Pathology and microbiology of respiratory disease 1, 2 and 3 Flashcards
List some bacteria that are normally present in the URT
Step - alpha haemolytic and non-haem and beta Pasteurella Staphylococci E.coli Actinobacillus Proteus Bordatella Pseudomonas Neisseria Lactobacillus Clostridium Bacillus Mycoplasmas Chlamydophila
T/F: all viruses that cause infections of the URT or LRT can predispose to bacterial infections
True
Outline features of bacterial infections of the LRT
primary/secondary
pure/mixed
Are primary or secondary bacterial infections of the LRT more clinically important?
secondary infections
Outline bacteria that can cause respiratory disease in small animals
Bordatella Pasteurella (B-haem strep) Actinomyces and Nocardia Chlamydophila (Mycoplasmas)
What are the 4 species of Bordatella?
B.bronchisceptica
B. pertussis (whooping cough)
B. parapertussis (humans, sheep)
B. avium
Describe B. bronchiseptica
Strict aerobe, Gram negative rod No different serotypes Slow growing Normal URT inhabitant Exogenous or endogenous infection --> tracheobronchitis (KC) and bronchopneumonia (following distemper) 2 vaccines - live avirulent IN
Outline B. bronchiseptica in the cat
Resp. disease common (unclear bacteria involvement)
Serological evidence - early exposure in kittens
Cultured in 11% cats (not household)
Vaccine = NobivacBb
Pathogenesis and pathology - B. bronchiseptica
Initial trauma –> viral infection
Adherence (tracheal cilia)
Proliferation (airway)
Toxins released –> irritation and coughing
PATHOLOGY: Epithelial necrosis, peribronchial inflammation and interstitial pneumonia, severe pneumonia due to secondary invaders (e.g. b-haem strep)
What are the B. bronchiseptica pathogenicity factors? 2
ADHERENCE TO RESP. CILIATED EPITHELIUM - FHA, fimbriae and OMP
TOXINS - leucocyte toxin, tracheal cytotoxin (inhibits DNA synthesis), dermonecrotic toxin (ADP-ribosylation)
Properties - Pasteurella multocida
gram negative rod oxidase positive no growth on MacConkey strong catarrhal smell
Normal oral bacteria (dog and others) Secondary infection - URT infections Common after bite wounds Capsular serotypes - A and D Vaccines (inappropriate currently)
Pathology - Pasteurella multocida - cats/dogs
severe suppurative pneumonia and pleuritis (pyothorax/empyaema)
Cat bites and wounds
Often mixed infections
What is another name for rabbit snuffles?
enzootic pasteurellosis
Describe rabbit snuffles clinical signs
Pasteurella multocida/ennzootic pasteurellosis
chronic nasal discharge and sneezing, purulent material filling sinuses, multifocal pulmonary abscesses
sometimes fatal
colonisation - respT (URT), middle ear, genitalia, occasionally lungs (ciliotropic)
Enzootic amongst rabbit colonies
difficult to eradicate
easy transmitted to uninfected rabbits.
Control - rabbit snuffles
Bacterin vaccines - fail
Long-term AM therapy (enrofloxacin) - to control and eliminate
T/F: rabbits don’t have neutrophils
True - they have heterophils instead.
Describe Actinomyces viscosus as a bacteria
Gram positive, filamentous, branching
aerobic growth
commensal - canine oral cavity
–> granulomatous thoracic infection (dogs)
localised granulomatous abscesses of skin (chronic and progressive)
Outline Nocardia asteroides
soil bacteria
gram ppositive rods
thin, short filaments
partially acid-fast (wax-like mycolic acid)
grow within and destroy macrophage
chronic, progressive, suppurative thoracic granulomas
Treatment - Nocardia asteroides
Resistant to penicillin and some other AMs
Prolonged use of TMPS, TCs, Ampicillin
Pathology - nocardiosis
Copious red-brown exudate in pleural cavity
May become chronic with adhesion formation
Exudate contains ‘sulphur granules’
What are sulphur granules on the pleural surface typical of?
filamentous bacteria (very hard for ABs to reach these bacteria here).
