The effects of topical chloramphenicol and ciprofloxacin on conjunctival bacterial flora of healthy dogs

Normal bacterial flora of the conjunctiva, which inhibits growth of opportunistic organisms, has an important role in the prevention of ocular infections. If resident flora is inhibited by disease or long-term application of antibiotics, opportunistic pathogens overgrow, leading to disease. The aim of this study was to investigate the effects of ophthalmic chloramphenicol and ciprofloxacin on bacterial conjunctival flora in healthy dogs. A total of 16 animals were divided into 2 equal groups which received either chloramphenicol (CHL) (0.5%) or ciprofloxacin (CIP) (0.3%). In both groups, the right eye of each animal was treated with 2 drops of antibiotics every 8 and 6 hours, respectively, for 1 week and the left eye received artificial tear solution and served as control. Bacterial and fungal cultures were performed 8 hours before and after the treatment. Fisher’s Exact test and SPSS software were used for statistical analyses (p<0.05). There were no statistically significant differences between control and test eyes and bacterial isolates in both groups. In CHL group, after treatment Staphylococcus spp (62.5%), Bacillus spp (12.5%) from the right eyes and Staphylococcus spp (75%) and Bacillus spp (12.5%) from left eyes were isolated. In CIP group, after treatment the bacterial isolates of right eyes were Staphylococcus spp (87.5%), Aerococcus spp (37.5%), Viridans streptococcus (25%), Micrococcus spp (12.5%), Bacillus spp (12.5%); Staphylococcus spp (75%), Micrococcus spp (25%), Bacillus spp (12.5 %) were isolated from left eyes of dogs after 1 week administration of artificial tear. Topically applied chloramphenicol and ciprofloxacin had no significant changes in or detrimental effects on normal bacterial flora of treated dogs.