Comparison of genomic DNA sequencing to anerobic cultures to detect efficacy of hydrogen peroxide at reducing cutibacterium acnes bacterial burden during primary shoulder arthroplasty

Background

The purpose of this investigation is to compare Cutibacterium acnes diagnosis using culturing vs. genomic DNA sequencing (NextGen) at various timepoints and locations during primary total shoulder arthroplasty. Additionally, we intend to compare the effects of hydrogen peroxide on standard culture technique results with genomic DNA sequencing.

Methods

A prospective diagnostic study of 40 patients undergoing primary total shoulder arthroplasty was performed. Intraoperatively, 4 tissue samples were collected per patient: subdermal skin edge following initial skin incision, subdermal skin edge following hydrogen peroxide soak for 5 minutes, glenohumeral joint capsule, and subdermal skin edge prior to wound closure. Each tissue specimen was collected twice (one for culture analysis and the other for genomic (NextGen) DNA sequencing analysis) for a total of 8 specimens per patient and 320 tissue specimens in total. All anaerobic cultures were held for 14 days. Each culture plate was divided into quadrants and the amount of growth was quantified. Tissue samples were collected for genomic sequencing DNA analysis. Genomic sequencing results provided relative percentage of bacteria for each specimen detected.

Results

There were 18/40 males (45%) and no postoperative complications. Average age was 72.2 ± 11.8. Overall, 18% (29/160) of standard anaerobic cultures were positive for C. Acnes and 26% (942/160) were positive with genomic (Nextgen) DNA sequencing. When comparing the NextGen results with anaerobic standard cultures, there was a calculated negative predictive value of 85.6% and positive predictive value of 28.6%. Sensitivity of the NextGen was 41.4% and specificity was 77.1%. Bacterial culture rates did not significantly change from the beginning to the end of surgery as demonstrated on standard culturing and the NextGen analysis (P > .05). After treatment with hydrogen peroxide, the standard culturing technique showed no significant difference between the samples; however, there was a significant increase in bacterial burden (12.4%) noted with NextGen analysis (P = .0147).

Conclusion

NextGen culturing is a novel technique to help identify shoulder prosthetic joint infections. These results show that, NextGen is better at identifying the absence of infection, but has a high false positive rate indicative of its ability to identify contaminants as compared to standard anaerobic culturing methods. The increase in bacterial burden after peroxide treatment noted with NextGen could also be secondary to the test’s increased ability to identify both living and dead bacterial pathogens.