García-Cobos, SilviaMoscoso, MiriamPumarola, FélixArroyo, MargaritaLara Fuella, NoeliaPerez-Vazquez, MariaAracil, BelenOteo-Iglesias, JesusGarcía, ErnestoCampos, Jose2026-01-292026-01-292014-09Silvia García-Cobos, Miriam Moscoso, Félix Pumarola, Margarita Arroyo, Noelia Lara, María Pérez-Vázquez, Belén Aracil, Jesús Oteo, Ernesto García, José Campos, Frequent carriage of resistance mechanisms to β-lactams and biofilm formation in Haemophilus influenzae causing treatment failure and recurrent otitis media in young children, Journal of Antimicrobial Chemotherapy, Volume 69, Issue 9, September 2014, Pages 2394–2399, https://doi.org/10.1093/jac/dku158.https://hdl.handle.net/20.500.12105/27199Objectives: Non-typeable Haemophilus influenzae are a major cause of acute otitis media (AOM), including chronic and recurrent otitis in young children. The objective of this study was to determine whether non-typeable H. influenzae isolates causing these infections produce biofilms and carry resistance mechanisms to β-lactams. Methods: A collection of 48 H. influenzae isolates was obtained by tympanocentesis or from otorrhoea samples from individual patients <3 years of age and diagnosed with recurrent or treatment failure AOM. Each isolate was surveyed for the presence of blaTEM genes, amino acid substitutions in the transpeptidase domain of penicillin-binding protein 3 (PBP3) and biofilm formation in microtitre plates. Results: In 43 of the 48 isolates (89.6%), at least one of the three tested conditions was identified: biofilm formation (83.3%) and resistance mechanisms to β-lactams (33.3%), modifications in the transpeptidase domain of PBP3 being the most prevalent (22.9%), followed by β-lactamase production (10.4%). Additionally, 13 (27.1%) isolates had two or more of these three traits. In relation to biofilm formation, those isolates with an amoxicillin MIC ≤ 0.5 mg/L had higher optical density values than isolates with an amoxicillin MIC ≥ 1 mg/L (Mann-Whitney U-test, P=0.048). Conclusions: These findings suggest that the successful treatment of non-typeable H. influenzae causing chronic and recurrent AOM in young children may be compromised by the high biofilm-forming capacity of the isolates and the presence of β-lactam resistance mechanisms, particularly PBP3 mutations.engVoRAOMH. influenzaegBLNAR248914326992394-910.1093/jac/dku158Journal of Antimicrobial Chemotherapymetadata only access