Carriage epidemiology of Moraxella catarrhalis in an all-age, community cohort between 2016 - 2018

Moraxella catarrhalis is an increasingly important pathogen, recognised as a common cause of respiratory tract infections. It is particularly known for its role in causing otitis media in children and exacerbations of chronic obstructive pulmonary disease (COPD) in adults. With growing interest in developing vaccines against M. catarrhalis, a deeper understanding of epidemiology in both carriage and disease is crucial. Here we present an all-age, community-based, upper respiratory tract carriage study (the Solent SMART Study) designed to investigate the epidemiology of, and risk factors for M. catarrhalis carriage. In total, n = 1,622 community-based participants were recruited with an additional n = 79 individuals recruited from care/nursing homes in the Southampton/Hampshire UK region from whom a total of n = 228 M. catarrhalis were isolated. Carriage prevalence was 8% (95% CI: 6.7-9.4%) in community-based participants, 19% (95% CI: 11.0-29.4%) in care/nursing home residents and 4.7% (95% CI: 1.6-10.7%) in the community-based subset with COPD (n = 106). Nasopharyngeal carriage site, young age, microbial co-carriage with Streptococcus pneumoniae, Haemophilus influenzae and Neisseria meningitidis, and recent/concurrent respiratory tract infection were all positively associated with the carriage of M. catarrhalis. Antimicrobial resistance (AMR) testing showed n = 91 (41.4%) of the 220 isolates tested resistant to at least one antibiotic, with the most frequent being resistance to chloramphenicol (n = 76, 34.5%) and ciprofloxacin (n = 64, 29.1%).