Molecular epidemiology and antibiotic resistance profiles of invasive Haemophilus influenzae from Norway 2017-2021

Ragnhild Tønnessen; Ignacio García; Nadia Debech; Jonas Christoffer Lindstrøm; Astrid Louise Wester; Dagfinn Skaare

doi:10.3389/fmicb.2022.973257

Molecular epidemiology and antibiotic resistance profiles of invasive Haemophilus influenzae from Norway 2017-2021

Front Microbiol. 2022 Aug 29:13:973257. doi: 10.3389/fmicb.2022.973257. eCollection 2022.

Authors

Ragnhild Tønnessen^{1

2}, Ignacio García³, Nadia Debech³, Jonas Christoffer Lindstrøm⁴, Astrid Louise Wester³, Dagfinn Skaare⁵

Affiliations

¹ Department of Infection Control and Vaccines, Norwegian Institute of Public Health, Oslo, Norway.
² European Public Health Microbiology Training Program (EUPHEM), European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden.
³ Department of Bacteriology, Norwegian Institute of Public Health, Oslo, Norway.
⁴ Department of Method Development and Analytics, Norwegian Institute of Public Health, Oslo, Norway.
⁵ Department of Microbiology, Vestfold Hospital Trust, Tønsberg, Norway.

Abstract

Invasive Haemophilus influenzae (Hi) disease has decreased in countries that included Hi type b (Hib) vaccination in their childhood immunization programs in the 1990s. Non-typeable (NT) and non-b strains are now the leading causes of invasive Hi disease in Europe, with most cases reported in young children and the elderly. Concerningly, no vaccines toward such strains are available and beta-lactam resistance is increasing. We describe the epidemiology of invasive Hi disease reported to the Norwegian Surveillance System for Communicable Diseases (MSIS) (2017-2021, n = 407). Whole-genome sequencing (WGS) was performed on 245 isolates. We investigated the molecular epidemiology (core genome phylogeny) and the presence of antibiotic resistance markers (including chromosomal mutations associated with beta-lactam or quinolone resistance). For isolates characterized with both WGS and phenotypic antibiotic susceptibility testing (AST) (n = 113) we assessed correlation between resistance markers and susceptibility categorization by calculation of sensitivity, specificity, and predictive values. Incidence rates of invasive Hi disease in Norway ranged from 0.7 to 2.3 per 100,000 inhabitants/year (mean 1.5 per 100,000) and declined during the COVID-19 pandemic. The bacterial population consisted of two major phylogenetic groups with subclustering by serotype and multi-locus sequence type (ST). NTHi accounted for 71.8% (176). The distribution of STs was in line with previous European reports. We identified 13 clusters, including four encapsulated and three previously described international NTHi clones with bla _TEM-1 (ST103) or altered PBP3 (rPBP3) (ST14/IIA and ST367/IIA). Resistance markers were detected in 25.3% (62/245) of the isolates, with bla _TEM-1 (31, 50.0%) and rPBP3 (28, 45.2%) being the most frequent. All isolates categorized as resistant to aminopenicillins, tetracycline or chloramphenicol possessed relevant resistance markers, and the absence of relevant substitutions in PBP3 and GyrA/ParC predicted susceptibility to cefotaxime, ceftriaxone, meropenem and quinolones. Among the 132 WGS-only isolates, one isolate had PBP3 substitutions associated with resistance to third-generation cephalosporins, and one isolate had GyrA/ParC alterations associated with quinolone resistance. The detection of international virulent and resistant NTHi clones underlines the need for a global molecular surveillance system. WGS is a useful supplement to AST and should be performed on all invasive isolates.

Keywords: Haemophilus influenzae (Hi); Norway; antibiotic resistance; epidemiology; invasive; surveillance; vaccine; whole-genome sequencing (WGS).