Biofilm Formation & β- lactamase Production of Haemophilus influenzae Isolated from Lower Respiratory Tract Infections

Abstract

Objectives:To explore the biofilm formation and β-lactamase production of H. influenzae isolated from lower respiratory tract infections.Methods:For the period from 1st Jun/2004 to 30th April/2005, 142 sputum samples were collected from patients with lower respiratory tract infections. These patients were attending TB and Chest disease center or Baquba general hospital. The specimens were cultured on chocolate agar plates with multivitex (Multi-vitamins, BDH-UK) under 10% CO2. Isolation and identification of H. influenzae were based on standard bacteriological and biochemical criteria plus serotyping with specific antisera (Bio-RAD Laboratories-Japan). An in vitro biofilm formation was assayed by microtiter plate technique. The β - lactamase production was determined by direct capillary tube method.Results:Forty isolates of H. influenzae were recovered throughout this study. The isolation rate from males was higher than females (72.5% vs 27.5%). The highest isolation rate was recovered from patients with 40 years and older 17(42.5%) compared to other age groups. 17.5% isolates were H. influenzae type b (Hib), and the remaining 82.5% isolates were nontype b. twenty percent of the isolates were found to be β-lactamase producers. Furthermore, 37.5% of isolates were found to have the ability for biofilm formation and the majority (66.7%) was β-lactamase producers.Conclusion:Characterization of biofilms may be important in understanding the pathogenesis of H. influenzae infection in human.