"Are we barking up the wrong tree? Too much emphasis on Cutibacterium acnes and ignoring other pathogens"- a study based on next-generation sequencing of normal and diseased discs.

BACKGROUND: The majority of literature on bacterial flora in the disc stands disadvantaged in utilizing traditional culture methods and targeting a single bacterium, Cutibacterium acnes. PURPOSE: Our objective was to document the diversity in the bacterial flora between normal and degenerated discs for shortlisting potential pathogens using next-generation genomic tools. STUDY DESIGN: Experimental case-control study. METHODS: Researchers employed 16S metagenome sequencing to profile bacterial diversity in magnetic resonance imaging normal healthy discs from brain-dead organ voluntary donors (n=20) and 40 degenerated disc samples harvested during surgery (Modic [MC]=20 and non-Modic [NMC]=20). The V3-V4 region was amplified using universal bacterial primers 341F and 806R, and the libraries were sequenced using Illumina NovoSeq 6000 platform. Statistical significance was set at bacteria with a minimum of 100 operational taxonomic unit (OTU) and present in at least 70% of the samples. The quality check-filtered reads were processed using the QIIME-2 pipeline. The OTU clustering and taxonomic classification were carried out for the merged reads using the Greengenes/SILVA reference database. Validation was done by identification of bacterial metabolites in samples using the liquid chromatography-mass spectrometry approach. RESULTS: Abundant bacteria differing widely in diversity, as evidenced by Alfa and Beta diversity analysis, were present in all control and degenerative samples. The number of bacterial genera was 27 (14-gram-positive: 13-gram-negative) in the control group, 23 (10-gram-positive: 11-gram-negative) in the Modic group, and 16 (11-gram-positive: 5-gram-negative) in the non-Modic group. In the Modic group, gram-negative bacteria OTUs were found to be predominant (more than 50% of the total bacteria identified), whereas in control and non-Modic groups the OTUs of gram-positive bacteria were predominant. Species-level analysis revealed an abundance of opportunistic gram-negative pathogens like Pseudomonas aeruginosa, Sphingomonos paucibacillus, and Ochrobactrum quorumnocens in the discs with Modic changes, more than in non-Modic discs. The presence of bacterial metabolites and quorum-sensing molecules like N-decanoyl-L-homoserine lactone, 6-hydroxynicotinic acid, 2-aminoacetophenone, 4-hydroxy-3-polyprenylbenzoate, PE (16:1(9Z)/18:0) and phthalic acid validated the colonization and cell-cell communication of bacteria in disc ruling out contamination theory. Cutibacterium acnes was not the predominant bacteria in any of the three groups of discs and in fact was in the 16th position in the order of abundance in the control discs (0.72%), seventh position in the Modic discs (1.41%), and 12th position (0.53%) in the non-Modic discs. CONCLUSION: This study identified a predominance of gram-negative bacteria in degenerated discs and highlights that Cutibacterium acnes may not be the only degeneration-causing bacteria. This may be attributed to the environment, diet, and lifestyle habits of the sample population. Though the study does not reveal the exact pathogen, it may pave the way for future studies on the subject. CLINICAL SIGNIFICANCE: These findings invite further investigation into causal relationships of bacterial profile with disc degeneration phenotypes as well as phenotype-driven clinical treatment protocols.

Spinal Hypertrophic Pachymeningitis Causing Thoracic Myelopathy in a Patient of Takayasu Arteritis: A Case Report.

CASE: A 52-year-old man presented with thoracic myelopathy, and his magnetic resonance imaging (MRI) was suggestive of T1-T4 hypertrophic-pachymeningitis. Incidentally, circumferential thickening of the infra-renal abdominal aorta and right common iliac artery was seen, which along with the findings in a contrast computed tomography was consistent with Takayasu arteritis (TA). The patient underwent T1-T4 laminectomy, thinning of dura, biopsy, and steroid therapy. At the 1-year follow-up, he was asymptomatic and MRI revealed resolution of the lesion. CONCLUSION: This is the first report describing an association between TA and hypertrophic spinal pachymeningitis, emphasizing the unusual neurological manifestation of myelopathy and complete resolution of symptoms with timely and appropriate intervention.

Macrodystrophia Lipomatosa of Thoracic Spine Causing Progressive Neurodeficit: A Case Report and Review of Literature.

CASE: We report the first case of a 21-year-old male patient with macrodystrophia lipomatosa (MDL), with local gigantism involving the thoracic spine and progressively worsening neurodeficit. Imaging studies revealed fatty infiltration and hypertrophied intercostal nerves, dextroscoliosis, osseous hypertrophy between C4 and T2, and severe canal stenosis at the T4 to T5 level secondary to lamino-facetal hypertrophy. He underwent debulking of the lesion and posterior instrumented decompression in a staged manner. His neurodeficit improved postoperatively and was ambulant without support at the end of the 2-year follow-up. CONCLUSION: Surgery in patients with MDL is technically challenging and fraught with complications such as neurological deficit and significant blood loss.