Isolates recovered from infected sites were from wounds, pleural fluid and blood cultures collected in patients from hospitals in Bengaluru, Mumbai, Delhi, and Hyderabad. Data on community origin of these isolates is limited to a few as
the isolates were sent to us from physicians from different hospitals. Ethical clearances and written consents for publication were obtained from the respective VX-680 hospitals. Phenotypic characterization S. aureus isolates were selected after growth on chromogenic agar medium (chromAgar, bioMérieux, Marcy-L’Etoile, France) and identified after characterization by Gram staining, selleck detection of catalase, coagulase and DNAse as described elsewhere . Antibiotic susceptibility testing Susceptibility testing was performed by Kirby-Bauer disc diffusion according to the guidelines recommended
by the CLSI (formerly NCCLS) on Mueller-Hinton agar plates at 37°C using antibiotic discs. Minimum Inhibitory Concentration (MIC) for oxacillin and cefoxitin was determined by the broth dilution method in Mueller-Hinton Broth after 24 hrs selleckchem of incubation at 37°C in micro titer plates . Chromosomal DNA isolation Chromosomal DNA was extracted according to previously published procedures using lysostaphin . PCR for detection of SCCmec elements and ccr types SCCmec typing by determination of mec and ccr complexes for types IV and V SCCmec elements was carried out by multiplex PCR [28–30]. Subtyping of type IV SCCmec was performed according to the procedure of Zhang et al and Milherico et al [31, 32]. Identification of accessory gene regulator (agr) alleles by PCR The four agr alleles were determined by a multiplex PCR as described in Gilot et al . Detection of toxins The presence of PVL genes was detected by PCR using the published primers and procedure SPTBN5 . Presence of staphylococcal entero-toxins A, B, C, D and E, exfoliating toxins A and B and toxic shock syndrome toxin tst (TSST-1) and enterotoxin gene cluster (egc) cluster were detected by several multiplex PCRs using published procedures
[35, 36]. MLST and spa typing MLST and spa typing were done as described earlier [37, 38]. PFGE PFGE was performed as described before . eBURST analysis Clonal relationship of the isolates was determined by using eBURST v3 program with the entire MLST database. Microarray Analysis using CLONDIAG® Microarray was performed for selected isolates from each of the clonal complexes. Diagnostic DNA microarray based on the Array/Tube platform (CLONDIAG, Jena, Germany) were utilized as described by Monecke et al . The micro-array covers 185 distinct genes and about 300 alleles there of, including species- specific controls, agr alleles, genes including virulence factors, and microbial surface components recognizing adhesive matrix molecules (MSCRAMMS), capsule- type specific genes, as well as resistance determinants and immune evasion factors.