Penetration and decay of meropenem into the human aqueous humor and vitreous

Susceptibility of Ocular Surface Bacteria to Various Antibiotic Agents in a Romanian Ophthalmology Clinic

Periodic assessment of bacterial contamination is necessary as it allows proper guidance in cases of eye infections through the use of appropriate antibiotics. Due to the extensive use of antibiotic treatment, many strains of the microbiota that cause infections are resistant to the usual ophthalmic antibiotics. The present study provides an updated assessment of the susceptibility of Gram-positive and Gram-negative bacteria found on the ocular surface to the most commonly used antibiotic agents in patients undergoing cataract surgery. A total of 993 patients were included in the study with ages between 44 and 98 years old. Conjunctival cultures were collected 7 days before cataract surgery. The response of Gram-positive and Gram-negative bacteria to various antibiotic classes, such as glycopeptides, cephalosporins, carbapenems, fluoroquinolones, aminoglycosides, phenicols, tetracyclines, rifamycins, macrolides and penicillins, was assessed. From the tested antibiotics, vancomycin had 97.8% efficacy on Gram-positive bacteria. In the cephalosporin category, we observed a high level of resistance of the cefuroxime for both Gram-positive and negative bacteria. Antibiotics that have more than 90% efficacy on Gram-positive bacteria are meropenem, imipenem, netilmicin, amikacin and rifampicin. On Gram-negative bacteria, we found 100% efficacy of all tested fluoroquinolones, i.e., aminoglycosides (except for tobramycin), doxycycline, azithromycin, clarithromycin and chloramphenicol. The current study illustrates patterns of increased resistance in certain bacteria present on the ocular surface to some of the commonly used antibiotics in ophthalmological clinical practice. One such revealing example is cefuroxime, which has been highly used as an intracameral antibiotic for the prevention of bacterial endophthalmitis after cataract surgery.

Hypervirulent Klebsiella pneumoniae infection in a woman with a CDH1 gene mutation

The CDH1 gene, which encodes E-cadherin, may be associated with cancer when mutated, but the significance of mutations in the context of infection is unknown. In this report, we describe a case of disseminated hypervirulent Klebsiella pneumoniae infection in a 49 year old Caucasian woman with a documented CDH1 mutation.

Comparative review of imipenem/cilastatin versus meropenem

INTRODUCTION

Carbapenems are broad-spectrum antibacterial molecules. Imipenem-cilastatin and meropenem are the two main molecules used in French healthcare services.

OBJECTIVE

We aimed to evaluate the relative strengths and weaknesses of these two molecules by considering their pharmacokinetic, pharmacodynamic, microbiological, and clinical properties. We demonstrated that imipenem-cilastatin and meropenem are not alike.

METHOD

Review of the literature by querying the MEDLINE network.

RESULTS

Imipenem-cilastatin is the first marketed molecule of the carbapenem class. It is more effective against Gram-positive cocci. Its stability does not allow for long infusions and its main adverse effect on the central nervous system limits its use. Meropenem is more effective against Gram-negative bacilli. Its stability and its milder adverse effects distinguish it from imipenem-cilastatin.

CONCLUSION

Meropenem is preferred for daily use in healthcare services when carbapenems are to be used.

NOVEL CASE OF CLOSTRIDIUM PERFRINGENS ENDOPHTHALMITIS AFTER ANTI-VASCULAR ENDOTHELIAL GROWTH FACTOR INJECTION

INTRODUCTION

Endophthalmitis after anti-vascular endothelial growth factor injection is a rare complication but may lead to rapid destruction of structures within the eye. Infection with Clostridium perfringens has not previously been reported in this context.

CASE REPORT

A 90-year-old woman presented with endophthalmitis of the right eye, 2 days after an intravitreal injection of ranibizumab. Initial examination showed a high intraocular pressure, refractive to topical treatment, reduced vision, and a hypopyon. Gram stain showed a Gram-positive bacillus, which was identified as C. perfringens. Despite the use of intravitreal and intravenous antibiotics, the patient went on to develop cornea-scleral melt of the right eye. She required an evisceration on the fifth day after ranibizumab.

