Evaluation of the BD Phoenix system for detection of methicilin resistance in Staphylococcus aureus isolates in comparison to BD GeneOhm MRSA assay.
BACKGROUND
In order to identify methicillin-resistant Staphylococcus aureus isolates quickly, automated and semiautomated systems, commercial media, and identification kits are widely used. The Phoenix system (BD, Sparks, MD, USA) has been available since 2004 in our laboratory. This study evaluated the reliability of the Phoenix system for the detection of methicillin resistance in Staphylococcus aureus isolates in comparison to BD GeneOhm MRSA assay (Becton Dickinson Diagnostics GeneOhm, CA, USA).


METHODS
A total of 206 clinically significant Staphylococcus aureus isolates, submitted to the clinical microbiology laboratory between March 2011 and May 2013, were included in the study. Phoenix panels were studied for identification and susceptibility testing according to manufacturers' instructions. The detection of MRSA was performed using the BD GeneOhm MRSA assay (Becton Dickinson Diagnostics GeneOhm, CA, USA). The assay is a qualitative real-time PCR method.


RESULTS
The Phoenix system results and mecA gene pozitivity were concordant for 134 methicillin-resistant and 71 methicillin-susceptible strains. One discordant isolate, identified as mecA negative by the PCR method, was methicillin-resistant Staphylococcus aureus positive by the Phoenix system (oxacilline MIC = 2 microg/mL; cefoxitin MIC = 8 microg/mL). In this study, Phoenix automated system's sensitivity, specificity, negative predictive value, and positive predictive value are found as 100%, 100%, 100%, and 100%, respectively.


CONCLUSIONS
As a result of our study, use of the Phoenix automated identification method for the detection of methicillin-resistant Staphylococcus aureus isolates is a practical and reliable approach for daily clinical laboratory procedures.
Yesim
Y
Cekin
Hatice
H
Yazisiz
Mert Ahmet
MA
Kuskucu
Gozde
G
Ongut
Betil Ozhak
BO
Baysan
Hafize
H
Kilinckaya
Dilara
D
Ogunc
Kenan
K
Midilli
Nevgun Sepin
NS
Ozen
Dilek
D
Colak
D001426:Bacterial Proteins / Q000235:genetics; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification*; D025202:Molecular Diagnostic Techniques / Q000295:instrumentation* / Q000379:methods*; D046915:Penicillin-Binding Proteins; D013203:Staphylococcal Infections / Q000382:microbiology
D001426:Bacterial Proteins; D046915:Penicillin-Binding Proteins; C487789:mecA protein, Staphylococcus aureus