Pharmacokinetics of ciprofloxacin in the human eye: a clinical study and population pharmacokinetic analysis

Tularemia treatment: experimental and clinical data

Tularemia is a zoonosis caused by the Gram negative, facultative intracellular bacterium Francisella tularensis. This disease has multiple clinical presentations according to the route of infection, the virulence of the infecting bacterial strain, and the underlying medical condition of infected persons. Systemic infections (e.g., pneumonic and typhoidal form) and complications are rare but may be life threatening. Most people suffer from local infection (e.g., skin ulcer, conjunctivitis, or pharyngitis) with regional lymphadenopathy, which evolve to suppuration in about 30% of patients and a chronic course of infection. Current treatment recommendations have been established to manage acute infections in the context of a biological threat and do not consider the great variability of clinical situations. This review summarizes literature data on antibiotic efficacy against F. tularensis in vitro, in animal models, and in humans. Empirical treatment with beta-lactams, most macrolides, or anti-tuberculosis agents is usually ineffective. The aminoglycosides gentamicin and streptomycin remain the gold standard for severe infections, and the fluoroquinolones and doxycycline for infections of mild severity, although current data indicate the former are usually more effective. However, the antibiotic treatments reported in the literature are highly variable in their composition and duration depending on the clinical manifestations, the age and health status of the patient, the presence of complications, and the evolution of the disease. Many patients received several antibiotics in combination or successively. Whatever the antibiotic treatment administered, variable but high rates of treatment failures and relapses are still observed, especially in patients treated more then 2-3 weeks after disease onset. In these patients, surgical treatment is often necessary for cure, including drainage or removal of suppurative lymph nodes or other infectious foci. It is currently difficult to establish therapeutic recommendations, particularly due to lack of comparative randomized studies. However, we have attempted to summarize current knowledge through proposals for improving tularemia treatment which will have to be discussed by a group of experts. A major factor in improving the prognosis of patients with tularemia is the early administration of appropriate treatment, which requires better medical knowledge and diagnostic strategy of this disease.

Ocular pharmacokinetics and toxicity of nanoparticular acetazolamide: In vivo distribution and safety of PHBV-ACZ nanoparticle

Diabetic macular edema (DME) is defined as fluid accumulation in the macular region, between the retinal layers, due to many diseases, especially diabetes. DME is one of the major complications of diabetic retinopathy (DRP). Carbonic anhydrase inhibitors (CAI) are a pharmaceutical agent used in different fields, especially glaucoma treatment. Acetazolamide (ACZ), which is a CAI, is an active substance that has been used off-label for many years in the treatment of macular edema due to diabetes and many other diseases. The low solubility and bioavailability of ACZ limit its use in the treatment of DME. In this study, a nanoparticulate formulation was developed that would increase the solubility and bioavailability of ACZ and allow it to be administered intravitreally. ACZ was loaded on poly(3-hydroxybutyrate-co-3-Hydroxyvalerate) (PHBV) nanoparticles and the loading efficiency was 71.58 ± 1.22%. Toxicity of nanoparticles after intravitreal application was evaluated with anterior segment and posterior segment examination findings, intraocular pressure (IOP) measurements and electrophysiological tests. At the end of the 3-month follow-up, electroretinography (ERG) measurements demonstrated that ACZ loaded PHBV (PHBV-ACZ) nanoparticles did not cause loss of function in retinal cells. On histological examination, rare degenerative changes were observed in several cell groups. In addition, pharmacokinetic studies were performed to determine the tissue distribution of ACZ at various periods. ACZ was identified in vitreous humor and retina at the highest concentration. Based on our results, the prepared nanoparticle formulation can release long-term CAI for DRP therapy and accordingly can reduce the need for monthly intravitreal injections.

A Literature-Based Review and Analysis of the Pharmacodynamics of the Dose Frequency of Topical 0.3% Ciprofloxacin and 0.3% Ofloxacin in the Day-1 Treatment of Bacterial Keratitis

Purpose: To determine the appropriate dose frequency for the second-generation fluoroquinolones (2FQs), ciprofloxacin 0.3% and ofloxacin 0.3%, in the day-1 treatment of bacterial keratitis (BK) based on the corneal concentrations achievable and required Minimum Inhibitory Concentration₉₀ (MIC₉₀) of common BK isolates. Methods: Literature-based ocular MIC₉₀ required to treat bacterial isolates of BK patients were determined for each fluoroquinolone. Published corneal concentrations for each 2FQ, and the drop regimens used to reach these concentrations, were then analyzed to determine the relationship between the corneal 2FQ concentration and the amount of drug applied per hour and the total amount applied. Results: Significant relationships were found to exist for corneal concentrations of both ciprofloxacin and ofloxacin and the amount of drug applied per hour (both P = 0.005), and the total amount of drug applied (P = 0.003 and P = 0.0004, respectively). Derived ciprofloxacin drops/hour corneal concentrations agreed well with both a literature-based regimen and the manufacturers' day-1 drop regimen for various MIC₉₀. Derived ofloxacin drops per hour indicated a higher rate than that suggested by the manufacturer. Conclusions: Both a literature-based and the manufacturers' drop regimens for the day-1 treatment of BK using 0.3% ciprofloxacin have a pharmacodynamic basis, which is related to the required MIC₉₀ of commonly encountered isolates in BK. Dose frequency for 0.3% ofloxacin should be in line with the manufacturers' maximum suggested drop regimen. Commonly suggested drop regimens below these recommendations for either FQ may need to be revised in view of these findings.

