RESUMEN
Methicillin-resistant Staphylococcus aureus can become resistant to many different classes of antibiotics. Objective: To characterize aminoglycoside and macrolide resistance mechanisms in MRSA strains in relation to antibiotic susceptibility patterns. Materials and methods: We tested 86 MRSA strains using multiplex PCR for detection of genes mecA, aac(6')-Ie/aph(2â³), ant(4')-Ia, aph(3')-IIIa, ermA, ermC and msrA. Results: There was a prevalence of msrA (32.5%), ermC (30.2%) and aph(3')-IIIa (61.6%) genes, which are less frequently reported in MRSA. Most msrA genes was detected in PVL positive strains (92.8%) and was associated only with non-MDR strains, while ermC genes were associated with MDR strains. PVL producing strains were characterized by the presence of aph(3')-IIIa (93.1%) and msrA genes (93.1%), being phenotypically susceptible to clindamycin. Conclusions: Detection of aminoglycoside and macrolide resistance genes allowed us to establish the concordance between genotypic and phenotypic methods and to correlate the presence of certain resistance genes with the type of circulating strain and the production of virulence factors.
Asunto(s)
Aminoglicósidos/farmacología , Antibacterianos/farmacología , Farmacorresistencia Bacteriana Múltiple/genética , Genes Bacterianos , Macrólidos/farmacología , Staphylococcus aureus Resistente a Meticilina/genética , Infecciones Estafilocócicas , Genotipo , Humanos , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Pruebas de Sensibilidad Microbiana/métodos , Fenotipo , Prevalencia , Rumanía/epidemiología , Infecciones Estafilocócicas/tratamiento farmacológico , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/microbiologíaRESUMEN
UNLABELLED: The aim of the present study was to investigate S. aureus isolates for the presence of methicillin-resistance and Panton-Valentine leukocidin (PVL) genes and to further characterize positive strains by means of antibiotic resistance patterns. MATERIAL AND METHODS: We used a triplex Real-Time PCR method for simultaneous detection of nuc, mecA and pvl genes in clinical isolates from 188 patients admitted to "Sf. Parascheva" Infectious Diseases Hospital lasi, during a 3 year period (2008-2010). RESULTS: The study revealed a relatively high rate of PVL-producing strains (23.93%), mainly community-associated (CA-MRSA) (51.11%). Most pvl-positive CA-MRSA isolates were resistant to erythromycin (91.3%), but none was resistant to clindamycin, fluoroquinolones, rifampicin, chloramphenicol or fusidic acid. CONCLUSIONS: Antibiotic susceptibility testing showed a high rate of multidug-resistance among strains classified as CA-MRSA (54.83%), but not among PVL-producers (4.44%). Although resistance to fusidic acid was previously proposed as a marker for PVL-producing CA-MRSA, our data suggest that we cannot rely on resistance to fusidic'acid to screen for PVL-producing CA-MRSA in our setting.