Outline Chlamydophila felis as a bacteria
intracellular
gram-negative rods
no growth on laboratory media
Clinical signs - Chlamydophila felis?
Conjunctivitis (cats, most commonly)
Progress to interstitial bronchopneumonia (rare, only really if immunosuppression present too)
Diagnosis - Chlamydophila felis?
PCR - increasingly commonly
ELISA - Ag
Kosters stain (modified ZN) or fluorescein-labelled Ab.
Prevention - Chlamydophila felis?
Fel-O-Vax 4 or 5
No disease in the dog.
What causes canine nasal aspergillosis?
Aspergillus fumigatus
Diagnosis - canine nasal aspergellosis
Radiology Endoscopy Serology (ID presence of fungi) Culture (ID species) Microscopy
Pathology - nasal aspergellosis
nasal turbinates progressivley destroyed by chronic granulomatous (and eosinophilic) inflammation
yellow-green mycotic exudate in caudal nasal cavity
Pathology - nasal aspergellosis
numerous fungal hyphae (histopathological exam)
Special strains = Grocott (black hyphae) and PAS (stains LPS pink)
Which breeds are prone to nasal aspergellosis?
GSDs Doliocephalics (long head)
Treatment - nasal aspergellosis
long course of antifungals
Bacteria causing respiratory disease in sheep and cattle -7
Mannheimia Pasteurella Histophilus Mycobacterium Mycoplasma Actinomyces Actinobacillus
What factors lead to complex respiratory infections?
crowding, viruses, bacteria, stress, poor ventilation etc
What effects do viruses have on epithelial cells of the resp.T.?
cilia clumping
mucous pooling
eventual loss of cilia (increases secondary infection risk)
Other names of bovine respiratory disease complex (BRDC)? 2
Enzootic pneumonia
‘Shipping Fever’
What viruses contribute to BRDC?
PI3
RSV
BHV/IBR
What other pathogens are implicated in BRDC (other than PI3, RSV and BHV/IBR)? 3
Mycoplasma bovis
Followed by:
Pasteurella multocida
Mannheimia haemolytica
Outline IBR infection?
causes ‘red nose’
URT infections –> fibrinous laryngitis and tracheitis
Diagnosis - Pathology - intranuclear viral inclusions Vaccines available (multiple pathogens)
Bovine Respiratory Syncytial Virus (BRSV):
Family
Effect
Prevention
Family = Paramyxoviridae
Effect = URT infections, bronchitis and bronchiolitis. Cytopathic effect is syncytia formation due to fusion protein which is produced.
{revention = Vaccines availablePI3:
Family
Effect
Prevention
Family = Paramyxoviridae Effect = URT infections Prevention = vaccine (multivalent)
T/F: in BRDC, if you prevent the viral infection, you will stop the bacterial infection.
True
What disease does Mannheimia haemolytica cause in cattle?
Epizootic (endemic) pneumonia in cattle
Shipping Fever
Bovine pneumonic pasteurellosis
SHEEP - pasteurelloosis
T/F: M. haemolytica is a normal commensal in the nasopharynx of ruminants.
True
Outline M.haemolytica bacterial properties
beta-haemolytic on sheep blood agar
growth (weak) on MacConkey
Oxidase positive
What is the primary agent responsible for calf pneumonia (numbers and severity wise)?
Mannheimia haemolytica
How many biotypes of M.haemolytica are there?
2 - biotype A and T
What allows M.haemolytica serotype A1 to cause disease (i.e. Bovine pneumonic pasteurellosis)?
