title: Non typable-Haemophilus influenzae biofilm formation and acute otitis media.
abstract: BACKGROUND
  Non-typable Haemophilus influenzae (NT-Hi) infection is frequently associated with acute otitis media (AOM) treatment failure, recurrence or chronic otitis media. Persistence of otopathogens in a biofilm-structured community was implicated in these situations. Here, we compared biofilm production by H. influenzae strains obtained by culture of middle ear fluid (MEF) from children with AOM treatment failure and by strains isolated from nasopharyngeal (NP) samples from healthy children or those with AOM (first episode or recurrence). We aimed to evaluate an association of clinical signs and in vitro biofilm formation and establish risk factors of carrying a biofilm-producing strain.
  
  
  METHODS
  We used a modification of the microtiter plate assay with crystal violet staining to compare biofilm production by 216 H. influenzae strains: 41 in MEF from children with AOM treatment failure (group MEF), 43 in NP samples from healthy children (NP group 1), 88 in NP samples from children with a first AOM episode (NP group 2, n = 43) or recurrent (NP group 3, n = 45) and 44 in NP samples from children with AOM associated with conjunctivitis (NP group 4).
  
  
  RESULTS
  At all, 106/216 (49%) H. influenzae strains produced biofilm as did 26/43 (60.5%) in NP samples from healthy children. Biofilm production in MEF samples and NP samples did not significantly differ (40.5% vs 60.5%, 55.8%, 56.8% and 31.1% for NP groups 1, 2, 3 and 4, respectively). On multivariate analysis, only presence of conjunctivitis was significantly associated with low biofilm production (OR = 0.3, CI [0.16-0.60], p = 0.001). The ampicillin resistance of H. influenzae produced by penicillin-binding protein modification was significantly associated with low biofilm production (p = 0.029).
  
  
  CONCLUSIONS
  We found no association of biofilm production and AOM treatment failure or recurrence. Biofilm production was low from H. influenzae strains associated with conjunctivitis-otitis syndrome and from strains with modified penicillin-binding protein.
authors.forename: Assaf
authors.initials: A
authors.lastname: Mizrahi
authors.forename: Robert
authors.initials: R
authors.lastname: Cohen
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Varon
authors.forename: Stephane
authors.initials: S
authors.lastname: Bonacorsi
authors.forename: Stephane
authors.initials: S
authors.lastname: Bechet
authors.forename: Claire
authors.initials: C
authors.lastname: Poyart
authors.forename: Corinne
authors.initials: C
authors.lastname: Levy
authors.affiliation: Université Paris Descartes, Hôpital Cochin, Bactériologie, 27 rue du Faubourg Saint Jacques, 75679 Paris cedex 14, France. josette.raymond@cch.aphp.fr.
authors.forename: Josette
authors.initials: J
authors.lastname: Raymond
mesh_terms: D000208:Acute Disease; D018441:Biofilms; D002675:Child, Preschool; D006193:Haemophilus influenzae / Q000302:isolation & purification*; D006801:Humans; D007223:Infant; D015999:Multivariate Analysis; D009305:Nasopharynx; D010033:Otitis Media / Q000175:diagnosis* / Q000382:microbiology*; D012008:Recurrence; D012307:Risk Factors; D013296:Streptococcus pneumoniae / Q000302:isolation & purification; D017211:Treatment Failure