title: Resistance of non-typeable Haemophilus influenzae biofilms is independent of biofilm size.
abstract: The inflammatory middle ear disease known as otitis media can become chronic or recurrent in some cases due to failure of the antibiotic treatment to clear the bacterial etiological agent. Biofilms are known culprits of antibiotic-resistant infections; however, the mechanisms of resistance for non-typeable Haemophilus influenzae biofilms have not been completely elucidated. In this study, we utilized in vitro static biofilm assays to characterize clinical strain biofilms and addressed the hypothesis that biofilms with greater biomass and/or thickness would be more resistant to antimicrobial-mediated eradication than thinner and/or lower biomass biofilms. Consistent with previous studies, antibiotic concentrations required to eliminate biofilm bacteria tended to be drastically higher than concentrations required to kill planktonic bacteria. The size characterizations of the biofilms formed by the clinical isolates were compared to their minimum biofilm eradication concentrations for four antibiotics. This revealed no correlation between biofilm thickness or biomass and the ability to resist eradication by antibiotics. Therefore, we concluded that biofilm size does not play a role in antibiotic resistance, suggesting that reduction of antibiotic penetration may not be a significant mechanism for antibiotic resistance for this bacterial opportunist.
authors.affiliation: Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, NC 27106, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Reimche
authors.affiliation: Department of Otolaryngology, Wake Forest School of Medicine, Winston-Salem, NC 27106, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Kirse
authors.affiliation: Department of Otolaryngology, Wake Forest School of Medicine, Winston-Salem, NC 27106, USA.
authors.forename: Amy S
authors.initials: AS
authors.lastname: Whigham
authors.affiliation: Department of Microbiology and Immunology, Wake Forest School of Medicine, Winston-Salem, NC 27106, USA swords@uab.edu.|Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: W Edward
authors.initials: WE
authors.lastname: Swords
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D024881:Drug Resistance, Bacterial; D006192:Haemophilus Infections / Q000382:microbiology*; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000502:physiology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D010033:Otitis Media / Q000188:drug therapy / Q000382:microbiology
chemical_list: D000900:Anti-Bacterial Agents
keywords: Haemophilus; antibiotic; biofilm; otitis media