Discriminatory Indices of Typing Methods for Epidemiologic Analysis of Contemporary Staphylococcus aureus Strains. Issue 37 (September 2015)

• Record Type: Journal Article
• Authors: Rodriguez, Marcela; Hogan, Patrick G.; Satola, Sarah W.; Crispell, Emily; Wylie, Todd; Gao, Hongyu; Sodergren, Erica; Weinstock, George M.; Burnham, Carey-Ann D.; Fritz, Stephanie A.; Yagupsky., Pablo
• Is Part Of: Medicine. Volume 94:Issue 37(2015)
• Publication Date: 2015-09
• Subjects: Medicine -- Periodicals; Medicine -- Periodicals; Médecine -- Périodiques; Geneeskunde; Medicine; Periodicals; Periodicals; 610.5
• DOI: 10.1097/MD.0000000000001534
• Languages: English
• ISSNs: 0025-7974

Abstract

<abstract> <title> <x xml:space="preserve">Abstract</x> </title> <sec> <title>Abstract</title> <p>Historically, a number of typing methods have been evaluated for <italic>Staphylococcus aureus</italic> strain characterization. The emergence of contemporary strains of community-associated <italic>S. aureus</italic>, and the ensuing epidemic with a predominant strain type (USA300), necessitates re-evaluation of the discriminatory power of these typing methods for discerning molecular epidemiology and transmission dynamics, essential to investigations of hospital and community outbreaks. We compared the discriminatory index of 5 typing methods for contemporary <italic>S. aureus</italic> strain characterization.</p> <p>Children presenting to St. Louis Children's Hospital and community pediatric practices in St. Louis, Missouri (MO), with community-associated <italic>S. aureus</italic> infections were enrolled. Repetitive sequence-based PCR (repPCR), pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), staphylococcal protein A (<italic>spa</italic>), and staphylococcal cassette chromosome (SCC) <italic>mec</italic> typing were performed on 200 <italic>S. aureus</italic> isolates. The discriminatory index of each method was calculated using the standard formula for this metric, where a value of 1 is highly discriminatory and a value of 0 is not discriminatory.</p> <p>Overall, we identified 26 distinct strain types by repPCR, 17 strain types by PFGE, 30 strain types by MLST, 68 strain types by <italic>spa</italic> typing, and 5 strain types by SCC<italic>mec</italic> typing. RepPCR had the highest discriminatory index (<italic>D)</italic> of all methods (<italic>D</italic> = 0.88), followed by <italic>spa</italic> typing (<italic>D</italic> = 0.87), MLST (<italic>D</italic> = 0.84), PFGE (<italic>D</italic> = 0.76), and SCC<italic>mec</italic> typing (<italic>D</italic> = 0.60). The method with the highest <italic>D</italic> among MRSA isolates was repPCR (<italic>D</italic> = 0.64) followed by <italic>spa</italic> typing (<italic>D</italic> = 0.45) and MLST (<italic>D</italic> = 0.44). The method with the highest <italic>D</italic> among MSSA isolates was <italic>spa</italic> typing (<italic>D</italic> = 0.98), followed by MLST (<italic>D</italic> = 0.93), repPCR (<italic>D</italic> = 0.92), and PFGE (<italic>D</italic> = 0.89). Among isolates designated USA300 by PFGE, repPCR was most discriminatory, with 10 distinct strain types identified (<italic>D</italic> = 0.63). We identified 45 MRSA isolates which were classified as identical by PFGE, MLST, <italic>spa</italic> typing, and SCC<italic>mec</italic> typing (USA300, ST8, t008, SCC<italic>mec</italic> IV, respectively); within this collection, there were 5 distinct strain types identified by repPCR.</p> <p>The typing methods yielded comparable discriminatory power for <italic>S. aureus</italic> characterization overall; when discriminating among USA300 isolates, repPCR retained the highest discriminatory power. This property is advantageous for investigations conducted in the era of contemporary <italic>S. aureus</italic> infections.</p> </sec> </abstract>