Brucella inopinata sp. nov., isolated from a breast implant infection

Abstract

A Gram-negative, non-motile, non-spore-forming coccoid bacterium (strain BO1T) was isolated recently from a breast implant infection of a 71-year-old female patient with clinical signs of brucellosis. Affiliation of strain BO1T to the genus Brucella was confirmed by means of polyamine pattern, polar lipid profile, fatty acid profile, quinone system, DNA–DNA hybridization studies and by insertion sequence 711 (IS711)-specific PCR. Strain BO1T harboured four to five copies of the Brucella-specific insertion element IS711, displaying a unique banding pattern, and exhibited a unique 16S rRNA gene sequence and also grouped separately in multilocus sequence typing analysis. Strain BO1T reacted with Brucella M-monospecific antiserum. Incomplete lysis was detected with bacteriophages Tb (Tbilisi), F1 and F25. Biochemical profiling revealed a high degree of enzymic activity and metabolic capabilities. In multilocus VNTR (variable-number tandem-repeat) analysis, strain BO1T showed a very distinctive profile and clustered with the other ‘exotic’ Brucella strains, including strains isolated from marine mammals, and Brucella microti, Brucella suis biovar 5 and Brucella neotomae. Comparative omp2a and omp2b gene sequence analysis revealed the most divergent omp2 sequences identified to date for a Brucella strain. The recA gene sequence of strain BO1T differed in seven nucleotides from the Brucella recA consensus sequence. Using the Brucella species-specific multiplex PCR assay, strain BO1T displayed a unique banding pattern not observed in other Brucella species. From the phenotypic and molecular analysis it became evident that strain BO1T was clearly different from all other Brucella species, and therefore represents a novel species within the genus Brucella. Because of its unexpected isolation, the name Brucella inopinata with the type strain BO1T (=BCCN 09-01T=CPAM 6436T) is proposed.