These authors nicely review the relationship of Cutibacterium acnes to periprosthetic infections (PJI) of the shoulder.
They point out that PJI caused by C acnes rarely manifests with the same clinical, laboratory, or imaging features associated with infections from more virulent organisms.
They reference the 2018 International Consensus Meeting on Musculoskeletal Infection: Research Priorities from the General Assembly Questions, which include following statement:
"Two positive cultures from the same joint identifying the same organism by tissue or fluid remain as one of the major criteria for the diagnosis of PJI. "
They reference the 2018 International Consensus Meeting on Musculoskeletal Infection: Research Priorities from the General Assembly Questions, which include following statement:
"Two positive cultures from the same joint identifying the same organism by tissue or fluid remain as one of the major criteria for the diagnosis of PJI. "
The authors point out that because Cutibacterium is a commensal organism of normal human skin, its presence in wounds many not incite the inflammatory reaction or other obvious signs usually associated with infection from other organisms. If one accepts the definition of an infection as "bacteria doing harm", it is evident that positive cultures in the presence of an otherwise normal shoulder do not meet the definition. However, because of the relatively slow growth rate of Cutibacterium, infections from these organisms may not be recognized until years after the index arthroplasty; furthermore, the evidence of "harm" may be subtle, such as the unexplained onset of pain and stiffness after months or years of excellent post-arthroplasty function.
Other methods for identifying organisms in specimens obtained at the time of revision arthroplasty include 16S rRNA sequencing and next generation sequencing (NGS). While these techniques often reveal nucleotides from other bacteria, the organism they most commonly identify in failed arthroplasties is Cutibacterium. Interestingly, NGS may not detect Cutibacterium in specimens that are culture positive for this organism. Furthermore, NGS may suggest the presence of organisms that are not commonly cultured from shoulder infections, such as as Acinetobacter radioresistens. Acinetobacter are aerobic Gram-negative coccobacilli commonly present in soil and water as free-living saprophytes. Some species are common commensals of skin, throat and secretions of healthy people. They are also commonly cultured from domestic water supplies. There are no reported cases of A. radioresistens infections of the shoulder.
Current evidence suggests that
(1) Cutibacterium is present in the dermis of many individuals having shoulder arthroplasty
(2) These bacteria are not eliminated by current prophylactic measures, and, therefore can be introduced into the shoulder arthroplasty wound at the time of surgery.
(3) Cutibacterium are the most commonly organisms recovered from specimens harvested at the time of surgical revision of a failed arthroplasty.
(4) Whether these bacteria "do harm" may depend on a number of factors including (a) the virulence of the organism, (b) the size of the inoculum, (c) the type of implant (n.b. that titanium alloys favor the formation of a Cutibacterium biofilm), (d) the host response to the bacteria inoculated into the wound, and (e) the surgeon's use of antibacterial measures (irrigation, topical antibiotics),
(5) The clinical presentation of a Cutibacterium infection is typically delayed for months or years after the index arthroplasty.
(6) The clinical presentation of a Cutibacterium infection is typically subtle, such as the unexplained onset of pain and stiffness after a "honeymoon" of good function following a shoulder arthroplasty.
(7) Multiple deep tissue and explant cultures may be required to detect the presence of cutibacterium.
(8) Culture results may be best characterized in terms of the load of bacteria in the specimen, rather than simply characterized as "positive" or "negative".
(9) We still have a lot to learn.
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To see our new series of youtube videos on important shoulder surgeries and how they are done, click here.
Use the "Search" box to the right to find other topics of interest to you.
You may be interested in some of our most visited web pages arthritis, total shoulder, ream and run, reverse total shoulder, CTA arthroplasty, and rotator cuff surgery as well as the 'ream and run essentials'
