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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/10873

Title: Evaluation of Chromogenic Media for Detection of Methicillin-Resistant Staphylococcus aureus
Authors: Malhotra-Kumar, Surbhi
Cortinas Abrahantas, Jose
Sabiiti, Wilber
Lammens, Christine
Vercauteren, Greetje
Ieven, Margareta
Molenberghs, Geert
Aerts, Marc
Goossens, Herman
Issue Date: 2010
Citation: JOURNAL OF CLINICAL MICROBIOLOGY, 48(4). p. 1040-1046
Abstract: Rapid laboratory diagnosis is critical for treating, managing, and preventing methicillin-resistant Staphylococcus aureus (MRSA) infections. We evaluated and compared the potential for MRSA detection of five chromogenic media, Brilliance MRSA agar (Oxoid), ChromID (bioMerieux), MRSASelect (Bio-Rad), CHROMagar (CHROMagar Microbiology), and BBL-CHROMagar (BD Diagnostics). Media were tested with log serial dilutions (100 to 106 CFU) of pure isolates of MRSA (n = 60), non-MRSA (n = 27), and defined mixtures thereof simulating clinical samples (n = 84). Further evaluations were done on pre-enriched nasal and groin screening swabs (n = 213) from 165 hospitalized patients. Randomized samples were spiral plated on each medium and independently scored by five investigators for characteristic colonies at 24 and 48 h of incubation. Confirmatory testing of up to five putative MRSA colonies recovered from each medium was done. The cumulative average sensitivity with isolates, mixtures, and clinical samples was the highest for Brilliance MRSA agar (97%) and similar for the other four media (>= 92%). The cumulative average specificity was the highest for BBL-CHROMagar (99%), followed by MRSASelect (98%), CHROMagar (97%), ChromID (89%), and Brilliance MRSA agar (86%). All of the media detected MRSA at 10 and 1 CFU, although at these low loads, few MRSA samples harboring SCCmec type III or IV were misinterpreted as non-MRSA by investigators. False-positive results were mainly due to methicillin-resistant S. epidermidis. For an arbitrary MRSA prevalence of 5% and based on patient sample evaluations, the positive predictive values for BBL-CHROMagar and CHROMagar (similar to 84%) were the highest. The negative predictive values of all of the media were >= 92% for MRSA prevalences ranging from 5% to 30%. In conclusion, BBL-CHROMagar and CHROMagar gave the best overall results for detection of MRSA, irrespective of the sample concentration, investigator, or incubation period.
Notes: [Malhotra-Kumar, Surbhi; Sabiiti, Wilber; Lammens, Christine; Vercauteren, Greetje; Ieven, Margareta; Goossens, Herman] Univ Antwerp, Dept Med Microbiol, Vaccine & Infect Dis Inst, B-2610 Antwerp, Belgium. [Abrahantes, Jose Cortinas; Molenberghs, Geert; Aerts, Marc] Hasselt Univ, Ctr Stat, Diepenbeek, Belgium. [Ieven, Margareta; Goossens, Herman] Univ Antwerp Hosp, Antwerp, Belgium. surbhi.malhotra@ua.ac.be
URI: http://hdl.handle.net/1942/10873
DOI: 10.1128/JCM.01745-09
ISI #: 000276153200004
ISSN: 0095-1137
Category: A1
Type: Journal Contribution
Validation: ecoom, 2011
Appears in Collections: Research publications

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