Characterisation of invasive clinicalHaemophilus influenzaeisolates in Queensland, Australia using whole-genome sequencing

SUMMARYHaemophilus influenzaeis an important aetiological organism of both adult and child respiratory disease. The number of non-typeable (NTHi) invasiveH. influenzaeisolates referred to the Queensland (QLD) Public Health Microbiology laboratory has increased notably year-by-year. In this study we used whole-genome sequencing to molecularly characterise 100 referred invasiveH. influenzae, including 74 NTHi isolates over a 15-year period, observing the carriage of capsular and putative virulence genes, including the major adhesins, antimicrobial resistance genes and population diversity. Encapsulated isolates were largely clonal, however NTHi isolates displayed high genetic variability by MLST and single nucleotide polymorphism typing with no dominant clone observed. The only mechanism forβ-lactam resistance identified in the QLD isolates wasβ-lactamase production. No single set of virulence determinants was conclusively associated with invasive QLD NTHi isolates.