Thoracic Extension of an Odontogenic Deep Neck Space Infection: A Case of Carbapenem-Resistant Acinetobacter baumannii (CRAB) Empyema in an Immunocompetent Patient

Background: Deep neck space infections (DNSIs) of odontogenic origin are serious infections that may extend into mediastinal and thoracic compartments, causing life-threatening complications. Empyema secondary to carbapenem-resistant Acinetobacter baumannii (CRAB) in an immunocompetent patient is extremely rare and illustrates the therapeutic challenges posed by multidrug-resistant pathogens. Case Presentation: A 22-year-old previously healthy Arab male presented to the emergency department with fever, left facial swelling, trismus, and dysphagia following untreated dental caries. Examination and imaging revealed a descending infection from deep neck space abscess toward the thoracic cavity. Despite incision and drainage of the buccal abscess, from which Acinetobacter baumannii was isolated, he developed respiratory distress. Chest imaging confirmed a large left-sided pleural empyema, and drainage yielded 1000 mL of purulent fluid. Pleural cultures identified CRAB, resistant to all tested agents except colistin. The patient was treated with chest drainage, intravenous colistin, and repeated wound irrigation. Clinical status improved with resolution of fever, normalization of inflammatory markers, and radiological reduction of the empyema. He was discharged with portable chest drains and referred for thoracic follow-up. Discussion: This case underscores the aggressive nature of odontogenic DNSIs and their potential for thoracic extension even in immunocompetent young adults. It also highlights that highly drug-resistant organisms such as CRAB may occasionally be encountered in severe infections outside classical intensive-care environments, particularly in settings with extensive antibiotic exposure and limited access to newer agents. Early diagnosis, multidisciplinary management, and culture-guided therapy were key to a favorable outcome. Conclusion: Odontogenic DNSIs complicated by empyema represent a rare but severe condition. The unusual involvement of CRAB in this context emphasizes both the clinical severity and the therapeutic limitations associated with multidrug-resistant pathogens and underlines the need for timely drainage and appropriate, susceptibility-guided antibiotic therapy. Keywords: deep neck space infection, odontogenic infection, pleural empyema, carbapenem-resistant Acinetobacter baumannii , case report