Sunday, May 15, 2016

Is the Propionibacterium in my skin today the same that was there previously?

Temporal Stability of the Human Skin Microbiome.

This article addresses a topic important for shoulder surgeons and their patients. Propionibacterium is the most common organism found at surgical revision of failed shoulder surgery. The source of these organisms is the patient's skin (dermal sebaceous glands). These investigators found that the strains of skin microbes (bacteria, fungi, and viruses) are shaped by the host's physiology and are stable over time in spite of the external exposures shown in this cartoon.

Their abstract: "Biogeography and individuality shape the structural and functional composition of the human skin microbiome. To explore these factors' contribution to skin microbial community stability, we generated metagenomic sequence data from longitudinal samples collected over months and years. Analyzing these samples using a multi-kingdom, reference-based approach, we found that despite the skin's exposure to the external environment, its bacterial, fungal, and viral communities were largely stable over time. Site, individuality, and phylogeny were all determinants of stability. Foot sites exhibited the most variability; individuals differed in stability; and transience was a particular characteristic of eukaryotic viruses, which showed little site-specificity in colonization. Strain and single-nucleotide variant-level analysis showed that individuals maintain, rather than reacquire, prevalent microbes from the environment. Longitudinal stability of skin microbial communities generates hypotheses about colonization resistance and empowers clinical studies exploring alterations observed in disease states."

Both P. acnes and Propionibacterium phage (the virus associated with it) are abundant in sebaceous sites (such as the shoulder, chest and back). They observed a strong anti correlation in sebaceous communities that contain both P. acnes and its phage; this anti-correlation together with the observed phage-host dynamics over time suggests antagonism (see the green graph below). Note the abundance of both the Propi phage and Propi in the sebaceous areas.

They found that individuals have distinct microbial SNV signatures that are stable over time across body sites for time periods of a year (see figure below). Temporal stability, short- or long-term, surpassed the similarity between individuals, indicating that P. acnes stability likely derives from maintaining an individual’s strains over time and less from the acquisition of new strains from the environment or other individuals. "B" shows the relative abundance plots for different strains of Propi for the chest of three different individuals.

The authors surmise that despite the continuous perturbation that human skin undergoes in daily life and in the absence of major perturbations, dominant characteristics of skin microbial communities would remain stable indefinitely as is the case for gut communities. However, extrinsic perturbations (probiotics, prebiotics, antimicrobials, antibiotics, long-term environmental relocations, diet, immunosuppression, illness, or the occurrence of disease) can alter the skin microbiota. Do these changes make a person more or less likely to acquire Propionibacterium in and around their shoulder arthroplasty components?

Can the Propi Phage virus be used to treat Priopi infection, as suggested by Ian Whitney (see link)(one of our past shoulder fellows)?