Gross and Histopathological Charactersation of Pulmonary Abscessation due to Staphylococcus aureus and Escherichia coli in a Collared Mangabey (Cercocebus torquatus): A Case Report

Abstract

Bacterial lower respiratory tract infections (LRTIs) can result in severe and fatal diseases in non-human primates (NHPs), and the disease process of pulmonary abscessation in the Collared Mangabey (Cercocebus torquatus), an endangered West and Central African cercopithecid, has been underreported. A gross and histopathological evaluation of a 12-year-old captive female C. torquatus that had a 14-month history of intermittent coughing and that had a polymicrobial co-infection with S. aureus and E. coli is presented. At post-mortem examination, bilateral fibrinous to fibrous pleuritis with pleural adhesions to the thoracic wall and pericardium were noted. The left lung was very enlarged, fluctuant, and distorted to a spherical or irregularly ovoid shape. On cut section, a large proportion of the lung substance was replaced with a central cavity filled with semi-solid to pasty, yellow to off-white debris, which was largely necrotic and included purulent exudate; similar necrotic material was seen in the bronchi of the contralateral lung. The histopathological features confirmed multifocal colonies of coccoid bacteria in perivascular spaces of pulmonary vessels, interstitial thickening, and a discrete focus of suppurative inflammation circumscribed by the zone of fibrous connective tissue and proliferating fibroblasts, which is characteristic of abscess encapsulation. Foreign bodies were also found in alveolar spaces, suggesting chronic exposure to particulate matter in the environment as a possible contributing factor. Aerobic culture results were positive for S. aureus and E. coli, and antimicrobial susceptibility test revealed in vitro activity against S. aureus and E. coli for chloramphenicol and tigecycline. To the authors' knowledge, it is the first time that pulmonary abscessation has been documented in C. torquatus, and in other cercopithecids, the authors have never observed this condition, and so far, it has been the only baseline for the lesions associated with respiratory disease in an endangered species, C. torquatus, in captivity.