Background
The bacterial order Actinomycetales comprises 3 families: Actinomycetaceae, Mycobacteriaceae, and Streptomycetaceae. The genus Actinomyces, a member of the family Actinomycetaceae, grows as a fragile branching filament that tends to fragment into bacillary and coccoid forms producing chains of either conidia or arthrospores. [1, 2]
Actinomyces israelii species is a gram-positive, cast-forming, non–acid-fast, non–spore-forming anaerobic bacillus that is difficult to isolate and identify.
Actinomyces israelii (non–spore-forming, gram-positive bacilli). Courtesy of Medical Education Information Center, Department of Pathology and Laboratory Medicine, The University of Texas-Houston Medical School.
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. [3, 4, 5, 6]
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. [7] 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. [8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
Other ocular involvement
Actinomycetes have been described as causative organisms in conjunctivitis, blepharitis, carunculitis, dacryocystitis, lacrimal gland ductulitis, crystalline keratopathy, postsurgical endophthalmitis, and infected porous orbital implant. Cervicofacial actinomycosis has also been reported. [21, 22, 23]
Postoperative endophthalmitis
Acute postoperative endophthalmitis caused by Actinomyces neuii after uncomplicated phacoemulsification with posterior chamber intraocular lens implant in a 58-year-old male has been reported. On postoperative day 6, he presented with pain, redness, and decreased visual acuity. Chronic endophthalmitis by Actinomyces neuii subspecies anitratus after uneventful phacoemulsification with implantation of a foldable posterior chamber intraocular lens in a 75-year-old man has been reported as well. Four weeks after surgery, anterior chamber and vitreous cellular debris developed in this eye. [24]
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. [25]
Actinomycosis may be the cause of endophthalmitis after anti-VEGF intravitreal injection. [26]
Endogenous endophthalmitis has been reported with Actinomyces israelii. [27]
Lacrimal Sac
Actinomycosis of the lacrimal sac may masquerade as a lacrimal sac malignancy. [28]
Orbital actinomycosis
Painful ophthalmoplegia resulting from orbital actinomycosis has been reported. [29, 30, 31, 32, 33, 34]
Epidemiology
Frequency
United States
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.
International
Actinomycosis occurs worldwide, with a likelihood for higher prevalence rates in areas with low socioeconomic status.
In a literature review of lacrimal canaliculitis presented by Freedman et al in 2011, the prevalence of Actinomyces species infection was 30.3%. [20]
Race
No racial predilection exists.
Sex
No sexual predisposition exists.
Age
Actinomycosis can affect people of all ages. No age predisposition exists.
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Canaliculitis of the left lower lid. Courtesy of Peter Rubin, MD, Director, Eye Plastics Service, Massachusetts Eye and Ear Infirmary, Harvard Medical School.
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Canaliculitis of the right upper lid. Courtesy of Peter Rubin, MD, Director, Eye Plastics Service, Massachusetts Eye and Ear Infirmary, Harvard Medical School.
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A pediatric patient with canaliculitis. Courtesy of Peter Rubin, MD, Director, Eye Plastics Service, Massachusetts Eye and Ear Infirmary, Harvard Medical School.
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A patient presenting with pseudocanaliculitis secondary to a chalazion. Courtesy of Peter Rubin, MD, Director, Eye Plastics Service, Massachusetts Eye and Ear Infirmary, Harvard Medical School.
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A patient presenting with pseudocanaliculitis secondary to a chalazion. Courtesy of Peter Rubin, MD, Director, Eye Plastics Service, Massachusetts Eye and Ear Infirmary, Harvard Medical School.
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Actinomyces israelii (non–spore-forming, gram-positive bacilli). Courtesy of Medical Education Information Center, Department of Pathology and Laboratory Medicine, The University of Texas-Houston Medical School.
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Actinomyces israelii. (The image is labeled.)
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Actinomycosis.
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Clinical slit-lamp photographs of Actinomyces infectious crystalline keratopathy (A) upon initial presentation, (B) immediately following first repeat penetrating keratoplasty, and (C and D) low and high magnification of recurrent corneal opacities 6 months later. White arrows highlight temporal opacity within host cornea.
