A study on the toxicity of intravitreal levofloxacin in rabbits

Successful management of drug-resistant rhizobium radiobacter endophthalmitis: A case report

PurposeTo report a unique case of post-cataract surgery endophthalmitis caused by Ceftazidime-resistant Rhizobium radiobacter, successfully managed with timely vitrectomy and intravitreal LevofloxacinCase reportA healthy 73-year-old man underwent phacoemulsification and posterior chamber intraocular lens implantation in his left eye. Postoperative ocular examination (OE) one day after the surgery revealed no specific findings. However, on postoperative day 6, he presented with a painful and red left eye. Diagnosed with postoperative endophthalmitis on day 8 at another hospital, he received IVI of Ceftazidime and Vancomycin before being urgently referred to our hospital on the same day. Early vitrectomy and anterior chamber irrigation were performed timely when he arrived on day 8, with cultures identifying Ceftazidime-resistant Rhizobium radiobacter, sensitive to Levofloxacin. Repeated IVI of Levofloxacin (500 mcg/0.1 ml) ensued on post-cataract operative days 13 and 18. Six months post-cataract surgery, the corrected distance visual acuity of the left eye stabilized at 20/33, and OE remained stable.ConclusionEarly vitrectomy and vitreous culture prove effective in managing postoperative endophthalmitis in drug-resistant Rhizobium radiobacter. IVI of Levofloxacin, though rare, proved to be effective in treating Ceftazidime-resistant and Levofloxacin-sensitive pathogens in our case.

Efficacy of Intravitreal Levofloxacin 0.5% Ophthalmic Solution in Treating Pseudomonas Aeruginosa Endophthalmitis on a Rabbit Model

PURPOSE

To evaluate the efficacy of intravitreal levofloxacin 0.5% ophthalmic solution as treatment of Pseudomonas aeruginosa endophthalmitis in a rabbit model.

DESIGN

This is a parallel randomized experimental study.

METHODS

Twenty-six New Zealand white rabbits were enrolled. P. aeruginosa was inoculated intravitreally on the right eyes of all rabbits, which were further categorized into 2 groups, the treatment group (Group A) receiving 0.1 mL intravitreal injection levofloxacin 0.5% 24 hours after inoculation and the control group (Group B), which had 0.1 mL intravitreal aqua destilata (placebo). Clinical observation of the eyes in each group was performed on the first until the sixth day after the inoculation using clinical grading scale. On the sixth day, the eyes were examined for microbiological and histopathologic evaluations.

RESULTS

The total clinical grading scores of each group were similar 24 hours after P. aeruginosa inoculation (P > 0.05). The total clinical grading scores of Group A on the sixth day and the difference in total clinical scores on the first and the sixth day were shown to be significantly lower than that of Group B (P < 0.05). Microbiological analysis revealed that there was a lower bacterial count in Group A (mean = 1.18 ± 0.93 logCFU/0.1 mL) compared with Group B (mean = 4.09 ± 1.51 logCFU/0.1 mL), and the histopathologic scores of both groups were also significantly different (P < 0.05).

CONCLUSIONS

Intravitreal levofloxacin 0.5% ophthalmic solution at 0.1 mL dose appeared to be effective in treating P. aeruginosa endophthalmitis in rabbits.

Evaluation of the levofloxacin release characters from a rabbit foldable capsular vitreous body

The authors have manufactured a novel rabbit foldable capsular vitreous body (FCVB). The aim of this study was to determine whether this rabbit FCVB can release levofloxacin in vitro and in vivo, and to evaluate the release characteristics. In vitro, the rabbit FCVB with levofloxacin 500 μg/mL was immersed in cups of modified Franz diffusion cells. Following this, 200 μL of liquid was aspirated at intervals from 10 minutes to 24 hours. In vivo, the FCVB with levofloxacin was implanted into the right eyes of five rabbits. After implantation, the aqueous humor was aspirated on days 1, 7, 14, 28, and 56. The levofloxacin concentrations in the cups and aqueous humor samples were detected by high-performance liquid chromatography–tandem mass spectrometry. The FCVB was observed under a scanning electron microscope. The results showed that the released levofloxacin was stabilized at 20 ng/mL at time points from 10 minutes to 24 hours in vitro. In vivo, levofloxacin concentrations in the aqueous humor were 132, 50, 39, 11, and 15 ng/mL on days 1, 7, 14, 28, and 56, respectively. In the FCVB capsules, 300 nm apertures were observed. These results suggest the rabbit FCVB released levofloxacin stably in vitro and sustainably in vivo. This study provides a novel combined approach, with the FCVB as a vitreous substitute and drug delivery system for the treatment of bacterial endophthalmitis.

[Fluoroquinolones in ophthalmology: indications and current use]

Fluoroquinolones are commonly used in ophthalmology, either for conjunctival infections or endophthalmitis. Use of these antibiotics requires good knowledge of the pharmacokinetic profile and adverse effects, and contraindications must be respected. Fluoroquinolones are useful in 2008 given their antibacterial spectrum, good ocular penetration, and the potential benefit of intravitreal injection.

Retinal safety of a new fluoroquinolone, pradofloxacin, in cats: assessment with electroretinography

PURPOSE

To investigate the safety of a new fluoroquinolone, pradofloxacin, on the cat retina using electroretinogram.

METHODS

Ganzfeld ERGs were recorded in 40 cats treated orally for 23 days in 4 groups: CTRL (n = 9): placebo-vehicle; PRADO30 (n = 10): pradofloxacin 30 mg/kg/day; PRADO50 (n = 14): pradofloxacin 50 mg/kg/day; and ENRO30 (n = 7): enrofloxacin at toxic doses of 30 mg/kg/day. ERG was performed before treatment and once weekly during the treatment period. An extended ISCEV protocol with addition of 8 steps of increasing luminance in dark adapted condition was carried out to assess: V (max) (saturated scotopic b-wave amplitude) and k (luminance inducing V (max)/2). OCT and retinal histological changes were also investigated.

