Kan P, et al. - Because Porphyromonas gingivalis is a major pathogen and has a high detection rate in periodontal disease, researchers analyzed the impacts of sub-minimal inhibitory concentrations (sub-MICs) of azithromycin on the adherence of P. gingivalis, concentrating on the inhibition of fimbriae expression and hemagglutinin activity. According to findings, sodium dodecyl sulfate-polyacrylamide gel electrophoresis results indicated that 41-kDa fimbrial protein expression and hemagglutinin activities were inhibited by azithromycin sub-MICs. Compared with the adherence levels without antibiotic, the adherence of P. gingivalis to human gingival epithelial cells was reduced by sub-MICs of azithromycin. These outcomes show that azithromycin sub-MICs may decrease P. gingivalis adherence to host cells by inhibiting fimbriae and hemagglutinin production activities. Azithromycin can, therefore, be used as a biofilm treatment of periodontal disease caused by P. gingivalis.