title: Controlled multicenter evaluation of a bacteriophage-based method for rapid detection of Staphylococcus aureus in positive blood cultures.
abstract: Staphylococci are a frequent cause of bloodstream infections (BSIs). Appropriate antibiotic treatment for BSIs may be delayed because conventional laboratory testing methods take 48 to 72 h to identify and characterize isolates from positive blood cultures. We evaluated a novel assay based on bacteriophage amplification that identifies Staphylococcus aureus and differentiates between methicillin-susceptible and methicillin-resistant S. aureus (MSSA and MRSA, respectively) in samples taken directly from signal-positive Bactec blood culture bottles within 24 h of positive signal, with results available within 5 h. The performance of the MicroPhage KeyPath MRSA/MSSA blood culture test was compared to conventional identification and susceptibility testing methods. At four sites, we collectively tested a total of 1,165 specimens, of which 1,116 were included in our analysis. Compared to standard methods, the KeyPath MRSA/MSSA blood culture test demonstrated a sensitivity, specificity, positive predictive value, and negative predictive value of 91.8%, 98.3%, 96.3%, and 96.1%, respectively, for correctly identifying S. aureus. Of those correctly identified as S. aureus (n = 334), 99.1% were correctly categorized as either MSSA or MRSA. Analysis of a subset of the data revealed that the KeyPath MRSA/MSSA blood culture test delivered results a median of 30 h sooner than conventional methods (a median of 46.9 h versus a median of 16.9 h). Although the sensitivity of the test in detecting S. aureus-positive samples is not high, its accuracy in determining methicillin resistance and susceptibility among positives is very high. These characteristics may enable earlier implementation of appropriate antibiotic treatment for many S. aureus BSI patients.
authors: UMDNJ-Robert Wood Johnson Medical School, New Brunswick, New Jersey, USA.
authors: T
authors: T
authors: Bhowmick
authors: S
authors: S
authors: Mirrett
authors: L B
authors: LB
authors: Reller
authors: C
authors: C
authors: Price
authors: C
authors: C
authors: Qi
authors: M P
authors: MP
authors: Weinstein
authors: T J
authors: TJ
authors: Kirn
mesh_terms: D000293:Adolescent; D000328:Adult; D016470:Bacteremia / Q000175:diagnosis* / Q000382:microbiology; D001431:Bacteriological Techniques / Q000379:methods*; D001769:Blood / Q000382:microbiology*; D005260:Female; D006801:Humans; D008297:Male; D016106:Methicillin Resistance; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D013203:Staphylococcal Infections / Q000175:diagnosis* / Q000382:microbiology; D013204:Staphylococcus Phages / Q000254:growth & development*; D013211:Staphylococcus aureus / Q000145:classification / Q000302:isolation & purification* / Q000821:virology; D013997:Time Factors; D055815:Young Adult
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