[Evaluation of Hemofast MRSA for identification of Staphylococcus aureus and detection of methicillin-resistance staphylococci, directly in blood culture broths].
The newly developed Hemofast MRSA system for Staphylococcus aureus identification and methicillin-resistant staphylococci (MRS) detection in blood culture broths was evaluated in 106 Bactec broths containing grapelike clusters of Gram-positive cocci. All 26 S. aureus positive broths were correctly identified by Hemofast MRSA within two hours, and 81% were identified within one hour. Sensitivity and specificity were both 100%. Accuracy of MRS detection was 100%, i.e., no discrepancies versus the agar diffusion method were found. When the 28 broths containing coagulase negative staphylococci (CNS) were tested using an inoculum ten fold larger than for S. aureus testing, a number of discrepancy were recorded. For 49 other broths containing CNS, accuracy was 98.5% when the test was interpreted based on the growth rate of the strain, according to the manufacturer's instructions. One broth containing S. epidermidis strain susceptible yielded a false result with Hemofast MRSA, indicating that it probably contained a contaminant. The other discrepancies occurred with specimens containing mixed populations with CNS or a Micrococcus strain. Most (85%) results were available within 4 hrs 30 min, irrespective of the S. aureus or CNS strains. Avoiding the isolation step on agar, Hemofast MRSA saves 24 to 48 hours, thus allowing earlier antistaphylococcal treatment.
Service de Microbiologie, C.H. de Versailles, Le Chesnay, France.
S
S
Langlet
J M
JM
Scheftel
H
H
Monteil
J C
JC
Ghnassia
D001431:Bacteriological Techniques / Q000295:instrumentation*; D001769:Blood / Q000382:microbiology*; D005189:False Positive Reactions; D006801:Humans; D016106:Methicillin Resistance; D011933:Reagent Kits, Diagnostic; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013203:Staphylococcal Infections / Q000175:diagnosis*; D013210:Staphylococcus / Q000145:classification* / Q000187:drug effects / Q000302:isolation & purification; D013211:Staphylococcus aureus / Q000145:classification* / Q000187:drug effects / Q000302:isolation & purification
D011933:Reagent Kits, Diagnostic
Evaluation d'Hémofast MRSA pour l'identification de Staphylococcus aureus et la détection des staphylocoques résistants à la méticilline, directement à partir des bouillons d'hémocultures.