Repeat serology tests are preferred for confirming the Dx
It is interesting that our patient’s initial Brucella serology by ELISA was negative, because it was ordered months after her initial symptoms. Antibodies should be seen within a month of symptom onset. The Centers for Disease Control and Prevention (CDC) recommends taking 2 serum samples to establish a serologic diagnosis of brucellosis. The first should be drawn within 7 days of symptom onset and the second should be taken 2 to 4 weeks later. A greater than 4-fold rise in the antibody titer confirms the diagnosis. While ELISA is an acceptable serologic test, the CDC recommends using a serum tube agglutination test called the Brucella microagglutination test (BMAT).12 Repeat serology was not performed on our patient because the diagnosis had been confirmed by blood culture.
A combination of antibiotics is the recommended treatment
Treatment of brucellosis should include a tetracycline for at least 6 weeks in combination with an aminoglycoside or rifampin 600 mg/d for an all-oral regimen.13 Doxycycline 100 mg twice a day is preferred due to fewer gastrointestinal adverse effects than tetracycline. Relapse is not uncommon (10%) and usually occurs within one year of completing the antibiotics.8 However, there is a case report of a patient having reactivated brucellosis manifested as acalculous cholecystitis 28 years after completing antibiotics.8
Our patient was started on oral doxycycline 100 mg twice a day and oral rifampin 600 mg/d for 6 weeks. Within days of starting the antibiotics, her joint symptoms and fatigue rapidly abated and her appetite returned. Follow-up radiological testing was not performed after her initial hospital studies due to her lack of financial resources.
The patient’s daughter had also been experiencing night sweats, chills, malaise, anorexia, joint pains, weight loss, and alopecia over the previous 2 months. Her blood cultures were positive for B melitensis as well, and she was started on the same antibiotic regimen as her mother. The daughter was also seen in our clinic by another physician and improved quickly within a week of starting treatment.
Both our patient and her daughter remained symptom-free 6 years after treatment.
THE TAKEAWAY
Brucellosis is rare in the United States, but international travel to endemic areas is commonplace and consumption of unpasteurized Mexican dairy products from goats and sheep is widespread. Brucellosis has a wide range of symptoms, but a prompt diagnosis by an ELISA or BMAT serologic test and appropriate treatment can avoid morbidity and mortality. Treatment includes a tetracycline for at least 6 weeks in combination with an aminoglycoside or rifampin.