Scleritis Caused byIn VitroLinezolid-ResistantNocardia asteroides

Abstract

Purpose. To describe a case of postoperative scleritis caused by a novel strain of Nocardia resistant to linezolid and trimethoprim-sulfamethoxazole (TMP-SMX). Methods. Case report of a patient with microbiologically proven scleritis due to Nocardia asteroides. Results. The patient presented with pain, redness, and nodules on the sclera three months following pterygium excision with mitomycin C and amniotic membrane placement. As no response was noted with empiric treatment for bacterial scleritis, debridement was performed. The cytopathology report showed gram positive filamentous bacteria. A presumptive diagnosis of Nocardia scleritis was made and therapy was initiated based on a literature review on treatments for Nocardia infections. Cultures returned growing Nocardia asteroides. Antibiotic sensitivity testing revealed resistance to linezolid and TMP-SMX which are the traditional drugs of choice for Nocardia. The patient was treated with amikacin and imipenem as well as extensive debridement with pedicle grafts. The patient's scleritis resolved with a good visual outcome. Conclusions. Cultures should be obtained in all cases of necrotizing scleritis in patients with a recent history of conjunctival surgery to rule out unusual organisms such as Nocardia. Although literature states that resistance to linezolid and TMP-SMX is rare in Nocardia, sensitivity testing can be useful in unresponsive cases.

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

“…Gram-staining was the most common diagnostic modality, revealing Gram-positive, thin, branching beaded rods. 1 , 3 , 6 , 7 , 10 , 12 , 13 , 17 , 18 , 19 , 20 , 22 , 23 , 24 , 25 , 26 , 22 , 23 , 24 , 25 , 26 Nocardia was weakly positive on acid-fast staining (1%, w/v) and thin branching rods were evident on Ziehl-Neelsen staining. 1 , 3 , 7 , 10 , 22 , 25 About 20% of cases were negative on acid-fast staining.…”

“…14 The predisposing factors were, in decreasing order: prior ocular trauma (21/43), prior surgery (17/43), the use of steroids (7/43), and a previous corneal infection (2/43). A single case report suggested the following predisposing factors: diabetes mellitus, 13 subtenon steroid administration, 24 pterygial surgery, 26 and prior penetrating keratoplasty. 17 Nocardial scleritis could occur in the absence of prior ocular surgery or trauma and could mimic immunological necrotizing scleritis.…”

“…The most common nocardial agent was N. asteroides . 1 , 3 , 6 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 23 , 24 , 25 , 26 , 23 , 24 , 25 , 26 Of six patients with serious complications, such as scleral thinining, 3 , 6 , 17 , 18 endophthalmitis, 6 and enucleation, 23 all were infected with N. asteroides . 1 , 3 , 6 , 17 , 18 , 23 The prognosis of resolution was fair (83%) if treatment commenced early.…”

“… 1 , 3 , 6 , 17 , 18 , 23 The prognosis of resolution was fair (83%) if treatment commenced early. 1 , 2 , 3 , 7 , 8 , 10 , 12 , 14 , 19 , 20 , 21 , 22 , 24 , 25 , 26 , 7 , 8 , 10 , 12 , 14 , 19 , 20 , 21 , 22 , 24 , 25 , 26 , 24 , 25 , 26 …”

“… 1 , 2 , 3 , 7 , 8 , 10 , 12 , 13 , 14 , 17 , 18 , 19 , 20 , 21 , 7 , 8 , 10 , 12 , 13 , 14 , 17 , 18 , 19 , 20 , 21 , 17 , 18 , 19 , 20 , 21 Oral linezolid (600 mg 12/12 h) 27, 42,44 was considered the next best alternative. 26 If both SMZ/TMP and linezolid resistance were evident, the use of imipenem was suggested. 26 …”