Epidemiology and genetic analysis of Haemophilus parainfluenzae in a tertiary-care hospital in Barcelona, Spain (2018–2022).
Haemophilus parainfluenzae is increasingly recognised as an opportunistic pathogen in urogenital infections and an emerging reservoir of antimicrobial resistance. We conducted a retrospective laboratory-based study including all H. parainfluenzae isolates collected at a tertiary hospital in Barcelona between 2018 and 2022. We performed antimicrobial susceptibility testing on all isolates and conducted whole-genome sequencing of multidrug-resistant (MDR) and capsulated strains. In total, 529 isolates from 504 individuals were analysed (258 respiratory, 223 urogenital and 48 from other sample types). Urogenital isolates were associated with younger individuals, whereas respiratory isolates predominated in older age groups. Overall, 85/529 (16.1%) isolates were MDR, with markedly higher prevalence among urogenital than respiratory samples (30.5% vs 6.2%). Symptomatic urogenital MDR episodes commonly presented with STI-compatible syndromes, predominantly urethritis, and H. parainfluenzae was the only STI-related organism cultured in 65.3% of cases. Genomic analyses revealed high population diversity, with resistance determinants distributed across unrelated lineages. Resistance was explained by acquired genes and target-site substitutions, including ß-lactamases (blaTEM-1, blaROB-1 and blaCTX-M-15), substitutions in PBP3, macrolide efflux determinants, QRDR mutations, and resistance mechanisms affecting chloramphenicol, folate metabolism and tetracyclines. Mobile genetic elements were frequent, including diverse integrative and conjugative elements, chromosomal insertions, and small ß-lactamase plasmids. Capsular operons were detected in 6.6% of the isolates, mainly urogenital, including two operons not observed previously at our centre; 26/35 capsulated isolates were MDR and capsular loci occurred across multiple lineages. These findings support H. parainfluenzae as an STI-associated urogenital pathogen and highlight an evolving, mobile resistome warranting strengthened genomic surveillance.
Haemophilus parainfluenzae is increasingly recognised as an opportunistic pathogen in urogenital infections and an emerging reservoir of antimicrobial resistance. We conducted a retrospective laboratory-based study including all H. parainfluenzae isolates collected at a tertiary hospital in Barcelona between 2018 and 2022. We performed antimicrobial susceptibility testing on all isolates and conducted whole-genome sequencing of multidrug-resistant (MDR) and capsulated strains. In total, 529 isolates from 504 individuals were analysed (258 respiratory, 223 urogenital and 48 from other sample types). Urogenital isolates were associated with younger individuals, whereas respiratory isolates predominated in older age groups. Overall, 85/529 (16.1%) isolates were MDR, with markedly higher prevalence among urogenital than respiratory samples (30.5% vs 6.2%). Symptomatic urogenital MDR episodes commonly presented with STI-compatible syndromes, predominantly urethritis, and H. parainfluenzae was the only STI-related organism cultured in 65.3% of cases. Genomic analyses revealed high population diversity, with resistance determinants distributed across unrelated lineages. Resistance was explained by acquired genes and target-site substitutions, including ß-lactamases (blaTEM-1, blaROB-1 and blaCTX-M-15), substitutions in PBP3, macrolide efflux determinants, QRDR mutations, and resistance mechanisms affecting chloramphenicol, folate metabolism and tetracyclines. Mobile genetic elements were frequent, including diverse integrative and conjugative elements, chromosomal insertions, and small ß-lactamase plasmids. Capsular operons were detected in 6.6% of the isolates, mainly urogenital, including two operons not observed previously at our centre; 26/35 capsulated isolates were MDR and capsular loci occurred across multiple lineages. These findings support H. parainfluenzae as an STI-associated urogenital pathogen and highlight an evolving, mobile resistome warranting strengthened genomic surveillance.
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