Correlation between the VITEK2 system and cefoxitin disk diffusion for the daily detection of oxacillin resistance in a large number of clinical Staphylococcus aureus isolates.
The aim of the present study was to compare the performance of the new VITEK2 AST-P551 card with the cefoxitin disk diffusion method for the daily detection of methicillin resistance with a high number of Staphylococcus aureus clinical isolates. Detection of the PBP2a protein or mecA gene was performed for each discordant case. Seventy (3.3%) isolates out of 2,107 clinical strains showed discordant results, two very major errors, four major errors and 64 minor errors. Fifty-nine (84%) discordant results were resolved, with a final overall agreement of 99.5%. Eleven (0.5%) strains remained discordant (minor error [mE]). Four of 370 MRSA strains were misclassified as susceptible in daily practice by the cefoxitin disk diffusion method. All of these strains were resistant to aminoglycosides and/or fluoroquinolones. The VITEK2 system is highly reliable for methicillin resistance detection at the routine level. Oxacillin-susceptible classified clinical strains with associated resistance patterns required attention.
Bemer
P
P
Service de Bactériologie-Hygiène, CHU de Nantes, Nantes, France. pascale.bemer@chu-nantes.fr
Juvin
M E
ME
Le Gargasson
G
G
Drugeon
H
H
Reynaud
A
A
Corvec
S
S
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics; D002440:Cefoxitin; D003951:Diagnostic Errors / Q000706:statistics & numerical data; D006801:Humans; D016106:Methicillin Resistance; D055624:Methicillin-Resistant Staphylococcus aureus / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests / Q000379:methods; D010068:Oxacillin / Q000494:pharmacology*; D046915:Penicillin-Binding Proteins / Q000032:analysis; D012680:Sensitivity and Specificity; D013203:Staphylococcal Infections / Q000382:microbiology*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D046915:Penicillin-Binding Proteins; C487789:mecA protein, Staphylococcus aureus; D002440:Cefoxitin; D010068:Oxacillin