Fernández, M.I.*
Instituto Argentino de Diagnóstico y Tratamiento, Buenos Aires, Argentina.
Actinomyces species are gram-positive branching filamentous rod (GPBFR) mainly involved in cervicofacial, abdominal, thoracic infections and associated with the use of intrauterine device. Due to the few infectious cases appearing in the literature in the past 10 years, about actinomycosis of the central nervous system (CNS), it seems to me very interesting to report two cases of brain abscess caused by Actinomyces israelii.
1°. A 31 year old woman who suffered a vanal head trauma with left hemiparesis and headache. She has a history of Webber-Rendu-Osler disease. Computed tomography (CT) and magnetic resonance (MR) of the brain demonstrated an homogeneous subcortical space-occupying lesion with great edema and mass effect. Initial antibiotic therapy (AT) was begun with cefotaxime and metronidazole. After the result of the Gram stain, AT was changed to penicillin G (20 million units per day). Treatment was continued for five weeks and the patient was discharged from the hospital taking amoxicillin to complete a 6 months course of antibiotic. Since 1993, she has not had any neurologic sequelae.
2°. A 70 year old man with a malignant astrocytoma. CT revealed a right subdural and epidural collection with mass effect. Empirical AT with vancomycin and cefotaxime was started but, with the result of Gram stain, the AT was changed to penicillin G (high-dose). The empyema was cured after 4 weeks, but the patient died because of complications related to his primary malignancy. Stereotactic needle aspirations were performed in both patients. Gram stain of these pus showed GPBFR and a great inflammatory reaction (appearence of polymorphonuclear leukocytes). In both cases, non acid-fast GPBFR grew in anaerobic culture between 6 - 8 days of incubation. They gave the following reactions: catalase (-) nitrate reduction (-), gelatin hydrolysis (-), H2S production (+), esculin hydrolysis (+), urease (-), xylose (+), glucose (+), mannitol (+), raffinose (+), trehalose (-) and were identified as Actinomyces israelii. Penicillin and amoxicillin- sulbactam MICs were 0.12 ug / ml (both of them). Although infrequent, Actinomyces israelii can be involved in important infections of the CNS, and when it is, the actinomycotic lesions are metastatic and secondary to other infectious focus that, a lot of times, remains undetected.