SEVERE INFECTIONS CAUSED BY PROPIONIBACTERIUM-ACNES - AN UNDERESTIMATED PATHOGEN IN LATE POSTOPERATIVE INFECTIONS

Propionibacterium acnes belongs to the cutaneous flora of humans and i s rarely considered a pathogen in human diseases. It is a frequent con taminant in blood cultures; however, in some patients it has been iden tified as the causative agent of life-threatening infections. Within t he last years we have observed an abrupt increase in severe P. acnes i nfections which prompted us to study in detail the clinical and microb iological features, risk factors, and outcomes of these cases. In a re trospective review of microbiological records of 905 Propionibacterium isolates from a five-year period (1990-95), 70 were identified from 2 0 patients with clinical and microbiological evidence of a P. acnes in fection. The clinical syndromes included endocarditis (7 patients), po st-craniotomy infections (6 patients), arthritis and spondylodiscitis (4 patients), endophthalmitis (2 patients) and pansinusitis (1 patient ). The predominant predisposing conditions were previous surgery prece ding the infection from 2 weeks to 4 years and implantation of foreign bodies such as prosthetic heart valves, intraocular lenses and ventri culo-peritoneal shunts. Therapy consisted of intravenous antibiotics i n all cases and surgical procedures to remove infected tissue in eight een patients. The outcome was favorable in sixteen patients (80 percen t) who had a complete, recovery. These data confirm the pathogenic pot ential of P. acnes in late post-surgical infections, in particular aft er implantation of a foreign body, and suggest a combined therapeutic approach with intravenous antibiotics and surgical removal of the infe cted tissue.