Dominance of multidrug resistant CC271 clones in macrolide-resistant <it>streptococcus pneumoniae </it>in Arizona

• Main Authors: Bowers Jolene R, Driebe Elizabeth M, Nibecker Jennifer L, Wojack Bette R, Sarovich Derek S, Wong Ada H, Brzoska Pius M, Hubert Nathaniel, Knadler Andrew, Watson Lindsey M, Wagner David M, Furtado Manohar R, Saubolle Michael, Engelthaler David M, Keim Paul S
• Format: Article
• Language: English
• Published: BMC 2012-01-01
• Series: BMC Microbiology
• Online Access: http://www.biomedcentral.com/1471-2180/12/12

<p>Abstract</p> <p>Background</p> <p>Rates of resistance to macrolide antibiotics in <it>Streptococcus pneumoniae </it>are rising around the world due to the spread of mobile genetic elements harboring <it>mef</it>(E) and <it>erm</it>(B) genes and post-vaccine clonal expansion of strains that carry them.</p> <p>Results</p> <p>Characterization of 592 clinical isolates collected in Arizona over a 10 year period shows 23.6% are macrolide resistant. The largest portion of the macrolide-resistant population, 52%, is dual <it>mef</it>(E)/<it>erm</it>(B)-positive. All dual-positive isolates are multidrug-resistant clonal lineages of Taiwan^19F-14, mostly multilocus sequence type 320, carrying the recently described transposon Tn<it>2010</it>. The remainder of the macrolide resistant <it>S. pneumoniae </it>collection includes 31% <it>mef</it>(E)-positive, and 9% <it>erm</it>(B)-positive strains.</p> <p>Conclusions</p> <p>The dual-positive, multidrug-resistant <it>S. pneumoniae </it>clones have likely expanded by switching to non-vaccine serotypes after the heptavalent pneumococcal conjugate vaccine release, and their success limits therapy options. This upsurge could have a considerable clinical impact in Arizona.</p>