First identification and molecular characterization of CTX-M-15 extended-spectrum β-lactamase and OXA-9 β-lactamase in Haemophilus influenzae in the Iberian Peninsula.

We describe, for the first time, the presence and characterization of CTX-M-15 and OXA-9 in two Haemophilus influenzae strains: PTHi-14525 (CTX-M-15) from Portugal and HUB-HI042681 (OXA-9) from Spain. Multidrug-resistant PTHi-14525 carried blaCTX-M-15 (two copies) and blaTEM-1 in an ICEHpaHUB5-like element. HUB-HI042681, resistant to β-lactams and aminoglycosides, carried a novel ICEHinHUB1. These findings highlight the genomic plasticity and expanded resistome of H. influenzae, raising concerns about treatment and emphasizing the need for continuous genomic surveillance.