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Characterization and Biofilm Assessment of Haemophilus influenzae Isolates from Patients with Chronic Obstructive Pulmonary Disease and Otitis Media
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Haemophilus influenzae is a commensal microorganism of the human nasopharynx,
responsible for both invasive and non-invasive diseases. This work focused on the study of 93 H. influenzae isolates, collected between 2013 and 2018, from patients with two epidemiologically relevant non-invasive diseases: Chronic Obstructive Pulmonary Disease (COPD) and Otitis Media (OM). Phenotypical and molecular characterizations were performed for the isolates, regarding capsular typing, β-lactamase production, antibiotic susceptibility, genetic diversity by MLST, presence/absence of virulence factors (pilA, hifA, hmw1A, hmw2A, hia and ompP5) and ability to produce biofilms.
COPD isolates were collected from adults (100%), while 98.2% of OM isolates were collected from children. Non-typeable H. influenzae (NTHi) was the aetiological agent in COPD (97.4%) and OM (100%). Regarding antibiotic susceptibility, it should be noticed that 15.1% of the isolates were β- lactamase producers. MLST revealed a high genetic diversity among COPD and OM isolates, with 31 STs in 41 analysed isolates. pilA and ompP5 genes were present in more than 50% of COPD and OM isolates. hifA and hia genes were identified in less than half of the isolates, with a higher prevalence of
these among OM isolates. hmw1A and hmw2A genes were respectively identified in 25.5% and 32.7% of OM isolates, while both hmw genes were present in 76.3% of COPD isolates. Biofilm production was observed for 14.0% and 29.0% of all isolates after 24h and 48h, respectively. No relationship between biofilm production and clinical source could be established, as well as with the presence of virulence factors (pilA, hmw1A e hmw2A) involved in biofilm production.
COPD and OM are frequently associated with NTHi. Since no vaccines are available,
monitoring of these diseases is highly recommended, as these constitute a Public Health threat associated with a high economic and social burden.
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Haemophilus influenzae COPD OM virulence factors biofilms NTHi