In vitro interference of cefotaxime at subinhibitory concentrations on biofilm formation by nontypeable Haemophilus influenzae

• Published in: Asian Pacific Journal of Tropical Biomedicine
• Main Authors: Sudarat Baothong, Sutthirat Sitthisak, Duangkamol Kunthalert
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wolters Kluwer Medknow Publications 2016
• Subjects: Biofilm formation; Cefotaxime; Nontypeable Haemophilus influenzae; Subinhibitory concentration; Sub-MIC; Arctic medicine. Tropical medicine; RC955-962; Biology (General); QH301-705.5; Arctic
• Online Access: https://doi.org/10.1016/j.apjtb.2016.07.003; https://doaj.org/article/6f3fbaae80884cd19656c35692b52b64

Objective: To investigate the in vitro interference of cefotaxime at subinhibitory concentrations [sub-minimal inhibitory concentrations (MIC)] on biofilm formation by nontypeable Haemophilus influenzae (NTHi). Methods: The interference of subinhibitory concentrations of cefotaxime on biofilm formation of the clinical strong-biofilm forming isolates of NTHi was evaluated by a microtiter plate biofilm formation assay. The effect of sub-MIC cefotaxime on bacterial cell-surface hydrophobicity was determined using a standard microbial adhesion to n-hexadecane test. Additionally, the effects on bacterial adherence to human fibronectin and expression of bacterial adhesins were also investigated. Results: Subinhibitory concentrations of cefotaxime, both at 0.1× and 0.5× MIC levels, efficiently reduced the NTHi biofilm formation, and this effect was independent of decreasing bacterial viability. Sub-MIC cefotaxime also decreased bacterial cell-surface hydrophobicity and reduced adherence to human fibronectin. Inhibition in the P2 and P6 gene expressions upon exposure to sub-MIC cefotaxime was also noted. Conclusions: Taken together, our results indicate that sub-MIC cefotaxime interferes with the formation of NTHi biofilm, and this effect is feasibly related to the interference with cell-surface hydrophobicity, fibronectin-binding activity as well as alteration of the P2 and P6 gene expression. The findings of the present study therefore provide a rationale for the use of subinhibitory concentrations of cefotaxime for treatment of NTHi-related diseases.