Impact of altering gut microbiota metabolism on osteomyelitis severity in obesity-related type 2 diabetes

Staphylococcus aureus is an opportunistic pathogen causing osteomyelitis through hematogenous seeding or contamination of implants and open wounds following orthopedic surgeries. The severity of S. aureus-mediated osteomyelitis is enhanced in obesity-related type 2 diabetes (obesity/T2D) due to chronic inflammation impairing both adaptive and innate immunity. Obesity-induced inflammation is linked to gut dysbiosis, with modification of the gut microbiota by high-fiber diets leading to a reduction in the symptoms and complications of obesity/T2D. However, our understanding of the mechanisms by which modifications of the gut microbiota alter host infection responses is limited. To address this gap, we monitored tibial S. aureus infections in obese/T2D mice treated with the inulin-like fructan fiber, oligofructose. Treatment with oligofructose significantly decreased S. aureus colonization and lowered proinflammatory signaling post-infection in obese/T2D mice, as observed by decreased circulating inflammatory cytokines (TNF-α) and chemokines (IP-10, KC, MIG, MCP-1, and RANTES), indicating partial reduction in inflammation. Oligofructose markedly shifted diversity in the gut microbiota of obese/T2D mice mice, with notable increases in the anti-inflammatory bacterium, Bifidobacterium pseudolongum. Analysis of the cecum and plasma metabolome suggested polyamine production was increased, specifically spermine and spermidine. Oral administration of these polyamines to obese/T2D mice resulted in reduced infection severity similar to oligofructose supplementation, suggesting polyamines can mediate the beneficial effects of fiber on osteomyelitis severity. These results demonstrate the contribution of gut microbiota metabolites to the control of bacterial infections distal to the gut and polyamines as an adjunct therapeutic for osteomyelitis in obesity/T2D.

Fungal Infections of the Central Nervous System

Fungal infections within the central nervous system (CNS) occur more commonly in patients with immunosuppressive conditions but occasionally are diagnosed in immunocompetent patients as well. This may reflect the route of infection and the specific pathogen. Fungal infections resulting from hematogenous seeding are typically encountered in patients with profound and prolonged immunosuppression (including neutropenia); however, pathogens such as Cryptococcus gattii and some dimorphic fungi can also produce CNS disease in otherwise healthy persons. A common avenue of infection in immunocompetent patients is traumatic or nosocomial inoculation, including neurosurgical procedures, foreign body implants, and contaminated spinal fluid injections.

Micromonas micros Infection of a Prosthetic Hip Joint: A Case Report and Review of the Literature

Micromonas micros is an oral anaerobic Gram-positive coccus and is a commensal of the mouth, and it is rarely isolated in prosthetic joint infections (PJIs) and even less frequently related to a preceding dental procedure with eventual hematogenous seeding of the prosthetic joint. Here, we present a case of a 56-year-old male with a prosthetic hip joint who developed Micromonas micros prosthetic hip joint infection with symptoms starting a few days after a dental procedure and not having received periprocedural antibiotic prophylaxis. He recovered well with surgical intervention and antimicrobial therapy. We conducted a literature review of prosthetic hip joint infections caused by Micromonas micros as well as briefly discuss current guidelines on antibiotic prophylaxis in patients with prosthetic joints undergoing dental procedures and some knowledge gaps.

Hyperbaric oxygen for intracranial abscess

The term “intracranial abscess” (ICA) includes cerebral abscess, subdural empyema, and epidural empyema, which share many diagnostic and therapeutic similarities and, frequently, very similar etiologies. Infection may occur and spread from a contiguous infection such as sinusitis, otitis, mastoiditis, or dental infection; hematogenous seeding; or cranial trauma. In view of the high morbidity and mortality of ICA and the fact that hyperbaric oxygen therapy (HBO2) is relatively non-invasive and carries a low complication rate, the risk-benefit ratio favors adjunct use of HBO2 therapy in selected patients with intracranial abscess.

Late hematogenous seeding and infection of a femoropopliteal Omniflow II bypass

Introduction Omniflow II is promoted as an infection-resistant vascular graft. It is used to treat vascular graft infection; nevertheless, early graft infection has been reported. Report: A 71-year-old patient was treated with an Omniflow II bypass for a non-healing diabetic foot ulcer. Seven months postoperatively, late infection occurred secondary to hematogenous spread from a persistent foot infection. Conclusion We report on the first case of late infection of an Omniflow II vascular graft caused by hematogenous spread. Despite promising results of the Omniflow II graft in the treatment of vascular graft infection, late infection may not be avoided.

