Pathobiology And Microboiology Of Respiratory Infections Flashcards
What are proteobacteria?
Phylum of gram negatives including E.coli, Salmonella, Vibrio, Helicobacter
Where are proteobacteria found in the respiratory tract?
URT+LRT
What types of infection are more common, primary or secondary?
Secondary
How do secondary bacterial infections occur?
Facilitated by initial viral or sometimes parasitic infection or by environmental stress
Are bacterial infections most commonly pure or mixed?
Mixed
What viruses can cause infections of the URT and spread down to cause bronchitis and bronchiolitis?
Influenza virus (horses, pigs, dogs)
Bovine respiratory syncytial virus
What pathogens are associated with feline upper respiratory disease?
Usually associated with viral infection - FHV-1 or FCV
Some bacteria can be primary pathogens - Chlamydia felis, Bordatella bronchiseptica
What pathogens are associated with canine upper airway disease (CIRD)
Often primary viral infection with
Bordatella bronchiseptica
How severe does small animal upper airway disease tend to be?
Self limiting, can usually recover without the need for antimicrobials
What would an URT infection that hadn’t subsided after 10 days indicate?
What could you give?
Systemic disease
Doxycycline
Why is culturing from nasal swabs a bad idea?
Will culture commensals
Chlamydia and mycoplasma are not culturable
what is the observation period for URT disease?
10 days
What is the drug of choice for severe (e.g. bronchopneumonia) or persisting infections?
Doxycycline
Describe chlamydia felis
obligate intracellular
Gram negative rods
How does chlamydia felis usually manifest in cats?
Bilateral conjunctivitis
Possible nasal discharge (can be mucopurulent)
How could you identify chlamydia felis?
PCR
Koster’s stain
Outline the reproductive cycle of chlamydia
Infection with EB
Reticulate body formation, multiplication and maturation
Elementary body release
What is the difference between elementary and reticulate bodies?
EB - infecting particles, metabolically inactive
RB - metabolically active, multiply in cells
Describe Bordatella bronchiseptica
Strict aerobes,
Small gram negative rods
Coccobacillus shape
What is Bordatella bronchiseptica associated with in pigs?
Atrophic rhinitis
Where is B. Bronchiseptica normally found in dogs?
URT (Commensal)
What needs to happen before Bbronchiseptica can cause tracheobronchitis or bronchopneumonia in dogs?
Viral infection (e.g. distemper), stress, immunosuppressive drugs
Describe the pathogenesis of B.bronchiseptica
Initial trauma
Adherence to respiratory epithelium of trachea
Proliferation
Release of toxins -> irritation and coughing
Epithelial necrosis
Peribronchial inflammation and bronchopneumonia
SECONDARY infection - e.g. beta haemolytic strep
What antimicrobial therapy would you recommend for mild pneumonia?
Doxycycline
What antimicrobial therapy would you recommend for severe pneumonia or pyothorax?
Fluroquinolone
AND
Penicillin or Clindamycin
Describe pasteurella multocida
Gram negative rod
Oral commensal
SMELLS LIKE MICE
In which part of the respiratory tract does P.multocida typically cause disease?
LRT
What respiratory pathology is P.Multocida associated with?
SUPPURATIVE pneumonia + pleuritis
What gross clues are present in lungs that the cause of the pneumonia is bacteria?
Hyperaemic rim
- increased arterial blood flow delivering inflammatory cells
What causes ‘snuffles’ in rabbits?
PASTEURELLA MULTICIDA
What clinical signs are associated with snuffles?
Chronic nasal discharge and sneezing
Sinisitis/rhinitis
Respiratory disease
Sometimes head tilt due to otitis media
Lungs - Pulmonary abscesses
Where does P.multocida colonise in rabbits?
Resp tract
Middle ear
Genitalia
Occasionally lungs
URT or LRT
Describe actinomyces sp.
Gram positive Aerobe
Branching filaments
Responsive to penicillin
Where is actinomyces found normally?
Oral cavity
How can actinomyces cause lower respiratory disease?
Pyogranulomatous lesions on the pleura (often w/ pyothorax)
Respiratory distress main CS
Where are nocardia found?
Soil
Describe nocardia
Gram positive
Branching filaments
ACID - FAST
RESISTANT TO PENICILLIN
Why are nocardia sp. resistant to penicillin?
What antimicrobial is indicated?
Lipids (mycolic acids) in cell wall mean that penicillin can’t penetrate TMP sulphonamides
How can you differentiate actinomyces and nocardia?
Atmospheric requirement for culture (A- aerobic, N - 10% CO2)
Nocardia - ZN, dextrose agar
Actinomyces - susceptible to pen
What is seen with nocardiosis/ actinomycosis?
Red-brown exudate in pleural cavity
SULPHUR GRANULES
May become chronic with adhesion formation
What are sulphur granules?
Colonies of bacteria surrounded by host protein (Ig and complement)
What causes canine aspergillosis?
Aspergillus fumigatus
When does aspergillosis occur?
In immunocompromised individuals
What are the two types of aspergillosis in dogs?
Systemic aspergillosis
Nasal aspergillosis
What is systemic aspergillosis?
Clinical signs depend on location
— can be in bones - lameness
BAD PROGNOSIS
What is nasal aspergillosis?
Invasive sinusitis with persistent and profuse sanguino-purulent nasal discharge (usually unilateral)
How is nasal aspergillosis treated?
Tubes inserted into sinus and antifungal infused
Describe a colony of A.fumigatus
Blue colony with colourless periphery
What breeds are predisposed to nasal aspergillosis?
