D-087. Production of Biofilm by Haemophilus influenzae Isolated from Pediatric Intractable Otitis Media

S. Moriyama, M. Hotomi, D. S. Billal, N. Yamanaka;
Wakayama Med. Univ., Wakayama, JAPAN.

Background. Intractable acute otits media (AOM) against antimicrobial treatment has become a serious problem among young children in Japan. Biofilm are considered to be involved into the persistent bacterial infections such as otitis media and bronchitis, especially the disease caused by nontypeable Haemophilus influenzae (NTHi). While several studies focused on the production of biofilm by NTHi, the impact of biofilm on clinical courses of AOM has not been well documented yet. In this study, we evaluated production of biofilm by NTHi isolated from children with AOM in comparison with clinical outcome of the disease. Methods. A total 110 NTHi clinical isolates were used in this study and their biofilm formations were evaluated by crystal violet stain and confocal laser microscope. We evaluated correlation between biofilm formation by NTHi and (i) antimicrobial susceptibility and (ii) clinical outcome of AOM. Results. About 87.2 % of clinical isolates of NTHi from AOM formed biofilm. NTHi producing biofilm were highly identified among NTHi strains with MIC to ABPC ≤1 µg/ml rather than those with MIC to ABPC ≥ 2µg/ml. The levels of biofilm formation were higher in NTHi isolated from children with AOM did not improved by AMP rather than those from children with AOM improved by AMP.Discussion. The current results suggest that production of biofilm by NTHi would be associated with unfavorable clinical outcome of AOM.