A good bug gone bad? Whole genome sequence and phenotypic characterisation of a soil organism, Bacillus paralicheniformis MB647, isolated from an infected orthopaedic implant.

An isolate of a rod-shaped, endospore-forming Gram-positive facultative anaerobe was recovered from infected orthopaedic implant samples collected from a hospital in Islamabad, Pakistan. The isolate was motile and displayed optimal growth at 37°C (pH 7.0). The whole genome sequence of strain showed 97% similarity with the Bacillaceae family and 90% with Bacillus paralicheniformis. This species is only rarely associated with diseases in humans, and to the best of our knowledge, this is the first report of Bacillus paralicheniformis MB647 being isolated from an infected orthopaedic implant. To understand better why MB647 might cause infections in humans, we carried out whole genome sequencing. This revealed a number of antibiotic resistance mechanisms (conferring resistance to tetracycline, bicyclomycin, bacitracin, erythromycin, and various β-lactams). Several virulence factors were identified in the genome, including genes linked to biofilm formation, hemolysins production and the secretion of proteolytic enzymes such as proteases and gelatinases, which may contribute to the pathogenic potential of MB647 in implant associated infections. Based on the consensus of whole genome sequencing, multi-locus sequencing typing (MLST) and phenotypic analyses, we conclude that this strain represents a novel lineage with a unique sequence type (ST48) within the genus Bacillus.