Investigations of Mycoplasma pneumoniae infections in the United States: trends in molecular typing and macrolide resistance from 2006 to 2013.

Mycoplasma pneumoniae is a leading cause of respiratory infections, including community-acquired pneumonia (CAP). Currently, pathogen-specific testing is not routinely performed in the primary care setting, and the United States lacks a systematic surveillance program for M. pneumoniae. Documentation of individual cases and clusters typically occurs only when severe illness and/or failure to improve with empirical antibiotic therapy is observed. Outbreaks, some lasting for extended periods and involving a large number of cases, occur regularly. However, many more likely go unrecognized due to the lack of diagnostic testing and structured reporting. We reviewed data from 17 investigations of cases, small clusters, and outbreaks of M. pneumoniae infections that were supported by the Centers for Disease Control and Prevention (CDC) between 2006 and 2013. We examined 199 M. pneumoniae-positive specimens collected during this time period in order to identify trends in antimicrobial resistance and circulating types. Overall, macrolide resistance was identified in approximately 10% of M. pneumoniae infections occurring during this time period. Typing of strains revealed cocirculation of multiple multilocus variable-number tandem-repeat analysis (MLVA) and P1 types throughout this period, including diversity in types detected within individual outbreaks. Three MLVA types (4572, 3562, and 3662) accounted for 97% of the infections during the study period. A systematic surveillance program is necessary to understand the burden of M. pneumoniae disease in the United States, facilitate case and outbreak identification, and inform appropriate therapeutic and infection control strategies.