AUTHOR=Liu Ya-Li , Xiao Meng , Cheng Jing-Wei , Xu He-Ping , Xu Zhi-Peng , Ye Sha , Zhang Wen-Juan , Kudinha Timothy , Kong Fanrong , Xu Ying-Chun 

TITLE=Moraxella catarrhalis Macrolide-Resistant Isolates Are Highly Concentrated in Two MLST Clonal Complexes -CCN10 and CC363

JOURNAL=Frontiers in Microbiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.00201

DOI=10.3389/fmicb.2017.00201

ISSN=1664-302X

ABSTRACT=<p>To gain some insights into the molecular evolution of <italic>Moraxella catarrhalis</italic> macrolide resistance, PCR and sequencing analysis of the 23S rRNA gene, <italic>copB</italic> typing and multilocus sequence typing (MLST) were performed on 181 <italic>M. catarrhalis</italic> isolates. The isolates were obtained from children (<italic>n</italic> = 47) and adults (<italic>n</italic> = 134) presenting with respiratory disease in the years 2010–2014. Macrolide resistance was highly age-related, and nucleotide position alterations at A2330T could be detected in all macrolide-resistant isolates. <italic>copB</italic> 0 and <italic>copB</italic> NT (non-typable) were only found in macrolide-susceptible isolates from adults. Furthermore, <italic>copB</italic> I/III was the main type in adult or macrolide-susceptible isolates, while <italic>copB</italic> II was the most common type in children or macrolide-resistant isolates. Twenty-two different MLST clusters (sharing 7 of the 8 identical loci) were detected and only four likely primary founders (ST224, ST363, STN08, and STN10) which belong to clonal complex (CC) 224, CC363, CCN08, and CCN10, were detected, respectively. Macrolide-resistant <italic>M. catarrhalis</italic> isolates were highly concentrated in two CCs (CCN10 and CC363), which indicates some potential evolutionary advantage or co-evolution to some extent. However, further studies are needed to fully elucidate the evolution of CCN10 and CC363 in macrolide resistance.</p>