Predisposing injury
Outline histopathological features of Mannheimia haemolytica/pneumonic pasteurellosis
Fibrinous fluid
Fibrin, influx of cells (neutrophils predominantly)
Pathology - pneumonic pasteurellosis - cattle
80% cases involve M.haemolytica and P.multocida
- Bronchopneumonia is fibrinous to necrotising (leukotoxin and LPS)
- pleuritis frequent
- implicated in meningitis, also polyarthritis (2-4 month old housed calves)
- sporadic cases of peracute fatal mastitis in cows
Pathology - M. haemolytica
Pasteurellosis (lambs <3 months old)
septicaemia, severe pleuritis and pericarditis
Sheep/goats - severe mastitis
Vaccination - M. haemolytica
CATTLE - natural protection via Ab to leukotoxin and capsular polysaccharide. (Bacterins not effections, Leukotoxin not effective. Iron-restricted OMP in combination with leukotoxin may be better). Bovipast RSP (RSV, PI3 and M. haemolytica).
What does Pasteurella trehalosii cause?
acute/peracute septicaemia, older lambs (5-12months)
T/F: you normally vaccinate sheep against M.haemolytica and P.trehalosii
True
Outline Histophilus somnii infection
Normal commensal (genitals, transiently in URT) Causes peracute death (young calves): acute thromboembolic meningoencephalitis, pneumonia, myocarditis
What are the 2 categories of mycobacteria
Pathogenic mycobacteria and atypical mycobacteria (environmental saprophytes)
Features - mycobacterium
Strict aerobes, very slow growing
Resistant - drying and chemicals
Virulent spp fully resist intracellular killing
Can bovine TB kill a cow?
Yes - chronic eventually fatal, pneumonia and wasting.
What is an open case of TB?
continuous shedding into the environment from lesions excreting to the exterior (kidney, udder)
Diagnosis - bTB
Comparative ID test (PPD)
New methods = gamma IFN stimulation test (take a blood sample, take lymphocytes and stimulate with PPD then see if yIFN is produced in response to PPD. Positive reaction indicates prior exposure)
Pathology - bovine TB
granulomatous pneumonia and lymphadenitis. Nodules have characteristic caseating (‘cheesy’) cut surface.
Why are dairy cattle most at risk of bTB?
intensive management
Outline Mycoplasma infections
inhabit mucosal surfaces
acquire host Ag to evade IR
infection may depress performance (90%)
involved in BRDC
Why aren’t Mycoplasmas susceptible to B-lactam ABs?
no cell wall
What does Myocplasma bovis (i.e. not Mycobacterium bovis) cause?
Arthritis, mastitis (and pneumonia)
Resp.T. commensal
‘Cuffing’ pneumonia in calves
Gross pathology - Mycoplasma bovis - ‘cuffing’ pneumonia in calves
- Part of calf pneumonia complex
- Progressive cranioventral consolidation (bronchiectasis)
- On cut surface, exudate in the main airways of affected lobules with thickening of the surrounding CT.
Microscopic features - Mycoplasma bovis - ‘cuffing’ pneumonia in calves
- Lymphoid nodules and follicles around airways
- Follicles may compress bronchial lumina
- Mixed cellular exudate in airways
- Partial alveolar collapse
- Slight thickening of alveolar walls (lymphocytes)
- NO TOXINS
Define BALT
bronchiolar lymphoid tissue
What causes contagious bovine pleuropneumonia (CBPP)?
Mycoplasma mycoides subspecies mycoides SC (notifiable)
Significance of contagious bovine pleuropneumonia (CBPP)
Not so much in western world, otherwise mortality up to 50% in indigenous breeds, no specific age association, transmission (aerosol, close contact),
DIAGNOSIS - CFT
Pathology - CBPP - 5
- Fibrino-necrotic bronchopneumonia with fibrinous pleuritis
- Dorsocaudal areas may be affected
- Interstitial septa widened by fibrinous exudate and oedema
- Necrotic areas may be encapsulated (sequestra)
- lung involvement is usually UNILATERAL
Which mycoplasmas can affect sheep and goats?
M. ovipneumoniae - pneumonia
M. capricolum - pneumonia
M. mycoides sbsp. capri - pneumonia
List 3 respiratory viruses of sheep.
PI3 (occasionally causes lamb penumonia)
RSV
Adenoviruses (ovine and bovine)
Isolated from resp. disease sheep but roles not certain - may predispose M.haemolytica (part of enzootic pneumonia complex in sheep).
