Objective: To observe the change in resistance of Pseudomonas aeruginosa (PA) to gentamicin (GM) during in vitro subculturing.
Methods: Twenty -- six strains of PA with resistance to GM isolated from burn patients were subcultured in vitro for 30 generations. The strains were also divided into high level (20 strains) and medium level (6 strains) of resistant groups according to their MIC (minimum inhibition concentration) values. The MIC and MBC (minimal bactericidal concentration) levels were examined in every strains of the 1st, 10th, 20th, and 30th filial generations of PA strain.
Results: There was no significant general difference of MIC and MBC values among the filial generations in each group (P < 0.05) when multiple comparisons of MIC and MBC mean values were made among every filial generations in high and medium levels of GM resistant groups.
Conclusion: There was no evident difference in GM resistance among all the filial generations of PA. The result indicated that, the PA with different levels of GM resistance clinically found might come from different PA strains.