Pediatric Brucellosis Workup
- Author: Nicholas John Bennett, MB, BCh, PhD; Chief Editor: Russell W Steele, MD more...
Laboratory Studies
- Diagnosis of brucellosis is definitive when Brucella organisms are recovered from blood, bone marrow, or other tissue. Some Brucella species require 5-10% carbon dioxide for primary isolation. In vitro replication is fairly slow; therefore, alert laboratory personnel to maintain cultures for 4 weeks or longer. Blood culture results can be positive in 75% of patients with acute disease, while bone marrow culture allows isolation in 90% of patients.
- The serum agglutination test (SAT) uses killed B abortus cells as antigen. SAT is the most commonly used serologic test and detects antibodies against B abortus, B suis, and B melitensis. B canis– specific antigen is used to detect its antibodies. SAT titers of 1:160 or higher indicate active infection. Repeat serologic tests are recommended if the initial titers are low. The vaccine strain RB-51 does not induce antibody responses detectable using standard assays but has been associated with some human disease.[8]
- The 2-mercaptoethanol test detects immunoglobulin G (IgG), and titers higher than 1:80 define active infection. A high IgG antibody titer or a titer that is higher after treatment suggests persistent infection or relapse. Prozone inhibition can cause false-negative results in the presence of sera with high titers, and dilution of sera is necessary to avoid this problem. Brucella antibodies can possibly cross-react with other organisms, such as Yersinia enterocolitica serotype O9, Francisella tularensis, and Vibrio cholera. Enzyme immunoassay (EIA) is the most sensitive method for detection of immunoglobulin M (IgM), immunoglobulin A (IgA), and IgG anti -Brucella antibodies.
- Polymerase chain reaction (PCR) tests have been developed for the detection and rapid diagnosis of Brucella species in human blood specimens but are only available in specialist laboratories.[9]
- WBC counts in patients with brucellosis are usually within reference range or lower. Anemia is reported in 75% of patients, thrombocytopenia is reported in 40%, and pancytopenia is reported in 6% of patients.
- Elevated levels of liver enzymes may reflect the severity of hepatic involvement and correlate clinically with hepatomegaly.
Imaging Studies
- Scanning techniques, including CT scanning and MRI, can be used for diagnosis of an occult focus of infection.
Other Tests
- Bone marrow examination may reveal erythrophagocytosis. Microangiopathic hemolytic anemia, thrombocytopenic purpura,[10] and Coombs-positive hemolytic anemia have been reported in brucellosis.
- Neurobrucellosis: Cerebral spinal fluid (CSF) reveals pleocytosis, elevated protein levels, and hypoglycorrhea. CSF culture results are positive in fewer than 50% of patients. CSF antibodies are present in most patients.
Histologic Findings
- Analysis of liver biopsy specimens may reveal granulomatous hepatitis and hepatic microabscesses. Specimens from bone marrow biopsy may test positive for granulomas, hemophagocytosis, or both.
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| Nomina Species | Biovars | Preferred Host |
| B abortus | 1-6, 9 | Cattle |
| B melitensis | 1-3 | Goats, sheep |
| B suis | 1-3 | Swine |
| 4 | Reindeer | |
| 5 | Rodents | |
| B canis | None | Dogs[7] |
| Age | Antimicrobial Agents | Dose |
| Patients >8 y | Doxycycline plus streptomycin or doxycycline plus gentamicin | Doxycycline: 2-4 mg/kg/d PO qd or divided bid for 6 wk; not to exceed 200 mg/d Streptomycin: 1 g/d IM for 2 wk Gentamicin: 3-5 mg/kg/d IM/IV divided q8h for 1 wk |
| Alternative in patients >8 y | Doxycycline plus rifampin | Doxycycline: 2-4 mg/kg/d PO qd or divided bid for 6 wk; not to exceed 200 mg/d Rifampin: 15-20 mg/kg/d PO for 6 wk; not to exceed 600-900 mg/d |
| Patients < 8 y | Trimethoprim-sulfamethoxazole (TMP-SMZ) plus rifampin | TMP-SMZ: 8-10 mg (based on TMP component)/kg/d for 45 d; not to exceed 2 double-strength tab/d Rifampin: 15-20 mg/kg/d PO for 45 d; not to exceed 600-900 mg/d |
| Patients >8 y with meningitis,* endocarditis, or osteomyelitis | Doxycycline plus streptomycin or doxycycline plus gentamicin | Doxycycline: 2-4 mg/kg/d PO qd or divided bid for 4-6 mo; not to exceed 200 mg/d Streptomycin: 20 mg/kg/d IM for 1-2 wk; not to exceed 1 g/d Gentamicin: 3-5 mg/kg/d IM/IV divided q8h for 1-2 mo |
| Patients < 8 y with meningitis,* endocarditis, or osteomyelitis | TMP-SMZ plus rifampin | TMP-SMZ: 8-10 mg (based on TMP component)/kg/d PO divided bid for 4-6 mo Rifampin: 15-20 mg/kg/d PO for 4-6 mo; not to exceed 600-900 mg/d |
| *The use of corticosteroids as adjunctive therapy to antibiotics may be beneficial in culture-proven meningitis. | ||
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