Detection of blaCTX-M-15 in an integrative and conjugative element in four extensively drug resistant Haemophilus parainfluenzae strains causing urethritis
Haemophilus parainfluenzae is a commensal organism which, due to the rise of multidrug-resistant (MDR) strains, has become an emerging opportunistic pathogen with increasing clinical relevance in urogenital infection. This work aimed to identify and characterize the molecular mechanisms of resistance associated with four cephalosporin-resistant H. parainfluenzae strains collected from patients with urethritis. Antimicrobial resistance was determined by microdilution following European Committee on Antimicrobial Susceptibility Testing criteria. Strains were then analyzed by whole genome sequencing to determine their clonal relationship and the molecular basis of antimicrobial resistance. Finally, a phylogenetic analysis was performed on all urogenital MDR strains of H. parainfluenzae previously isolated in our hospital. All strains were resistant to ß-lactams, macrolides, tetracycline, fluoroquinolones, chloramphenicol, cotrimoxazole, and aminoglycosides. The resistance profile was compatible with the presence of an extended-spectrum ß-lactamase (ESBL). Whole genome sequencing detected blaCTX-M-15 that conferred high minimum inhibitory concentrations to cephalosporins in two novel integrative and conjugative elements (ICEHpaHUB6 and ICEHpaHUB7) that also harbored a blaTEM-1 ß-lactamase. We report a novel blaCTX-M-15 ESBL carried in an integrative conjugative element in four extensively drug resistant H. parainfluenzae strains. The possibility that this resistance determinant could be transmitted to other sexually transmitted pathogens is a cause for concern.