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. 2023 Sep 1;49(9):368-374.
doi: 10.14745/ccdr.v49i09a02.

A Pediatric Investigators Collaborative Network on Infections in Children (PICNIC) multi-centre Canadian descriptive analysis of Haemophilus influenzae bacteremia in children: Emerging serotypes

Craig Frankel  1 , Joan Robinson  2 , Sarah Khan  3 , Mohammad Alghounaim  4 , Jane McDonald  4 , Alison Lopez  5 , Sergio Fanella  5 , John Gunawan  2 , Jacqueline Wong  3 , Jeannette Comeau  6 , Jennifer Bowes  7 , Robert Slinger  7 , Angela Kalia  8 , Ashley Roberts  8 , Kirk Leifso  9 , Marina Ulanova  10 , Michelle Barton  1
Affiliations

A Pediatric Investigators Collaborative Network on Infections in Children (PICNIC) multi-centre Canadian descriptive analysis of Haemophilus influenzae bacteremia in children: Emerging serotypes

Craig Frankel et al. Can Commun Dis Rep. .

Abstract

Background: There has been dramatic reduction in Haemophilus influenzae serotype b (Hib) since introduction of Hib vaccines, but children still experience serious invasive Haemophilus influenzae (Hi) disease caused by various serotype and non-typeable bacteria. The object of this study was to describe the serotype distribution and clinical spectrum of Hi bacteremia in children admitted to Canadian hospitals.

Methods: All children with Hi bacteremia admitted 2013 through 2017 to 10 centres across Canada were included. Demographic, clinical, treatment and outcome data were collected.

Results: Haemophilus influenzae bacteremia occurred in 118 children of median age 12 months (inter-quartile range: 7-48 months). Forty-three (36%) isolates were non-typeable (NTHi) and 8 were not typed. Of the 67 typeable (THi), Hia (H. influenzae serotype a) (n=36, 54%), Hif (serotype f) (n=19, 26%) and Hib (serotype b) (n=9, 13%) dominated. The THi was more likely than NTHi bacteremia to present as meningitis (p<0.001), particularly serotype a (p=0.04) and less likely to present as pneumonia (p<0.001). Complicated disease (defined as intensive care unit admission, need for surgery, long-term sequelae or death) occurred in 31 (26%) cases and were more likely to have meningitis (p<0.001) than were those with uncomplicated disease.

Conclusion: In the era of efficacious conjugate Hib vaccines, NTHi, Hia and Hif have emerged as the leading causes of invasive Hi in Canadian children, with Hia being most likely to result in meningitis and complicated disease. A vaccine for all NTHi and THi would be ideal, but knowledge of the current disease burden from circulating strains will inform prioritization of vaccine targets.

Keywords: Haemophilus influenzae; bacteremia; children; invasive disease; meningitis; non-typeable; serotype a; serotype b; serotype f.

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Conflict of interest statement

Competing interests None.

Figures

Figure 1
Figure 1
Haemophilus influenzae serotype distribution by year in paediatric population, Canada Abbreviation: NTHi, non-typeable Haemophilus influenzae
Figure 2
Figure 2
Serotype-specific distribution of Haemophilus influenzae invasive disease in ten centres across Canadaa Abbreviations: NTHi, non-typeable Haemophilus influenzae; THi, typeable Haemophilus influenzae disease including disease caused by serotypes a, b, c, e, f a Centre names: Winnipeg Children’s Hospital (Winnipeg, Manitoba); Montreal Children’s Hospital (Montréal, Québec); Children’s Hospital of Western Ontario (London, Ontario); Stollery Children’s Hospital (Edmonton, Alberta); British Columbia Children’s Hospital (Vancouver, British Columbia); Children’s Hospital of Eastern Ontario (Ottawa, Ontario); McMaster Children’s Hospital (Hamilton, Ontario); Sioux Lookout (Sioux Lookout, Ontario); Kingston Health Sciences Centre (Kingston, Ontario); IWK Health Centre (Halifax, Nova Scotia)
See this image and copyright information in PMC

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