title: Haemophilus influenzae biofilm formation in chronic otitis media with effusion.
abstract: Otitis media with effusion (OME) is a highly prevalent disease in children, but the exact pathogenesis and role of bacteria are still not well understood. This study aimed to investigate the presence of otopathogenic bacteria in the middle ear effusion (MEE) and adenoid of children with chronic OME (COME), and to investigate in vivo whether these bacteria, especially Haemophilus influenzae, are organized as a biofilm in the middle ear fluid. MEE and adenoid samples were collected from 21 patients with COME. Extensive bacterial culturing and genotyping was performed on all middle ear and adenoid samples. Fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy (CLSM) was used to visualize possible biofilm structures for a selection of middle ear effusion samples. 34 MEE samples were collected from 21 patients of which 64.7 % were culture positive for bacteria and 47.0 % were culture positive for Haemophilus influenzae, Moraxella catarrhalis, Staphylococcus aureus and/or Streptococcus pneumoniae. All 21 adenoid samples were culture positive for one or more of these four otopathogens. H. influenzae (35.3 %) and S. pneumoniae (76.2 %) were the most frequently cultured bacteria in the MEE and adenoid samples, respectively. The same bacterial species was found in MEE and adenoid for 84.6 % of the patients and in 81.2 % of the cases where the same species was found in more than one site it involved the same bacterial genotype. FISH and CLSM demonstrated the presence of H. influenzae specific biofilm structures in five of the eight culture positive MEEs that were tested, but in none of the two culture negative MEEs. The findings in this study indicate that the adenoid acts as a reservoir for bacteria in MEE and confirms that biofilms, in at least half of the cases consisting of H. influenzae, are indeed present in the MEE of children with COME. Biofilms may thus play a crucial role in the pathogenesis of COME, which is important in the understanding of this disease and the development of potential future treatment options.
authors.affiliation: Department of Otorhinolaryngology, Ghent University Hospital, De Pintelaan 185, 9000, Ghent, Belgium. helen.vanhoecke@ugent.be.
authors.forename: Helen
authors.initials: H
authors.lastname: Van Hoecke
authors.affiliation: Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
authors.forename: Ann-Sophie
authors.initials: AS
authors.lastname: De Paepe
authors.affiliation: Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
authors.forename: Edward
authors.initials: E
authors.lastname: Lambert
authors.affiliation: Laboratory Bacteriology Research, Department of Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
authors.forename: Jonas D
authors.initials: JD
authors.lastname: Van Belleghem
authors.affiliation: Laboratory Bacteriology Research, Department of Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
authors.forename: Piet
authors.initials: P
authors.lastname: Cools
authors.affiliation: Laboratory Bacteriology Research, Department of Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
authors.forename: Leen
authors.initials: L
authors.lastname: Van Simaey
authors.affiliation: Laboratory Bacteriology Research, Department of Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
authors.forename: Pieter
authors.initials: P
authors.lastname: Deschaght
authors.affiliation: Laboratory Bacteriology Research, Department of Clinical Chemistry, Microbiology and Immunology, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
authors.forename: Mario
authors.initials: M
authors.lastname: Vaneechoutte
authors.affiliation: Department of Otorhinolaryngology, Ghent University Hospital, De Pintelaan 185, 9000, Ghent, Belgium.
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Dhooge
mesh_terms: D000234:Adenoids / Q000382:microbiology; D018441:Biofilms / Q000254:growth & development*; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease; D004432:Ear, Middle / Q000382:microbiology; D005260:Female; D005838:Genotype; D006193:Haemophilus influenzae / Q000302:isolation & purification / Q000502:physiology*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007223:Infant; D008297:Male; D018613:Microscopy, Confocal; D001936:Moraxella catarrhalis / Q000302:isolation & purification / Q000502:physiology; D010034:Otitis Media with Effusion / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000302:isolation & purification / Q000502:physiology; D013296:Streptococcus pneumoniae / Q000302:isolation & purification / Q000502:physiology
keywords: Biofilm; Chronic otitis media with effusion (COME); Confocal scanning laser microscopy (CLSM); Fluorescent in situ hybridization (FISH); Haemophilus influenzae