Rare, post-periodontitis spondylodiscitis caused by Fusobacterium nucleatum in a patient with multiple sclerosis: challenge of diagnosis and treatment

Fusobacterium nucleatum-infected periodontitis promotes renal interstitial fibrosis in rats through the TGF-β/SMAD2/3 and β-catenin signaling pathways

OBJECTIVES

Periodontitis is associated with Fusobacterium nucleatum (F.n) infection. Although the colonization of renal tissue by F.n is well documented, its specific role in kidney disease has yet to be determined. This study aimed to investigate the potential association between F.n-induced periodontitis and renal interstitial fibrosis.

METHODS

The rat gingival sulcus was injected with F.n suspension, while the control group (NC) was injected with PBS. The levels of total protein (TP), albumin (ALB), creatinine, and urea nitrogen (BUN) in rat serum and/or urine were quantified using the appropriate kits. Renal interstitial fibrosis and epithelial-mesenchymal transition (EMT) were evaluated in rats using Masson staining, Periodic Schiff-Methenamine (PASM) staining, and immunohistochemical staining. The levels of fibrosis- and EMT-related proteins and the TGF-β/SMAD2/3 and β-catenin signaling pathways were determined using Western blot analysis. F.n in the kidney tissues was quantitatively determined using bacterial 16S rRNA technology.

RESULTS

Serum levels of TP, ALB, creatinine, and BUN were not significantly decreased in F.n-infected rats with periodontitis. The levels of creatinine and ALB in the urine were not statistically different between two groups. Masson and PASM staining showed that F.n-induced periodontitis could promote renal interstitial fibrosis in rats. The levels of collagen I, fibronectin (FN), vimentin, and α-SMA were upregulated in the kidney tissues of rats with F.n-induced periodontitis and in F.n-treated HK-2 cells. However, E-cadherin levels were reduced. F.n promoted renal interstitial and HK-2 cell fibrosis in rats by modulating the TGF-β/SMAD2/3 and β-catenin signaling pathways. F.n colonization increased renal interstitial fibrosis in rats.

CONCLUSION

F.n-induced periodontitis promoted EMT by activating the TGF-β/SMAD2/3 and β-catenin signaling pathways, thus promoting renal interstitial fibrosis in rats.

Isolated Fusobacterium nucleatum Growth in the Blood Culture of a Middle-Aged Man With Lumbar Discitis, Surrounding Psoas Abscesses, and an Inferior Vena Cava Thrombus

Pyogenic spinal infections (PSI) have an incidence of 0.5-2.2 cases per 100,000 population, though diagnosis can be delayed by up to three months. The incidence of Fusobacterium nucleatum bacteremia is rare, occurring in 0.22-0.34 cases per 100,000 population, whilst its implication in spinal infections is rarer still. A man in his 60s with a background of chronic lower back pain presented to the emergency department with a two-week history of worsening back pain associated with fever and difficulty voiding. He was initially managed as pyelonephritis due to the recent history of urinary tract infection (UTI) with fever and flank pain. However, there were radiculopathy and bilateral pain on hip flexion with reduced power on the right side. The light-touch sensation was reduced over the right hallux and distal L4 dermatome. These neurological deficits associated with deranged infective markers made a diagnosis of discitis plausible. Discitis and native vertebral osteomyelitis (NVO) should be suspected in patients reporting a fever and back pain of recent onset or increasing in severity. Once discitis was confirmed, the patient was subsequently tested for tuberculosis (TB) using a T-SPOT, human immunodeficiency virus (HIV), hepatitis B virus, and hepatitis C virus, with no positive findings, but in the days following, blood cultures yielded F. nucleatum. Guided by knowing the natural reservoirs in the body, establishing the source of F. nucleatum could be achieved through head and neck imaging and investigating the gastrointestinal tract for malignant or inflammatory processes.

Implementation of full-length 16S nanopore sequencing for bacterial identification in a clinical diagnostic setting

This study describes the implementation of 16S nanopore sequencing in a diagnostic lab for pathogen identification without prior enrichment. First, the universality of the test and taxonomic resolution was evaluated for 78 clinically relevant bacteria (69 known and 9 unknown bacterial cultures). Next, the diagnostic value of the test was evaluated based on clinical samples. It was shown that 16S sequencing can be used both for identification of unknown cultures and to find bacteria directly in the clinical sample without cultivation. All culture-positive samples (n=11) tested positive with 16S sequencing directly performed on the sample, but bacteria were found as well in 15/30 culture-negative samples. Pathogenic bacteria were found in a background of commensal flora, and even complex polymicrobial infections could be unraveled. This study demonstrates the feasibility of implementing 16S nanopore sequencing in a clinical diagnostic setting and demonstrates its value for the diagnosis of culture-negative and polymicrobial infections.

Vertebral osteomyelitis caused by Fusobacterium nucleatum with an associated asymptomatic liver abscess in an immunocompetent adult: a case report and literature review

Fusobacterium nucleatum rarely causes vertebral osteomyelitis or liver abscesses, and no reports exist of it concurrently causing vertebral osteomyelitis and pyogenic liver abscess. A 58-year-old woman with a history of periodontitis presented with worsening lumbago, left lower leg pain, numbness, and fever for a week. Physical examination indicated knocking pain at the L2-L3 levels with a psoas sign on the left side. A magnetic resonance image showed L2-S1 vertebral osteomyelitis and intervertebral discitis, with a left psoas major muscle abscess. Vertebral osteomyelitis caused by Staphylococcus aureus was suspected; blood cultures were obtained, and intravenous cefazolin was administered. Computed tomography, which was performed to detect disseminated foci, revealed a multilocular liver abscess. On day 4 of incubation, the anaerobic blood culture bottles were positive for characteristic filamentous gram-negative rods. The empiric antimicrobial therapy was changed to ampicillin/sulbactam. The isolate was identified as F. nucleatum based on 16S rRNA gene sequencing. The liver abscess was drained on day 12. Based on the antimicrobial susceptibility test results, the patient was treated with intravenous ampicillin/sulbactam for 4 weeks followed by oral amoxicillin/clavulanate for an additional 8 weeks and remained disease-free at the 1-year follow-up. Clinicians should consider F. nucleatum as the causative organism for vertebral osteomyelitis presenting with asymptomatic pyogenic liver abscess. The gold standard for identifying and diagnosing F. nucleatum infections is 16S rRNA gene sequencing, and gram staining helps determine appropriate antimicrobials.