Pneumonia in Lambs Inoculated with Bordetella parapertussis: Bronchoalveolar Lavage and Ultrastructural Studies

Abstract

Abstract. Eight colostrum-deprived lambs were inoculated intratracheally with ovine isolates of Bordetella parapertussis. Fluids obtained by bronchoalveolar lavage had a large increase in total cell counts 24 hours after inoculation; up to 93% of cells were neutrophils. From 3 days after inoculation, the number of alveolar macrophages in lavage samples was markedly increased. From 5 days onwards, many alveolar macrophages had moderate to severe cytoplasmic vacuolation. Topographically, tracheal and bronchial epithelium was covered by a large amount of inflammatory exudate 24 hours after inoculation. Later, the tracheobronchial epithelium showed focal extrusions from ciliated cells, which were occasionally associated with B. parapertussis organisms. Ultrastructurally, cytopathological changes associated with B. parapertussis infection were mild focal degeneration of airway epithelium with slight loss of cilia, moderate to severe degeneration of type I and type I1 alveolar epithelial cells, and focal inflammation in the lungs. These results suggest that the primary targets of B. parapertussis infection are alveolar macrophages and the epithelial cells of bronchioles and alveoli.Bordetella parapertussis is one of the causative agents of whooping cough, a noninvasive infection of the lower respiratory tract of humans. l 9 Recently, this organism has also been isolated in New Zealand from the respiratory tract of both healthy lambs and lambs affected with chronic non-progressive pneumonia (CNP). Subsequent studies showed that the organism could attach to cilia and damage the ciliary epithelium of ovine tracheal organ cultures3 and caused a subacute bronchopneumonia in mice by intranasal inoculation. l oIn a previous study we described histopathologic and bacteriologic observations on experimental B. parapertussis infection in colostrum-deprived lambs and demonstrated the pathogenicity of B. parapertussis for the ovine respiratory tract. Major lesions in infected lambs were those of acute mild tracheobronchitis and acute bronchopneumonia. However, no specific morphologic interface was found between the infected respiratory tract and the organisms, and the pathogenesis of the lesions remains unknown. We now report observations on bronchoalveolar lavage samples and ultrastructural features in experimental ovine pneumonia caused by B. parapertussis, which were carried out in order to better understand the potential importance of this organism in the ovine respiratory disease. Materials and MethodsTwelve colostrum-deprived, 1 -week-old lambs were assigned to two age-matched groups. Lambs in Group 1 ( n = 4) were given 5 ml of sterile phosphate buffered saline (PBS) intratracheally as controls; lambs in Group 2 (n = 8) were given 5 ml of B. parapertussis suspension with a viable cell count of 2.3 x 1 O6 colony-forming units/ml intratracheally. Lambs were killed on post-inoculation days (PID) 1, 3, 5, and 9.At necropsy, one lamb from each group was used for a cytological study of bronchoalveolar lavage (BAL). The trachea wa...

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“…Previous experimental inoculations with B. parapertussis have been conducted in mice [22,23], and in lambs using intratracheal inoculation [24,25]. To simulate the dynamics of natural infection more accurately, we inoculated adult ewes intranasally with a large dose of either the sequenced human strain of B. parapertussis (12822), an ovine strain (Bpp5), or media alone.…”

Mast Cells in the Ovine Lower Respiratory Tract: Heterogeneity, Morphology and Density

“…These were fixed in 3% glutaraldehyde in 0.1 M phosphate buffered saline overnight, and processed and examined under a transmission electron microscope as de scribed previously [16],…”

The Differentiation of Bordetella parapertussis and Bordetella bronchiseptica from Humans and Animals as Determined by DNA Polymorphism Mediated by Two Different Insertion Sequence Elements Suggests Their Phylogenetic Relationship

“…Conversely, B. pertussis is an obligate human pathogen, causing whooping cough or pertussis. Although it has been assumed that B. parapertussis is also a strictly human pathogen (12), this organism has recently been isolated from both healthy sheep and sheep affected with chronic nonprogressive pneumonia (5,8,24).It has been estimated that between 5 and 30% of all pertussis cases are caused by B. parapertussis (16,20 parapertussis (1 1, 30).Multilocus enzyme electrophoresis (MEE) analysis has revealed that the genetic diversity of human B. parapertussis and B. pertussis strains is very limited, suggesting that these organisms descended from a common ancestor recently (23). B.…”

“…Conversely, B. pertussis is an obligate human pathogen, causing whooping cough or pertussis. Although it has been assumed that B. parapertussis is also a strictly human pathogen (12), this organism has recently been isolated from both healthy sheep and sheep affected with chronic nonprogressive pneumonia (5,8,24).…”