Accuracy of phenotypic methicillin susceptibility methods in the detection of Staphylococcus aureus isolates carrying different SCCmec types.
A total of 138 isolates, 118 methicillin-resistant Staphylococcus aureus (MRSA) isolates (staphylococcal cassette chromosome type II, 20 isolates, type III, 39 isolates and type IV, 59 isolates) and 20 methicillin-sensitive S. aureus isolates were evaluated by phenotypic methods: cefoxitin and oxacillin disk diffusion (DD), agar dilution (AD), latex agglutination (LA), oxacillin agar screening (OAS) and chromogenic agar detection. All methods showed 100% specificity, but only the DD tests presented 100% sensitivity. The sensitivity of the other tests ranged from 82.2% (OAS)-98.3% (AD). The LA test showed the second lowest sensitivity (86.4%). The DD test showed high accuracy in the detection of MRSA isolates, but there was low precision in the detection of type IV isolates by the other tests, indicating that the genotypic characteristics of the isolates should be considered.
Departamento de Microbiologia Médica, Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil.
Pricilla D M de
PD
Matos
Ricardo P
RP
Schuenck
Fernanda S
FS
Cavalcante
Roberta M F
RM
Caboclo
Kátia Regina N dos
KR
Santos
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002440:Cefoxitin / Q000494:pharmacology*; D052978:Disk Diffusion Antimicrobial Tests; D006801:Humans; D007841:Latex Fixation Tests; D016106:Methicillin Resistance / Q000235:genetics*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000235:genetics; D010068:Oxacillin / Q000494:pharmacology*; D010641:Phenotype; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics
D000900:Anti-Bacterial Agents; D002440:Cefoxitin; D010068:Oxacillin