Automated systems in the identification and determination of methicillin resistance among coagulase negative staphylococci.
Coagulase-negative staphylococci (CoNS) are an important cause of nosocomial bacteremia, specially in patients with indwelling devices or those submitted to invasive medical procedures. The identification of species and the accurate and rapid detection of methicillin resistance are directly dependent on the quality of the identification and susceptibility tests used, either manual or automated. The objective of this study was to evaluate the accuracy of two automated systems--MicroScan and Vitek--in the identification of CoNS species and determination of susceptibility to methicillin, considering as gold standard the biochemical tests and the characterization of the mecA gene by polymerase chain reaction, respectively. MicroScan presented better results in the identification of CoNS species (accuracy of 96.8 vs 78.8%, respectively); isolates from the following species had no precise identification: Staphylococcus haemolyticus, S. simulans, and S. capitis. Both systems were similar in the characterization of methicillin resistance. The higher discrepancies for gene mec detection were observed among species other than S. epidermidis (S. hominis, S. saprophyticus, S. sciuri, S. haemolyticus, S. warneri, S. cohnii), and those with borderline MICs.
Caierão
Juliana
J
Departamento de Microbiologia e Parasitologia, Fundacão Faculdade Federal de Ciêncas Médicas de Porto Alegre, Brasil.
Superti
Silvana
S
Dias
Cícero Ag
CA
d'Azevedo
Pedro Alves
PA
D001426:Bacterial Proteins / Q000235:genetics*; D015373:Bacterial Typing Techniques / Q000379:methods*; D003030:Coagulase / Q000378:metabolism*; D006801:Humans; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests / Q000379:methods*; D046915:Penicillin-Binding Proteins; D016133:Polymerase Chain Reaction; D015203:Reproducibility of Results; D013210:Staphylococcus / Q000145:classification / Q000187:drug effects / Q000201:enzymology*
D001426:Bacterial Proteins; D003030:Coagulase; D046915:Penicillin-Binding Proteins; C487789:mecA protein, Staphylococcus aureus