Formation of biofilm by Haemophilus influenzae isolated from pediatric intractable otitis media.
OBJECTIVE
The aims of this study are to evaluate biofilm formation by nontypeable Haemophilus influenzae (NTHi) isolated from children with acute otitis media (AOM) and its relation with clinical outcome of the disease.


METHODS
Biofilm formations by NTHi clinical isolates from pediatric AOM patients were evaluated by a crystal violet microtiter plate and a 98 well pin-replicator assay with a confocal laser scanning microscopy (CLSM). Optical density values of clinical isolates were compared with a positive control and the ratio of clinical isolates to a positive control was defined as biofilm formation index (BFI).


RESULTS
84.3% clinical isolates of NTHi were biofilm forming strains (BFI> or =0.4). The BFI represented the levels of biofilm formation and adherence on the surface. The identical strains isolated from both middle ear fluids (MEFs) and nasopharynx showed biofilm formation at the same level. The prevalence of biofilm forming isolates was significantly higher among the susceptible strains than resistant strains. The level of biofilm formation of NTHi isolated from AOM cases who was not improved by amoxicillin (AMPC) was significantly higher than that of NTHi isolated from AOM cases who was improved by AMPC.


CONCLUSIONS
We clearly showed the biofilm formation of clinical NTHi isolates from AOM children. In addition, the biofilm formed by NTHi would play an important role in persistent or intractable clinical course of AOM as a result of lowered treatment efficacy of antibiotics.
Moriyama
Satomi
S
Department of Otolaryngology-Head and Neck Surgery, Wakayama Medical University, Japan.
Hotomi
Muneki
M
Shimada
Jun
J
Billal
Dewan S
DS
Fujihara
Keiji
K
Yamanaka
Noboru
N
D000658:Amoxicillin / Q000627:therapeutic use; D000667:Ampicillin / Q000494:pharmacology / Q000627:therapeutic use; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D001422:Bacterial Adhesion; D018441:Biofilms / Q000254:growth & development*; D002675:Child, Preschool; D004432:Ear, Middle / Q000382:microbiology; D005260:Female; D005838:Genotype; D006192:Haemophilus Infections / Q000188:drug therapy; D006193:Haemophilus influenzae / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D007223:Infant; D008297:Male; D008826:Microbial Sensitivity Tests; D009305:Nasopharynx / Q000382:microbiology; D010033:Otitis Media / Q000382:microbiology*; D016896:Treatment Outcome
D000900:Anti-Bacterial Agents; D000667:Ampicillin; D000658:Amoxicillin