Abstract
Overview
Propionibacterium species are members of the normal microbial flora of human skin and the mouth. A role for Propionibacterium acnes in the pathogenesis of acne has been debated for decades, but never adequately proven (Bojar & Holland, 2004). Serious infections due to P. acnes are rarely reported, but this bacterium is increasingly recognized as a cause of serious infections, such as endocarditis, prosthetic joint infection, endophthalmitis, osteomyelitis and central nervous system infections (Bruggemann, 2005). In such cases, an indwelling medical device such as a prosthetic heart valve, cerebrospinal fluid shunt or intraocular lens is often involved. Here, we review the clinical features of endocarditis caused by Propionibacterium species and the diagnostic difficulties frequently encountered with this pathogen. We illustrate some of these issues with our own experience of this condition and highlight an apparent predisposition of this low-grade pathogen to cause intracardiac abscesses and prosthetic valve dehiscence.
Review methodology
A prospectively collected database of all endocarditis cases seen at the General Infirmary at Leeds has been maintained since 1998, and this was used to identify patients with Propionibacterium endocarditis seen between January 1998 and December 2005. A literature search was carried out using the Pubmed and Medline databases with the search terms Propionibacterium, propionibacteria, endocarditis, infective endocarditis, P. acnes and P. granulosum. Further references were identified from the reference lists of papers identified. Any papers describing one or more cases of Propionibacterium endocarditis within the last 25 years with sufficient information to categorize the episode using modified Duke criteria were included (Li et al., 2000).
Review-derived data
A review of the world literature identified 28 papers describing 33 cases in sufficient detail. Clinical details are summarized in Table 1. The median age of affected patients was 48 years (range 1578) and 27 (81.8 %) of the patients were male. Twenty-six cases (78.8 %) were definite by Duke criteria and seven (21.2 %) were possible. Fever was the commonest presenting complaint, reported in 27 cases (81.8 %); lethargy and malaise were reported in 14 (42.4 %) and sweats or chills in 9 (27.2 %). Examination findings were limited: a murmur was reported in 15 (45.4 %), but in only four cases (12.1 %) were classical stigmata of infective endocarditis seen (e.g. Osler nodes, Janeway lesions, splinter haemorrhages, macular haemorrhage, etc.). Fourteen cases (42.4 %) involved native valves, 16 (48.5 %) involved prosthetic valves and three (9.1 %) were associated with other intracardiac prosthetic material (pacing wires in two cases and a Teflon patch in the third). Ten of the 14 (71.4 %) patients with native valve infection had an underlying cardiac factor predisposing to infection. In this group, the valves most commonly affected were the mitral and aortic valves, while those with prosthetic valves were more likely to have aortic valve involvement than mitral valve involvement, partly due to the pattern of the valves replaced. The infecting organism was P. acnes in 29 cases, Propionibacterium granulosum in three cases and an unspecified Propionibacterium species in the one remaining case. Intracardiac abscesses were commonly encountered, with Propionibacterium endocarditis occurring in 28.6 % of native valve infections and 52.9 % of prosthetic valve infections. Valve dehiscence was also a common finding in prosthetic valve infections, occurring in 52.9 % of cases. Valve replacement surgery was undertaken in 70.6 % of all prosthetic infections and 64.3 % of native valve infections.