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Editor,—Ocular infection withRhodococcus is rare.1-4 In previous reportsRhodococcus species caused endophthalmitis1-3 and keratitis which failed to respond to treatment.4 We present a case ofRhodococcus keratitis which was successfully treated.
Eleven weeks after simple pterygium excision, an otherwise healthy 56 year old woman developed a corneal ulcer. No organisms were identified from corneal scrapes. Resolution had not occurred after 5 weeks’ treatment with topical cefuroxime, gentamicin, and econazole. The patient was referred to Moorfields Eye Hospital and treatment was stopped. On examination there was a central epithelial defect (1 × 2 mm) associated with stromal thinning (60%), adjacent temporal multifocal infiltrates, nasal stromal neovascularisation, a 2 mm hypopyon, and scleritis (Fig 1A). After a further corneal scrape, treatment with topical amphotericin was commenced. Further deterioration occurred and a 6 mm diameter, 0.3 mm deep lamellar corneal biopsy was performed. The keratitis responded to this removal of infected tissue and treatment with hourly topical ofloxacin and oral ciprofloxacin. Histopathology suggested a nocardial infection (Fig 1C and D). The latter was confirmed by microbiological culture and the organism identified as a Rhodococcus. The organism was resistant to all 10 antibiotics tested except imipenem. Complete resolution of the keratitis occurred after 5 weeks’ treatment with topical imipenem 0.5% (Fig 1B).
Rhodococcus species possess characteristics of bothMycobacteria and Nocardia, and exhibit pleomorphism growing as cocci, short rods, or branching filaments, although the Rhodococcus species have a less well developed mode of branching than the other species. The organism is ubiquitous and is a common cause of pneumonia in foals.4Most reported Rhodococcus infections in humans have occurred in immunocompromised patients, including those with AIDS.5 The present case is of interest because of its rarity and because the patient was not immunocompromised. In addition, the infection responded to keratectomy and non-standard antibiotic therapy.
The authors are grateful to the Mycotic Reference Laboratory (Bristol) for typing the Rhodococcus organism.