Open AccessEffect of erythromycin on Shigella infection of Caco‐2 cells
Author(s) -
Honma Yasuko,
Sasakawa Chihiro,
Tsuji Takao,
Iwanaga Masaaki
Publication year - 2000
Publication title -
fems immunology & medical microbiology
Language(s) - English
Resource type - Journals
eISSN - 1574-695X
pISSN - 0928-8244
DOI - 10.1111/j.1574-695x.2000.tb01424.x
Subject(s) - shigella flexneri , virulence , microbiology and biotechnology , shigellosis , biology , plasmid , shigella , agar , enterobacteriaceae , erythromycin , agar plate , strain (injury) , gentamicin protection assay , in vitro , antibiotics , bacteria , escherichia coli , gene , genetics , anatomy , western blot
Erythromycin (EM), one of the macrolides, shows a dose‐dependent effect on Shigella flexneri invasion of Caco‐2 cells even at concentrations less than the minimum inhibitory concentration (subMIC). LS13, a strain of S. flexneri 1b, invaded Caco‐2 cells in vitro. When the strain was treated with subMIC of EM, the invasion efficiency decreased. The carrier rate of the invasion plasmid containing virulence genes was reduced by EM treatment, as determined by the colony pigmentation test on Congo red agar plates. Presence of the invasion plasmid was found to increase susceptibility of the organisms to EM. The growth of virulent organisms carrying the invasion plasmid was inhibited at 25 μg ml −1 of EM, whereas the growth of organisms without the plasmid was inhibited at 100 μg ml −1 of EM. This was supported by the finding that the MIC of EM for a virulent isolate of S. flexneri 2a YSH6000 (6.25 μg ml −1 ) and for the mutant strain del‐17 (50 μg ml −1 ), carrying the type III apparatus, impaired plasmid. These findings suggested that EM passed through the type III apparatus and suppressed the growth of invasive organisms selectively. This mechanism may account for the clinical effect of EM on shigellosis.