Agar diffusion, agar dilution, Etest, and agar screening test in the detection of methicillin resistance in staphylococci.
Methicillin resistant Staphylococcus is an important worldwide problem. Resistance is verified in strains harboring the mecA gene and laboratory methods used to detect resistance are object of constant investigation. In the present study, 99 clinical isolates of staphylococci (41 S. aureus, 33 S. epidermidis, 12 S. saprophyticus and 13 members of other species) were submitted to different phenotypic methods and conditions. Detection of the mecA gene by PCR was used as the reference method and detected 14/41, 10/33, and 10/25 isolates of S. aureus, S. epidermidis and other species, respectively. Results showed that, for S. aureus and S. epidermidis, agar diffusion, agar dilution, and the E test incubated during 24h at 35 degrees C correctly discriminated mecA positive from mecA negative isolates. For other species, all methods and conditions presented low specificity (ranging from 20% to 66.7%) and, particularly S. saprophyticus, may need molecular methods to correctly assess methicillin resistance.
Rowe
Fabiana
F
Hospital Mãe de Deus, Porto Alegre, Brazil. cicero@fffcmpa.tche.br
Vargas Superti
Silvana
S
Machado Scheibe
Rosane
R
Dias
Cícero Gomes
CG
D000362:Agar; D001426:Bacterial Proteins; D001431:Bacteriological Techniques / Q000379:methods; D001483:Base Sequence; D002352:Carrier Proteins / Q000032:analysis* / Q000235:genetics / Q000276:immunology; D004058:Diffusion; D005798:Genes, Bacterial / Q000235:genetics; D006602:Hexosyltransferases; D005779:Immunodiffusion / Q000379:methods*; D016106:Methicillin Resistance / Q000235:genetics; D008826:Microbial Sensitivity Tests / Q000379:methods*; D002267:Muramoylpentapeptide Carboxypeptidase / Q000032:analysis* / Q000235:genetics / Q000276:immunology; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases; D016133:Polymerase Chain Reaction; D013210:Staphylococcus / Q000201:enzymology / Q000235:genetics / Q000276:immunology / Q000502:physiology*
D001426:Bacterial Proteins; D002352:Carrier Proteins; D046915:Penicillin-Binding Proteins; D000362:Agar; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase