Rare Zoonotic Pulmonary Infection in Humans: Bordetella bronchiseptica - A Case report

Abstract

Bordetella bronchiseptica is a zoonotic Gram-negative coccobacillus that commonly causes respiratory infections in animals but is rarely implicated in human disease. The patient presented with recurrent hemoptysis for one month and a history of two previous presentations of pulmonary tuberculosis, treated with antitubercular therapy. In view of persistent symptoms, the patient was evaluated for other causes of chronic pulmonary infection. Differential diagnosis, including chronic pulmonary aspergillosis, non-tuberculous mycobacterial infection and subacute invasive aspergillosis was considered and ruled out by appropriate investigations. Microbiological culture of respiratory samples, bronchoalveolar lavage (BAL), revealed non-lactose fermenting colonies, and Gram staining showed small, gram-negative coccobacilli and the isolate was identified as Bordetella bronchiseptica by MALDI-TOF mass spectrometry. The patient had a history of close exposure to dogs, suggesting zoonotic transmission. In the absence of established treatment guidelines and CLSI-defined breakpoints for Bordetella bronchiseptica, treatment was guided by antimicrobial susceptibility testing with results interpreted using surrogate criteria for non-fermenting gram-negative bacilli. The patient showed clinical improvement with cefoperazone–sulbactam followed by cotrimoxazole. This case highlights the importance of considering rare zoonotic pathogens in patients with underlying lung disease and the role of advanced diagnostic techniques in accurate identification.