because of the difficulty of isolating the organism, a Serologic test, the serum agglutination test (SAT), is Ifridely used and detects antibodies to Brucella abortus, B. melitensis, and B. suis; SAT will not detect B. canis antibodies. A titer of 1:160 or greater in-the SAT is |pnsidered diagnostic if this result fits the clinical and qjidemiologic findings. The SAT can cross-react with jîtass M immunoglobulins with a variety of bacteria ¡such as Francisella tularensis and Vibrio cholera. Htzyme-linked immunosorbent assays (ELISAs) also have been developed, but further evaluation must be 4one before these assays replace the SAT. In patients v fth neurobrucellosis, ELISA offers significant diagnostic advantages over conventional agglutination inethods.5
antimicrobial susceptibility testing and therapy
¡Because of the fastidious nature of these organisms .coupled with their intracellular localization, in vitro susceptibility testing is not reliable.3 Prolonged treatment with antibiotics that can penetrate macrophages and act in the acidic intracellular environment (6 weeks) is given to patients with brucellosis to prevent relapse of infection. For initial therapy, doxycydine in combination with streptomydn or rifampin is recommended. Sometimes, surgical drainage is also required to treat localized fori of infection.
Prevention of brucellosis in humans is dependent on the elimination of disease in domestic livestock. Vaccines directed against B. abortus or JS. melitensis have been used in the appropriate animal host (i.e., cattle and goats/ sheep, respectively) and are very successful in eradicating the disease in animals. An effective vaccine against B. suis and various human vaccines using killed brucellae fractions are under development.
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