Using the 91% cutoff, 46 MLVA patterns were defined out of the 69 MRSA strains evaluated. Applying a 75% similarity value generated 13 clusters from 56 strains, excluding 13 strains from these clusters (Fig. 2a). Isolates belonging to the same cluster differed by up to four bands. MLVA

of the clinical S. aureus isolates using either cutoff value revealed that the majority of isolates do not belong to the same clusters as US S. aureus clones (USA100, USA200, USA300, and USA600) and suggest that the isolates collected from the Illinois area are not clonal. For PA, using the 97% cutoff value, 43 MLVA banding patterns were formed out of the 44 strains. When a cutoff value of 75% was applied, CHIR-99021 purchase 10 clusters were generated comprising 28 strains, and 26 MLVA banding patterns were discerned (Fig. 2b). Strains that group according to these two cutoff values are in a variety selleck products of clusters, demonstrating that the isolates studied were not clonal. Armed with the knowledge that the collection of MRSA and PA clinical isolates were sufficiently diverse, an effort was made to define the prevalence of TA genes in the strains. For the MRSA isolates, gene-specific PCR

primers were used to amplify the genes for the mazEF homolog (called mazEFSa) observed on the S. aureus COL genome (Pandey & Gerdes, 2005). The PA isolates were probed for homologs of the higBA, parDE and relBE systems identified in PA strain PAO1 (Pandey & Gerdes, 2005). The oligonucleotide sequences of all PCR primers used to amplify TA genes are listed in Table 1 and the homologous regions are represented in Fig. 1. Total DNA preparations from each of the 78 MRSA and 42 PA strains were analyzed by PCR, and results

were designated as positive if a distinct band was observed at the expected size on an agarose gel. The PCR screen revealed that the mazEFSa TA system was present in all MRSA isolates (78/78, 100%). For the 42 PA isolates, relBEPa (42/42, 100%) and higBAPa (42/42, 100%) were ubiquitous, whereas parDEPa (13/42, 30%) was less prevalent. Supporting Information G protein-coupled receptor kinase Table S1 contains a complete list of all MRSA and PA isolates and the TA genes detected by PCR. Comparison of the MLVA genotypes of PA strains that carry parDEPa showed that these strains are dispersed throughout the dendrogram, indicating that there is no correlation between genome relatedness and carriage of parDEPa. DNA sequencing was performed on ∼10% of all PCR products. For the MRSA isolates, sequenced PCR products revealed strong sequence identity (95.6–99.5%) to the reference TA system sequence (mazEFSa alignments are shown in Fig. S1). For the PA isolates, sequenced PCR products also revealed strong sequence identity (97.8–100%) to the reference TA system sequences [higBAPa, 99.4% average identity; parDEPa, 99.6% average identity; and relBEPa, 98.