C O N F E R E N C E 25 1 May 2019
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Joint Pathology Center Veterinary Pathology Services WEDNESDAY SLIDE CONFERENCE 2018-2019 C o n f e r e n c e 25 1 May 2019 CASE I: N261/13 (JPC 4037902). Laboratory results: Both Bordetella bronchiseptica and Mycoplasma felis were Signalment: 5 month old, female, Devon cultured from samples of lung. rex, Felis domesticus, feline. Microscopic Description: Multifocally, History: This young, fully vaccinated, there is extensive necrosis of contiguous pedigree Devon rex cat with no previous alveolar walls with filling of associated history of illness became acutely ill with airspace with cell debris, protein-rich pyrexia and severe dyspnea, the morning fluid/fibrin, and admixed intact and following its attendance at a cat show where degenerate inflammatory cells it had won both classes of competition for (predominantly neutrophils with fewer which it had been entered. Despite immediate macrophages and lymphocytes). Myriad veterinary attention and antibiotic treatment, loosely scattered to clumped basophilic the animal died within 36 hrs and was coccobacilli (bacteria), and small numbers of submitted for necropsy. Gross Pathology: The carcass is well preserved with adequate body fat reserves. Periocular and perinasal regions are encrusted with light brown discharge. Tracheal and bronchial lumens filled with frothy mucopurulent exudate. There is multifocal consolidation in all lung lobes: on sectioning coalescing pale firm foci are present. The kidneys are bilaterally congested at the cortico-medullary junction. The stomach contains mucus only. Feces of Lung, cat. Approximately 33% of the section is effaced by normal color and consistency in rectum. The areas of hyper\cellularity centered on small airways, and urinary bladder is empty. there are multifocal, largely subpleural areas of hemorrhage and edema. (HE, 4X) 1 erythrocytes also noted in these areas. in this species, infection typically manifests Bronchioles frequently contain similar when pulmonary defenses are impaired by inflammatory debris and bacteria, and feline calicivirus or herpes virus infections, focally, necrosis of bronchiolar epithelia is or by stressful environmental conditions detected. Widespread hyperemia with small (while occasional structures possibly number of medium-caliber blood vessels suspicious of basophilic intra-nuclear variously exhibiting fibrinoid necrosis and inclusions were observed in bronchiolar leucocytoclastic vasculitis. Occasional gland epithelium in this case, these were thrombi noted (not visible in all sections). considered equivocal: immunohistochemistry was not Contributor’s Morphologic Diagnoses: performed).2,4,10 The clinical consequences Lung: necrotizing bronchopneumonia, acute, on infection can vary dramatically: from mild severe with myriad bacteria (identified as pyrexia, coughing and sneezing to severe Bordetella bronchiseptica on culture). pneumonia and death as seen in this case. Contributor’s Comment: Bordetella Details of the pathogenesis of infection in the bronchiseptica is a gram-negative cat are inferred from studies in other species. coccobacillus commonly carried in the Bacterial virulence is regulated by the nasopharynx of healthy cats. In a survey of Bordetella virulence gene (bvg) operon, respiratory pathogens in multi-cat (≥5 cats) which orchestrates the expression of the households, B. bronchiseptica was detected adhesin filamentous haemagglutinin (FHA), by PCR in 5% of cats from households with pertactin, and the fimbriae that facilitate disease, and in 1.3% of cats without.6 adherence to the ciliated epithelium, as well Considered a somewhat uncommon pathogen as to macrophages and neutrophils within the Lung, cat. Areas of inflammation are centered on necrotic airways, which are filled with numerous viable and degenerate neutrophils, cell debris, fibrin, and bacterial colonies. The exudate has ruptured through the wall and spilled into the surrounding alveoli. (HE, 163X) 2 lungs.2,6 Following attachment the pathogen immunocompromised individuals, have been secretes the RTX adenylate cyclase toxin reported.8,11 (hemolysin) that results in impaired leucocyte phagocytosis and oxidative burst, Mycoplasma felis can colonize the upper and may induce their apoptosis. A respiratory tract of cats, but evidence lipooligosaccharide with endotoxin activity suggests it is not a significant primary and a soluble peptidoglycan-derived tracheal pathogen. Molecular detection techniques cytotoxin are also produced that induce have found Mycoplasma spp in the lower ciliostasis and the apoptosis of ciliated respiratory tract of 15.4% of cats with epithelial cells.2,6 respiratory disease, with M. felis, M. gateae and M. feliminutum the species identified. Bacterial culture (as in this case) and PCR are However, the pathogenic significance of their used to conform the diagnosis, although both presence remains unclear.7 It is likely that M. lack sensitivity.6,9 In regions where vaccines felis contributed to the severity of the against B. bronchiseptica are available, it is pneumonia in this case through opportunist recommended that cats should not be secondary involvement. routinely vaccinated, given the typically mild disease that occurs. However, vaccination is This case represented a sudden and highly encouraged in units such a shelters where traumatic loss for the owner concerned as populations are in continuous turnover, and they witnessed the rapid clinical deterioration thus at increased risk of infectious disease.6 and death of their prize-winning animal over Organisms are shed in oral and nasal a period of 36 hrs. We may speculate that secretions of infected cats and infected dogs contact with other cats at the cat show are considered an infection risk for cats.5,6 provided a source of the infection, and how Rare zoonosis, typically in possibly the stress of transport or attendance Lung, cat. Within affected areas there are discontinuous alveolar septa, characteristic of septal necrosis (black arrows.) (HE, 313X) 3 at this event could have precipitated disease. In any event, the rapidity of disease progression suggests the strain of B. bronchiseptica involved was particularly virulent. Contributing Institution: Room 012, Veterinary Sciences Centre, School of Veterinary Medicine, University Lung, cat. Large colonies of bacillii are present within College Dublin, Belfield, Dublin 2, Ireland airways and alveoli in close proximity. (HE, 400X) http://www.ucd.ie/vetmed/ role in fatal pneumonia as exemplified in this JPC Diagnosis: Lung: Bronchopneumonia, case. B. bronchiseptica has been identified in fibrinosuppurative and necrotizing, between 12 and 78% of dogs with lower multifocal to coalescing, severe, with respiratory tract infections, and 5-13% of numerous bacterial colonies. cats.9 At a major university veterinary school, a retrospective study identified B. JPC Comment: The contributor has bronchiseptica via immunohistochemistry provided an excellent review of Bordetella and/or bacterial culture in 8 of 36 of canine bronchiseptica in this case, as well as the and 14 of 31 feline cases of fatal pathogenesis of the disease across species bronchopneumonia. Upon close review, lines. Bordetella bronchiseptica is an bacteria could be visualized among the cilia important, if sporadic, pathogen of the in 4 of 36 canine cases and 5 of 31 feline respiratory system in a wide range of cases.9 Close review of columnar epithelium mammalian species. Previous WSC cases in this case also disclosed the presence of include Bordetella bronchopneumonia cilia-associated bacteria; it was seen only on infection in a chinchilla (WSC 2014-2015, intact cells, as necrotic or attenuated Conf 18, Case 4), an African green monkey epithelium has probably already lost its cilia. (WSC 2011-2012, Conf 22, Case 3), squirrel This may be an important finding in such monkeys (WSC 2007-2008, Conf 9, Case 3, cases, as the lesions associated with the pigs (WSC 1996-1997, Conf 20, Case 2), a bronchopneumonia in these cases, in the rabbit (WSC 1995-1996), among others. authors’ opinion, were not specific for any particular pathogen. There are three species of Bordetella of veterinary importance, including B. Bordetella bronchiseptica can be an bronchiseptica (whose dermonecrotic toxin opportunistic pathogen in humans as well, also causes atrophic rhinitis in pigs and particularly immunosuppressed individuals rabbits), B. hinzii which causes limited and cystic fibrosis patients. B. respiratory disease in turkey poults and rare bronchiseptica and B. pertussis, (the septicemia in humans, and B. pertussus a causative agent of whooping cough) exhibit potent pathogen in humans which may cause little genetic variation,1 with B. pertussis lower respiratory disease in lambs. being a more recent derived, human adapted bacterium derived as a consequence of gene Well known for its involvement in non-fatal deletions and loss of genetic regulatory tracheobronchitis (aka “kennel cough”), a functions. Both organisms possess the recent publication9 has detailed Bordetella’s Bordetella virulence gene as discussed 4 of pneumonia in the lung across animal species. In this particular case, attendees were split on whether the appropriate morphologic diagnosis would be bronchopneumonia (based on the traditional pathogenesis of this aerogenous bacteria and the obvious necrosis within airways) or bronchointerstitial, based on the Lung, cat: Careful evaluation of the HE slide may disclose the presence of bacilli lining cilia widespread necrosis of columnar airway epithelium (arrows).