Paediatric endophthalmitis: a UK retrospective study

INTRODUCTION

Paediatric endophthalmitis is a severe but rare complication of intraocular surgery, penetrating trauma and far less commonly extra-ocular surgery or endogenous origin. We set out to establish the incidence and risk factors of exogenous endophthalmitis in children, and to develop an evidence-based protocol that can be used for treatment of suspected exogenous endophthalmitis in children.

METHODS

Microbiology reports and operation numbers were obtained from two large tertiary referral hospitals sharing 24-h paediatric ophthalmology cover for the period January 2009-December 2016. All cases of aqueous and/or vitreous tap performed on children aged ≤18 years were identified and case notes reviewed for complete information on each case.

RESULTS

Sixteen cases were eligible for inclusion as 'postoperative endophthalmitis': complete data was found on 13 cases. The incidence of postoperative endophthalmitis was 0.17% over 7 years. The mean age of presentation was 5.5 years (range from 7 months to 16 years and 9 months), from 3 days-78 months post operatively. In all, 11/13 had at least one glaucoma procedure. Microbiology results showed growth in 8/13. Most isolates were Gram-positive bacteria but Gram-negatives were also isolated and in one case Candida from a conjunctival swab. The antibiotic regime varied depending on age, organism identified and sensitivities. In all, 9/13 had hand movement or worse vision after treatment.

CONCLUSION

Paediatric endophthalmitis may present to any paediatric/general ophthalmologist. It is a rare but devastating condition with poor visual prognosis, requiring prompt recognition and aggressive management. Previous glaucoma surgery is a long-term risk factor in our local paediatric population. Based on our study, an evidence-based protocol for management is proposed in order to improve outcomes.

Revisiting systemic treatment of bacterial endophthalmitis: a review of intravitreal penetration of systemic antibiotics

BACKGROUND

Adjunctive systemic antibiotic therapy for treatment of bacterial endophthalmitis is controversial but common practice due to the severity of the disease. In the absence of guidance documents, several antibiotic regimens are being used without applying evidence-based prescribing, leading to inappropriate treatment of this serious eye condition.

OBJECTIVES

To summarize available data on intravitreal penetration of systemically administered antibiotics and to discuss their usefulness from a microbiological and pharmacological point of view.

SOURCES

We performed a systematic PubMed search of studies investigating antibiotic concentrations in the vitreous after systemic administration in humans, and selected animal models.

CONTENT

The best-documented agents achieving therapeutic levels in the vitreous are meropenem, linezolid and moxifloxacin. Vancomycin, cefazoline, ceftriaxone, ceftazidime, imipenem and trimethoprim-sulfamethoxazole reach levels justifying their use in specific situations. Available data do not support the use of ciprofloxacin, levofloxacin, aminoglycosides, aminopenicillins, piperacillin, cefepime and clarithromycin. With very limited but available promising data, the use of daptomycin and rifampicin deserves further investigation.

IMPLICATIONS

The choice of the adjunctive systemic antibiotic agent-in situations where it is considered relevant for treatment-must to date be made on an individual basis, considering microbiological aspects as well as operative status and inflammation of the eye. This review gives a systematic overview of antibiotic options and provides guidance to the clinician striving for optimal systemic antibiotic treatment of bacterial endophthalmitis.

The risk profile of rhegmatogenous retinal detachment before and after using a fluoroquinolone: a 12 year nationwide self-controlled case series study

Objectives

To determine whether or not fluoroquinolone use increases the incidence of retinal detachment.

Design

Self-controlled case series analysis.

Participants

Participants were identified using the South Korean National Health Insurance Database between 1 January 2004 and 31 December 2015. A total of 15 134 patients who experienced rhegmatogenous retinal detachment (RRD) with at least one prescription of a fluoroquinolone were included.

Methods

Incidence rate ratios (IRRs) and their 95% CIs were calculated using conditional Poisson regression. The main outcome measure was a recorded diagnosis of RRD (ICD-10: H33.0) with a claim for the surgical code for RRD.

