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.