Bronchiectasis Infected by Pasteurella Multocida: A Case Report

Pasteurella multocida is a gram-negative bacterium that is part of the oropharyngeal microbiota of several domestic animals, especially dogs and cats. Although it is a well-known cause of soft tissue infections after bites or scratches, cases of pneumonia associated with P. multocida have been described, particularly in immunocompromised patients or those with chronic lung disease. Recognition of this etiology is essential due to the potential for severe progression and the need for specific antimicrobial management. This work aims to report a case of pneumonia due to Pasteurella multocida in a patient with bronchiectasis of unknown secondary etiology, highlighting clinical, epidemiological, and therapeutic aspects. This is a prospective and descriptive case report based on chart review. A 46-year-old female patient, with a history of household contact with a pet dog, had a diagnosis of secondary bronchiectasis of unknown etiology. She reported productive cough with greenish sputum and dyspnea on mild exertion. She was admitted to a tertiary hospital for hygienic bronchoscopy and collection of bronchoalveolar lavage for culture, aiming at directed antimicrobial therapy. Chest CT showed scattered bronchiectasis more evident on the left and bullous emphysema associated with consolidative areas in the left lung base. Aerobic culture of the bronchoalveolar lavage confirmed the presence of Pasteurella multocida with a colony count greater than 1,000,000 colony-forming units. Treatment with amoxicillin-clavulanate was started, with significant improvement in dyspnea, reduction in sputum volume, clearing of secretions and decreased oxygen requirement after initiation of antibiotic therapy. The patient was discharged after 6 days of antimicrobial therapy to complete treatment at home, with a planned total duration of 10 days. Although pneumonia due to Pasteurella multocida is rare, it should be considered in the differential diagnosis of respiratory infections, especially in patients with a history of contact with animals and predisposing conditions, immunocompromised patients, or those with chronic lung disease. Proper diagnosis and targeted treatment are fundamental for a favorable clinical outcome.