Actinomyces israelii species is a gram-positive, cast-forming, non–acid-fast, non–spore-forming anaerobic bacillus that is difficult to isolate and identify. Its filamentous growth and mycelialike colonies have a striking resemblance to fungi. They are soil organisms, often found in decaying organic matter (eg, wet hay, straw). It is primarily a commensal microbe found in normal oral cavities, in tonsillar crypts, in dental plaques, and in carious teeth.

Pathophysiology:

Keratitis

Most reported cases of Actinomyces keratitis (keratoactinomycosis) are caused by A israelii. It is characterized by a dry ulceration with central necrosis, surrounded by a gutter of demarcation, usually accompanied by iritis and hypopyon. In severe cases, descemetocele and perforation may occur.

A primary corneal ulcer attributable to Actinomyces species is rare and usually follows corneal trauma. A rare case of keratoactinomycosis developing in the absence of any known ocular trauma was reported in Kuala Lumpur.

Canaliculitis

Primary chronic canaliculitis is an uncommon problem caused by A israelii (Streptothrix). McKellar presented a 10-year-old girl with a 6-month history of intermittent conjunctivitis and discharge from her pouted left lower punctum. Topical treatment with chloramphenicol/polymyxin sulphate failed despite a diagnosis of probable A israelii infection confirmed by microbiology. Surgical exploration revealed a canalicular diverticulum and 3 canaliculiths demonstrating solid casts of Actinomycetes on histologic examination. A therapeutic triad of punctoplasty, cast removal, and adjunctive topical cefazolin resulted in resolution.

Other ocular involvement

Actinomycetes have been described as causative organisms in conjunctivitis, blepharitis, dacryocystitis, postsurgical endophthalmitis, and infected porous orbital implant. Cervico-facial actinomycosis has also been reported.

Endophthalmitis, attributable to Actinomyces viscosus, developed in a 78-year-old man after cataract surgery. Postoperative endophthalmitis with this organism is a rare occurrence. Inflammation was characterized by anterior segment and vitreous cellular debris in cases of chronic postoperative endophthalmitis associated with Actinomyces species.

Frequency:

• In the US: Primary chronic canaliculitis is an uncommon problem that can be overlooked; however, it may account for approximately 2% of all tearing problems. Actinomycosis may form in up to 2% of all lacrimal disease. Its occurrence is probably much less in other areas.

Race: No racial predilection exists.

Sex: No sexual predisposition exists.