Determination of Nontoxic Concentrations of Piperacillin/Tazobactam for Intravitreal Application

ALTERNATIVE INTRAVITREAL ANTIBIOTICS: A Systematic Review for Consideration in Recalcitrant or Resistant Endophthalmitis

PURPOSE

To organize, categorize, and create a quick reference guide for the use of intravitreal antibiotic alternatives to the standard combination of vancomycin and ceftazidime for the treatment of endophthalmitis.

METHODS

A systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines. The authors searched for all available information regarding intravitreal antibiotics in the last 21 years. Manuscripts were selected according to relevance, level of information, and the available data regarding intravitreal dose, potential adverse effects, bacterial coverage, and relevant pharmacokinetic information.

RESULTS

The authors included 164 of 1810 manuscripts. The antibiotics were classified according to their class into fluoroquinolones, cephalosporins, glycopeptide and lipopeptide, penicillins and beta-lactams, tetracyclines, and miscellaneous. The authors also included information regarding intravitreal adjuvants for the treatment of endophthalmitis and one ocular antiseptic.

CONCLUSION

The treatment of infectious endophthalmitis is a therapeutic challenge. The current review summarizes the properties of possible intravitreal antibiotic alternatives that should be considered in cases of suboptimal response to initial treatment.

Intravitreal piperacillin-tazobactam in endophthalmitis caused by Mycobacterium abscessus in silico ne-filled eye: A case report

A 28-year-old female came to us one month after retinal detachment surgery with a sudden painless drop in vision. The condition gradually worsened with ongoing treatment so she was taken up for lensectomy with silicone oil removal and intravitreal antibiotics and steroids. The microbiological analysis of silicone oil revealed Mycobacterium complex and gene sequencing isolated Mycobacterium abscessus, which showed antibiotic sensitivity to only piperacillin-tazobactam. Repeated intravitreal injections of the same led to the resolution of infection. This case report highlights the impact of sparsely used piperacillin-tazobactam in cases of Mycobacterium positive endophthalmitis, and the role of gene sequencing.

Ocular Permeation of Topical Tazocin and Its Effectiveness in the Treatment of Pseudomonas aeruginosa Induced Keratitis in Rabbits

PURPOSE

Pseudomonas aeruginosa is the most common causative organism for contact lens-associated corneal ulcer and is commonly treated with fluoroquinolones. With the emergence of resistant strains, it is important to investigate alternative therapies. Despite well-established efficacy of tazocin against systemic Pseudomonas infections, its topical use for the treatment of Pseudomonas keratitis has not been described, hence this study was aimed to find the ocular permeation of Tazocin and its efficacy in treating keratitis in rabbit eyes.

METHODS

We investigated the ocular permeation of topical tazocin after single drop application in normal rabbit eyes by estimating piperacillin and tazobactam concentrations in cornea, aqueous, and vitreous using a validated LC-MS/MS method. Furthermore, we determined the efficacy of repeated dose administration of tazocin against experimentally induced P. aeruginosa keratitis in rabbits in comparison to moxifloxacin. To determine the efficacy, clinical examination, histopathological examination, and estimation of bacterial load and inflammatory cytokines in cornea were done.

RESULTS

Significant corneal concentration of piperacillin and tazobactam was detected in normal rabbit corneas after single dose treatment with tazocin. In rabbits with Pseudomonas-induced keratitis, topical tazocin caused significant clinical and histopathological improvement. This improvement was associated with reduction in corneal bacterial load and inflammatory cytokines. Compared to moxifloxacin 0.5%, tazocin treated group showed greater clinical response which was associated with higher interleukin (IL)-1β, lower tumor necrosis factor (TNF)-α, a comparable level of IL-8, greater reduction in corneal bacterial load, and lesser inflammatory cell infiltration.

CONCLUSION

Tazocin showed good ocular penetration and was effective in treatment of Pseudomonas induced keratitis in rabbits.

Pharmacokinetics of intravitreal antibiotics in endophthalmitis

Intravitreal antibiotics are the mainstay of treatment in the management of infectious endophthalmitis. Basic knowledge of the commonly used intravitreal antibiotics, which includes their pharmacokinetics, half-life, duration of action and clearance, is essential for elimination of intraocular infection without any iatrogenic adverse effect to the ocular tissue. Various drugs have been studied over the past century to achieve this goal. We performed a comprehensive review of the antibiotics which have been used for intravitreal route and the pharmacokinetic factors influencing the drug delivery and safety profile of these antibiotics. Using online resources like PubMed and Google Scholar, articles were reviewed. The articles were confined to the English language only. We present a broad overview of pharmacokinetic concepts fundamental for use of intravitreal antibiotics in endophthalmitis along with a tabulated compendium of the intravitreal antibiotics using available literature. Recent advances for increasing bioavailability of antibiotics to the posterior segment with the development of controlled drug delivery devices are also described.

Intravitreal injection of therapeutic agents

BACKGROUND

Intravitreal injection (IVI) with administration of various pharmacological agents is a mainstay of treatment in ophthalmology for endopthalmitis, viral retinitis, age-related macular degeneration, cystoid macular edema, diabetic retinopathy, uveitis, vascular occlusions, and retinal detachment. The indications and therapeutic agents are reviewed in this study.

