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

BACKGROUND

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).

HYPOTHESIS

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.

PATIENTS AND METHODS

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 analysed the presence of the Modic-like changes on the magnetic resonance imaging.

RESULTS

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. Further, there were no significant relationships identified between the clinical variables, including Modic alterations and positive cultures.

DISCUSSION

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.

[Role of the Aß1-42/Aß1-40 ratio in the concept 'Alzheimer's disease contributes to mild cognitive impairment']

INTRODUCTION

Evidence of cerebral amyloidosis, by altered levels of the peptide Aß1-42 or the Aß1-42/Aß1-40 ratio, is a necessary condition to accept the presence of Alzheimer's disease (AD), according to the 2018 criteria of the National Institute on Aging and Alzheimer's Association (NIA-AA 2018).

AIM

To calculate the diagnostic gain obtained from calculating the Aß1-42/Aß1-40 ratio with respect to the exclusive use of the peptide Aß42 to identify patients belonging to the 'Alzheimer's disease contributes to mild cognitive impairment (MCI)' group, according to NIA-AA 2018 criteria.

PATIENTS AND METHODS

Between April 2018 and April 2020, we included 62 patients with MCI, according to Petersen's 2006 criteria, who underwent lumbar puncture as part of the diagnostic process. Cerebrospinal fluid was analysed using the immunochemiluminescence methodology, which makes it possible to quantify core AD biomarkers in cerebrospinal fluid and the peptide Aß1-40.

RESULTS

Forty-two patients (67.7%) presented criteria supporting 'AD contributes to MCI'. The use of the Aß1-42/Aß1-40 ratio, compared to the exclusive use of Aß1-42 levels, represents a diagnostic gain of 19% (eight patients) to establish the presence of amyloidosis in the cerebrospinal fluid of these patients.

CONCLUSION

The calculation of the Aß1-42/Aß1-40 ratio is a clear diagnostic gain for identifying patients belonging to the 'AD contributes to MCI' group, and we therefore recommend its use, as reported in the most recent literature. To our knowledge, this is the first publication of its kind in Spanish.