Mediastinitis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Anthony Gallo, B.S. [2]

Mediastinitis is inflammation or infection of the tissues in the mid-chest, or mediastinum.^[1] This disorder is rare, but is most often observed among patients following chest surgery or endoscopy. Mediastinitis may occur at any age.^[2] It may be classified according to cause into 2 groups: acute or chronic (sclerosing or fibrosing). Acute mediastinitis is usually bacterial and due to rupture of organs in the mediastinum. Chronic sclerosing (or fibrosing) mediastinitis, while potentially serious, is caused by a long-standing inflammation of the mediastinum, leading to growth of acellular collagen and fibrous tissue within the chest and around the central vessels and airways. Life threatening causes of mediastinitis include esophageal perforation. Common causes of mediastinitis include trauma, beta-hemolytic streptococcus, forceful or constant vomiting, and median sternotomy. If left untreated, fibrosing mediastinitis may progress to sepsis and subsequently, death. The presence of mediastinitis among patients following chest surgery is observed to have a particularly poor prognosis; there is a serious risk of mortality.^[3] Common complications of mediastinitis include sepsis and spread of the infection. Symptoms of mediastinitis include chest pain, malaise, and shortness of breath.^[4] Common physical examination findings of mediastinitis include clinical signs of sepsis, tachycardia, and tachypnea.^[5] CT scan may be diagnostic of mediastinitis. On CT scan, findings suggestive of mediastinitis include the presence of calcified mediastinal mass. The mainstay of therapy in acute mediastinitis secondary to cardiothoracic surgery includes clindamycin and ceftriaxone. The preferred regimen for preoperative prophylaxis against acute mediastinitis includes either a second generation cephalosporin or vancomycin. Aggressive surgical debridement is recommended among patients with descending necrotizing mediastinitis.

Chronic mediastinitis was first described by Dr. Thomas T. Whipham, MD, a British physician, in 1899.^[6]

Mediastinitis may be classified according to cause into 2 groups: acute or chronic (sclerosing or fibrosing).^[7] Additionally, acute mediastinitis may be classified according to the cause of the disease.^[8]

Mediastinitis is the inflammation or infection of the mediastinum.^[1] The pathogenesis of the infection remains unknown; radiographic, serologic, and/or histopathologic evidence of prior Histoplasma capsulatum infection, histoplasmosis, or chronic granulomatous disease is always observed.^[9] Additionally, mediastinitis may also present as the result of Staphylococcus aureus or Staphylococcus epidermidis infection following chest surgery.^[10]

Common causes of mediastinitis include bacterial and fungal infections, including group A beta-hemolytic streptococci, Mycobacterium tuberculosis, and Histoplasma capsulatum. ^[11]

Mediastinitis must be differentiated from other diseases that cause fever and chest pain, such as myocardial infarction, pneumothorax, and pneumonia.^[12]

The most potent risk factor for mediastinitis is recent chest surgery. Other risk factors include recent endoscopy, smoking, and obesity.^[2][13]

If left untreated, fibrosing mediastinitis may progress to sepsis and subsequently, death.^[6] Mortality rates related to mediastinitis vary, though some estimates predict rates greater than 60%.^[11] Common complications of mediastinitis include sepsis and pneumonia.

The diagnosis of mediastinitis is based on the CDC criteria, which includes histopathologic evidence, imagining findings, and other positive findings.

Specific areas of focus when obtaining a history from the patient include chest surgery, pharyngeal surgery, and endoscopy. Symptoms of mediastinitis include chest pain, cough, chills, and shortness of breath.

Common physical examination findings of mediastinitis include clinical signs of sepsis, tachycardia, and tachypnoea.^[5]

Laboratory findings consistent with the diagnosis of mediastinitis include positive confirmation of organisms found upon sternal culture during chest surgery or fine needle aspiration of the mediastinum including Staphylococcus aureus and Histoplasma capsulatum.^[14]

On chest x-ray, mediastinitis may be characterized by calcification, widening of the mediastinum, and increased right hilar bronchovascular bundles. The chest x-ray findings associated with mediastinitis are very non-specific.

