Propionibacteria and disease

From a medical microbiology perspective, the species Propionibacterium acnes, Propionibacterium avidum, Propionibacterium granulosum, and Propionibacterium propionicum, are the most relevant within the genus Propionibacterium. Of these, Propionibacterium acnes has the greatest pathogenic potential and is associated with a diverse range of infections and clinical conditions, ranging from inflammatory acne to prosthetic joint infections and prostate cancer. In this chapter, we provide an overview of the genus Propionibacterium, and describe the role played by the ‘cutaneous’ propionibacteria, especially P. acnes, in human disease. We also cover virulence factors, mechanisms of antibiotic resistance, insights from whole-genome sequencing and immune responses. The potential therapeutic effects of propionibacteria when used as adjuvants/vaccines are also considered, along with molecular-based approaches for differentiation and characterization of propionibacteria associated with human infection.