BRUCELLOSIS -
Brucellosis is a zoonosis transmitted to humans from infected animals
ETIOLOGY 4 species affecting humans: Brucella melitensis (most common and most virulent) acquired primarily from goats/sheep/camels; B. abortus from cattle; B. suis from hogs; and B. canis from dogs. Aerobic/gram-negative bacilli/uncapsulated/intracellular. Killed by boiling or pasteurization of milk and milk products. Remains viable for up to 40 days in dried soil contaminated with infected-animal urine, stool, vaginal discharge, and products of conception and for longer periods in damp soil.
Transmission: ingestion of untreated milk/milk products/raw meat/via inhalation during contact with animals.
PATHOGENESIS AND IMMUNITY complements opsonizes Brucella-- ingestion by PMN’s and activated macrophages --- it resist intracellular phagocytic killing (by as the suppression of the MPO- peroxide-halide system and the production of superoxide dismutase) --- multiply -- localizing in the liver, spleen, bones, kidneys, lymph nodes, heart valves, nervous system, and testes -- noncaseating granulomas typically develop (caseating granulomas and abscesses also described).
CLINICAL MANIFESTATIONS AND COMPLICATIONS
It is a systemic disease with protean manifestations. I Pd from 1 to 3 weeks to several months,The onset may be either abrupt or gradual . Symptoms are fever, chills, diaphoresis, headaches, myalgia, fatigue, anorexia, joint and low-back pain, weight loss, constipation, sore throat, and dry cough. Signs: no abnormalities/pallor/lymphadenopathy/hepatosplenomegaly/arthritis/spinal tenderness, /epididymoorchitis/rash/ meningitis/ cardiac murmurs/pneumonia.
Bones and Joints Although monarticular septic arthritis/ reactive asymmetric polyarthritis /osteomyelitis of the lumbar vertebrae. In Brucella septic arthritis and osteomyelitis, the peripheral white cell count is typically normal, while the erythrocyte sedimentation rate may be either normal or elevated.
Heart include endocarditis, myocarditis, pericarditis, aortic root abscess, mycotic aneurysms, thrombophlebitis with pulmonary aneurysm, and pulmonary embolism.
Respiratory Tract A flulike illness with sore throat, tonsillitis, and dry cough is common and usually mild. Hilar and paratracheal lymphadenopathy, pneumonia, solitary or multiple pulmonary nodules, lung abscess, and empyema have been reported.
Gastrointestinal Tract and Hepatobiliary System mild and may include nausea, vomiting, constipation, acute abdominal pain, and/or diarrhea. Non caseating granuloma in liver.
Genitourinary Tract unilateral or bilateral epididymoorchitis,prostatitis, tuboovarian abscess, salpingitis.
Central Nervous System Uncommon but serious and includes meningitis, meningoencephalitis, multiple cerebral or cerebellar abscesses.
Other The bone marrow of Brucella-infected patients frequently contains noncaseating granulomas. Among the hematologic complications of brucellosis are anemia, leukopenia, and thrombocytopenia.
DIAGNOSIS
The combination of potential exposure, consistent clinical features, and significantly raised levels of Brucella agglutinin (with or without positive cultures of blood, body fluid, or tissues) confirms the diagnosis of active brucellosis. In endemic areas a Brucella antibody titer of 1:320 or 1:640 is significant, while in nonendemic areas an antibody titer of 1:160 is considered significant.
TREATMENT
Single-agent therapy/short course for brucellosis has now been abandoned because of the high rates of failure and relapse. The combination of doxycycline and an aminoglycoside (gentamicin, streptomycin, or netilmicin) for 4 weeks followed by the combination of doxycycline and rifampin for 4 to 8 weeks is the most effective regimen. An alternative regimen consists of the doxycycline/rifampin combination given for 8 to 12 weeks. The doxycycline/aminoglycoside combination is more effective than the doxycycline/rifampin combination in that rifampin reduces levels of doxycycline in plasma.
In pregnancy, trimethoprim-sulfamethoxazole (TMP-SMZ) can be given in combination with rifampin for 8 to 12 weeks.
PROGNOSIS
Deaths attributable to brucellosis should be avoidable. Even before the discovery of antibiotics, the mortality rate was 2% and endocarditis was most frequently the cause of death. Morbidity due to brucellosis remains significant; its severity depends on the infecting Brucella species and is greatest with B. melitensis. Spinal damage, paraplegia, and other neurologic deficits may occur. Nerve deafness due to meningitis or secondary to treatment with streptomycin has been documented.