On CT scan, the appearance of mediastinitis can be variable and dependent on the pattern of involvement. Typically, the disease affects the middle mediastinum and may demonstrate mediastinal or hilar mass, infiltrative regions of soft-tissue attenuation which obliterate normal mediastinal fat planes and encase or invade adjacent structures, or calcifications of the central mass or associated lymph nodes (especially if there has been preceding histoplasmosis).^[15]

On MRI, mediastinitis is characterized by mediastinal or hilar mass or soft-tissue attenuation. Pattern of involvement is essentially similar to CT scan for mediastinitis.^[15]

Other diagnostic studies for mediastinitis include positron emission tomography and fiberoptic bronchoscopy.^[1]

The mainstay of therapy in acute mediastinitis secondary to cardiothoracic surgery includes clindamycin and ceftriaxone. The preferred regimen for preoperative prophylaxis against acute mediastinitis includes either a second generation cephalosporin or vancomycin.

Aggressive surgical debridement is recommended among patients when combined with broad spectrum antibiotics that provide coverage against MRSA, beta-lactamase producing gram-negative organisms, and anaerobes.

Effective measures for the primary prevention of mediastinitis include nasal decolonization, hand hygiene, and antibiotic prophylaxis.

Effective measures for the secondary prevention of mediastinitis following sternotomy include reporting wound discharge to physician and aggressive treatment of hyperglycemia.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Anthony Gallo, B.S. [2]

Chronic mediastinitis was first described by Dr. Thomas T. Whipham, MD, a British physician, in 1899.^[1]

Chronic mediastinitis was first described by Dr. Thomas T. Whipham, MD, a British physician, in 1899. In his article, he chronicled various examples of mediastinitis in patients, and concluded that the disease more frequently occurs in adults compared to children. Additionally, he observed that the majority of patients are males by a ratio of 4:1 but could not identify a specific etiology.^[1]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Anthony Gallo, B.S. [2]

Mediastinitis may be classified according to the onset and duration of symptoms into 2 groups: acute or chronic.^[1] Additionally, acute mediastinitis may be classified according to the cause of the disease.^[2]

Mediastinitis may be classified according to the onset and duration of symptoms into 2 groups: acute or chronic. Each form of mediastinitis has a different pathophysiology and underlying etiologies.^[1]

Acute mediastinitis may be classified according to the cause of the disease, which include esophageal perforation, head and neck infections, spread of another infection, and median sternotomy.^[2]

• Boerhaave syndrome
• Nasogastric tube
• Swallowing foreign bodies
• Trauma

• Odontogenic infections
• Pharyngitis
• Tonsillitis

• Pneumonia
• Pneumonitis
• Tuberculosis
• Anthrax

• Open heart surgery
• Coronary artery bypass surgery
• Heart transplant
• Valve replacement

Chronic mediastinitis may be classified according to the cause, duration, and recurrence of the disease, which include:

• Chronic granulomatous disease
• Tuberculosis
• Histoplasmosis
• Radiation therapy

Additionally, mediastinitis can be divided into two subcategories: focal or diffuse, which are differentiated by radiological findings.^[3]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Anthony Gallo, B.S. [2]

Mediastinitis is the inflammation or infection of the mediastinum.^[1] The anterior and upper regions of the mediastinum are the most often affected.^[2] Although the pathogenesis of the infection remains unknown, radiographic, serologic, or histopathologic evidence of prior Histoplasma capsulatum infection, histoplasmosis, or chronic granulomatous disease is always observed.^[3] Additionally, mediastinitis may also present as the result of Staphylococcus aureus or Staphylococcus epidermidis infection following chest surgery.^[4] On gross pathology, a white, fibrotic mass and a distinct gap with adipose tissue are characteristic findings of mediastinitis. On microscopic histopathological analysis, inflammation with granulated tissue and avascular and paucicellular fibrohyaline tissue are characteristic findings of mediastinitis.