Control - respiratory viruses of sheep
No vaccines licensed for PI3, RSV or adenoviruses in sheep.
What fungi cause respiratory disease -cattle/sheep?
Aspergillus and Micropolysporum
Which bacteria cause respiratory disease in horses? 4
Step. equi subsp. equi
Rhodococcus
Actinobacillus
Mycoplasmas
Which viruses cause respiratory disease in horses? 3
Equine influenza virus
EHV - 1 and 4
Describe Strep. equi as a bacteria
gram positive obligate parasite of horses Lancefield group C 1 M-protein type strongly beta-haemolytic with mucoid colonies HA capsule becomes matt
How can Strep. equi be differentiated from other beta-haemolytic strep?
Biochemical tests - trehalose (neg), sorbitol (neg), salicin (pos)
Does Strep. equi cause lymphadenitis?
Yes (a suppurative lymphadenitis) - enlarged, abscessed LNs in head and neck. Also GP empyaema (site of long-term carriage). These can rupture and cause formation of draining tracts to skin surface.
Define empyaema
a collection of pus within a naturally existing anatomical cavity. DDx = abscess which is a collection of pus BUT in a newly-formed anatomical cavity
How can Strangles be prevented in horses?
Strepguard vaccine - ineffective
Equilis StrepE - live modified strain, inject in MM, now removed from market
T/F: Streptococcus pneumoniae is the main cause of respiratory disease in the training horse
False - Streptococcus pneumoniae is an occasional cause of respiratory disease in the training horse
Features - Rhodococcus equi
Gram positive rod (despite name) variably acid fast Actinomycete group Naturally in soil and GIT (horses) Persists in manure for a long time
Pathology - Rhodococcus equi - foals
- Important cause of suppurative bronchopneumonia - foals 2-6 months old
- Complex lipid cell wall - resists digestion
- Foci of caseous necrosis (lungs)
- Lesions often extensive before CS show
- High mortality (40-80%)
- Bronchial LNs may also contain caseating foci
- Dissemination to other organs
- Adult horses immune
Why does Rhodococcus equi cause granulomatous lesions in the lung?
It is a facultative intracellular pathogen –> undeveloped CMI
Which horses do Actinobacillus affect?
Adult thoroughbreds
Outline EIV as a respiratory disease: subtypes infection CS Secondary infections vaccines
- Subtypes (H7N7 or H3N8)
- URT infection, may spread to LRT and cause bronchitis and bronchiolitis
- CS: cough, pyrexia, depression
- Secondary infections: Strep, Staph, Klebsiella
- Vaccines: required for UK competing horses, inactivated vaccines containing both subtypes but aren’t protective against all strains.
Outline EHV as a respiratory disease:
Subtypes
Infection location
CS
Vaccines
EHV4 - main resp disease, rarely abortion
Also, EHV1 (resp disease, abortion, paresis), EHV5 (equine multinodular pulmonary fibrosis)
Infection - URT
CS: nasal discharge, cough, pyrexia
Vaccines: inactivated containing EHV1 and EHV4
What causes equine GP mycosis
Aspergillus nidulans
Why does equine GP mycosis cause severe nasal bleeding and dysphagia?
close associated to internal carotid artery
Diagnosis - equine GP mycosis
***Endoscopy*** Radiology Serology Culture Microscopy
Treatment - equine GP mycosis - 3
Local antifungal delivery
Ligate carotid artery
Systemic azole antifungal
List 4 bacteria causing respiratory disease in pigs
Bordatella/Pasteurella
Actinobacillus
Haemophilus
Mycoplasmas
List 3 viruses causing respiratory disease in pigs
PRRSV
Swine infleunza
Porcine circovirus
Aetiology - atrophic rhinitis - swine
Combination of early colonisation of NP with Bordatella bronchiseptica with a dermonecrotic toxin (damages osteoblasts –> turbinate atrophy) AND Pasteurella multocida (type A or D) producing the osteolytic toxin which stimulates osteoclasts –> turbinate bone resoption and atrophic rhinitis.
Why is swine atrophic rhinitis uncommon?
