[Analysis on susceptibility of ocular bacterial pathogens to four kinds of fluoroquinolone].

Objective: To assess the in vitro susceptibilities of ocular bacterial isolates to Gatifloxacin and other fluoroquinolones which are often used in ophthalmic treatment.

Methods: Non-randomized, non-comparative, retrospective study. Ocular bacterial isolates (n = 619) from Beijing Institute of Ophthalmology were tested for their susceptibilities to gatifloxacin, ciprofloxacin, ofloxacin and levofloxacin in vitro by the Kirby-Bauer disk diffusion method.

Results: The total number of ocular bacterial isolates was 619 from January, 2005 to December, 2006 including gram-positive cocci 372(60.1%), gram-negative cocci 7 (1.1%), gram-positive bacilli 60 (9.7%), gram-negative bacilli 177 (28.6%), other 3 (0.5%). The percentage of susceptibility in total ocular bacterial isolates to gatifloxacin, ciprofloxacin, ofloxacin and levofloxacin was 88.4%, 72.1%, 64.8% and 54.4%. The susceptibility of Staphylococcus species to gatifloxacin (89.9%) was significantly higher than ciprofloxacin (38.8%), ofloxacin (48.2%) and levofloxacin (61.6%). Streptococcus species showed significantly higher susceptibility to gatifloxacin (93.2%), levofloxacin (89.2%) and ofloxacin (87.8%) than ciprofloxacin (62.2%). The susceptibility of gram-positive bacilli to gatifloxacin (86.7%) was significantly higher than ciprofloxacin (58.3%); All above differences are significant (P < 0.0083). Gram-negative cocci, enteric bacilli family and Pseudomonas species have the equivalent susceptibility to gatifloxacin, ciprofloxacin, ofloxacin and levofloxacin (P > 0.05).

Conclusions: Most of ocular bacterial are susceptible to gatifloxacin in vitro, especially gram-positive bacteria including Staphylococcus species, Streptococcus species and gram-positive bacilli.