Nocardial scleritis: A case report and a suggested algorithm for disease management based on a literature review

Atypical microbial keratitis

Atypical microbial keratitis refers to corneal infections caused by micro-organisms not commonly encountered in clinical practice. Unlike infections caused by common bacteria, cases of atypical microbial keratitis are often associated with worse clinical outcomes and visual prognosis. This is due to the challenges in the identification of causative organisms with standard diagnostic techniques, resulting in delays in the initiation of appropriate therapies. Furthermore, due to the comparatively lower incidence of atypical microbial keratitis, there is limited literature on effective management strategies for some of these difficult to manage corneal infections. This review highlights the current management and available evidence of atypical microbial keratitis, focusing on atypical mycobacteria keratitis, nocardia keratitis, achromobacter keratitis, and pythium keratitis. It will also describe the management of two uncommonly encountered conditions, infectious crystalline keratopathy and post-refractive infectious keratitis. This review can be used as a guide for clinicians managing patients with such challenging corneal infections.

Etiology, Pathogens, Clinical Features and Treatment of Bacterial Scleritis

We retrospectively reviewed literature reports on pathogens, clinical features, diagnosis, treatment, and clinical and visual outcomes in patients with bacterial scleritis over the past decade. Eye surgery and trauma are the most common causes of bacterial infections. Subtenon triamcinolone acetonide injection, intravitreal ranibizumab, and wearing contact lenses are also causes of bacterial scleritis. Pseudomonas aeruginosa is the most common pathogenic microorganism causing bacterial scleritis. Mycobacterium tuberculosis ranks second. The main symptoms of bacterial scleritis are red and painful eyes. The patient's visual acuity decreased significantly. Bacterial scleritis caused by Pseudomonas aeruginosa often manifests as necrotizing scleritis, tuberculous scleritis and syphilitic scleritis are mostly nodular scleritis. Bacterial scleritis often involves the cornea, and approximately 37.6% (32 eyes) of patients had corneal bacterial infection. Hyphema was present in 18.8% (16 eyes). Elevated intraocular pressure was observed in 36.5% (31 eyes) of patients. Bacterial culture was an effective method of diagnosis. Most bacterial scleritis cases require both aggressive medical and surgical treatment, and the drug choice must be based on antibiotic susceptibility testing.

Nocardia arthritidis scleritis: A case report

Purpose

This report describes a case and management of a 69-year-old female with infectious scleritis found to be caused by Nocardia arthritidis species.

Observations

Our patient presented with severe constant pain in the left eye (OS) following cataract surgery. She had a pertinent past medical history significant for renal transplantation (on oral tacrolimus, mycophenolate, and prednisone). Slit lamp examination OS (1 month after cataract surgery) demonstrated 3+ injection temporally accompanied by scleral thickening and multiloculated abscesses with purulent drainage from small conjunctival erosions. The abscesses were debrided and sent for gram stain and culture. The patient was treated with repeated subconjunctival injections of antibiotics and an antifungal; topical amphotericin, vancomycin, and amikacin; and oral trimethoprim-sulfamethoxazole (double strength). Two separate gram stains with cultures confirmed the diagnosis and species identification. The patient responded well to repeat subconjunctival injections early on in addition to the prescribed regimen, remaining free of disease at the last follow-up (12 months following presentation).

Conclusions and Importance

This unique case demonstrates infectious scleritis caused by an uncommon Nocardia species (N. arthritidis) that was successfully treated with similar strategies used for other reported Nocardia species. As Nocardia scleritis can lead to adverse outcomes if not treated promptly and properly, it should be considered on the differential diagnoses in an immunocompromised patient who presents with acute ocular symptoms after any recent ocular surgery.

Infectious Scleritis: Pathophysiology, Diagnosis, and Management

ABSTRACT

Infectious scleritis (IS) is a rare and severe ocular disorder responsible for approximately 5%-15% of all scleritis cases. It is often associated with a poor prognosis due to its similar clinical presentation to autoimmune scleritis, resulting in a delayed diagnosis and treatment. Therefore, differentiating between infectious and noninfectious entities is critical. Several details extracted from the patient's history and clinical examination can raise suspicion for infection. The most common predisposing factor is previous ocular surgery, especially pterygium, cataract, and vitreoretinal surgeries. Ocular trauma, poor contact lens hygiene, "eye-whitening" procedures, and subtenon triamcinolone injections have also been implicated. Clinical features of infection include the presence of scleral necrosis, hypopyon, unifocal or multifocal scleral abscesses, and mucopurulent discharge. Thorough diagnostic testing is essential before excluding infection as a possibility. Empiric broad-spectrum topical and systemic antibiotic therapy should be initiated while awaiting laboratory results and adjusted accordingly. Most IS cases require both aggressive medical and surgical treatment, and various studies have reported favorable outcomes with this combination. At this time, there is no consensus on the management of this severe ocular condition, and future studies are needed to establish clear treatment guidelines.

Scleritis: Differentiating infectious from non-infectious entities

Scleritis is a rare painful ocular disorder, associated with severe ocular pain and tissue destruction. Although a majority of these cases are immune mediated and at least half of these are associated with systemic immune-mediated diseases, a smaller minority are due to infections of the sclera. The two conditions closely mimic each other, and a thorough knowledge of the subtle differences is necessary in order to reach a timely diagnosis. Diagnostic delay can lead to a poor outcome both due to the destruction caused by the uncontrolled infection and also due to propagation of the infection with the use of corticosteroids which may have been started for presumed immune mediated scleritis. In this review, we present the clinical features, etiological agents, and the differentiating features between immune and infectious scleritis. We also present diagnostic and management guidelines for managing scleral infection.

Clinicopathological, Microbiological and Polymerase Chain Reaction Study in a Case of Nocardia Scleritis

PURPOSE

To describe the clinicopathological, microbiological and polymerase chain reaction (PCR) study in a case of Nocardia scleritis.

METHODS

A retrospective chart review.

RESULTS

A 32-year old male presented with pain, redness and nodular scleral swelling in the left eye for the past two and a half months following an accidental rice powder injury. He was earlier diagnosed to have tubercular scleritis and treated with oral steroids and anti-tubercular therapy. A repeat scleral biopsy on histopathological examination showed granulomatous inflammation. Microbiological investigations revealed the growth of Gram +ve branching filamentous bacilli in culture suggestive of Nocardia sp. PCR based DNA sequencing identified the bacterium as Nocardia cyriacigeorgica. The patient responded to topical fortified amikacin (2.5%), fortified cefuroxime, oral sulfamethoxazole and trimethoprim with complete healing of scleritis.

CONCLUSIONS

Nocardia scleritis can be a diagnostic challenge for clinicians. Newer molecular techniques along with histopathological and microbiological investigations can clinch the diagnosis.