Rare Causes of Endogenous Endophthalmitis

Aspergillosis

Aspergillus species are ubiquitous, saprophytic molds commonly growing in soil, stored hay, and decaying vegetation [446]. Rare cases of endogenous aspergillus endophthalmitis (EAE) are usually associated with disseminated aspergillosis or with intravenous drug abuse. Antibiotics, corticosteroids, or immunosuppressors use commonly precedes the onset of septicemia. Aspergillus endophthalmitis has been reported following liver and lung transplantation [447, 448].

Acutely, patients present with rapid onset of pain and severe visual loss, often with involvement of the central macula. A confluent yellowish macular infiltrate begins in the choroid and the subretinal space. Preretinal or subretinal inflammatory exudates may be seen. Hemorrhages are not common. The infection then proceeds with retinal and ultimately vitreous involvement. Anterior segment involvement is rare. The features are characteristic and, in the context of known risk factors, highly suspicious of EAE [446]. Diagnosis can be confirmed by culture of anterior chamber or ­vitreous aspirate. Pars plana vitrectomy specimens assisted by Gram or Geimsa stain have the highest yield of positive cultures in aspergillosis. The drug of choice for treatment of aspergillosis is amphotericin B.

Cryptococcosis

Cryptococcus is a yeast-like fungus widely found in nature, especially in pigeon feces. Cryptococcus rarely causes disease in humans. Immunocompetent persons can be infected, but infection most commonly occurs in immunocompromised hosts, particularly AIDS patients [449].

Cryptococcal infection in AIDS patients has a predilection to the CNS causing either papilloedema from cryptococcal meningitis, optic neuritis, which may be unilateral or bilateral, [449] or optic atrophy [450] (Fig. 16.21). Posterior segment involvement includes retinal hemorrhages, exudates, and cotton-wool spots. Multifocal retinitis or chorioretinitis with discrete yellow retinal or chorioretinal lesions can be seen.

Factors that need to be considered in guiding treatment of cryptoccocosis are the presence or absence of underlying disease such as AIDS or other causes of

Fig. 16.21  Cryptococcal retinitis and optic neuritis in an AIDS patient

immunocompromise and the extent of infection (pulmonary or extrapulmonary). Options for treatment include amphotericin B, flucytosine, fluconazole, itraconazole, miconazole, and ketoconazole.

Histoplasmosis

Disseminated histoplasmosis in immunocompromised individuals may lead to malignant systemic disease with fever, generalized lymphadenopathy, hepatosplenomegaly, and bone marrow suppression. In these patients, ocular involvement with uveitis, diffuse chorioretinitis, and endophthalmitis resulting from histoplasma capsulatum has been reported [451–453]. Immunocompromised states associated with disseminated histoplasmosis included AIDS [453], as well as immunosuppression due to other causes [451, 454]. Surprisingly, endogenous histoplasma endophthalmitis has also been reported in nonimmunocompromised patients [455, 456]. Treatment is with intravenous and topical amphotericin B [453].

Pneumocystis carinii

Pneumocystis carinii is a common systemic opportunistic infection in AIDS and in immunocompromised patients. Aerosolized pentamidine isethionate used as a prophylaxis of P. carinii pneumonia is a risk factor for development of P. carinii choroiditis [457]. Several reports described extrapulmonary infections in patients receiving prophylactic aerosolized pentamidine therapy [458–460]. The clinical picture has been described as bilateral multifocal process characterized by round yellowish flat or slightly elevated choroidal lesions [459, 460]. Foster et al. 1991[458], however, described cases of unilateral and unifocal choroiditis. Inflammation of