Table 18.1 Nomenclature of bone tumors
• Incubation period is 1 week to 3 months.
• Patients may be asymptomatic or have nonspecific symptoms such as fever, sweats, malaise, weight loss, and depression.
• Bacteremic patients may have arthralgias or arthritis. Patients may rarely present with abdominal pain.
• Fever is the most common finding.
• Hepatomegaly, splenomegaly, or lymphadenopathy is possible.
• Localized disease:
1. Related to a single organ
2. Includes endocarditis, meningitis, and osteomyelitis (especially vertebral)
Chronic hepatosplenic suppurative brucellosis (CHSB) presents with hepatic or splenic abscesses. This form is thought to be a reactivation, and can occur years after the acute infection.
• Caused by infection with Brucella species:
1. Most commonly melitensis, but also suis, abortus, or canis
2. A small, gram-negative coccobacillus
• Acquired through breaks in the skin or by inhalation or ingestion of organisms.
• Most cases occur after exposure to animals (sheep, goats, swine, cattle, or dogs), or animal products (i.e., milk, hides, tissue).
• Most cases (in U.S.) occur in men with occupational exposure to animals (farmers, ranchers, veterinarians, abattoir workers).
• Laboratory acquisition is possible.
• May occur in tourists to other countries who ingest goat milk or cheese.
Blood (or bone marrow) cultures are positive during the acute phase of illness in 50% of patients (higher in B. melitensis), but prolonged culture is needed. In chronic disease serological tests are of greater value. The brucella agglutination test, which demonstrates a fourfold or greater rise in titre (> 1 in 160) over a 4-week period, is highly suggestive of brucellosis. An elevated serum IgG level is evidence of current or recent infection; a negative test excludes chronic brucellosis. In localized brucellosis antibody titres are low, and diagnosis is usually established by culturing the organisms from the involved site. Species-specific PCR tests are also available.
Many febrile conditions without localizing manifestations (i.e., TB, endocarditis, typhoid fever, malaria, autoimmune diseases)
• Cultures of blood, bone marrow, or other tissue (lymph node, liver) should be sent and held for 4 weeks, since Brucella grows slowly in vitro.
• Granulomas on biopsy are suggestive of diagnosis.
• WBC count: normal or low
1. Serum agglutination test (SAT) to detect antibodies to B. abortus, melitensis, and suis
2. Specific antibody test to identify antibodies to B. canis
3. False-negative SAT possibly resulting from a prozone effect Serologic studies may be nondiagnostic in CHSB
• Radiographs to show splenic calcifications in chronic disease
• Bone scan and radiographs of the spine to suggest osteomyelitis
• Ultrasound or CT scan of the abdomen to show an enlarged liver or spleen
• Echocardiogram to reveal vegetations in endocarditis
In CHSB, abscesses and calcifications may be seen in the liver and spleen
• Drainage of abscesses
• Valve replacement for endocarditis
ACUTE GENERAL Rx
Combination antibiotics required:
• Doxycycline 100 mg PO bid plus streptomycin 15 mg/kg IM qd for 6 weeks
• Less effective: doxycycline 100 mg PO bid plus rifampin 600 mg PO qd or sulfamethoxazole 800 mg/trimethoprim 160 mg one DS tablet PO qid
Courses <6 weeks are associated with higher relapse rates; longer courses are recommended for complicated disease.
See “Acute General Rx.”
Relapse is possible weeks to months after the completion of therapy, usually because of noncompliance with a prolonged medical regimen or a persistent focus of infection that requires surgical drainage. Reactivation with CHSB has been reported up to 35 years after initial illness.
The onset is insidious, with malaise, headache, weakness, generalized myalgia and night sweats. The fever pattern is classically undulant, although continuous and intermittent patterns are also seen. Lymphadenopathy and hepatosplenomegaly are common; sacro-iliitis, arthritis, osteomyelitis, epididymo-orchitis, meningoencephalitis and endocarditis have all been described.
Untreated brucellosis can give rise to chronic infection, lasting a year or more. This is characterized by easy fatiguability, myalgia, and occasional bouts of fever and depression. Splenomegaly is usually present. Occasionally infection can lead to localized brucellosis. Bones and joints, spleen, endocardium, lungs, urinary tract and nervous system may be involved. Systemic symptoms occur in less than one-third.