Intravenous treatment of experimental Staphylococcus aureus endophthalmitis: imipenem versus the combination of ceftazidime and amikacin

Clinical presentations, risk factors and outcomes of ceftazidime-resistant Gram-negative endophthalmitis

BACKGROUND

To describe the clinical features and outcomes of patients diagnosed with ceftazidime-resistant Gram-negative endophthalmitis and the role of intravitreal imipenem in these cases.

DESIGN

Retrospective consecutive interventional case series at a tertiary eye care centre in South India.

PARTICIPANTS

Consecutive cases of ceftazidime-resistant Gram-negative endophthalmitis from April 2010 to December 2014. Fifty-six cases diagnosed during this time period were included.

METHODS

All cases were managed with vitreous biopsy/vitrectomy, microscopy and undiluted vitreous culture, antimicrobial susceptibility of bacterial isolates and received intravitreal antibiotics.

MAIN OUTCOME MEASURES

Anatomic and visual outcome of these cases, antimicrobial susceptibility pattern of intravitreal imipenem and outcome of cases injected with it.

RESULTS

Commonest presentation was acute endophthalmitis following cataract surgery (27 eyes, 48.21%). Pseudomonas aeruginosa was isolated in 33 eyes (58.93%; 95% CI 46.05-71.81%). Nineteen eyes (34%; 95% CI 21.59-46.41%) developed phthisis; 14 eyes (25%; 95% CI 13.66-36.34%) had vision <20/200; 17 eyes (30.35%; 95% CI 18.31-42.39%) eyes had an ambulatory vision >20/200 (logMAR 1); 6 eyes (10.71%; 95% CI 2.61-18.81%) had a reading vision >20/40 (logMAR 0.3). Trend was towards better anatomic (72.73% vs. 40%) (P = 0.05) and visual improvement in the imipenem group (logMAR 3.94 + 0.21 to 2.43 + 1.4; P = 0.002), as compared with non-imipenem group (logMAR 2.99 + 1.3 to 2.55 + 1.4; P = 0.13).

CONCLUSIONS

Outcome of ceftazidime-resistant Gram-negative endophthalmitis is poor. P. aeruginosa is the commonest isolated organism. All cases were sensitive to imipenem. There was a trend towards better anatomic outcome in imipenem-treated eyes.

Modeling intraocular bacterial infections

Bacterial endophthalmitis is an infection and inflammation of the posterior segment of the eye which can result in significant loss of visual acuity. Even with prompt antibiotic, anti-inflammatory and surgical intervention, vision and even the eye itself may be lost. For the past century, experimental animal models have been used to examine various aspects of the pathogenesis and pathophysiology of bacterial endophthalmitis, to further the development of anti-inflammatory treatment strategies, and to evaluate the pharmacokinetics and efficacies of antibiotics. Experimental models allow independent control of many parameters of infection and facilitate systematic examination of infection outcomes. While no single animal model perfectly reproduces the human pathology of bacterial endophthalmitis, investigators have successfully used these models to understand the infectious process and the host response, and have provided new information regarding therapeutic options for the treatment of bacterial endophthalmitis. This review highlights experimental animal models of endophthalmitis and correlates this information with the clinical setting. The goal is to identify knowledge gaps that may be addressed in future experimental and clinical studies focused on improvements in the therapeutic preservation of vision during and after this disease.

Current knowledge about and recommendations for ocular methicillin-resistant Staphylococcus aureus

Staphylococcus aureus is the most important and common pathogen that infects patients following cataract surgery, laser in situ keratomileusis, and photorefractive keratectomy. It is reported to be the second most common pathogen causing bacterial keratitis around the world. Of special concern are increasing reports of postoperative methicillin-resistant S aureus (MRSA) infection. For example, MRSA wound infections have been reported with clear corneal phacoemulsification wounds, penetrating keratoplasty, lamellar keratoplasty, and following ex vivo epithelial transplantation associated with amniotic membrane grafts. These and other data suggest that MRSA has become increasingly prevalent worldwide. In this article, we review the current medical literature and describe the current challenge of ocular MRSA infections. Recommendations are made based on an evidence-based review to identify, treat, and possibly reduce the overall problem of this organism.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.