Abstract
BackgroundNon-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.MethodsWe 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).ResultsAt 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).ConclusionWe 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.
Highlights
Non-typable Haemophilus influenzae (NT-Hi) infection is frequently associated with acute otitis media (AOM) treatment failure, recurrence or chronic otitis media
Considering the influence of biofilm production on AOM recurrence, we found no difference between strains in NP during a first AOM episode or during recurrent AOM in the absence of conjunctivitis (NP group 2 vs NP group 3, 55.8% vs 56.8%, respectively, p = 0.93, odds ratios (ORs) = 0.96 [95% CI, 0.41; 2.24]) (Table 1)
We found no significant difference in biofilm production from strains in middle ear fluid (MEF) and strains in NP samples (NP groups 1, 2, 3 and 4): 40.5% vs 60.5% (p = 0.083, OR = 2.16 [0.90;5.16]), 55.8% (p = 0.19, 1.78 [0.75;4.24]), 56.8% (p = 0.16, 1.86 [0.79;4.40]) and 31.1% (p = 0.32, 0.64 [0.26;1.55]), respectively
Summary
Non-typable Haemophilus influenzae (NT-Hi) infection is frequently associated with acute otitis media (AOM) treatment failure, recurrence or chronic otitis media. 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). With the expanded use of 7-valent pneumococcal vaccination, Streptococcus pneumoniae and NT-Hi are the two most common bacteria implicated in AOM [1,2]. 7-valent Pneumococcal Conjugate Vaccine implementation in France, S. pneumoniae and NT-Hi infection were frequent among children with AOM treatment failure. NT-Hi is frequently associated with AOM treatment failure, recurrence and otitis media effusion [4,5].
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