Ocular infections: antibiotics and bacterial adhesion on biomaterials used in ocular surgery.

The in vitro antibacterial activity of ofloxacin, sagamycin and other antibiotics was evaluated against 85 bacterial isolates [coagulase-negative staphylococci (CNS), n = 37, Staphylococcus aureus, n = 28, and Pseudomonas aeruginosa, n = 20] obtained from patients with ocular infections. The antistaphylococcal activity of ofloxacin was quite elevated with a 90% minimal inhibitory concentration (MIC90) of 1.56 mg/l against CNS and S. aureus. Rokitamycin and erythromycin showed a good activity against methicillin-sensitive staphylococci, but were less active than ofloxacin and sagamycin against methicillin-resistant strains (MIC90 > 100 mg/l). Sagamycin was highly effective against staphylococci (MIC90 0.78 mg/l) and appeared to be the most active compound against P. aeruginosa (MIC90 6.25 mg/l), followed by ofloxacin, tobramycin and gentamicin. In a successive part of the study, the adhesive properties of slime-producing staphylococci were tested on biomaterials used in ocular surgery. Intraocular lenses, Silastic sheetings, circling bands and grooved strips showed a high affinity for slime-producing strains, while round silicone sponges were not covered by bacterial biofilm. In the last part of our study, we demonstrated how subMIC levels of ofloxacin increased the adhesion of slime-producing staphylococci. Our data confirmed the excellent activity of ofloxacin and sagamycin against ocular pathogens and the key role of adhesion in promoting colonization and infections of biomaterials.