RESULTS

Pradofloxacin showed no effects in respect to rod b-wave, V (max), k and maximum scotopic a-wave (P > 0.05). Oscillatory potentials, cone ERG and flicker were also unaltered (P > 0.05). Rod b-wave was undetectable after treatment in ENRO30 group, V (max) was reduced to 10.5% of the baseline (P < 0.05), accompanied by an increase of k by 1 log cd s/m(2) (P < 0.05). Oscillatory potentials, cone b-wave amplitude and 30 Hz flicker amplitude were reduced to 8.3%, 58.9% and 37.4% of the baseline, respectively (P < 0.05). Effects were also seen in OCT and retinal histology starting within one week after the start of treatment and thereafter remaining stable.

CONCLUSION

Pradofloxacin at 6 and 10 times the recommended doses was shown to have no retinal toxic effects in cats, neither on rod or cone function with ERG.

Antibiotics concentrations in a patient with postoperative endophthalmitis

We report a case of endophthalmitis who underwent a vitreous biopsy to assess sensitivity and to inject broad-spectrum intraocular antibiotics. Minimal inhibitory concentration (MIC) values of antibiotics against a coagulase-negative staphylococcus and Proprionibacterium acnes were also assessed.

Effect of H-7 and Lat-B on retinal physiology

PURPOSE

To investigate the effects of H-7 and Latrunculin B (Lat-B) on retinal vascular permeability and electrophysiology at concentrations that increase outflow facility in monkeys.

METHODS

One eye of 1 rhesus and 22 cynomolgus monkeys received an intravitreal bolus injection of H-7 or Lat-B; the opposite eye received vehicle. Multifocal electroretinograms (mfERGs), and photopic and scotopic full-field electroretinograms (ffERGs, sERGs) were recorded in subsets of monkeys at baseline and at multiple time-points post-H-7 or Lat-B. Vitreous fluorophotometry (VF) and fluorescein angiography (FA) were also performed.

RESULTS

No differences between the H-7 or Lat-B treated and control eyes were found in ffERGs, mfERGs, sERGs, or in FAs in any monkey. No significant difference was found in vitreous fluorescein levels between H-7 treated or Lat-B treated vs. control eyes.

CONCLUSIONS

No effect on retinal vascular permeability or retinal electrophysiology was apparent after intravitreal administration of H-7 or Lat-B at doses that increase outflow facility and lower IOP when given intracamerally.

Prevention of Staphylococcus aureus Endophthalmitis with Topical Gatifloxacin in a Rabbit Prophylaxis Model

PURPOSE

The aim of this study was to investigate the prophylactic use of 0.3% gatifloxacin drops to prevent endophthalmitis in a rabbit model.

METHODS

Forty (40) New Zealand white rabbits were randomly placed into group A (20 rabbits) where they received 1 drop of 0.3% gatifloxacin in their right eye every 15 min (0, 15, 30, and 45 min), or group B (20 rabbits) where they received 1 drop of balanced salt solution (BSS) in their right eye every 15 min (0, 15, 30, and 45 min). Following this treatment regimen, the anterior chamber of each rabbit was injected with 0.025 mL of saline containing 5 x 10(5) colonyforming units of a clinical isolate of Staphylococcus aureus (vancomycin-sensitive). After the inoculum injection, the treatment regimen continued: group A (1 drop of 0.3% gatifloxacin) or group B (1 drop of BSS) immediately postinjection, 6, 12, 18, and 24 h, at which time the animals were examined in a masked fashion, photographed, anesthetized, euthanized, and the aqueous and vitreous humors collected to determine the number of viable bacteria.

RESULTS

The median clinical scores for the gatifloxacin group were significantly lower than the control group (P < 0.05). Bacterial recovery of S. aureus was significantly higher in the control group in both the aqueous and vitreous humor (P < 0.05).

CONCLUSIONS

Gatifloxacin-treated eyes demonstrated significantly less inflammation, infection, and culture-positive endophthalmitis (P < 0.05), compared to the control animals. It is important to further investigate the clinical implications from this prophylatic study.

Intravitreal Toxicity of Levofloxacin and Gatifloxacin

BACKGROUND AND OBJECTIVE

To assess the retinal toxicity of varying concentrations of intravitreally injected gatifloxacin and levofloxacin.

MATERIALS AND METHODS

In this experimental, controlled study, levofloxacin (initial concentration = 25 mg/mL) and gatifloxacin (initial concentration = 2 mg/mL) were titrated using 5% dextrose solution to concentrations of 2,500 to 156 microg/0.1 mL and 400 to 50 microg/0.1 mL, respectively. Each concentration was injected intravitreally into two rabbit eyes (one eye per animal); two control eyes were injected with 0.1 mL of 5% dextrose solution. All animals were examined and electroretinography was performed before and 14 days after injection. The animals were killed at 14 days; the eyes were enucleated and prepared for light microscopy.

RESULTS

The levofloxacin group exhibited significant decreases in electroretinography in the eyes injected with 1,250 and 2,500 microg. No signs of retinal toxicity were observed on slit-lamp examination, indirect ophthalmoscopy, or light microscopy in all eyes injected intravitreally with 625 microg or less of levofloxacin or in any eyes given gatifloxacin.

CONCLUSION

Intravitreally injected concentrations of 625 microg or less of levofloxacin and 400 microg or less of gatifloxacin appeared nontoxic.