Independent evolution of cutaneous lymphoma subclones in different microenvironments of the skin

Mycosis fungoides (MF) is the most common cutaneous T-cell lymphoma. Lesions of MF are formed by hematogenous seeding the skin with polyclonal (clonotypically diverse) neoplastic T-cells which accumulate numerous mutations and display a high degree of mutational, intratumoral heterogeneity (ITH). A characteristic but poorly studied feature of MF is epidermotropism, the tendency to infiltrate skin epithelial layer (epidermis) in addition to the vascularized dermis. By sequencing the exomes of the microdissected clusters of lymphoma cells from the epidermis and the dermis, we found that those microenvironments comprised different malignant clonotypes. Subclonal structure witnessed the independent mutational evolution in the epidermis and dermis. Thus, the epidermal involvement in MF could not be explained by gradual infiltration from the dermis but was caused by a separate seeding process followed by a quasi-neutral, branched evolution. In conclusion, tissue microenvironments shape the subclonal architecture in MF leading to “ecological heterogeneity” which contributes to the total ITH. Since ITH adversely affects cancer prognosis, targeting the microenvironment may present therapeutic opportunities in MF and other cancers.

A Rare Case of Proximal Junctional Failure with Delayed Infection after Adult Spinal Deformity Surgery: A Report of Two Cases

Proximal junctional failure (PJF) is one of the most devastating complications that develop after adult spinal deformity (ASD) surgery. Here, we report 2 rare cases of PJF accompanied by delayed infection after ASD surgery with a review of the relevant literatures. Late-onset infection is an infrequent complication despite acute postoperative infection is common after posterior spinal instrumentation and fusion. Among them, delayed onset pyogenic spondylitis of the adjacent vertebra to the instrumented vertebrae is an extremely rare phenomenon. We do not have a clear explanation for this pathology. Since the delayed infections developed not in the fused segments but in the adjacent vertebra, the cause of the first case can be speculated as stimulation of low-virulent organisms to fester and hematogenous seeding and that of the second case as metal fretting and a sterile inflammatory response causing hematogenous microbial seeding, respectively. Additional studies on this phenomenon are warranted to elucidate the pathogenesis of this complication.

Fungal arthritis with adjacent osteomyelitis caused by Candida pelliculosa: a case report

Background Candida sp. osteoarticular infection is rare and most often due to hematogenous seeding during an episode of candidemia in immunocompromised patients. However, the diagnosis can be delayed in patients with subtle symptoms and signs of joint infection without a concurrent episode of candidemia. Case presentation A 75-year-old woman presented with a three-year history of pain and swelling of the left knee. Candida pelliculosa was detected from the intraoperative tissue when the patient had undergone left total knee arthroplasty 32 months ago, but no antifungal treatment was performed. One year after the total knee arthroplasty, C. pelliculosa was repeatedly isolated from the left knee synovial fluid and antifungal treatment comprising amphotericin B deoxycholate and fluconazole was administered. However, joint infection had extended to the adjacent bone and led to progressive joint destruction. The patient underwent surgery for prosthesis removal and received prolonged antifungal treatment with micafungin and fluconazole. Conclusions This case shows that C. pelliculosa, an extremely rare non-Candida albicans sp., can cause fungal arthritis and lead to irreversible joint destruction owing to delayed diagnosis and treatment.

Neurologic Deterioration, Instrumentation Failure, and Cervical Autofusion Secondary to Noncompliance following Reconstruction for Discitis

Pyogenic spondylodiscitis (PS) is an infection of the vertebral body, end plate, and intervertebral disc with potential to extend to surrounding structures, including the epidural space. Bacterial seeding to cause PS stems from three major pathways: hematogenous seeding, direct inoculation, and extension of adjacent tissue infection. Advanced cases have potential to cause structural instability and neurologic compromise, requiring aggressive surgical treatment. When the etiology of PS is hematogenous seeding secondary to intravenous drug use (IVDU), treatment becomes more complicated. Psychosocial factors and medical comorbidities often impact treatment options and patient compliance. We present a case of PS secondary to IVDU complicated by treatment noncompliance, resulting in need for 360° reconstructive surgery. After the patient had been immobilized in a halo fixator for 8 months due to failure to return for follow-up, an unintended C1–C2 autofusion was discovered, revealing the consequences of long-term halo use.

Lactobacillus acidophilus-Induced Endocarditis and Associated Splenic Abscess

Lactobacillus acidophilus is a rod-shaped, Gram-positive bacterium generally found in the normal flora of the oropharynx, gastrointestinal, and genitourinary tracts. It is commonly known as nonpathogen in the human body. Endocarditis due to Lactobacillus is rarely encountered and associated with impaired immunity. Splenic abscess is also an uncommon infection that classically results from endocarditis or another source of hematogenous seeding. Here, we present the case of bioprosthetic aortic valve endocarditis and associated splenic abscess caused by Lactobacillus acidophilus. The source of the Lactobacillus bacteremia should be investigated because of the risk of life-threatening conditions. Most of the time, identifying Lactobacillus species is challenging and can cause a delay in diagnosis and timely treatment. Especially in patients who have significant underlying clinical conditions, physicians should consider Lactobacillus species as a causative microorganism.