were considered as described previously [35, 36]. The D-test for determining inducible resistance of clindamycin using erythromycin was performed. A truncated or blunted clindamycin zone of inhibition (D-Shape) indicated inducible resistance. Constitutive resistance was recognized by a clindamycin zone diameter of ≤14 mm . Molecular characterization of the S. aureus isolates Characterization of 70 isolates was determined by detection of the Panton Valentine Leukocidin (PVL) gene , agr and coa gene typing .