The characterization of Moraxella catarrhalis carried in the general population

Moraxella catarrhalis is a common cause of respiratory tract infection, particularly otitis media in children, whilst it is also associated with the onset of exacerbation in chronic obstructive pulmonary disease in adults. Despite the need for an efficacious vaccine against M. catarrhalis, no candidates have progressed to clinical trial. This study, therefore, aimed to characterize the diversity of M. catarrhalis isolated from the upper respiratory tract of healthy children and adults, to gain a better understanding of the epidemiology of M. catarrhalis and the distribution of genes associated with virulence factors, to aid vaccine efforts. Isolates were sequenced and the presence of target genes reported. Contrary to prevailing data, this study found that lipooligosaccharide (LOS) B serotypes are not exclusively associated with 16S type 1. In addition, a particularly low prevalence of LOS B and high prevalence of LOS C serotypes was observed. M. catarrhalis isolates showed low prevalence of antimicrobial resistance and a high gene prevalence for a number of the target genes investigated: ompB2 (also known as copB), ompCD, ompE, ompG1a, ompG1b, mid (also known as hag), mcaP, m35, tbpA, lbpA, tbpB, lbpB, msp22, msp75 and msp78, afeA, pilA, pilQ, pilT, mod, oppA, sbp2, mcmA and mclS.