[Effects of erythromycin on the twitching motility of Pseudomonas aeruginosa].
OBJECTIVE
To observe the effects of low concentration of erythromycin on the twitching motility of Pseudomonas aeruginosa.


METHODS
Pseudomonas aeruginosa 1244 (PA1244) was cultured in LB plate or LB broth with added erythromycin at different concentrations 2.5, 0.5, 0.25 mg/L, and in cultures without erythromycin as the control. The changes of PA1244's twitching motility was observed by naked eyes, immunofluorescence, Western blot, dot blot and electron microscope.


RESULTS
SubMIC erythromycin inhibited the halation of twitching motility on the culture plates. The average diameters of bacterial halation after culture for 18 h were as below: group of 2.5 mg/L was (0.48 +/- 0.14) cm, group of 0.5 mg/L was (0.64 +/- 0.20) cm, group of 0.25 mg/L was (0.95 +/- 0.18) cm; the control group was (1.40 +/- 0.21) cm (F = 123.15, P < 0.01). After culture for 24 h: group of 2.5 mg/L was (0.67 +/- 0.12) cm, group of 0.5 mg/L was (0.82 +/- 0.23) cm, group of 0.25 mg/L was (1.18 +/- 0.24) cm; the control group was (1.58 +/- 0.28) cm (F = 76.37, P < 0.01). After culture for 36 h: group of 2.5 mg/L was (0.91 +/- 0.17) cm, group of 0.5 mg/L was (1.04 +/- 0.32) cm, group of 0.25 mg/L was (1.49 +/- 0.31) cm; the control group was (2.07 +/- 0.38) cm (F = 54.75, P < 0.01). Immunofluorescence showed that the key component of twitching motility was pilus VI located at the pole of the PA body. Western blot showed that the expression of pilus VI was increased with the decreasing concentration of erythromycin. Dot blot showed that pilus VI was expressed mostly at the outmost of the twitching zone and there was no significant difference between groups. Through transmission electron microscope, PA of the group of 2.5 mg/L had fewer pilus than the control group.


CONCLUSIONS
Diverse concentrations of erythromycin have inhibitory actions on the twitching motility of Pseudomonas aeruginosa.
Gu
Xiao-hua
XH
Department of Pulmonary Medicine, Shanghai Sixth People's Hospital, Shanghai Jiaotong University, Shanghai 200233, China.
Shen
Ce
C
Jiang
Yan-qun
YQ
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004917:Erythromycin / Q000494:pharmacology*; D010861:Fimbriae, Bacterial / Q000187:drug effects* / Q000502:physiology; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000502:physiology
D000900:Anti-Bacterial Agents; D004917:Erythromycin