ABSTRACT
In this work, the molecular and phenotypic antimicrobial resistance and clonal diversity of 10 linezolid-resistant Staphylococcus spp. isolates were investigated. The 7 Staphylococcus haemolyticus isolates presented Staphylococcal cassete chromosome mec (SCCmec) V and belonged to the same pulsed-field gel electrophoresis pulsotype. Their MICs for oxacillin, vancomycin, and linezolid were ≥ 256 µg/mL, 1-4 µg/mL, and 8-16 µg/mL, respectively. The 3 S. hominis presented MIC values 32 to >256 µg/mL, 2-4 µg/mL, and 12-24 µg/mL, and all carried the nontypeable SCCmec (ccr1 + mecA class) and belonged to 2 different genotypes. The cfr gene was not found, but the mutation G2603T was detected in S. haemolyticus and C2190T and G2603T in Staphylococcus hominis in 23S rRNA. This study demonstrates the spread of a linezolid-resistant S. haemolyticus genotype and, for the first time, describes the mutation C2190T among S. hominis isolates with a double mutation in Brazil.
Subject(s)
Acetamides/pharmacology , Drug Resistance, Bacterial/genetics , Mutation , Oxazolidinones/pharmacology , RNA, Ribosomal, 23S/genetics , Staphylococcus haemolyticus/genetics , Staphylococcus hominis/genetics , Anti-Bacterial Agents/pharmacology , Brazil , Drug Resistance, Bacterial/drug effects , Electrophoresis, Gel, Pulsed-Field , Hospitals , Humans , Linezolid , Microbial Sensitivity Tests , Staphylococcal Infections/microbiology , Staphylococcus haemolyticus/drug effects , Staphylococcus haemolyticus/isolation & purification , Staphylococcus hominis/drug effects , Staphylococcus hominis/isolation & purificationABSTRACT
This work characterizes MLS(b) resistance in 39 methicillin-resistant Staphylococcus aureus (MRSA) and 32 Staphylococcus epidermidis (MRSE) isolates. Of 21 erm(A) gene encoding MRSA isolates, 71.4% carried SCCmecIII, whereas of 12 isolates carrying the erm(C) gene, 83.3% carried SCCmecIV. Among the 25 MRSE isolates positive for the erm(C) gene, 80% had SCCmecIV or nontypeable cassettes. Isolates carrying these genes had MIC(90) ≥ 256 µg/mL to erythromycin and clindamycin. The msr(A) gene was associated with a low MIC(90) to these drugs. The erm(A) gene was associated with SCCmecIII in MRSA isolates, whereas the erm(C) gene was associated with SCCmecIV in both MRSA and MRSE isolates.