Effects Of Erythromycin On Pseudomonas Aeruginosa's Virulent Factors

Objective:Pseudomonas aeruginosa is one of the common clinical pathogen. Erythromycin has the inhibitory action on the virulent factors of pseudomonas aeruginosa which has been the evidence of antibiotic therapy. The aim of this study was to observe the function of low concentration of erythromycin to pseudomonas aeruginosa's twitching motility and the phagotrophic ability of macrophage to pseudomonas aeruginosa.Subjects and Methods:The 1244 strain of Pseudomonas aeruginosa was cultured in LB plate or LB broth in which diverse concentration of erythromycin(2.5mg/L,0.5 mg/L,0.25mg/L) was added and also cultured in the contrast group. The changes of pseudomonas aeruginosa 1244's twitching motility were observed by naked eyes, immunofluorescence, western blot, dot blot and electron microscope. Pseudomonas aeruginosa was cultured in LB broth for 18h in which added erythromycin and then incubated with macrophage from murine abdominal cavity for 2h. We observed the ratio of phagocytosis of macrophage through light microscopy and electron microscopy.Results:1. SubMIC erythromycin inhibited the halation of twitching motility on the culture plates.It displayed that the diameter of the halation was shorten with the increasing of the erythromycin's concentration. Immunofluorescence observation showed that the key component of twitching motility was pilus IV that located at the pole of the PA body. Western blot showed that the expression of pilus IV was increased with the decreasing of erythromycin's concentration. Dot blot displayed that pilus IV expressed mostly at the outmost of the twitching zone and there was no obvious difference between groups. Through transmission electron microscope, PA of the group in which added erythromycin had less pilus than the contrast group.2. We can see the ratio of phagocytosis of macrophage was decreased with the reduction of erythromycin's concentration through light microscopy. We can observe that the pseudopodia of macrophage were increased in the group in which erythromycin were added through light microscopy.Conclusion:Low concentration of erythromycin has inhibitory actions on pseudomonas aeruginosa's twitching motility and Low concentration of erythromycin may enhance the ability of macrophage in vitro by influencing the virulent factors of pseudomonas aeruginosa.