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Comments, Opinions, and Brief Case Reports
August 13/27, 2001

Pacemaker Infection Due to Brucella melitensis: A Case Report

Arch Intern Med. 2001;161(15):1910-1911. doi:

Brucellosis is a zoonosis, and virtually all infections derive directly or indirectly from exposure to infected animals.1 Because the consumption of unpasteurized dairy products is widespread in Turkey, it is still an endemic disease there.2 Systemic brucellosis is by far the most frequent clinical form encountered, but unusual focal multiorganic involvements such as meningitis, spondylitis, endocarditis, arthritis, uveitis, mammary abscess, sacroiliitis, prostatitis, and orchitis have been mentioned in the literature.3-7

Infection is the most serious complication after placement of permanent endocardial pacemakers. Usually these infections result from normal flora of the skin. Staphylococci (Staphylococcus epidermidis and Staphylococcus aureus), Streptococcus species, Enterobacteriaceae, Pseudomonas aeruginosa, and Enterococcus species are the most common microorganisms.8 Rates of these infections have varied from 0.13% to 19.9% of the devices implanted.9 Sometimes unusual microorganisms may be isolated from pacemaker infections because of metastatic spread.8,10 We report a case of pacemaker infection due to Brucella melitensis.

Report of a Case

A 68-year-old man living in a rural area was admitted to the hospital because of pain and swelling of the tissue surrounding his pacemaker implantation. His first pacemaker, which had been implanted in 1993 to treat sick sinus syndrome, was revised in May 2000 because of lead dysfunction. On January 15, 2001, he was hospitalized because of pacemaker infection and dilated cardiomyopathy. The generator pocket of the single-chamber pacemaker was infected. The pacemaker was removed completely, and the abscess was drawn and cultured.

Results from laboratory tests of the patient revealed a 5.4 × 103/µL white blood cell count, with a differential count of 63% polymorphonuclear leukocytes, 17% lymphocytes, 18% monocytes, and 2% eosinophils. The erythrocyte sedimentation rate was 47 mm/h, and the findings of his blood biochemical analysis were normal. Except for the swelling of the tissue surrounding his pacemaker implantation, findings from physical examination were normal (ie, without hepatosplenomegaly and lymphadenopathy). His medical history was not characteristic. He sometimes complained of malaise, fatigue, and chills, but he did not remember exactly the duration of these ailments.

An abscess specimen was processed using an automated monitoring system (BACTEC 9050; Becton, Dickinson and Company, Franklin Lakes, NJ), and it was positive for growth of a microorganism on the third day of incubation. Subcultures were plated on 5% sheep blood agar, chocolate agar, and eosin-methylene blue agar and incubated aerobically. After 48 hours of incubation, growth was observed on 5% sheep blood agar and chocolate agar. Findings of a Gram stain of colonies revealed faintly staining, small gram-negative coccobacillary microorganisms. Although it was a rare location, Brucella species were suspected based on microscopic examination findings. Oxidase and urease test results were positive, and results from a urease test were positive for brucellosis within 10 minutes. Two blood cultures were collected. A rose bengal test was performed, and a rapid agglutination was observed. The serologic titer was 1/1280 with the Wright agglutination test. After the patient was identified as having brucellosis, the strain was identified as B melitensis biotype 1 by the production of hydrogen sulfur, hydrolysis of urea, carbon dioxide requirements, and use of carbohydrates and amino acids. Blood cultures were negative after 30 days of incubation. Subcultures were collected twice weekly and were negative for B melitensis after 14 days of incubation. Treatment consisted of a 6-week regimen of rifampin and doxycycline hyclate.


Brucellosis is usually transmitted through contact with infected animals, ingestion of infected dairy products, or inhalation of contaminated aerosols. Transmission with milk and blood transfusion has also occurred.11,12 According to a MEDLINE search of the literature (performed on January 22, 2001) over the last 20 years, this is the third case of B melitensis complicating pacemaker implantation published in the English-language medical literature.8,10 The accurate diagnosis of infectious diseases with unusual presentations depends entirely on microbiological methods.7 The diagnosis of brucellosis is usually based on the findings from serologic examination rather than from a culture of the etiologic agent.13 In this case, the diagnosis was also based on microbiological methods rather than clinical presentation. Therefore, regarding the increasing number of unusual infectious agents complicating pacemaker implantation, B melitensis should always be kept in mind in pacemaker infection cases.

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