Mediastinitis is the inflammation or infection of the mediastinum.^[1] The anterior and upper regions of the mediastinum are the most often affected.^[2] Although the pathogenesis of the infection remains unknown, radiographic, serologic, or histopathologic evidence of prior Histoplasma capsulatum infection, histoplasmosis, or chronic granulomatous disease is always observed.^[5] Additionally, mediastinitis may also present as the result of Staphylococcus aureus or Staphylococcus epidermidis infection following chest surgery.^[4]

On gross pathology, characteristic findings of mediastinitis include:^[6][7]

• White, fibrotic mass
• Distinct gap between adipose tissue

On microscopic histopathological analysis, characteristic findings of mediastinitis include:^[6][7]

• Inflammation with granulated tissue
• Avascular and paucicellular fibrohyaline tissue
• Presence of Staphylococcus aureus, Staphylococcus epidermidis, or Histoplasma capsulatum

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ogheneochuko Ajari, MB.BS, MS [2], Anthony Gallo, B.S. [3]

Common causes of mediastinitis include bacterial and fungal infections.^[1]

Common causes of mediastinitis include:^[1]

• Group A beta-hemolytic streptococci
• Streptococcus milleri
• Mycobacterium tuberculosis
• Histoplasma capsulatum
• Bacillus anthracis
• Candida albicans

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Anthony Gallo, B.S. [2]

Mediastinitis must be differentiated from other diseases that cause fever and chest pain, such as myocardial infarction, pneumothorax, and pneumonia.^[1]

Mediastinitis must be differentiated from other diseases that cause fever, such as:^{[1][2][3][4][5]}

• Hodgkin’s lymphoma
• Pharyngitis
• Teratoma
• Thymoma
• Metabolic disorders
• Pulmonary embolism

Mediastinitis must be differentiated from other diseases that cause chest pain, such as:^{[1][2][3][4][5]}

• Myocardial infarction
• Pneumothorax
• Pneumonia
• Pulmonary tuberculosis
• Pulmonary embolism
• Aortic dissection
• Esophageal rupture

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Anthony Gallo, B.S. [2]

Generally, mediastinitis possesses a low incidence.^[1] Less than 5% of patients develop mediastinitis following chest surgery.

Generally, mediastinitis possesses a low incidence.^[1] However, mediastinitis is observed at a greater incidence in recent heart transplant patients than the general population.^[2][3][4]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Anthony Gallo, B.S. [2]

The most potent risk factor for mediastinitis is recent chest surgery. Other risk factors include recent endoscopy, smoking, and obesity.

Common risk factors in the development of mediastinitis include:^{[1][2][3][4][5]}

• Recent chest surgery
• Endoscopy
• Obesity
• Smoking
• Problems in the upper gastrointestinal tract
• Immunodeficiency
• Intensive care unit stay > 2 days
• Infection at another site
• COPD
• Drug users
• Diabetes
• Kidney failure
• Peripheral vascular disease
• Osteoporosis
• Male gender
• Large breast size

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Anthony Gallo, B.S. [2]

There is insufficient evidence to recommend routine screening for mediastinitis. Preoperative screening for and decolonization of Staphylococcus aureus has demonstrated a decrease in the number of cases of surgical site infections, including mediastinitis.^[1]

There is insufficient evidence to recommend routine screening for mediastinitis. Preoperative screening for and decolonization of Staphylococcus aureus has demonstrated a decrease in the number of cases of surgical site infections, including mediastinitis.^[1]

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Anthony Gallo, B.S. [2]

If left untreated, fibrosing mediastinitis may progress to sepsis and subsequently, death.^[1] Mortality rates related to mediastinitis vary, though some estimates predict rates greater than 60%.^[2] Common complications of mediastinitis include sepsis and pneumonia.

If left untreated, fibrosing mediastinitis may progress to sepsis and subsequently, death.^[1] Mortality rates related to mediastinitis vary, with some estimates predicting rates greater than 60%.^[2]

Common complications of mediastinitis include the following:^[1][3]

• Sepsis
• Spread of the infection to the:
  • Bones
  • Heart
  • Lungs
• Scarring
• Pneumonia

Generally, patients with mediastinitis have a poor prognosis with a mortality rate near 40%.^[4] Mediastinitis among post-sternotomy patients has a particularly poor prognosis with an elevated risk of mortality near 60%.^[2] Prognosis improves with antimicrobial therapy.^[1]

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