Results

We found an increased risk of retinal detachment in the first 1-30 days following the initiation of fluoroquinolone therapy (IRR 1.85; 95% CI 1.71-1.95), which rose for the 31-60 days period (IRR 2.05; 95% CI 1.43-2.95) but remained constant after more than 60 days (IRR 1.25; 95% CI 0.75-2.10). However, the elevated risk was also found in the 1-30 day period prior to the initiation of fluoroquinolone therapy (IRR 1.58; 95% CI 1.49-1.68) and also 31-60 days before medication use (IRR 1.11; 95% CI 1.03-1.19).

Conclusions

Our case-based study indicated that the risk after fluoroquinolone exposure doubled; however, the risk profile before and after fluoroquinolone use means that the association between fluoroquinolone use and retinal detachment might not be a causal relationship.

Signal Detection Between Fluoroquinolone Use and the Risk of Rhegmatogenous Retinal Detachment: Sequence Symmetry Analysis Using Nationwide South Korean Healthcare Database Between 2004 and 2015

BACKGROUND AND OBJECTIVES

The association between fluoroquinolone and rhegmatogenous retinal detachment (RRD) has been controversial as a result of inconsistent findings. We set out to detect a possible association of fluoroquinolone use and risk of RRD, using sequence symmetry analysis (SSA).

METHODS

We conducted an SSA, case-only design, using a Korean nationwide healthcare database between 2004 and 2015. Exposure was defined as new fluoroquinolone use and outcome as an incident RRD, defined by a diagnosis of RRD (ICD-10: "H33.0") or surgery for RRD. Pairs of exposure and RRD within a 1-year time-window were included. The sequence ratio (SR) was calculated by the ratio of the number of patients prescribed with exposure first and diagnosed with RRD second divided by the number of patients diagnosed with RRD first and prescribed with exposure second. SR was adjusted (aSR) for underlying trends and 95% confidence intervals (CIs) were calculated. In order to observe whether the estimated ratio stabilized over time, we did repeated time-sequential analyses with the cumulative data starting from the 3-year period 2004-2006 to 2015.

RESULTS

Fluoroquinolone use had a greater association with RRD as compared with other antibiotics [fluoroquinolone: 5234 pairs; aSR = 1.70 (95% CI 1.61-1.80), first-generation cephalosporin: 4139 pairs; aSR = 1.39 (95% CI 1.31-1.80), second-generation cephalosporin: 5914 pairs; aSR = 1.31 (95% CI 1.24-1.38), third-generation cephalosporin: 3650 pairs; aSR = 0.88 (95% CI 0.83-0.95), extended-spectrum penicillin: 4823 pairs; aSR = 1.29 (95% CI 1.31-1.47), macrolides: 4115 pairs; aSR = 1.31 (95% CI 1.24-1.39)]. Time-sequential analyses supported the association between fluoroquinolone and RRD.

CONCLUSIONS

Our detection suggests a possible association between fluoroquinolone use and RRD. However, possible overestimation and reverse causality bias may have influenced our findings due to the limitation of an SSA design.

Effects of contaminants of emerging concern on Megaselia scalaris (Lowe, Diptera: Phoridae) and its microbial community

Drought, rising temperatures, and expanding human populations are increasing water demands. Many countries are extending potable water supplies by irrigating crops with wastewater. Unfortunately, wastewater contains biologically active, long-lived pharmaceuticals, even after treatment. Run-off from farms and wastewater treatment plant overflows contribute high concentrations of pharmaceuticals to the environment. This study assessed the effects of common pharmaceuticals on a cosmopolitan saprophagous insect, Megaselia scalaris (Diptera: Phoridae). Larvae were reared on artificial diets spiked with contaminants of emerging concern (CECs) at environmentally relevant concentrations. Female flies showed no oviposition preference for treated or untreated diets. Larvae exposed to caffeine in diets showed increased mortality, and larvae fed antibiotics and hormones showed signs of slowed development, especially in females. The normal sex ratio observed in M. scalaris from control diets was affected by exposure to caffeine and pharmaceutical mixture treatments. There was an overall effect of treatment on the flies’ microbial communities; notably, caffeine fed insects displayed higher microbial variability. Eight bacterial families accounted for approximately 95% of the total microbes in diet and insects. Our results suggest that CECs at environmentally relevant concentrations can affect the biology and microbial communities of an insect of ecological and medical importance.

