Macrolide-Resistant Mycoplasma pneumoniae in Humans, Ontario, Canada, 2010–2011

AliReza Eshaghi, Nader Memari, Patrick Tang, Romy Olsha, David J. Farrell, Donald E. Low, Jonathan B. Gubbay, and Samir N. Patel

Author affiliations: Ontario Agency for Health Protection and Promotion, Toronto, Ontario, Canada (A. Eshaghi, N. Memari, P. Tang, R. Olsha, D.J. Farrell, D.E. Low, J.B. Gubbay, S.N. Patel); University of Toronto, Toronto (D.J. Farrell, D.E. Low, J.B. Gubbay, S.N. Patel); Mount Sinai Hospital, Toronto (D.E. Low, J.B. Gubbay); The Hospital for Sick Children, Toronto (J.B. Gubbay)

Abstract

Antimicrobial drug resistance rates for Mycoplasma pneumoniae was determined in clinical specimens and isolates obtained during 2011–2012 in Ontario, Canada. Of 91 M. pneumoniae drug-resistant specimens, 11 (12.1%) carried nucleotide mutations associated with macrolide resistance in the 23S rRNA gene. None of the M. pneumoniae specimens were resistant to fluoroquinolones or tetracyclines.

Mycoplasma pneumoniae is a major cause of community-acquired pneumonia among children and adults (1). Macrolides are recommended for treatment of M. pneumoniae pneumonia (1).
High rates of macrolide-resistant M. pneumoniae have been reported in China (> 90%) and Japan (87.1%) (2,3). In Europe, reports of macrolide resistance have ranged from 3% in Germany to 9.8% in France (4,5). In the United States, 8.2% of M. pneumonia–positive specimens identified during 2007–2010 were resistant to macrolides (6). M. pneumoniae confer macrolide resistance primarily as a result of nucleotide substitutions at specific positions in the V domain of the 23S rRNA gene. Mutations at nt 2063 (A2063T/G), 2064 (A2064G), and 2617 (C2617A/G) have been shown to be associated with increased MICs to macrolides, including erythromycin, azithromycin, and clarithromycin (2,3,7,8). Use of macrolides to treat macrolide-resistant M. pneumoniae result in lower effectiveness and increased clinical severity compared with macrolide-susceptible M. pneumoniae (9). In contrast to macrolides, resistance to quinolones or tetracyclines among clinical isolates of M. pneumoniae has not been reported, although development of such resistance after use of increased concentrations of fluoroquinolones or doxycycline has been demonstrated in in vitro settings (10,11).
The Public Health Ontario Laboratory, which is the reference microbiology laboratory for the province of Ontario, provides molecular testing for detection of M. pneumoniae for hospitalized and ambulatory patients. In August 2011, the positivity rate for specimens with M. pneumoniae increased to 9.3% and peaked in December 2011 to 17.5%. During the same time, increased numbers of cases of M. pneumoniae were reported throughout Europe. In response to the increased positivity rate and lack of data for Canada on macrolide resistance in M. pneumoniae, we investigated antimicrobial drug susceptibility profiles of M. pneumoniae detected during February 2010–January 2012 by using molecular methods. In addition, available M. pneumoniae isolates were characterized by sequencing the P1 gene to determine the prevalence of circulating types in Ontario, Canada (12,13).