METHODS

A search of the English, German, and Spanish language MEDLINE database was conducted. A total of 654 references spanning the period through early 2008 were individually evaluated.

RESULTS

The advantage of the IVI technique is the ability to maximize intraocular levels of medications and to avoid the toxicities associated with systemic treatment. Intravitreal injection has been used to deliver several types of pharmacological agents into the vitreous cavity: antiinfective and antiinflammatory medications, immunomodulators, anticancer agents, gas, antivascular endothelial growth factor, and several others. The goal of this review is to provide a detailed description of the properties of numerous therapeutic agents that can be delivered through IVI, potential complications of the technique, and recommendations to avoid side effects.

CONCLUSION

The IVI technique is a valuable tool that can be tailored to the disease process of interest based on the pharmacological agent selected. This review provides the reader with a comprehensive summary of the IVI technique and its multitude of uses.

Chronic, Postoperative Pseudomonas luteola Endophthalmitis

An interventional case report is described of a patient with chronic postoperative endophthalmitis caused by the gram-negative aerobic rod Pseudomonas luteola. A 61-year-old developed slowly progressive blurring of vision, hypopyon, and vitritis following cataract surgery. Diagnostic vitrectomy and intraocular lens explantation were performed. The undiluted vitreous samples and explanted lens were analyzed. Aerobic cultures revealed moderate growth of P. luteola. The patient responded to intravitreal injections of piperacillin/tazobactam and oral trimethoprim/sulfamethoxasole. Best-corrected visual acuity improved from hand motions to 20/40. A repeat anterior chamber tap was negative. P. luteola may be a relatively nonvirulent cause of chronic endophthalmitis. Good visual outcomes may be obtained with appropriate therapy.

The Efficacy of Intravitreal Piperacillin/Tazobactam in Rabbits with Experimental Staphylococcus epidermidis Endophthalmitis: A Comparison with Vancomycin

BACKGROUND

To investigate the efficacy of intravitreal piperacillin/tazobactam in rabbit eyes with experimental S. epidermidis endophthalmitis and to compare the outcomes with intravitreal vancomycin application.

MATERIAL AND METHODS

Twenty-four New Zealand white albino rabbits were divided into three equal groups (n=8 in each), and the right eyes received 0.1-ml intravitreal injections of S. epidermidis suspension. The left eyes served as uninfected controls and were injected with 0.1 ml of saline solution. The right eyes of rabbits in group 1 were treated with intravitreal injection of 250 microg/0.1 ml piperacillin/tazobactam 24 h after intravitreal inoculation of S. epidermidis whereas group 2 eyes received intravitreal 1 mg/0.1 ml vancomycin. Group 3 eyes received no treatment and served as infected controls. Clinical examination of the eyes in each group was performed on the 1st, 3rd and 6th day after the inoculation of S. epidermidis. On the 6th day, 0.1-ml vitreous aspirates were obtained for microbiological analysis, and then the eyes were enucleated for histopathological evaluation.

RESULTS

There were no statistically significant differences in mean clinical scores between the groups on the first day after S. epidermidis inoculation (p>0.05). On the 6th day, the mean clinical score of group 3 was significantly higher (p<0.001), but the mean clinical scores of groups 1 and 2 were similar (p=0.812). The mean logarithmic value of colony-forming units per milliliter of groups 1, 2 and 3 were 0.6+/-1.3, 0.5+/-1.5 and 5.3+/-0.7, respectively. Mean histopathological scores of the groups were 8.3+/-0.9, 7.5+/-1.3 and 15.6+/-1.2, respectively. Group 3 eyes had significantly more colony-forming units per milliliter and a higher histopathological score (for each, p<0.001), and there were no statistically significant differences in microbiological and histopathological scores between groups 1 and 2 (for each, p>0.05).

CONCLUSION

Intravitreal application of 250 microg/0.1 ml piperacillin/tazobactam seems to be approximately equally effective with intravitreal 1 mg/0.1 vancomycin application in the treatment of experimental S. epidermidis endophthalmitis. Therefore, intravitreal piperacillin/tazobactam may be an alternative therapeutic option in the treatment of S. epidermidis endophthalmitis.

A comparison of intravitreal piperacillin/tazobactam with ceftazidime in experimental Pseudomonas aeruginosa endophthalmitis

