Respiratory Pathogens 2 (SA) Flashcards
What is the most common respiratory bacterial pathogen of horses?
Rhodococcus equi (foals)
What are the characteristics of Rhodococcus equi?
- Gram-positive
- Facultative intracellular organism
What are the virulence factors of Rhodococcus equi?
Mycolic acids: Inhibits phagocytosis and complement which promotes phagocytic survival in macrophages and granuloma formation.
VapA protein: Surface expressed protein interferes with phagolysosome formation, promoting intracellular survival.
What is the pathogenesis of Rhodococcus equi?
Inhalation of soil dust particles is the major route of pulmonary infection → transmission through infective droplets → Swallowing expectorated sputum may lead to enteric disease.
What is the primary route of pulmonary infection by Rhodococcus equi in foals?
Inhalation of soil dust particles
Which lesions do you see with Rhodococcus equi?
- Pyogranulomatous bronchopneumonia
- Multi-focal ulcerative enterocolitis
- Typhlitis
How can you diagnose Rhodococcus equi?
- Culture and susceptibility
- Cytology
- Bronchoalveolar lavage (BAL)
- Tracheal wash aspirates
What are the four most common respiratory bacterial pathogens of dogs?
- Bordetella bronchiseptica
- Streptococcus equi zooepidemicus
- Streptococcus canis
- Mycoplasma cynos
What are the characteristics of Bordetella bronchiseptica?
- Gram-negative
- Obligate aerobe
- Obligate pathogen
Natural habitat is the URT of many animals
What is the pathogenesis of Bordetella bronchiseptica?
Colonization → altered respiratory epithelial cell function → excessive mucussecretion → further impairment of the local innate immune defenses → predispose to infection by other opportunistic secondary pathogens.
What are the five most common respiratory bacterial pathogens of cats?
- Chlamydia felis
- Mycoplasma felis
- Bordetella bronchiseptica
- Pasteurella multocida
- Streptococcus canis
In cats, what clinical sign is Chlamydia felis commonly associated with?
Conjunctivitis
Feline Infectious Respiratory Disease (FIRD) often involves coinfections with which two viruses?
Feline Herpesvirus Type 1 (FHV-1) and calicivirus
What are the most common respiratory bacterial pathogens of birds?
- Chlamydia psittaci
- Mycoplasma spp.
- E. coli
What are the common transmission routes for Chlamydia psittaci?
Fecal-oral, inhalation, and vertical (respiratory discharge and feces contain elementary bodies that remain infective for several months)
What is unique about culturing Chlamydia psittaci?
It cannot be growth on agar plates (requires growth in embryonated eggs) so it cannot be cultured!
Which stage of the Chlamydia lifecycle is infectious?
The elementary body
Which stage of the Chlamydia lifecycle is non-infectious?
The reticulate body
Which form of Chlamydia is metabolically active and replicates within lysosomes of phagocytic cells?
The reticulate body
Which stage of the Chlamydia lifecycle is persistent?
The aberrant body
What samples should you collect to test for Chlamydia psittaci?
- Nasal swabs
- Fecal
- Live bird
- Blood
How can you diagnose Chlamydia psittaci?
You CANNOT culture
Do PCR, ELISA, or IHC
What is the preferred method for diagnosing Chlamydia psittaci in birds?
PCR
True or False: Chlamydia psittaci is zoonotic
True, it is the causative agent of psittacosis or ‘Parrot Fever’ in humans (provincially notifiable disease in Alberta)
