A cost-saving algorithm for rapid diagnosis of Staphylococcus aureus and susceptibility to oxacillin directly from positive blood culture bottles by combined testing with BinaxNOW® S. aureus and Xpert MRSA/SA assay

• Published in: Diagnostic microbiology and infectious disease Vol. 78; no. 4; pp. 352 - 355
• Main Authors: Yossepowitch, Orit, Dan, Michael, Kutchinsky, Anuta, Gottesman, Tamar, Schwartz–Harari, Orna
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2014
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Algorithms; Bacteremia - diagnosis; Bacteremia - microbiology; BinaxNOW S. aureus Assay; Blood - microbiology; Blood cultures; Cost Savings; Female; Humans; Infectious Disease; Internal Medicine; Male; Methicillin-Resistant Staphylococcus aureus - isolation & purification; Microbial Sensitivity Tests - economics; Microbial Sensitivity Tests - methods; Middle Aged; Molecular Diagnostic Techniques - methods; Sensitivity and Specificity; Staphylococcal Infections - diagnosis; Staphylococcal Infections - microbiology; Staphylococcus aureus; X pert MRSA/SA BC Assay; Young Adult; BinaxNOW S. aureus Assay; Staphylococcus aureus; Blood cultures; X pert MRSA/SA BC Assay
• ISSN: 0732-8893; 1879-0070; 1879-0070
• DOI: 10.1016/j.diagmicrobio.2014.01.001

We studied an algorithm combining 2 rapid methods to detect Staphylococcus aureus and its susceptibility to oxacillin directly from positive blood cultures; our goal was to reduce the cost of the procedure, while maintaining accuracy and a short turnaround time. A total of 581 blood cultures containing gram-positive cocci in clusters were tested by BinaxNOW® Staphylococcus aureus Test. Positive samples were further assessed by the Xpert MRSA/SA BC Assay. Phenotypic methods have identified coagulase-negative staphylococci in 505 samples and S. aureus in 76 samples, of which 51 were oxacillin sensitive and 25 were oxacillin resistant. Sensitivity and specificity of the BinaxNOW® Test were 92% and 99%, respectively, compared to the phenotypic method. The Xpert MRSA/SA BC Assay showed complete concordance with phenotypic identification and antimicrobial susceptibility results. The combined rapid assays produced results within 2 hours and reduced the cost by 75% compared with the Xpert MRSA/SA BC Assay if used alone on all blood bottles.