New contributions on chronic low back pain: disc infection or contaminated cultures?

There is controversy about the likely infectious origin of chronic low back pain, because it has been suggested the possibility of a relationship with infection by Cutibacterium acnes (C. acnes). The aim of this study is to compare four methods to determine the presence of a likely infection caused by C. acnes in surgical disc samples. This work is a cross-sectional observational study in which there are included 23 patients with microdiscectomy indication. Disc samples were taken during surgery and analysis was done by culture, Sanger sequencing, next-generation sequencing (NGS), and real-time PCR (qPCR). Furthermore, clinical data collection was conducted, and it was analyzed the presence of the Modic-like changes on the magnetic resonance imaging. In 5 of the samples from among the 23 patients (21.7%), C. acnes was isolated by culture. However, in none of the samples could its genome be detected through Sanger sequencing, the less sensitive method. Only the qPCR and NGS were able to detect very few copies of the genome of this microorganism in all the samples, with no significant quantitative differences being observed between the patients in whom isolation of the microorganism by culture was evident or not. Furthermore, there were no significant relationships identified between the clinical variables, including Modic alterations and positive cultures. The most sensitive methods to the detect C. acnes were NGS and qPCR. The data obtained do not suggest association between the presence of C. acnes and the clinical process and support the hypothesis that C. acnes is found in these samples only because it is a contamination from the skin microbiome.