Ocular disposition of ciprofloxacin from topical, PEGylated nanostructured lipid carriers: Effect of molecular weight and density of poly (ethylene) glycol

Ciprofloxacin (CIP) is an antibacterial agent prescribed for the treatment of ocular infections. The objective of the present project is to investigate the effect of surface PEG functionalization of the Nano structured lipid carriers (NLCs) on formulation stability, ocular penetration and distribution. CIP NLCs were tested with different molecular weight (poly ethylene glycol) PEGs ranging from (2K to 20K) grafted onto the phospholipid and with different chain lengths (14-18 carbons) of phospholipids derivatized with PEG-2K. Drug load in the formulations was maintained at 0.3%w/v. Formulations prepared were evaluated with respect to in vitro release, transcorneal permeation, autoclavability, morphological characteristics and in vivo ocular tissue distribution. Scanning Transmission electron microscopy (STEM) studies revealed that the PEG-CIP-NLCs were spherical in shape. Transcorneal penetration of CIP was optimum with PEG molecular weight in between 2K-10K. Carbon chain length of the phospholipid, however, did not affect transcorneal penetration of CIP. In vivo ocular tissue CIP concentrations attained from the various formulations was consistent with the in vitro data obtained. The results suggest that surface functionalization of PEGs, within a specified range of molecular weight and surface packing density, significantly enhance trans-ocular penetration and impart sterilization-stabilization characteristics into the formulations.

Ocular ciprofloxacin hydrochloride mucoadhesive chitosan-coated liposomes

The aim of this work is to improve the ocular bioavailability of ciprofloxacin hydrochloride (CPX) through the preparation of ocular mucoadhesive chitosan (CS)-coated liposomes. Liposomes were prepared by the thin film hydration technique, using different molar ratios of L-α-phosphatidylcholine (PC), cholesterol (CH), stearylamine (SA) and dicetyl phosphate (DP). CS was used to coat the optimal liposomal formulae. The prepared formulae were characterized regarding encapsulation efficiency (%EE), particle size, physical morphology and in vitro drug release. The in vivo characterization of the prepared formulae was performed through evaluating the level of CPX in the external eye tissue of nine albino rabbits. Results showed an alteration in release rate and %EE of CPX from liposomal formulae upon varying the molar ratios of the lipid bilayer composition. The optimal liposomal formulae F1 (10:0, PC:CH), F12 (10:0:0.5, PC:CH:SA) and F15 (10:0:1, PC:CH:DP), showed % EE of 38.5 ± 2.10, 39.65 ± 1.85 and 30.05 ± 0.75 and % in vitro release after 8 hours (Q(8h)) of 78.15 ± 2.4, 54.07 ± 2.3 and 62.14 ± 2.9, respectively. In vitro drug release and in vivo results confirmed that CS-coated liposomal formulae have exhibited a higher retention of CPX. Consequently, CS-coated liposomes could be a promising approach to increase the ocular bioavailability of CPX.

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

The purpose of this study was to evaluate the pharmacokinetics of intravenously administered moxifloxacin, a fourth-generation fluoroquinolone, in different parts of the non-inflamed eye. Moxifloxacin was administered intravenously at a dose of 20mg/kg moxifloxacin over 30min. Sampling of peripheral blood, aqueous humour and vitreous was performed at standard time intervals post infusion once in each animal. Moxifloxacin levels were estimated by high-performance liquid chromatography with fluorescence detection. Mean serum concentrations were 3.43, 2.74, 1.48 and 1.12microg/mL at 0.5, 3, 6 and 24h after the end of drug infusion, respectively. Respective concentrations in aqueous humour were 2.44, 2.03, 1.30 and 1.09microg/mL and in vitreous body they were 1.68, 1.87, 1.78 and 1.15microg/mL. It is concluded that systemic administration of moxifloxacin in rabbits was accompanied by efficient penetration into both the aqueous humour and the vitreous body at concentrations well above the minimum inhibitory concentration for most causative pathogens of endophthalmitis. Further research is mandatory to clarify the clinical significance of these findings.

Ocular penetration of intravenously administered enrofloxacin in the horse

REASON FOR PERFORMING STUDY

Information on antibiotic concentrations in the equine eye following systemic therapy is limited. Reports that Leptospira spp. are frequently present in the eyes of horses with recurrent uveitis, emphasises a need for studies on ocular concentrations of specific antibiotics.

HYPOTHESES

1) Enrofloxacin, administered i.v. at 7.5 mg/kg bwt q. 24 h, results in aqueous humour concentrations greater than the reported minimum inhibitory concentration (MIC) for Leptospira pomona. 2) Aqueous humour paracentesis sufficiently disrupts the blood-aqueous humour barrier (BAB) to cause an increase in aqueous humour protein and enrofloxacin concentrations.

METHODS

Aqueous humour enrofloxacin and total protein concentrations were determined in 6 healthy, mature horses after i.v. administration of enrofloxacin. Paracentesis was performed on the left eye on Days 3 and 4, 1 h following enrofloxacin administration, to determine enrofloxacin concentrations in healthy eyes and in eyes with mechanical disruption of the BAB. Paracentesis was also performed on the right eye 23 h after enrofloxacin administration. Blood samples were collected from the horses at identical times to determine enrofloxacin aqueous humour:plasma ratios.

RESULTS

Mean +/- s.d. enrofloxacin concentration in the aqueous humour 1 h post administration on Day 3 was 0.32 +/- 0.10 mg/l (range 0.18-0.47); and aqueous humour enrofloxacin, total protein and aqueous humour:plasma enrofloxacin ratios were higher on Day 4 than Day 3.