In the present study, we aimed at comparing the efficacies of intravitreal piperacillin/tazobactam and ceftazidime applications in the treatment of experimental Pseudomonasaeruginosa endophthalmitis in rabbit eyes. Twenty-four New Zealand white albino rabbits were divided into three groups (n=8 in each), and the right eyes received 0.1 ml intravitreal injections of P. aeruginosa suspension. The left eyes served as uninfected control and were injected with 0.1 ml of saline solution. The right eyes of rabbits in group 1 were treated with intravitreal injection of 250 microg/0.1 ml piperacillin/tazobactam 24 hr after intravitreal inoculation of P. aeruginosa, whereas group 2 eyes received intravitreal 1 mg/0.1 ml ceftazidime. Group 3 eyes received no treatment and served as infected controls. Clinical, microbiological and histopathological evaluations of the eyes in each group were performed on the 1st, 3rd, and 6th day after the inoculation of P. aeruginosa. The mean clinical scores of each group were similar at the first day after P. aeruginosa inoculation (P>0.05). At the 6th day, there was no statistically significant difference in mean clinical scores between group 1 and 2, but mean clinical score of group 3 was significantly higher (P<0.001). Microbiological analysis and histopathological scoring demonstrated no statistically significant difference between group 1 and 2 (for each, P>0.05). Group 3 eyes had a significantly more CFU/ml and higher histopathological score (for each, P<0.001). In conclusion, intravitreal application of 250 microg/0.1 ml piperacillin/tazobactam seems to be effective in the treatment of P. aeruginosa endophthalmitis in rabbits, but is not superior to intravitreal ceftazidime application. Therefore, intravitreal piperacillin/tazobactam may be a useful alternative to ceftazidime for pseudomonal endophthalmitis.

Excessive maternal caffeine exposure during pregnancy is cataractogenic for neonatal crystalline lenses in rats: a biomicroscopic and histopathologic study

PURPOSE

To investigate histologically the influence of maternal caffeine exposure during pregnancy in vivo on crystalline lenses in neonatal rats.

METHODS

Experimentally naive, female Wistar-albino rats (200-220 g) were mated with adult male rats over 2 days for copulation. After confirming pregnancy with a vaginal smear method, 50 gravid rats (dams) were randomly divided into five groups (n = 10 in each), consisting of one control and four experimental groups. Groups 1, 2 and 3 experimental dams were treated with intraperitoneal (i.p.) caffeine at doses of 25, 50 and 100 mg/kg/day, respectively, during pregnancy from gestational day 9 through to day 21. Group 4 dams were treated with caffeine in distilled water in a gavage at a dose of 50 mg/kg/day. Group 5 control dams were given i.p. saline solution daily for the same period. After normal delivery, the eyes were examined by slit-lamp biomicroscopy. The neonates were then killed by decapitation at postnatal days 1 or 30 and the eyes removed for histopathologic investigation of the lenses.

RESULTS

Group 1 and control eyes had normal anterior lens capsules with a single layer of anterior cuboidal epithelial cells, regularly oriented cortical and nuclear lens fibres, and a clear posterior lens capsule with no lining epithelial cells behind the equator. In the remaining groups, histopathologic findings suggesting cataractogenesis included eosinophilic degeneration, lens fibre cell swelling and liquefaction, central lens fibres with retained nuclei, and prominent epithelial cells lining the posterior lens capsule behind the equator. Moreover, some lenses in group 3 had immature cataract on slit-lamp biomicroscopic examination at postnatal day 30.

CONCLUSION

Excessive maternal caffeine exposure during pregnancy had cataractogenic effects on developing crystalline lenses in newborn rat eyes, both macroscopically and histopathologically. If an appropriate dose of caffeine can be identified, caffeine-induced cataract formation may be used as a new experimental cataract model in animal studies.

Deep Sclerectomy with Various Implants: An Experimental and Histopathologic Study in a Rabbit Model

BACKGROUND AND OBJECTIVE

To investigate the effectiveness of various implants used in experimental deep sclerectomy and to report tissue reactions developed to these implants histopathologically.

MATERIALS AND METHODS

Forty eyes of 40 New Zealand white albino rabbits underwent deep sclerectomy with various implants. The rabbits were divided into four groups; each consisted of 10 eyes. Deep sclerectomy was performed using copolymer materials in group 1, silicone materials in group 2 and chromic catgut suture in group 3. No implants were used in the control group (group 4). Clinical and histopathological examinations were performed to investigate the effectiveness of implants.

RESULTS

Mean preoperative intraocular pressure (IOP) was 14.4 +/- 1.6 mm Hg in group 1, 14.5 +/- 1.8 mm Hg in group 2, 13.8 +/- 1.5 mm Hg in group 3 and 14.5 +/- 1.2 mm Hg in group 4. The final postoperative IOPs were 10.7 +/- 0.9, 10.6 +/- 0.8, 13.5 +/- 1.0, and 14.5 +/- 1.4 mm Hg, respectively. At 2 months, the decrease in IOPs from baseline and the persistence of the filtering bleb were significantly marked in group 1 and group 2 (p < 0.001). Histopathological evaluation revealed that copolymer and silicone materials formed a smooth and regular intrascleral space. There were no foreign body reaction, tissue destruction or fibrosis in group 1 and group 2, but chromic catgut sutures caused severe fibrosis and inflammatory reaction in group 3. Mean histopathologic score of group 1, group 2, group 3 and group 4 was 0.7 +/- 0.5, 0.8 +/- 0.5, 2.4 +/- 0.6, and 0.1 +/- 0.3, respectively.

CONCLUSION

Copolymer or silicone materials may increase the success rate of surgery by maintenance of a large and regular intrascleral space after deep sclerectomy and prevention of collapse of the flap.