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Mediastinitis is inflammation or infection of the tissues in the mid-chest, or mediastinum. This disorder is rare, but is most often observed among patients following chest surgery or endoscopy. Mediastinitis may occur at any age. 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. Common complications of mediastinitis include sepsis and spread of the infection. Symptoms of mediastinitis include chest pain, malaise, and shortness of breath. Common physical examination findings of mediastinitis include clinical signs of sepsis, tachycardia, and tachypnea. 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.
Mediastinitis may be classified according to cause into 2 groups: acute or chronic (sclerosing or fibrosing). Additionally, acute mediastinitis may be classified according to the cause of the disease.
Mediastinitis is the inflammation or infection of the mediastinum. 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. Additionally, mediastinitis may also present as the result of Staphylococcus aureus or Staphylococcus epidermidis infection following chest surgery.
Common causes of mediastinitis include bacterial and fungal infections, including group A beta-hemolytic streptococci, Mycobacterium tuberculosis, and Histoplasma capsulatum. 
Differentiating Mediastinitis from Other Diseases
Mediastinitis must be differentiated from other diseases that cause fever and chest pain, such as myocardial infarction, pneumothorax, and pneumonia.
The most potent risk factor for mediastinitis is recent chest surgery. Other risk factors include recent endoscopy, smoking, and obesity.
Natural History, Complications and Prognosis
If left untreated, fibrosing mediastinitis may progress to sepsis and subsequently, death. Mortality rates related to mediastinitis vary, though some estimates predict rates greater than 60%. 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.
History and Symptoms
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.
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.
Chest X Ray
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).
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.
Other Imaging Findings
Other diagnostic studies for mediastinitis include positron emission tomography and fiberoptic bronchoscopy.
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.
- ↑ 1.0 1.1 1.2 Koksal D, Bayiz H, Mutluay N, Koyuncu A, Demirag F, Dagli G; et al. (2013). "Fibrosing mediastinitis mimicking bronchogenic carcinoma". J Thorac Dis. 5 (1): E5–7. doi:10.3978/j.issn.2072-1439.2012.07.03. PMC 3548007. PMID 23372962.
- ↑ 2.0 2.1 Abboud CS, Wey SB, Baltar VT (2004). "Risk factors for mediastinitis after cardiac surgery". Ann Thorac Surg. 77 (2): 676–83. doi:10.1016/S0003-4975(03)01523-6. PMID 14759458.
- ↑ Mediastinitis: a potentially lethal infection. Thoracics (2012). http://thoracics.org/2012/03/03/mediastinitis-noncardiac-surgery/ Accessed on September 25, 2015.
- ↑ Lewandowski B, Pakla P, Wołek W, Jednakiewicz M, Nicpoń J (2014). "A fatal case of descending necrotizing mediastinitis as a complication of odontogenic infection. A case report". Kardiochir Torakochirurgia Pol. 11 (3): 324–8. doi:10.5114/kitp.2014.45685. PMC 4283893. PMID 26336443.
- ↑ 5.0 5.1 Acute Mediastinitis Following a Laparotomy for Small Bowel Obstruction. Journal of Current Surgery (2014) http://jcs.elmerpress.com/index.php/jcs/article/view/252 Accessed on September 28, 2015
- ↑ 6.0 6.1 The Lancet. Google Books (2015). https://books.google.com/books?id=Zxw6AQAAMAAJ&pg=PA947&lpg=PA947&dq=the+lancet+mediastinitis+1896&source=bl&ots=izLFx5SXRB&sig=mXN15zc74xrPIn00rWnfoZ_NQ9Y&hl=en&sa=X&ved=0CB0Q6AEwAGoVChMIgPPf0aiByAIVAW0-Ch3LpgUe#v=onepage&q=lancet%20mediastinitis%201896&f=false Accessed on September 18, 2015
- ↑ Mediastinitis. Wikipedia (2015) https://en.wikipedia.org/wiki/Mediastinitis Accessed on September 21, 2015
- ↑ Mandell GL. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. Churchill Livingstone; 2010.
- ↑ Histopathologic Overlap between Fibrosing Mediastinitis and IgG4-Related Disease. International Journal of Rheumatology (2012). http://www.hindawi.com/journals/ijr/2012/207056/ Accessed on September 25, 2015
- ↑ Konvalinka A, Erret L, Fong IW (2006). "Impact of treating Staphylococcus aureus nasal carreiers on wound infections in cardiac surgery". J Hosp Infect. 64 (2): 162–8. PMID 16930768.
- ↑ 11.0 11.1 Martínez Vallina P, Espinosa Jiménez D, Hernández Pérez L, Triviño Ramírez A (2011). "[Mediastinitis]". Arch Bronconeumol. 47 Suppl 8: 32–6. doi:10.1016/S0300-2896(11)70065-5. PMID 23351519.
- ↑ Kang DW, Canzian M, Beyruti R, Jatene FB (2006). "Sclerosing mediastinitis in the differential diagnosis of mediastinal tumors". J Bras Pneumol. 32 (1): 78–83. PMID 17273573.
- ↑ Risk factors for mediastinitis after cardiac surgery – a retrospective analysis of 1700 patients. Journal of Cardiothoracic Surgery (2007). http://www.cardiothoracicsurgery.org/content/2/1/23 Accessed on September 21, 2015
- ↑ CDC/NHSN Surveillance Definitions for Specific Types of Infections. CDC (2015). http://www.cdc.gov/nhsn/PDFs/pscManual/17pscNosInfDef_current.pdf Accessed on September 21, 2015
- ↑ 15.0 15.1 Fibrosing mediastinitis. Radiopedia.org (2015) http://radiopaedia.org/articles/fibrosing-mediastinitis Accessed on October 2, 2015