Identification and detection of methicillin resistance in non-epidermidis coagulase-negative staphylococci.
The NCCLS (2004) presented a new methodology to detect, by disk-diffusion agar, oxacillin-resistance using a cefoxitin disk. We identified coagulase-negative staphylococci (SCoN) to the species level and compared the use of cefoxitin disks (30 microg) with oxacillin disks (1 microg), agar dilution (minimum inhibitory concentration of oxacillin) and mecA gene detection in isolates of coagulase-negative bacteria other than Staphylococcus epidermidis (SCoNne). A total of 238 SCoNne was evaluated; oxacillin-resistance (the mecA gene) was detected in 71% of the isolates. All methods gave 100% sensitivity, based on presence of the mecA gene. The specificity of the cefoxitin disk was 100%, while the oxacillin disk gave a specificity of 91% and agar dilution oxacillin gave a specificity of 88%. We conclude that the cefoxitin disk is an efficient test, and it is an easy method for use in clinical laboratories to detect oxacillin-resistance in staphylococci.
Secchi
Carina
C
Post Graduation Program in Medical Sciences of Federal University of Health Sciences of Porto Alegre, Porto Alegre, RS, Brazil. csecchi@gmail.com
Antunes
Ana Lúcia Souza
AL
Perez
Leandro Reus Rodrigues
LR
Cantarelli
Vlademir Vicente
VV
d'Azevedo
Pedro Alves
PA
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics*; D003030:Coagulase; D052978:Disk Diffusion Antimicrobial Tests / Q000379:methods*; D006801:Humans; D016106:Methicillin Resistance / Q000235:genetics; D046915:Penicillin-Binding Proteins; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013210:Staphylococcus / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D003030:Coagulase; D046915:Penicillin-Binding Proteins; C487789:mecA protein, Staphylococcus aureus