Abstract
An unclassified Pasteurella species was isolated at necropsy from lung and subcutaneous abscesses in two Wahlberg’s epauletted fruit bats (Epomophorus wahlbergi). The bats were part of a group of three Wahlberg’s epauletted fruit bats previously housed at the Oregon Zoo, Portland, Oregon. They were transported to the Lubee Foundation, Florida and became part of a breeding colony consisting of four males and ten females. Physical examination performed at the beginning and end of a 30-day quarantine period revealed no abnormalities.
Five days following the end of quarantine, an adult, gravid female (case 1) died after an attack by a cagemate. Gross and histopathologic examination revealed suppurative pneumonia of the left lung with chronic abscessation and intralesional gram-negative bacterial rods. Bacterial culture of the lung tissue yielded heavy growth of an aerobic gram-negative non-enteric rod. Nine days following the death of case 1, an adult male bat (case 2) was evaluated at the Veterinary Medical Teaching Hospital, University of Florida, with a history of lethargy and anorexia of three days duration. A complete blood count revealed leukopenia (2,700/µl) characterized by monocytosis and neutropenia with a degenerative left shift. This animal was found dead with hemorrhage from the mouth and nares 24 hours following initial presentation. Gross and histopathologic examination revealed diffuse, subacute bronchopneumonia with intralesional gram-negative rods present in both lungs and a 2.5 cm focal abscess adherent to the pericardium and the parietal pleura of the right ribcage. Culture of the lung resulted in heavy growth of an aerobic non-enteric gram-negative rod.
Samples of the aerobic, non-enteric, gram-negative rod obtained from both bats were found to be morphologically and biochemically similar. A sample of the organism from case 2 was submitted to the National Veterinary Services Laboratories, Ames, Iowa and was identified as an aerogenic Pasteurella species. Further characterization of this organism was performed by the Special Bacteriology Reference Laboratory, Centers for Disease Control and Prevention (CDC), Atlanta, Georgia. Although the CDC found the biochemical and cellular fatty acid profiles of this organism to be consistent with either Pasteurella or Actinobacillus species, it did not correspond to any known pathogens.
The remaining Wahlberg’s epauletted fruit bats were screened for the presence of this organism by culturing pharyngeal swabs. Aerobic, non-enteric, gram-negative rods, morphologically and biochemically similar to the pathogen isolated from case 2 were identified in 80% (8/10) of bats cultured. This organism appeared sensitive to a wide variety of antimicrobials, as demonstrated by Kirby-Bauer susceptibility testing. The Oregon Zoo, Portland, Oregon, also experienced mortalities due to pneumonia in a collection of Wahlberg’s epauletted fruit bats. Six of the 50 bats in the collection died with necropsy findings consisting primarily of severe, unilateral suppurative pneumonia with abscess formation. Four of five of these animals cultured for bacteria demonstrated heavy growth of a Pasteurella sp. organism, species non-multocida.
The cause of death in the two E. wahlbergi bats discussed in this report was determined to be bacterial pneumonia produced by a newly identified Pasteurella or Actinobacillus species. Historical data provided by the Oregon Zoo indicates that pneumonia had been occurring in this species prior to their arrival at the Lubee Foundation. Culture screening of the remaining captive E. wahlbergi population at the Lubee Foundation suggests that this organism is a component of normal flora. In asymptomatic bats, this organism comprised a smaller percentage of the total bacterial population than in symptomatic bats. This is consistent with Pasteurella-associated disease occurring in other mammalian species.
Acknowledgments
The authors would like to acknowledge the assistance of Dana LeBlanc and John Seyjagat in this study.
†Published as Lubee Journal Series No. 49.