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Minimal biofilm eradication concentration of antimicrobial agents against nontypeable Haemophilus influenzae isolated from middle ear fluids of intractable acute otitis media


Nontypeable Haemophilus influenzae (NTHi) makes the clinical course of acute otitis media (AOM) intractable by forming a biofilm that may hamper the clearance of the bacteria from middle ear cavity. In this study, we evaluated the minimum biofilm eradication concentration (MBEC) of antimicrobial agents against biofilm-forming NTHi strains. Twelve NTHi strains isolated from middle ear fluids of Japanese children with intractable AOM before antimicrobial treatment were evaluated for MBEC of fluoroquinolones in comparison with those of β-lactams and macrolides. AMPC and CDTR required much higher concentration, i.e., high MBECs, to suppress the biofilm formation of NTHi. In contrast, fluoroquinolones followed by macrolides showed lower MBECs. MBEC would be a good parameter to infer the efficacies of antimicrobials against NTHi in biofilm.

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This work was supported by national grants from the Japanese Ministry of Education, Culture, Sports, Science and Technology (grant 24791800).

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We declare no conflict of interest for this study.

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Correspondence to Muneki Hotomi.

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S. Takei and M. Hotomi contributed equally to this work.

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Takei, S., Hotomi, M. & Yamanaka, N. Minimal biofilm eradication concentration of antimicrobial agents against nontypeable Haemophilus influenzae isolated from middle ear fluids of intractable acute otitis media. J Infect Chemother 19, 504–509 (2013).

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  • Haemophilus influenzae
  • Biofilm
  • Minimal biofilm eradication concentration
  • Antimicrobial agents