A Case of Isolation of a Brucella melitensis Strain from a Patient with Infectious Endocarditis in Medical Organization

The aim of the work consisted in verification and detailed identification of the causative agent of brucellosis isolated from a patient diagnosed with infectious endocarditis with extensive tricuspid valve damage.

Materials and methods. We investigated the clinical material from the affected person (blood, blood serum) and the obtained culture of brucellosis agent. Medical organization performed tests for sterility of blood using a BC60 hemoculture analyzer. Identification of the grown colonies was carried out on a VITEK® MS mass spectrometer. The Indication Center conducted studies of clinical material samples from the patient and an in-depth study of the Brucella spp. 1079 strain obtained from the medical organization using bacteriological, serological, mass spectrometric, molecular-genetic methods, and high-throughput sequencing.

Results and discussion. The strain, primarily identified as Brucella spp., was isolated from a patient’s blood sample in a laboratory at the medical facility. Following in-depth testing at the Indication Center using a combination of phenotypic and molecular biological methods, this strain was verified and assigned to Brucella melitensis genotype IIi. The culture is sensitive to gentamicin, streptomycin, levofloxacin, doxycycline, rifampicin, amikacin, kanamycin, and tetracycline. It is intermediately resistant to nalidixic acid and ciprofloxacin, and is insensitive to ceftriaxone and trimethoprim-sulfamethoxazole. Nucleotide sequences of the omp25 and omp2a genes of Brucella were detected in blood and serum samples from the patient. These sequences confirmed the presence of B. melitensis in the samples. IgM and IgG antibodies to the causative agent of brucellosis were detected in the patient’s blood serum. As a result of the study, the brucellosis agent isolate obtained at the medical facility from a patient diagnosed with infectious endocarditis with extensive tricuspid valve damage was verified and identified as B. melitensis genotype IIi. This case confirms the need for increased awareness among healthcare personnel regarding particularly dangerous infections, as well as coordinated efforts across various agencies.

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