CONCLUSIONS AND POTENTIAL RELEVANCE

Following disruption of the BAB, enrofloxacin concentrations were above the reported MIC for Leptospira pomona.

Endogenous endophthalmitis: microorganisms, disposition and prognosis

PURPOSE

Endogenous endophthalmitis is a severe and potentially blinding complication caused by haematogenous spreading of microorganisms. We evaluated the causative microorganisms, disposition to and prognosis of the disease.

METHODS

Thirty-one eyes of 28 patients were treated between 1996 and 2006 as the result of an endogenous endophthalmitis.

RESULTS

The microorganisms responsible for infection could be identified in 94% of all eyes investigated. Candida isolates were obtained in 15, gram-positive isolates in 11, gram-negative in one and Aspergillus in two of the 29 eyes studied. The majority of patients suffered from severe general disease (immuno-deficiency, severe surgical procedures, diabetes mellitus) and one third were intravenous drug abusers. Only one patient was otherwise healthy. The prognosis depended on the causative microorganisms. Whereas none of the eyes with Candida infection became blind, all except two of the eyes with gram-positive bacteria, Nocardia or Aspergillus infection lost visual function or had to be enucleated.

CONCLUSION

Compared to postoperative endophthalmitis, patients with endogenous endophthalmitis are more likely to have Candida isolates. Visual prognosis depends mainly on the underlying microorganisms, and is particularly poor in the case of infection with gram-positive bacteria or Aspergillus.

Penetration of levofloxacin into the anterior chamber (aqueous humour) of the human eye after intravenous administration

In the study presented here, levofloxacin concentrations in serum samples and the aqueous humour (AH) of 16 patients undergoing cataract extraction were measured in order to determine the penetration characteristics of levofloxacin into the AH of the non-inflamed human eye. Cataract removal was performed at various times (from 90 to 270 min) after the end of a 30-min intravenous infusion of 500 mg of levofloxacin. Serum samples were obtained 1 h after the end of levofloxacin administration (Cmax); AH and a second serum sample were taken simultaneously during the operation, and the concentrations of levofloxacin in AH (C(AH)) and serum (C(S)) were determined using a rapid high-performance liquid chromatography assay. The mean Cmax was 6.07 microg/ml (range 3.75-9.53 microg/ml, SD 1.83). The mean C(AH) at the first hour following levofloxacin administration was 1.37 microg/ml (range 1.17-1.6 microg/ml, SD 0.22) and the mean ratio (R=C(AH)/C(S)) was 0.26 (range 0.24-0.3, SD 0.02). The mean C(AH) at 125-270 min following levofloxacin administration was 1.39 microg/ml (range 0.82-1.98 microg/ml, SD 0.33) and the mean R was 0.3 (range 0.15-0.53, SD 0.11). Of 16 patients, 15 had a C(AH) of >1 microg/ml 1 h after levofloxacin administration. In conclusion, 1 h after administration of 500 mg of levofloxacin, the levels obtained were higher than the MIC at which 90% of methicillin-susceptible Staphylococcus aureus and certain gram-negative bacteria strains are inhibited.

Bacteria commonly isolated from keratitis specimens retain antibiotic susceptibility to fluoroquinolones and gentamicin plus cephalothin

PURPOSE

Patients presenting with presumed infective keratitis were studied to determine predisposing factors, the current susceptibilities of the bacterial isolates to a range of relevant antibiotics, the success rate of topical antibiotic treatment of keratitis and predictors of failure of topical therapy.

METHODS

Corneal scrapings taken from patients who presented between January 2002 and December 2003 to the Sydney Eye Hospital Emergency Department with keratitis were cultured. The minimum inhibitory concentration of selected antibiotics was determined for each bacterial isolate using an agar dilution technique.

RESULTS

One hundred and twelve consecutive patients presented with corneal ulcers. Forty-seven of the 112 (42%) patients had a growth from the corneal scraping. Potential predisposing factors were identified in 64% of patients, most frequently contact lens wear (36% of patients). Coagulase-negative staphylococci were the most common species isolated. Other common organisms isolated include Pseudomonas aeruginosa, Corynebacterium spp., Staphylococcus aureus and Streptococcus spp.

CONCLUSIONS

Most microorganisms isolated from patients with bacterial keratitis showed susceptibility to ciprofloxacin and aminoglycosides. Cephalothin plus aminoglycoside constituted an effective initial broad-spectrum antibiotic combination. The success rate of topical antibiotic treatment of corneal abscess is 89%. Predictors of failure include older age group, medium or large ulcer, culture-negative keratitis, hypopyon and poor visual acuity.

