Characterization of Staphylococcus caprae Clinical Isolates Involved in Human Bone and Joint Infections, Compared with Goat Mastitis Isolates.

Staphylococcus caprae is an emerging microorganism in human bone and joint infections (BJI). The aim of this study is to describe the features of S. caprae isolates involved in BJI (H for human) compared with those of isolates recovered in goat mastitis (A for animal). Fourteen isolates of each origin were included. Identifications were performed using a Vitek 2 GP ID card, tuf gene sequencing, and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) Vitek MS. Molecular typing was carried out using pulsed-field gel electrophoresis (PFGE) and DiversiLab technology. The crystal violet method was used to determine biofilm-forming ability. Virulence factors were searched by PCR. Vitek MS technology provides an accurate identification for the two types of isolates compared to that of gold-standard sequencing (sensitivity, 96.4%), whereas the Vitek 2 GP ID card was more effective for H isolates. Molecular typing methods revealed two distinct lineages corresponding to the origin despite few overlaps: H and A. In our experimental conditions, no significant difference was observed in biofilm production ability between H and A isolates. Nine isolates (5 H isolates and 4 A isolates) behaved as weak producers while one A isolate was a strong producer. Concerning virulence factors, the autolysin atlC and the serine aspartate adhesin (sdrZ) genes were detected in 24 isolates (86%), whereas the lipase gene was always detected, except in one H isolate (96%). The ica operon was present in 23 isolates (82%). Fibrinogen-binding (fbe) or collagen-binding (cna) genes were not detected by using primers designed for Staphylococcus aureus or Staphylococcus epidermidis, even in low stringency conditions. Although S. caprae probably remains underestimated in human infections, further studies are needed to better understand the evolution and the adaptation of this species to its host.

Propionibacterium acnes, an emerging pathogen: from acne to implant-infections, from phylotype to resistance.

Propionibacterium acnes colonizes the lipid-rich sebaceous glands of the skin. This preferential anaerobic bacterium is easily identified if cultures are prolonged. It is involved in the inflammation process of acne, but until recently, it was neglected in other clinical presentations. Despite a reported low virulence, the new genomic, transcriptomic, and phylogenetic studies have allowed better understanding of this pathogen's importance that causes many chronic and recurrent infections, including orthopedic and cardiac prosthetic, and breast or eye implant-infections. These infections, facilitated by the ability of P. acnes to produce a biofilm, require using anti-biofilm active antibiotics such as rifampicin. The antibiogram of P. acnes is not systematically performed in microbiology laboratories because of its susceptibility to a wide range of antibiotics. However, in the last 10 years, the rate of antibiotic-resistant bacteria has increased, especially for macrolides and tetracyclines. Recently, rpoB gene mutations conferring resistance to rifampicin have been also reported. Thus in case of a biofilm growth mode, the therapeutic strategy should be discussed, according to the resistance phylotype and phenotype so as to optimize the treatment of these severe infections.

First report of a hip prosthetic and joint infection caused by Lactococcus garvieae in a woman fishmonger.

We describe the first case of hip prosthetic infection due to Lactococcus garvieae. The patient, a 71-year-old woman fishmonger, developed a hip infection 7 years after total hip arthroplasty. The origin of infection was possibly due to the manipulation or intake of seafood or fish contaminated with Lactococcus garvieae.