Abstract
We analyzed 90 nonduplicates community-associated methicillin-resistant S. aureus (CA-MRSA) strains isolated from skin and soft-tissue infections. All strains were mecA positive. Twenty-four of the 90 strains showed inducible macrolide-lincosamide-streptogramin B resistance. All strains produced α-toxin; 96% and 100% of them displayed positive results for lukS-F and cna genes, respectively. Eigthy-five strains expressed capsular polysaccharide serotype 8. Six different pulsotypes were discriminated by pulsed-field gel electrophoresis (PFGE) and three predominant groups of CA-MRSA strains (1, 2, and 4) were identified, in agreement with phenotypic and genotypic characteristics. Strains of group 1 (pulsotype A, CP8+, and Panton-Valentine leukocidin (PVL)+) were the most frequently recovered and exhibited a PFGE band pattern identical to other CA-MRSA strains previously isolated in Uruguay and Brazil. Three years after the first local CA-MRSA report, these strains are still producing skin and soft-tissue infections demonstrating the stability over time of this community-associated emerging pathogen.
Highlights
Staphylococcus aureus is capable of establishing a wide spectrum of interactions with the human host
The mecA gene was detected in the 90 community-associated methicillin-resistant S. aureus (CA-methicillin-resistant S. aureus (MRSA)) strains analyzed
3 out of the 90 strains displayed oxacillin inhibition zone diameters ≥13 mm. These results were similar to those described previously by other authors regarding the best performance of cefoxitin 30 μg disk versus oxacillin 1 μg disk for the screening of the MRSA phenotype confered by the mecA gene [31, 32]
Summary
Staphylococcus aureus is capable of establishing a wide spectrum of interactions with the human host. S. aureus harbors several virulence factors including surface-associated adhesins, secreted exo-proteins and toxins [2,3,4,5]. Another important characteristic of S. aureus is the capacity to acquire resistance to antimicrobial agents. Methicillin resistance is conferred by the mecA gene which codes for an additional penicillin-binding protein, namely, 2a (PBP2a) with reduced affinity to β-lactam agents. This gene is located in a mobile genetic element of variable size called staphylococcal cassette chromosome mec (SCCmec). Seven types and several subtypes of SCCmec have been characterized [8,9,10,11]
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