[Analysis on the susceptibility of fusidic acid for common gram positive bacteria].

OBJECTIVE

To assess in vitro susceptibility of the fusidic acid, vancomycin, tobramycin and ofloxacin for 8 kinds of ocular gram-positive bacteria.

METHODS

It was an experimental study. One hundred strains of ocular gram-positive bacterial isolates selected from Beijing Institute of Ophthalmology, cultivated and identified by the routine, were tested for their susceptibilities to fusidic acid, vancomycin, tobramycin and ofloxacin, with in vitro by the Kirby-Bauer disk diffusion method. Significant differences between groups were evaluated by SPSS 11.5 chi-square test of four-fold table.

RESULTS

In the study, the percentage of susceptibility for in vitro gram-positive bacterial isolates to tobramycin, ofloxacin, vancomycin and fusidic acid was 55.0%, 65.0%, 98.0% and 53.0%. The susceptibility to vancomycin was significantly higher than to tobramycin, ofloxacin and fusidic acid (chi(2) = 51.425, 36.113, 54.737; P < 0.05). The susceptibility of common staphylococci to fusidic acid (85.5%) was just lower than to vancomycin (100.0%) (chi(2) = 6.605, P < 0.05), but was significantly higher than to tobramycin (58.2%) and ofloxacin (54.5%) (chi(2) = 10.106, 12.511; P < 0.05). The susceptibility of common streptococcus to fusidic acid (0.0%) was lower than to vancomycin (100.0%) and ofloxacin (85.0%) (chi(2) = 40.000, 29.565; P < 0.05), but the susceptibility to fusidic acid and tobramycin (15.0%) were equivalent (chi(2) = 1.441, P > 0.05). The gram-positive bacilli and nocardia showed significantly lower susceptibility to fusidic acid (24.0%) than that to the other three antibiotics (tobramycin 80.0%, ofloxacin 72.0%, vancomycin 92.0%) (chi(2) = 23.727, 22.430, 11.538; P < 0.05).

CONCLUSION

The in vitro susceptibility of fusidic acid to staphylococci is higher, while to streptococcus and gram-positive bacilli is obviously lower than other three kinds of antibiotics.