Because it is effectively vaccinated against.
What causes contagious pleuropneumonia in pigs?
Actinobacillus pleuropneumoniae
Outline contagious swine pleuropneumonia
Acute or chronic fibrinohaemorrhagic pneumonia with pleurisy
- intensive pig production
- worldwide
- high morbidity and mortality
- initial cases severe - progresses to chronic with sporadic cases
- subclinical carriers and recovered carriers (depends on degree of immunity)
Pathology - contagious pleuropneumonia - pigs
- Fibrinonecrotic bronchopneumonia with pleuritis (cranioventral but spreads rapidly)
- Pleural adhesions form in chronic cases.
Bacterial features of Actinobacillus pleuropneumoniae
NAD-dependent (growth on chocolate agar) waxy, sticky colonies delicate gram negative 15 serotypes (UK serotypes are 8, 2 and 6)
Pathogenicity factors - Actinobacillus pleuropneumoniae
Apx toxins (these are RTX proteins. Cytolytic and haemolytic--> massive cytokine release --> pulmonary inflammation, haemorrhage and oedema) Capsule polysaccharide Takes iron from porcine transferrin
How can you protect against Actinobacillus pleuropneumoniae?
- Porcillis APP - subunit, Europe
- Suvaxyn HPP - killed, UK, no longer marketed
What disease does Actinobacillus suis cause?
Pleuropneumonia-like disease (mild) in high health-status animals
What disease does Haemophilus parasuis cause?
Glasser’s disease - polyserositis
Fibrinos exudate in high health-status animals
Define polyserositis
= inflammation of several serous membranes (e.g. pleura, pericardium and peritoneum) at the same time
Pathology - Glasser’s disease/Haemophilys parasuis - pigs
- suppurative bronchopneumonia
- polyserositis
- lesions may be present singly or in combination
- mortality high in young animals
- predisposing factors include stress
- multi-systemic disease
What causes enzootic pneumonia (EP) in the pig (esp. young growing pigs)?
Mycoplasma hyopneumoniae 80-90% pig herds widespread predisposition to other respiratory disease aerosol transmission
Pathology - enzootic pneumonia/EP/Mycoplasma hyopneumoniae in pigs
- usually chronic, non-fatal disease unless secondary infection is present
- seen commonly at slaughter
- reduced growth rate and coughing
GROSS = cranioventral consolidation and red/grey discolouration
MICROSCOPY = similar to ‘cuffing pneumonia’ in calves = lymphoid nodules and follicles around airways, follicles may compress bronchial lumina, mixed cellular exudate in airways, partial alveolar collapse, slight thickening of alveolar walls with lymphocytes.
Define lung consolidation
becomes more solid
Diagnosis - M.hyopneumoniae
serological diagnosis by competition ELISA
What other mycoplasmas can affect the pig?
- M.hyosynoviae - arthritis
- M.hyorhinis - commonly found in RespT, cause of polyserositis and arthritis
What causes PRRS?
the PRRS virus (Arteriviridae)
Outline PRRS:
Effects
CS
Predisposes what
Effects- infects URT, systemic spread in macrophages
CS - frequently subclinical respiratory signs and interstitial pneumonia
Predisposes or enhances effects of infection with other viruses or bacteria (influenza, M. hyopneumoniae)
Part of PRDC
Outline swine influenza
Subtypes (H1N1, H3N2 and H1N2)
CS - sudden outbreaks of resp. disease with barking cough and respiratory distress (naive herds)
Effects - bronchiolitis and pneumonia. If endemic in the herd, weaned pigs will develop CS as soon as MAb levels decline.
Primary pathogen but if endemic will contribute to PRDC.
No vaccines licensed in UK
Zoonotic risk
Outline PCV2:
effects
vaccines
- Effects: Immuno-suppressive. Predisposes pigs to other infections. Possible involvement in PRDC, PMWS and porcine dermatitis and nephropathy syndrome (PDNS). Overall this is referred to as PCAD = porcine circovirus associated disease.
- 2 vaccines licensed in UK
