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Susceptibility of corneal and conjunctival pathogens to ciprofloxacin
H P Knauf1, R Silvany, P M Southern
1Departments of Ophthalmology, University of Texas Southwestern Medical Center at Dallas, USA.
Abstract:
Ciprofloxacin 0.3% ophthalmic solution has been shown to be effective in the treatment of bacterial keratitis and conjunctivitis, and many physicians use ciprofloxacin as sole therapy in these conditions. In this retrospective study, we found seven of 84 isolates from corneal and conjunctival cultures that were resistant to ciprofloxacin. All of the resistant organisms were gram positive. Six of the isolates (Staphylococcus aureus, Staphylococcus hominis, and four isolates of the Streptococcus viridans group) were from corneal cultures, and one (Staphylococcus aureus) was from a conjunctival culture. Yearly records of systemic isolates from 1988 to 1993 (n = 35,308) demonstrated a statistically significant decrease in susceptibility for several organisms that are common pathogens in the conjunctiva and cornea: Pseudomonas aeruginosa (95-90%, p = 0.001); Staphylococcus aureus (96-87%, p < 0.0001); Staphylococcus spp., coagulase negative (97-81%, p < 0.0001); Enterococcus spp. (92-79%, p < 0.0001); Acinetobacter anitratus (97-77%, p = 0.0006); and Enterobacter cloacae (100-96%, p = 0.03). Although the susceptibility of corneal and conjunctival isolates in this series remained relatively high (91.7%), a much larger series of systemic isolates that are common ocular pathogens revealed a statistically significant increase in resistance to ciprofloxacin over the preceding 5 years.
Insights
Ciprofloxacin ophthalmic solution is effective for bacterial eye infections. However, this study found increasing resistance in common eye pathogens, particularly Gram-positive bacteria, necessitating careful monitoring of ciprofloxacin resistance.
Area of Science:
- Ophthalmology
- Microbiology
- Infectious Diseases
Background:
- Ciprofloxacin 0.3% ophthalmic solution is a common monotherapy for bacterial keratitis and conjunctivitis.
- Emerging antibiotic resistance is a significant concern in treating ocular infections.
Purpose of the Study:
- To assess the prevalence of ciprofloxacin resistance in ocular isolates.
- To evaluate trends in ciprofloxacin susceptibility among common ocular pathogens.
Main Methods:
- Retrospective analysis of corneal and conjunctival cultures.
- Review of systemic isolate susceptibility data from 1988-1993.
- Statistical analysis of susceptibility trends over time.
Main Results:
- Seven of 84 ocular isolates (8.3%) showed resistance to ciprofloxacin, primarily Gram-positive organisms.
- Significant decreases in ciprofloxacin susceptibility were observed in systemic isolates of common ocular pathogens, including Pseudomonas aeruginosa and Staphylococcus aureus.
- Corneal and conjunctival isolate susceptibility remained relatively high at 91.7% in this series.
Conclusions:
- While ocular isolate resistance was low in this study, a concerning trend of increasing ciprofloxacin resistance is evident in systemic isolates of common ocular pathogens.
- Physicians should be aware of potential treatment failures due to ciprofloxacin resistance.
- Continued surveillance of antibiotic susceptibility is crucial for effective management of bacterial eye infections.