Pharmacokinetics of intravenously administered moxifloxacin in eye compartments: an experimental study

Intraocular penetration of systemic antibiotics in eyes with penetrating ocular injury

PURPOSE

To determine whether penetrating scleral or corneal injury can enhance intraocular penetration of systemic moxifloxacin, vancomycin, and ceftazidime.

METHODS

Thirty rabbits were divided into 3 groups for each antibiotic and then further subdivided to receive either scleral or corneal injury to the right eye. The left eye served as a control. Intravenous antibiotics were given following injury, and eyes were subsequently enucleated. Vitreous antibiotic concentration was determined by high-performance liquid chromatography analysis. Plasma concentration was measured for comparison.

RESULTS

Intravitreal moxifloxacin concentration was unchanged by injury. Minimum inhibitory concentration (MIC90) was achieved in the vitreous against the most common gram-positive endophthalmitis-causing organisms. Intravitreal vancomycin levels were not enhanced by injury and did not reach the MIC90 for gram-positive organisms commonly causing intraocular infection. Intravitreal ceftazidime was increased in the injured eyes, 67% and 73% higher in scleral and corneal injury eyes. It reached MIC90 of many gram-negative bacteria.

CONCLUSIONS

Intravitreal antibiotic penetration of systemic antibiotics with or without penetrating ocular injury varies depending on the antibiotic. For prevention or treatment of gram-positive-bacteria-causing endophthalmitis, intravitreal vancomycin is necessary and provides the most reliable coverage. Systemic ceftazidime can be used for many gram-negative bacteria, but intravitreal injection is recommended for better coverage, especially for more-potent organisms. Systemic moxifloxacin can be considered for most gram-positive and -negative infections due to its excellent intraocular penetration and broad coverage, but the patient's previous history of its topical use and increasing resistance patterns must be considered.

Assessment of vitreous drug concentration in the porcine eye following intracameral injection or irrigation with moxifloxacin

Introduction

Posterior capsule rupture causes instant vitreous contamination, resulting in endophthalmitis. However, transfer of intracameral moxifloxacin (MFLX) to the vitreous has not been examined in detail. We investigated vitreous antibiotic concentrations following intracameral MFLX in both ruptured and intact posterior capsular eyes.

Methods

Experiment 1: Intraocular lenses were inserted into 21 extracted porcine eyes by one of the following three methods: (1) Irrigation: Throughout surgery, 33-fold diluted MFLX irrigation solution (150 μg/mL) was used; (2) Bag and chamber flushing: After surgery, the anterior chamber and area behind the intraocular lenses were irrigated with 30-fold diluted MFLX (167 μg/mL) using a 5 mL syringe; (3) Simple injection: Tenfold diluted MFLX (50 μg in 0.1 mL) was injected intracamerally at the conclusion of surgery. The eyeballs were frozen and the anterior, central, and posterior portions of the vitreous were cubed. After defrosting, concentrations were measured using high-performance liquid chromatography. Experiment 2: The same procedure was conducted for 18 eyes in which the posterior capsule had been ruptured.

Results

Experiment 1: Transfer of intracameral MFLX to the anterior vitreous was approximately 1% (1.56–2.20 μg/mL) regardless of the administration method. Experiment 2: MFLX reached a high concentration in the vitreous with irrigation solution administration (maximum 30.22 μg/mL). The concentrations reached by simple injection or flushing were significantly less than those obtained by irrigation.

Conclusion

With an intact posterior capsule, intracameral MFLX exhibited limited effects on vitreous concentration. Despite the fact that the risk of infection clearly increases in cases of ruptured capsule, no special infection prevention protocol has been proposed. It was confirmed that irrigation solution caused vitreous contamination in ruptured eyes within only a short irrigation time. In this case, intracameral administration did not necessarily achieve preventive concentrations for endophthalmitis, but it appears that an effective drug concentration can be achieved in the vitreous by the administration of irrigation solution.

Endophthalmitis caused by Stenotrophomonas maltophilia

BACKGROUND AND OBJECTIVE

The authors investigate clinical settings, antibiotic susceptibility and resistance patterns, and visual outcomes associated with endophthalmitis caused by Stenotrophomonas maltophilia.

PATIENTS AND METHODS

Records of six patients with S. maltophilia endophthalmitis between January 1, 1998, and December 31, 2007, were reviewed.

RESULTS

Clinical settings included post-trauma (2 eyes), post-cataract extraction (2 eyes), post-keratoplasty with keratitis (1 eye), and post-vitreous lavage (1 eye). Presenting visual acuity ranged from counting fingers to no light perception. Final visual acuity ranged from 10/20 to no light perception. Initial treatment included pars plana vitrectomy in 4 eyes and tap in 2 eyes. Most isolates were susceptible to fluoroquinolones (ciprofloxacin, levofloxacin, or moxifloxacin) and sulfamethoxazole-trimethoprim; however, they were resistant to ceftazidime and aminoglycosides.

CONCLUSION

S. maltophilia is an uncommon causative agent of endophthalmitis and is resistant to commonly used antibiotics, such as ceftazidime and aminoglycosides. Based on in vitro antibiotic susceptibility testing, sulfamethoxazole-trimethoprim and new-generation fluoroquinolones may be preferable in the treatment of endophthalmitis caused by S. maltophilia.

Impact of antibiotic resistance in the management of ocular infections: the role of current and future antibiotics

Purpose:

This article reviews the effects of the increase in bacterial resistance on the treatment of ocular infections.

Design:

Interpretive assessment.

Methods:

Literature review and interpretation.

Results:

Ocular bacterial infections include conjunctivitis, keratitis, endophthalmitis, blepharitis, orbital cellulitis, and dacryocystitis. Treatment for most ocular bacterial infections is primarily empiric with broad-spectrum antibiotics, which are effective against the most common bacteria associated with these ocular infections. However, the widespread use of broad-spectrum systemic antibiotics has resulted in a global increase in resistance among both Gram-positive and Gram-negative bacteria to a number of the older antibiotics as well as some of the newer fluoroquinolones used to treat ophthalmic infections. Strategies for the prevention of the increase in ocular pathogen resistance should be developed and implemented. In addition, new antimicrobial agents with optimized pharmacokinetic and pharmacodynamic properties that have low toxicity, high efficacy, and reduced potential for the development of resistance are needed.

Conclusions:

New antimicrobial agents that treat ocular infections effectively and have a low potential for the development of resistance could be a part of strategies to prevent the global increase in ocular pathogen resistance.