Levofloxacin disposition over time in aqueous humor of patients undergoing cataract surgery

The ocular disposition of levofloxacin in patients receiving two 500-mg oral doses 10 h apart before cataract surgery was assessed with the intent of defining drug ocular exposure over time. The mean aqueous humor concentrations persisted above 1.5 mg/liter between 1.5 and 6.0 h after the second dose, with average aqueous-to-plasma ratios ranging between 0.33 and 0.57. This favorable ocular disposition provides support for trials of systemic levofloxacin for prophylaxis of postoperative endophthalmitis in selected patients or as adjunctive therapy for the treatment of this potentially devastating infective complication.

Management and Outcomes of Postoperative Endophthalmitis since the Endophthalmitis Vitrectomy Study

PURPOSE

To examine if changes in the diagnosis and management of postoperative endophthalmitis have occurred since 1995, and to identify factors that might predict final visual outcome.

DESIGN

Retrospective, population-based, noncomparative, consecutive case series.

PARTICIPANTS

Patients with clinically diagnosed endophthalmitis after cataract surgery and lens-related surgery in Western Australia from 1980 to 2000.

METHODS

Endophthalmitis cases were identified using record linkage and cross-referencing with the surgical logbooks of vitreoretinal surgeons before validation by medical record review.

MAIN OUTCOME MEASURES

Microbiological data (microorganisms isolated and antibiotic susceptibilities), diagnostic interventions, surgical procedures, therapeutic interventions, and visual acuity (VA).

RESULTS

During the 21-year period, 213 episodes of endophthalmitis occurred after cataract surgery. Since 1995, both anterior chamber sampling and vitreous sampling have increased significantly. The overall use of vitrectomy has also increased, but we did not observe a difference according to presenting VA. Intravitreal antibiotic use increased significantly, whereas the use of both subconjunctival and IV antibiotics decreased. In one third of patients, the VA at least 6 months after admission for endophthalmitis was worse than 6/18. This was associated with treatment that did not include the use of oral antibiotics (odds ratio [OR], 3.86; 95% confidence interval [CI], 1.21-12.39; P = 0.02), growth from intraocular samples of organisms other than coagulase-negative staphylococci (OR, 9.84; 95% CI, 2.84-34.09; P<0.001), and a discharge VA worse than 6/18 (OR, 6.10; 95% CI, 1.63-22.89; P = 0.01).

CONCLUSIONS

Although we observed noticeable changes in the diagnosis and management of endophthalmitis since 1995, visual outcomes have not improved and remain poor. Our finding that treatment with oral antibiotics may be associated with a better visual outcome warrants further investigation.

Penetration of moxifloxacin into the human aqueous humour after oral administration

AIMS

To determine the pharmacokinetics of moxifloxacin, a new generation fluoroquinolone, in the anterior chamber of the human uninflamed eye.

METHODS

35 patients undergoing cataract surgery received two doses of 400 mg of oral moxifloxacin with a 12 hour interval and were divided into six groups. Moxifloxacin levels in aqueous humour and serum were determined by a microbiological agar well diffusion technique at 2, 4, 6, 8, 10, and 12 hours after the second dose in each group respectively.

RESULTS

Mean moxifloxacin levels in the anterior chamber were 1.20 (SD 0.35) microg/ml at the 2 hours group, 1.22 (0.48) microg/ml at the 4 hours group, 1.20 (0.45) microg/ml at the 6 hours group, 1.58 (0.38) microg/ml at the 8 hours group, 1.37 (0.44) microg/ml at the 10 hours group, and 1.23 (0.55) microg/ml at the 12 hours group. The mean ratio of aqueous to serum moxifloxacin level was 38%.

CONCLUSION

Moxifloxacin penetrates well into the anterior chamber of the human uninflamed eye after oral administration, reaching early significant levels, which are maintained for at least 12 hours and are much higher than the MIC(90) values of Gram positive and Gram negative pathogens commonly implicated in intraocular infections with the exceptions of fluoroquinolone resistant staphylococci, MRSA, and Pseudomonas aeruginosa.

Ruggedness testing of an HPLC method for the determination of ciprofloxacin

The possibility of optimization of an HPLC method for the determinations of ciprofloxacin and ciprofloxacin impurity C was investigated according to the British Pharmacopoeia, using ruggedness testing. Four factors were selected to be tested in this ruggedness test (temperature of the column, volume of acetonitrile in the mobile phase, volume of the aqueous phase in the mobile phase and pH of the aqueous phase in the mobile phase). Seven responses were determined in each design experiment: retention times, peak heights, peak widths, number of theoretical plates, peak areas, peak areas RSD (%) and selectivity. A three-level design was used. The optimal conditions for the chromatographic procedure determined as the result of ruggedness testing were: pH of the aqueous phase in the mobile phase 3.0, column temperature 42 ?C and the acetonitrile to aqueous ratio in the mobile phase 14: 86 (v/v). The HPLC method using the optimal conditions was tested for selectivity linearity, precision, accuracy, limit of quantitation and limit of detection. The applicability of the suggested method was, as well, tested on the stability of ciprofloxacin in pharmaceutical preparations (tablets and infusion solution, products of Zdravlje-Pharmaco, Serbia) under stress stability data.