Long nosed breeds - GSDs
Immunocompromised animals
Describe the pathology of nasal aspergillosis
Nasal turbinates progressively destroyed by chronic granulomatous (and eosinophilic) inflammation
Yellow/green mycotic exudate in caudal nasal cavity
What viruses cause respiratory disease in cattle and sheep?
Bovine herpesvirus
Respiratory syncytial virus
Bovine parainfluenza virus
What bacteria cause respiratory disease in cattle and sheep?
Mannheimia haemplytica Pasteurella multocida Histophilus somni Mycobacterium spp. Mycoplasma Spp
What bacteria are associated with Bovine Respiratory disease?
Mannheimia
Pasteurella
Histophilus
(+some mycoplasma)
What is shipping fever?
Bovine Respiratory disease complex (BRDC)
- viruses - PI3 BVSV IBR
- Bacteria - Mycoplasma, pasteurella, mannheimia
How does PI3 result in BRDC?
Less pathogenic but damages the cilia to allow bacteria to colonise and cause disease
What area of the respiratory tract is targeted by BHV and BVSV?
URT
What clinical signs are associated with IBR?
Red nose - loss of epithelium over the nose and ulcerated nasal plenum
Trachea filled worth fibrinonecrotising diphtheria material - can cause asphyxiation
Compare M haemolytica and P multocida in terms of cell and colony morphology
BOTH coccobacilli
M - grey colonies
P- whiter mucoid colonies
How could you determine if histophilus is present?
Isolate from lung tissues - not distinctive clinical signs - pneumonia
What follows respiratory infection in histophilus infections?
Septicaemia
Thromboembolic meningoencephalitis (TEME0 - HYPERACUTE CALF DEATH
What antibiotic therapy is indicated for BRD?
Oxytetracycline
Ampicillin
Florfenicol
Macrolides
What is seen on the surface of the lungs in Mannheimia and pasteurella pneumonia?
Fibrin
From leaky vessels
Describe pneumonic pasteurellosis
Bronchopneumonia fibrinous to necrotising
Pleuritis frequent
Meningitis sometimes with poly arthritis in 2-4 month old housed calves
Sporadic peracute fatal mastitis in cows - transferred by suckling calves
Describe mycobacteria
Aerobic Non-motile Gram positive (with mycolic acid) Acid fast Bacilli
Describe the pathology of bovine TB
Granulomatous pneumonia and lymphadenitis
Nodules have characteristic caseating cut surface
-multifocal white lesions through lung
What are the smallest living bacteria?
Mycoplasma
Describe mycoplasma
Small
NO CELL WALL
Poor survival outside host
What disease complexes are mycoplasma involved in?
Bovine Respiratory Disease Complex
Porcine Respiratory Disease Complex
What can mycoplasma bovis cause in cows?
Arthritis
Mastitis
Pneumonia (alone or with other BRDC pathogens)
What pneumonia can mycoplasma cause in calves?
Cuffing pneumonia
Progressive cranioventral consolidation
Exudate in the main airways
Look similar to mycobacteria BUT tend to involve more neutrophils
Describe the microscopic features of cuffing pneumonia
Lymphoid nodules and follicles around airways
Follicles may compress bronchial lumen
Cellular exudate in lumen
Slight thickening of alveolar walls with lymphocytes
Partial alveolar collapse
What is the important goat mycoplasma?
M capricolum
- contagious caprine pleuropneumonia
What are the key respiratory viruses of sheep?
Are there vaccines available?
PI3
RSV
Adenovirus (ovine and bovine)
NOT IN SHEEP
What bacteria cause respiratory disease in horses?
Strep equi equi
Rhodococcus
Mycoplasma sp
What viruses cause resp disease in horses?
Equine influenza
Equine herpes 1+4
Describe strep equi
What is its lancefield group?
G+ cocci beta haemolytic
C
What are the subspecies of strep equi?
Which is associated with strangles?
Which is contagious?
equi
What is S.equi subsp zooepidemicus associated with?
Mastitis, URT+LRT infections navel infections
what antimicrobial are all veterinary streptococci susceptible to?
Penicillin
How can you gain a sample for suspected S. equi equi?
Nasal swab
Describe the pathology of strangles
Suppurative lymphadenitis - LNs can rupture out onto the surface
PUS VERY INFECTIOUS
Guttural pouch empyaema
Describe Rhodococcus equi
Aerobic non-motile Gram positive rods
Where is rhodococcus found?
How is it transmitted?
Soil
Inhalation of contaminated dust
What does rhodococcus cause?
Suppurative bronchopneumonia in foals (1-4 months)
How can you treat a rhodococcus infection in foals?
Erythromycin with rifampicin
What equine influenza subtypes infect the URT?
H7N7
H3N8
What secondary infections tend to arise from EIV infection?
Strep, Staph, Klebsiella
What causes guttural pouch mycosis in horses?
Aspergillus nidulans
What are the clinical signs associated with equine guttural pouch mycosis?
Severe bleeding from the nose
Dysphagia
What bacteria are associated with enzootic pneumonia in pigs?
Mycoplasma hypopneumoniae
Bbronchiseptica
-Multocida
Actinobacillus pleuropneumoniae
What is DNT?
Dermonecrotic toxin
Describe actinobacillus pleuroneumoniae
Aerobic
Gram negative
Rod
What is Glasser’s disease?
Haemophilus parasuis
Suppurative bronchopneumonia
Polyserositis
What causes contagious pleuropneumpnia in pigs?
ACTINOBACILLUS