CONCLUSION

This case describes a unique and virulent pathogen leading to globe loss after an anti-vascular endothelial growth factor injection. C. perfringens, naturally living in feces or soil, is more commonly associated with dirty traumatic open-globe injuries. However, it is an important pathogen to consider when there is rapid destruction of eye structures associated with endophthalmitis. Based on a root cause analysis of this case, our department has introduced patient information leaflets on hand hygiene to educate patients having intraocular injections.

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.

A case of postoperative endophthalmitis by extended-spectrum beta-lactamase-producing Escherichia coli

A 75-year-old female was transferred to our clinic three days after uneventful phacoemulsification with intraocular lens (IOL) implantation in the right eye that had been carried out at a local clinic. Under the diagnosis of postoperative endophthalmitis, the patient underwent pars plans vitrectomy, IOL explantation, silicone oil tamponade, and intravitreal antibiotic injection. Even after the procedure, the patient's condition was further aggravated, and extended-spectrum beta-lactamase-producing Escherichia coli were identified on bacterial identification test. Although meropenem was applied locally and systemically, the patient had no-light perception visual acuity.

Modeling Approach To Characterize Intraocular Doripenem Pharmacokinetics after Intravenous Administration to Rabbits, with Tentative Extrapolation to Humans

The aim of this study was to determine the penetration of doripenem administered intravenously into the rabbit aqueous and vitreous humors. Nineteen New Zealand White rabbits received a 20-mg dose of doripenem intravenously over 60 min. Specimens of aqueous humor, vitreous humor, and blood were obtained 30 min ( n = 5), 1 h ( n = 5), 2 h ( n = 5), and 3 h ( n = 4) after the beginning of the infusion and analyzed by high-performance liquid chromatography (HPLC). A pharmacokinetic (PK) model was developed to fit the experimental data. Doripenem concentrations in aqueous humor were lower than those in plasma ultrafiltrates at all sampling times, with an average aqueous humor-to-plasma ultrafiltrate area under the concentration-time curve ratio estimated as 8.3%. A pharmacokinetic model with peripheral elimination described the data adequately and was tentatively used to predict concentration-versus-time profiles and pharmacokinetic-pharmacodynamic (PK-PD) target attainment in patients under various dosing regimens. In conclusion, systematically administered doripenem does not seem to be a promising approach for the treatment of intraocular infections, especially since it could not be detected in the vitreous humor. However, this study has provided an opportunity to develop a new PK modeling approach to characterize the intraocular distribution of doripenem administered intravenously to rabbits, with tentative extrapolation to humans.

Determination and pharmacokinetic study of meropenem in rat bile using on-line microdialysis and liquid chromatography

Meropenem is a carbapenem antibiotic with a wide spectrum of activity against both Gram-positive and Gram-negative bacteria. Because of its clinical efficacy, meropenem is an excellent choice for the treatment of serious infections in both adults and children. The knowledge of tissue concentrations of antibiotic in an infection site is valuable for the prediction of treatment outcome. To investigate the biliary disposition of meropenem, we utilized a minimally invasive sampling technique with a shunt linear microdialysis probe for continuous sampling in the biliary excretion studies. Analysis of meropenem in the dialysates was achieved using a LiChrosorb RP-18 column (Merck, 250 x 4.6 mm I.D.; particle size 5 microm) maintained at ambient temperature. The mobile phase was 50 mM monosodium phosphoric acid-methanol (80:20, v/v, pH 3.0). The UV detector wavelength was set at 298 nm. The area under the concentration-time curve and elimination half-lives of meropenem were about 6144 +/- 1494 min microg/ml and 61 +/- 17 min, respectively. This study represents a successful application of the microdialysis technique, which is an effective method for pharmacokinetic and biliary drug excretion studies.