Propionibacterium avidum as an Etiological Agent of Prosthetic Hip Joint Infection

Abstract

Propionibacterium acnes is well-established as a possible etiologic agent of prosthetic joint infections (PJIs). Other Propionibacterium spp. have occasionally been described as a cause of PJIs, but this has not previously been the case for P. avidum despite its capacity to form biofilm. We describe two patients with prosthetic hip joint infections caused by P. avidum. Both patients were primarily operated with an anteriorly curved skin incision close to the skin crease of the groin, and both were obese. Initial treatment was performed according to the DAIR procedure (debridement, antibiotics, and implant retention). In case 1, the outcome was successful, but in case 2, a loosening of the cup was present 18 months post debridement. The P. avidum isolate from case 1 and two isolates from case 2 (obtained 18 months apart) were selected for whole genome sequencing. The genome of P. avidum obtained from case 1 was approximately 60 kb larger than the genomes of the two isolates of case 2. These latter isolates were clonal with the exception of SNPs in the genome. All three strains possessed the gene cluster encoding exopolysaccharide synthesis. P. avidum has a pathogenic potential and the ability to cause clinically relevant infections, including abscess formation, in the presence of foreign bodies such as prosthetic joint components. Skin incision in close proximity to the groin or deep skin crease, such as the anteriorly curved skin incision approach, might pose a risk of PJIs by P. avidum, especially in obese patients.

Conflict of interest statement

Competing Interests: Co-author Holger Brüggemann is a PLOS ONE Editorial Board member. This does not alter the authors’ adherence to PLOS ONE Editorial policies and criteria.

Figures

Fig 1. Anteriorly curved skin incision approach.

Case 1 left hip and. Red line indicates the anterior skin incision.

Fig 2. Anteriorly curved skin incision approach.

Case 2 right hip. Red line indicates the anterior skin incision.

Fig 3. Genome comparison of P. avidum and other cutaneous Propionibacteria.

P. avidum strain T13 was used as the reference genome. The most inner rings represent GC content and GC skew variation. Other P. avidum genomes (rings from inside to outside) are added according to their similarity to the reference genomes, i.e. T15 is most similar and HGH0353 is most dissimilar to T13. The comparison of P. avidum genomes with representative genomes of P. acnes/P. humerusii/P. granulosum shows overall genome synteny but also revealed P. avidum-specific genomic regions. These islands are numbered (1–20); gene content of the islands is shown in Table A1 in S1 File. Island 14 is the locus encoding EPS biosynthesis. The BRIG program was used to generate the figure.

Fig 4. A phylogenetic analysis of sequenced P. avidum strains and their relation to other cutaneous Propionibacteria.

The analysis is based on the shared core genome of the depicted organisms. T13, T14, and T15 cluster closely not only with each other, but also with strain 44067 (14), another clinical isolate from an abscess. Some strains (KPL2000, KPL2005, KPL1852, KPL1838) are currently not correctly assigned to P. avidum in the public databases. The population of P. avidum can be divided into three (phylogenetic) clusters: cluster A: T13, T14, T15, 44067; cluster B: ATCC25577, KPL2000, KPL2005, TM16; cluster C: KPL1852, KPL1838). Their gene content differences are shown in Table B1-3 in S2 File.