Myositis and Myonecrosis

Understanding Orthopaedic Infections: A Conceptual Approach

Background

Memorizing mounds of facts without having an effective conceptual framework to store them is often an unsuccessful learning style because memory frequently fails without understanding. To accomplish this goal, we offer a framework of ideas called "concept maps". Of the many strategies for metacognition (that is, thinking about thinking), concept mapping is proven to improve meaningful and independent learning. We used this approach to guide understanding of common orthopaedic infections. This paper is not meant to serve as an approach on how to treat, but rather as a storage system with the ability to assist in understanding orthopaedic infections.

Methods

Concept maps are constructed using information from over 30 sources of orthopaedic or infectious disease literature. The sequential levels of each concept map are referred to as levels of hierarchy. Boxes of each level of hierarchy are designed to be a point of differentiation between a similar concept. Branches form lower levels of hierarchy to further divide specific concepts.

Results

5 concept maps were constructed. One map is an overview of all concepts, and the key concept for each of the following map are as follows: osteomyelitis, synovial infection, myositis, and foreign material infection.

Conclusion

A conceptual approach is a way of learning material in a manner that allows effective storage and retrieval. This approach will ultimately lead to a better understanding of orthopaedic infections.

Musculoskeletal infections through direct inoculation

Musculoskeletal infections consist of different clinical conditions that are commonly encountered in daily clinical settings. As clinical findings and even laboratory tests cannot always be specific, imaging plays a crucial role in the diagnosis and treatment of these cases. Musculoskeletal infections most commonly occur secondary to direct inoculation into the skin involuntarily affected by trauma, microorganism, foreign bodies, or in diabetic ulcers; direct infections can also occur from voluntary causes due to surgery, vaccinations, or other iatrogenic procedures. Hematogenous spread of infection from a remote focus can also be a cause for musculoskeletal infections. Risk factors for soft tissue and bone infections include immunosuppression, old age, corticosteroid use, systemic illnesses, malnutrition, obesity, and burns. Most literature discusses musculoskeletal infections according to the diagnostic tools or forms of infection seen in different soft tissue anatomical planes or bones. This review article aims to evaluate musculoskeletal infections that occur due to direct inoculation to the musculoskeletal tissues, by focusing on the traumatic mechanism with emphasis on the radiological findings.

Otogenic Enterobacter cloacae meningitis complicated with pneumocephalus

Pneumocephalus refers to a pathologic collection of gas within the cranial cavity and is mostly caused by head trauma and neurosurgical procedures. Spontaneous nontraumatic pneumocephalus is a very rare condition. We herein report an unusual case of community-acquired bacterial meningitis with a combination of acute otitis media, Enterobacter cloacae, and nontraumatic pneumocephalus. A 75-year-old woman presented with fever, mental change, and neck stiffness. Brain imaging demonstrated pneumocephalus and fluid collection in the left mastoid air cells. E. cloacae was isolated from both blood and otorrhea cultures, and the patient was successfully treated with intravenous ceftazidime for 3 weeks. Although E. cloacae is a very rare cause of community-acquired bacterial meningitis in adults, it should be considered as a possible pathogen in otogenic meningitis complicated with pneumocephalus.

Under the Skin: A Case Series of Clostridium sordellii Necrotizing Soft Tissue Infections in Patients Who Inject Drugs

Clostridium sordellii has been well-associated as a cause of obstetric infections but is a less commonly recognized organism of necrotizing skin and soft tissue infections (NSTI). C. sordelli infections are rare with only 14 cases reported in the literature to date. These infections are often associated with profound septic shock and the mortality rate remains high. We report four patients who presented with C. sordellii NSTI over a period of two years at an academic medical center. Notably, injection drug use was the main risk factor for infection in these patients. Appropriate management of C. sordellii NSTI necessitates a combination of antibiotics and emergent surgical intervention. However, despite these efforts, the mortality rate remains high, with three of the four patients dying. Clinicians should consider NSTI in the differential diagnosis when evaluating skin and soft tissue infections in people who inject drugs. Furthermore, it is imperative to educate patients who engage in injection drug use on the potential risks associated with NSTI and inform them of warning signs that warrant immediate medical attention. The devastating consequences of C. sordellii-associated NSTI in this vulnerable population can be mitigated by enhancing awareness and facilitating early intervention.

Spontaneous myonecrosis with pyomyositis in a young male with type 2 diabetes mellitus: A case report

Diabetic myonecrosis is a rare complication of poorly controlled diabetes mellitus which commonly affects the thigh and is managed conservatively. Spontaneous ischemic necrosis of muscle is noted without a reduction in vascular supply. Pyomyositis caused by Staphylococcus aureus infection is another rare complication. Atypical presentation of myonecrosis and pyomyositis can occur in the form of simultaneous or sequential involvement of multiple muscle groups. We present a rare case of myonecrosis with pyomyositis in a 39-year-old male patient with a background of type 2 diabetes mellitus who presented with a 5-day history of worsening pain of the right thigh radiating to the right ankle, associated with groin swelling and fever. It is important for clinicians to have a low threshold of suspicion of this rare condition due to the other diverse and similar diagnoses, as well as to prevent further complications and morbidity.

Heterologous Immunity Between SARS-CoV-2 and Pathogenic Bacteria

Heterologous immunity, when the memory T cell response elicited by one pathogen recognizes another pathogen, has been offered as a contributing factor for the high variability in coronavirus disease 2019 (COVID-19) severity outcomes. Here we demonstrate that sensitization with bacterial peptides can induce heterologous immunity to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) derived peptides and that vaccination with the SARS-CoV-2 spike protein can induce heterologous immunity to bacterial peptides. Using in silico prediction methods, we identified 6 bacterial peptides with sequence homology to either the spike protein or non-structural protein 3 (NSP3) of SARS-CoV-2. Notwithstanding the effects of bystander activation, in vitro co-cultures showed that all individuals tested (n=18) developed heterologous immunity to SARS-CoV-2 peptides when sensitized with the identified bacterial peptides. T cell recall responses measured included cytokine production (IFN-γ, TNF, IL-2), activation (CD69) and proliferation (CellTrace). As an extension of the principle of heterologous immunity between bacterial pathogens and COVID-19, we tracked donor responses before and after SARS-CoV-2 vaccination and measured the cross-reactive T cell responses to bacterial peptides with similar sequence homology to the spike protein. We found that SARS-CoV-2 vaccination could induce heterologous immunity to bacterial peptides. These findings provide a mechanism for heterologous T cell immunity between common bacterial pathogens and SARS-CoV-2, which may explain the high variance in COVID-19 outcomes from asymptomatic to severe. We also demonstrate proof-of-concept that SARS-CoV-2 vaccination can induce heterologous immunity to pathogenic bacteria derived peptides.

Emergency physician-performed bedside ultrasound of pyomyositis

Point-of-care ultrasound (POCUS) is an indispensable tool for emergency physicians in the rapid bedside diagnosis of skin and soft tissue infections. The utility of POCUS for the differentiation of cellulitis and subcutaneous abscess is well established; however, there is a paucity of studies highlighting POCUS as a first-line imaging approach for pyomyositis, an uncommon skeletal muscle infection and/or intramuscular abscess formation requiring emergent diagnosis. This report describes a case in which emergency physician-performed POCUS led to the early detection and timely management of pyomyositis in the emergency department.