Objective: To evaluate the epidemiological and clinical aspects of acute mediastinitis and to characterize its treatment. Methods: A retrospective study conducted through review of the medical charts of patients diagnosed with acute mediastinitis at the Hospital Escola da Faculdade de Medicina do Triângulo Mineiro (Triângulo Mineiro Medical School Hospital) between 1987 and 2004. Results: A total of 21 patients were studied. Most (76.2%) were male, and the mean age was 52.5 years. Six patients (28.6%) died. The most common cause (in 38.1%) was median sternotomy, followed by esophageal perforation (in 33.3%) and cervical infection (in 14.3%). Staphylococcus aureus and Staphylococcus epidermidis were the causative agents most frequently isolated. In most cases, the treatment of choice was antibiotic therapy accompanied by surgery. The most frequent complications of the acute mediastinitis were pleural effusions (in 23.8%) and osteomyelitis (in 19.0%). The average hospital stay was 26.6 days. Conclusion: Acute mediastinitis is a serious complication of some diseases and procedures. Despite its low incidence, the mortality rate is high. Staphylococcus aureus and Staphylococcus epidermidis are the most common causative agents. The treatment used was antibiotic therapy accompanied by surgery.

Ludwig's angina is an infection of the submandibular space generally caused by an infection of the 2nd or 3rd lower molar. As a consequence, descending necrotizing mediastinitis, a rare and severe form of mediastinal infection, may occur. The descending necrotizing mediastinitis represents a rare form of mediastinal infection. It presents a high mortality and to decrease that rate it is necessary prompt diagnosis and surgical treatment. Two cases of descending necrotizing mediastinitis due to Ludwig's angina were treated with excellent results in our hospital. The transcervical mediastinal drainage is justified in patients with disease limited to the upper mediastinum. Even so, when there is extensive involvement of the whole mediastinum it is suitable the accomplishment of a wide thoracotomy.

Keywords: Ludwig's angina. Mediastinitis. Diagnosis. Treatment. Surgery.