Inhibition of choroidal neovascularization in rats by the urokinase-derived peptide A6

PURPOSE

To evaluate the inhibitory effects of a urokinase-derived octapeptide A6 on laser-induced choroidal neovascularization (CNV).

METHODS

In the first arm of the study, subcutaneous injection of A6 (200 mg/kg per day) into the right eyes in 20 rats and phosphate-buffered saline in 20 control rats was started 1 day before laser injury. Angiography was performed at week 2. To evaluate the dose response, a second arm of the study was performed in the left eyes. Half of the treatment group was treated with 400 mg/kg per day, and the remaining half continued to receive 200 mg/kg per day beginning on week 4. Laser injury was made at week 5 and angiography was performed at week 7. Angiographic evaluation, histopathologic evaluation including maximum CNV thickness and factor-VIII-stained endothelium counting were performed in the second arm of the study. Choroidal concentrations of A6 were measured.

RESULTS

In the first arm of the study, angiography showed a 40.8% reduction in CNV in the 200-mg/kg per day treatment group, compared with the control (P = 0.0008). In the second arm of the study, angiographic reduction in CNV was 37.9% in the 200-mg/kg per day group (P = 0.0314) and 70.0% in the 400-mg/kg per day group (P = 0.0124), compared with the control. CNV was significantly less in the 400-mg/kg per day group than in the 200-mg/kg per day group (P = 0.0393). Both CNV thickness and number of endothelial cells were reduced in a dose-dependent manner and significantly less than in the control (P < 0.05). Mean choroidal concentration of A6 2 hours after injection was 0.72 micro M in the 200-mg/kg per day (100 mg/kg every 12 hours) and 1.75 micro M in the 400-mg/kg per day (200 mg/kg every 12 hours) treatment groups. Levels at 11 hours after injections were undetectable.

CONCLUSIONS

A6 demonstrated antiangiogenic properties in a rat model of CNV and may be useful in the treatment of CNV.

Population pharmacokinetics of marbofloxacin in aqueous humor after intravenous administration in dogs

OBJECTIVE

To evaluate, by use of population pharmacokinetics, the disposition of marbofloxacin in the aqueous humor after IV administration in dogs and identify its potential usefulness in the prophylaxis and treatment of intraocular infection.

ANIMALS

63 dogs.

METHODS

Dogs received a single dose of marbofloxacin (2 mg x kg(-1), IV) at various time intervals before cataract surgery. Aqueous humor and blood samples were collected at the beginning of surgery. Marbofloxacin concentrations were measured by high-pressure liquid chromatography. Data were analyzed with a nonlinear mixed-effect model and, by use of population pharmacokinetic parameters, the time course of aqueous humor concentration was simulated for single doses of 3, 4, and 5.5 mg x kg(-1) IV. Pharmacodynamic surrogate markers and measured aqueous humor concentrations were used to predict in vivo antimicrobial activity.

RESULTS

A maximum marbofloxacin concentration of 0.41 +/- 0.17 microg x mL(-1) was reached in the aqueous humor 3.5 hours after IV administration. In the post-distributive phase, marbofloxacin disappeared from aqueous humor with a half-life of 780 minutes. The percentage penetration into the aqueous humor was 38%. Predictors of antimicrobial effects of marbofloxacin (2 mg x kg(-1), IV) indicated that growth of the enterobacteriaceae and certain staphylococcal species would be inhibited in the aqueous humor. Marbofloxacin administered IV at a dose of 5.5 mg x kg(-1) would be predicted to inhibit growth of Pseudomonas aeruginosa and all strains of staphylococci but would not eradicate streptococcal infections.

CONCLUSIONS AND CLINICAL RELEVANCE

Marbofloxacin administered IV can penetrate the aqueous humor of canine eyes and may be suitable for prophylaxis or treatment of certain anterior chamber infections.

Moxifloxacin efficacy and vitreous penetration in a rabbit model of Staphylococcus aureus endophthalmitis and effect on gene expression of leucotoxins and virulence regulator factors

