Continued expansion of USA300-like methicillin-resistant Staphylococcus aureus (MRSA) among hospitalized patients in the United States
Diagnostic Microbiology and Infectious Disease
We characterized spa types, SCCmec types, and antimicrobial resistance patterns of 516 methicillin-resistant Staphylococcus aureus (MRSA) isolates, collected between 2011 and 2014 from nares and blood cultures of United States patients. Among nares isolates, 45 spa types were observed; 29.9% were t002/SCCmec II and 30.9% were t008/SCCmec IV. Among blood isolates, 40 spa types were identified; 24.4% were t002/SCCmec II and 39.9% were type t008/SCCmec IV. Compared to data from our 2009–2010 survey, the percentage of t008/SCCmec IV isolates from nares increased significantly (20.4%–30.9%; P = 0.004) while the percentage from positive blood cultures remained similar (39.2% versus 39.9%; P = 0.921). There were also significant changes in the overall antimicrobial resistance patterns observed, including the decrease of the clindamycin, erythromycin, levofloxacin and moxifloxacin multidrug resistance pattern, likely the result of t002/SCCmec II strains being displaced by t008/SCCmec IV strains. Rates of high-level mupirocin resistance did not change significantly from our past study (4.1% compared to 4.7%; P = 0.758) but an increase in low-level resistance, particularly among t002/SCCmec II isolates, was observed.
Print ISSN: 0732-8893; Online ISSN: 1879-0070
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MRSA, Staphylococcus aureus, USA300, spa type, Clonal lineages, Mupirocin resistance
Tickler, Isabella A.; Goering, Richard V.; Mediavilla, Jose R.; Kreiswirth, Barry N.; and Tenover, Fred C., "Continued expansion of USA300-like methicillin-resistant Staphylococcus aureus (MRSA) among hospitalized patients in the United States" (2017). Biology Faculty Publications. 334.