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Ocular infections: antibiotics and bacterial adhesion on biomaterials used in ocular surgery
P Marone1, L Perversi, V Monzillo
1Laboratori Sperimentali di Ricerca-Istituto di Clinica delle Malattie Infettive, IRCCS S. Matteo, Università di Pavia, Italia.
Abstract:
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.
Insights
Ofloxacin and sagamycin show excellent antibacterial activity against ocular pathogens like Staphylococcus and Pseudomonas aeruginosa. Sub-inhibitory concentrations of ofloxacin may increase bacterial adhesion to biomaterials used in eye surgery.
Area of Science:
- Ophthalmology
- Microbiology
- Infectious Diseases
Background:
- Ocular infections pose a significant threat to vision.
- Bacterial adhesion to biomaterials is a key factor in ocular device-associated infections.
- Antibiotic resistance in ocular pathogens necessitates evaluation of new therapeutic agents.
Purpose of the Study:
- To evaluate the in vitro antibacterial activity of ofloxacin and sagamycin against common ocular pathogens.
- To investigate the role of bacterial adhesion to ocular biomaterials.
- To assess the impact of sub-minimum inhibitory concentrations (subMIC) of ofloxacin on bacterial adhesion.
Main Methods:
- Antibacterial activity was assessed using minimal inhibitory concentration (MIC90) assays against 85 bacterial isolates (CNS, S. aureus, P. aeruginosa).
- Adhesive properties of slime-producing staphylococci were tested on various ocular biomaterials.
- The effect of subMIC ofloxacin on bacterial adhesion was evaluated.
Main Results:
- Ofloxacin demonstrated high efficacy against coagulase-negative staphylococci (CNS) and Staphylococcus aureus (MIC90 = 1.56 mg/l).
- Sagamycin was highly effective against staphylococci (MIC90 = 0.78 mg/l) and the most active against Pseudomonas aeruginosa (MIC90 = 6.25 mg/l).
- Slime-producing staphylococci adhered readily to most ocular biomaterials, except round silicone sponges; subMIC ofloxacin enhanced this adhesion.
Conclusions:
- Ofloxacin and sagamycin are effective against key ocular pathogens.
- Bacterial adhesion to biomaterials is crucial for ocular infection development.
- Further research is needed to understand ofloxacin's effect on bacterial adhesion in vivo.