Are Cutibacterium acnes present at the end of primary shoulder prosthetic surgeries responsible for infection?
Cutibacterium are commonly isolated both in superficial and deep tissues after primary shoulder arthroplasty although the clinical significance of these positive cultures is yet to be defined.
Antibiotic prophylaxis and standard skin preparation are not universally effective in eradicating Cutibacterium in shoulder surgery. It is estimated that 20% of primary shoulder arthroplasties end with the presence of Cutibacterium both in superficial and in deep tissues.
Cutibacterium can create microcolonies and participate in the "race to the implant surface" with biofilm formation leading to arthroplasty failure months or years after.
These authors sought to investigate whether the Cutibacterium present at the end of a primary shoulder arthroplasty could be responsible for shoulder arthroplasty infection. In each of 156 patients 5 to 12 tissue samples were cultured for Cutibacterium. DNA was extracted from the Cutibacterium isolates and analyzed using whole genome sequencing (WGS).
In twenty-seven patients (17%), Cutibacterium were present at the end of surgery. Patients were followed for a minimum of two years. None of the patients with negative cultures at the time of arthroplasty developed prosthetic joint infection.
Two of these patients developed a Cutibacterium periprosthetic shoulder infection at 6 and 4 months after the arthroplasty. Both were 75-year-olds and males, yielding an infection rate of 7.7% for male. In both patients, the only microorganism present in all cultures was the Cutibacterium.
For the first patient, 12 cultures were obtained at the index surgery and eight of them turned to be
positive for Cutibacterium. At revision surgery, nine cultures were obtained and eight were positive for Cutibacterium.
For the second patient, five cultures were obtained at the index surgery and only one turned to be positive for Cutibacterium. At revision surgery, seven cultures were obtained and four were positive
for Cutibacterium.
In both patients, the same Cutibacterium strain was identified at the end of the primary surgery and during revision surgery for infection: WGS of Cutibacterium isolates from the revision surgeries were essentially identical to the isolates from the primary-surgery (99.89% similarity).
The genomic proximity between primary-surgery and revision-surgery isolates of Cutibacterium suggests that periprosthetic shoulder infections result from preexisting bacteria in the host rather than from contamination after surgery or selection of resistant strains.
Genotyping of multiple isolates at the time of implantation during shoulder surgery can be a means of
assessing the Cutibacterium burden inoculated at the time of surgery.
In the future, WGS will be useful in confirming whether infections are caused by a single pathogenic clone of Cutibacterium and in distinguishing infection, polyclonal infection, and contamination.
Comment: Two other interesting findings is this study are
(1) the onset of the two infections were delayed four and six months after surgery and
(2) of the 27 patients who had positive cultures for Cutibacterium at the end of the arthroplasty surgery, only 2 were noted to have developed a periprosthetic infection. This suggests that the other 25 patients had sufficient host defenses to manage the presence of Cutibacterium in the wound without manifesting symptoms of infection.
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Shoulder arthritis - what you need to know (see this link) The smooth and move for irreparable cuff tears (see this link) The total shoulder arthroplasty (see this link). The ream and run technique is shown in this link. The cuff tear arthropathy arthroplasty (see this link). The reverse total shoulder arthroplasty (see this link).
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