Rising Prevalence of Nontypeable Haemophilus influenzae and Haemophilus parainfluenzae in People With Primary Ciliary Dyskinesia: A Single-Center Experience.

Abstract

Background: Haemophilus influenzae (Hi) and Haemophilus parainfluenzae (Hpi) are common nasopharyngeal flora, yet both are potential lower airway pathogens, especially if mucociliary clearance is abnormal, such as in people with primary ciliary dyskinesia (pwPCD).

Methods: Retrospective data analysis of medical records, between 2013 and 2023, collecting demographic, clinical and microbiological data to assess prevalence and clinical impact.

Results: Throughout the observation period, the number of pwPCD attending the clinic increased from 19 to 49; median [interquartile range (IQR)] patient age was 10 years (5-15), and 28 (57%) were males. A total of 403 sputum cultures were tested, with a median (IQR) of 33 (11-52) per year and 7 (4-14) per patient. Hi prevalence increased from 0% to 35% (P = 0.01), and from 5% to 53% for Hpi (P < 0.01). Of all clinic patients, 27 (55%) ever had Hi and 36 (73%) ever had Hpi positive cultures. Co-infection occurred in 24 (49%) patients, while 11 patients (22.4%) never had either Hi or Hpi isolated. Median (IQR) age at first isolation was 9 years (4.5-16) for Hi, and 8 years (4-16) for Hpi, P = not significant. Both sexes were equally infected. Chronic infection occurred in 33% of pwPCD with Hi, and 34% for Hpi. Median forced expiratory volume in 1 second, percent predicted (FEV1%pred) was unaffected by infection with Hi or Hpi alone but decreased postcoinfection by a median (IQR) of -4% (-7 to -2), measured from 1 year before until 1 year after coinfection (P = 0.02).

Conclusions: Hi and Hpi prevalence increased in our PCD cohort over time. One-third of patients were chronically infected, yet had an insignificant influence on lung function.