Bacterial endophthalmitis is a serious complication of ocular surgery and of eye trauma; the leading causative organisms are Staphylococcus aureus strains. Tissue damage is due both to the host inflammatory response and to toxin synthesis by bacteria. Systemic treatment remains difficult because most antibiotics show poor ocular penetration. Moxifloxacin (MXF), a novel fluoroquinolone, was evaluated for its penetration into the vitreous of normal rabbit eyes and of eyes of rabbits infected for 24 h with methicillin-susceptible and methicillin-resistant S. aureus (MSSA and MRSA) following a single intravenous administration of 5 or 20 mg/kg. MXF penetration was rapid and efficient regardless of the dose, ranging from 28 to 52%. An inflammatory state of the vitreous significantly increased penetration after the 20-mg/kg dose, with penetration reaching 52%. Concentrations determined in the vitreous cavity following a 20-mg/kg administration showed a 3.5-fold decrease of the bacterial density within 5 h for MSSA (MIC, 0.125 micro g/ml) and a 1.6-fold decrease for MRSA (MIC, 4 micro g/ml) strains, respectively. By using a semiquantitative reverse transcription-PCR method, the expression of luk-PV and hlgCB, but not hlgA, encoding staphylococcal leukotoxins, was detected in the vitreous without MXF treatment. A slight decrease in the expression of leucotoxins and sarA, agr, and sigB virulence regulatory factors was observed 1 h following the administration of 5 mg of MXF per kg.

The Endophthalmitis Population Study of Western Australia (EPSWA): first report

BACKGROUND/AIM

Over the period of 19 years to 1999, cataract surgery numbers increased 6% per annum in Western Australia (WA), promoted by the convenience, efficacy, and general safety of outpatient phacoemulsification surgery. Although endophthalmitis is an uncommon complication, it is a major cause of post-cataract surgery blindness. The present population study investigates not only the prevalence of endophthalmitis but provides an accurate incidence of endophthalmitis in WA over the same period.

METHODS

Using the hospital morbidity data system (HMDS) of the WA Record Linkage Project, and cross validating against three independent databases (anaesthetic and microbiological databases and surgeons' logbooks) the authors examined 698 case notes that were potentially cases of endophthalmitis for the period 1980 to June 1999. As the database linkage was incomplete for 1999, only the 188 confirmed cases to 1998 were included in the present study. Additional case note validation was performed to confirm the correct codes for the cataract surgical procedure.

RESULTS

Despite changes in surgical technique and prophylaxis over the study period of 19 years, the incidence of endophthalmitis remained largely unchanged, averaging one in 500 surgical cases overall. However, the incidence fluctuated over time and varied with the location of surgery ranging from 0.65 per 1000 operations to 16.4 per 1000 operations.

CONCLUSION

These data highlight previously undescribed temporal and geographic variations in the incidence of endophthalmitis. It is uncertain whether the wide variation in prophylactic practices throughout the ophthalmic community has any bearing on the incidence of endophthalmitis.

Endophthalmitis

Australia and New Zealand continue to be at the forefront of endophthalmitis research. In this Clinical Controversy, an ophthalmologist from each country presents different approaches to the management of a 72-year-old patient with routine endophthalmitis following cataract surgery. Mark Elder concludes that this case needs aqueous and vitreous aspirates for culture and the initial treatment of choice is intracameral vancomycin and amikacin. The evidence for intravitreal steroids is equivocal. Systemic antibiotics are indicated if there is a possibility of a bacterial biofilm present on the intraocular lens. Nigel Morlet concludes that timely intervention with appropriate antibiotics delivered in the right concentration to the vitreous cavity is the crux of successful management of endophthalmitis. Aggressive treatment of the inflammatory response is also required to further reduce the damage to the intraocular structures. Both ophthalmologists agree that vitrectomy is not necessarily the most appropriate treatment option.

Bacterial endophthalmitis: epidemiology, therapeutics, and bacterium-host interactions

Endophthalmitis is a severe inflammation of the interior of the eye caused by the introduction of contaminating microorganisms following trauma, surgery, or hematogenous spread from a distant infection site. Despite appropriate therapeutic intervention, bacterial endophthalmitis frequently results in visual loss, if not loss of the eye itself. Although the pathogenicity of bacterial endophthalmitis has historically been linked with toxin production during infection, a paucity of information exists as to the exact mechanisms of retinal toxicity and the triggers for induction of the intraocular immune response. Recently, research has begun to examine the bacterial and host molecular and cellular events that contribute to ocular damage during endophthalmitis. This review focuses on the causative agents and therapeutic challenges of bacterial endophthalmitis and provides current data from the analysis of the role of bacterial virulence factors and host inflammatory interactions in the pathogenesis of eye infections. Based on these and related studies, a hypothetical model for the molecular pathogenesis of bacterial endophthalmitis is proposed. Identifying and understanding the basic mechanisms of these bacterium-host interactions will provide the foundation for which novel, information-based therapeutic agents are developed in order to prevent vision loss during endophthalmitis.

Endophthalmitis

Despite advances in treatment and diagnosis, postoperative endophthalmitis (POE) is still not an entirely manageable complication after cataract surgery. This review focuses on recent developments regarding epidemiology, diagnosis based on the polymerase chain reaction method, experimental antibiotic therapy and clinical experience with intravitreal steroids, and experimental findings of the inflammatory process of POE, all of which are areas that may contribute to a broader understanding of POE.