Neurobrucellosis

WALLACH, JORGE C; PABLO CESAR BALDI

Progress in Encephalitis Research

Nova Science Publishers

Lugar: New York; Año: 2006; p. 195 - 215

Brucellosis is a zoonotic infection caused by four Brucella species pathogenic for man: B. melitensis, B. suis, B. abortus and B. canis. Recently, two human cases caused by a new Brucella species usually isolated from marine mammals have been also reported. Humans become infected by contact with infected animals (cattle, goats, pigs, dogs, etc.) or their tissues, or by consumption of raw milk or meat. The most frequent clinical and pathological findings are undulant fever with sweats, asthenia, myoarthalgias, weight loss, hepatitis, splenomegaly, adenitis and leukopenia. Other less frequent findings are osteo-articular, visceral and neurological complications and/or focalizations. Neurobrucellosis is a relatively rare complication, though its frequency has recently been estimated to lay between 5% and 10%. Neurobrucellosis can constitute the initial manifestation or can occur at any evolutive stage of the disease. Neurological involvement usually occurs by hematogenous disemination, and lessions are produced by the presence of the bacterium, the action of inflamatory cytokines, or the demyelinizing effect of an immunopathological response. Rarely, neurological involvement is produced by spread of the infection from a granulomatous focal lesion or from an abscess in a vertebral body. Neurological manifestations may or may not be accompanied by systemic symptoms. While meningoencephalitis is the most frequent clinical manifestation, other pathological conditions such as myelitis, radiculitis, polyradiculitis, Guillain-Barré syndrome, cerebrovascular involvement, brain abscess and peripheral neuropathy have been described. Isolation of the bacterium from cerebrospinal fluid (CSF) to confirm the diagnosis is difficult, with a success rate of 20%. Therefore, different techniques to detect specific antibodies in cerebrospinal fluid must be used. Positive agglutination indicates neurobrucellosis, but agglutination tests can yield false negative results when the concentration of anti-Brucella agglutinins is low. To overcome these limitations, highly sensitive ELISA tests are used. These assays are more specific than agglutination, specially when Brucella proteins are used as antigens. These immunological tests, together with imaging (CT and MRI), are indispensable tools for the diagnosis and treatment of neurobrucellosis. Up to three antimicrobial drugs can be used in combination to treat this complication. The length of the antibiotic course must be adjusted to each particular case, but should never be less than 3 months. Doxycycline combined with rifampin and gentamicin is the treatment of choice. Doxycycline combined with rifampin and trimethoprim/sulfamethoxazole is an alternative treatment. The use of corticosteroids in the early stages of meningoencephalitis is usually of benefit.