SUMMARY CONFLICT OF INTEREST: none declared. Introduction Brucella endocarditis (BE) is a rare but severe and potentially lethal manifestation of brucellosis. Pre-existing valves lesions and prosthetic valves (PV) are favorable for BE. Case report We represent the case of a 46-year-old man who was treated at the Clinic for Infectious Diseases, Clinical Center of Sarajevo University, as blood culture positive (Brucella melitensis) mitral and aortic PV endocarditis. He was treated with combined anti-brucella and cardiac therapy. Surgical intervention was postponed due to cardiac instability. Four months later he passed away. Surgery was not performed.

During the last several years, brucellosis has become an important public-health problem on a large territory part of Bosnia and Herzegovina. The disease belongs to the zoonosis group, and can be caused by several bacterium species from Brucella genus. For human and veterinarian medicine, B. abortus, B. melitensis, B. suis and B. canis from Brucella genus are important, while other brucella species are found only in animals. The results of laboratory process of isolating Brucella melitensis, as well as of detection of specific antibacterial antibodies, are presented in this work. Namely, B. melitensis was isolated from blood samples (chemo-culture), as a causal agent of disease in one sixty years-old patient, treated during 2001. In pair serum samples of the patient, the presence of specific anti-brucella antibodies was confirmed qualitatively and quantitatively. In the serum I, ELISA test confirmed the presence of specific IgM antibodies of 25,7 U/ml, and IgG antibodies of 252 U/ml. In the serum II, IgM antibodies of 24,9 U/ml, and IgG antibodies of 311 U/ml were found. These results suggest and confirm established work diagnosis, and etiology causality of the disease with isolated bacterium.