Other gr - rods

Question 1

Bordatella

Answer 1

Gram negative, short rods
Obligate aerobes
Oxidase positive, motile
Grows on MacConkeys
* Pasteurella multocida cannot

Species of veterinary importance
* Bordetella bronchiseptica
* Bordetella avium

Question 2

Bordetella bronchiseptica

Answer 2

Obligate parasite of ciliated respiratory epithelium
Maintained in carrier animals (not normal flora)
Infected or carrier dogs who are coughing are the main source of infections for naïve dogs
Occasionally, infections can arise from bacteria present on their own respiratory epithelium (recrudescence)

Question 3

How is bordatella transmitted?

Answer 3

Inhalation is primary mode of transmission through aerosolized droplets
Risk Factors
* Introduction of new animals
* Ventilation
* Density of animals

Disease (Canine Cough) is considered to be contagious
Can get large outbreaks of disease in housed animals

Question 4

How does bordatella cause dz?

Answer 4

Uniquely adapted to set up conditions that allow colonization and disease of the respiratory tract
* Bind to respiratory cilia via fimbriae/pertactin
* Induce ciliostasis, death of cells and subsequent inflammation via dermonecrotic cytotoxin and tracheal cytotoxin
* Also has an osteotoxin which is important in Atrophic Rhinitis
* decrease phagocytosis and killing of bacteria via other exotoxin

Can predispose to more serious diseases

Question 5

What diseases does bordatella cause?

Answer 5

Canine Infectious Tracheobronchitis/Canine Cough/Kennel Cough
Tracheobronchitis/Pneumonia
Atrophic Rhinitis in pigs

Question 6

kennel cough

Answer 6

bordatella bronchiseptica (but can be other viruses/bacteria)
Usually see sudden onset of dry, hacking (“goose-honking”) cough that may be productive (common) or non-productive
Cough may be exacerbated by exercise, excitement or pressure of collar
Can also be elicited by tracheal palpation (inconsistent)
Gagging, retching or nasal discharge can also be observed in some cases
Do NOT usually show signs of systemic illness and if they do – should suspect more serious/underlying disease
B. bronchiseptica and/or viruses can cause the initial damage and allows secondary invasion by other bacteria that may enter the lower respiratory tract
* e.g., Klebsiella pneumonia

Some dogs can continue to shed the bacteria for up to 3 months after cessation of signs!

Question 7

tracheobronchitis and/or pneumonia from bordatella

Answer 7

Wide range of animals (dogs, cats, horses, rodents, people) may be infected
Usually involves other bacteria or viruses
Predisposing (e.g., Mycoplasma, herpesvirus or calicivirus in cats)
Secondarily (e.g. Klebsiella pneumoniae, E. coli)
It is the secondary invaders that cause serious dz (e.g., pneumonia)

Question 7

tracheobronchitis and/or pneumonia from bordatella

Answer 7

Wide range of animals (dogs, cats, horses, rodents, people) may be infected
Usually involves other bacteria or viruses
Predisposing (e.g., Mycoplasma, herpesvirus or calicivirus in cats)
Secondarily (e.g. Klebsiella pneumoniae, E. coli)
It is the secondary invaders that cause serious dz (e.g., pneumonia)

Question 8

atrophic rhinitis and bordatella

Answer 8

Sows are the carriers of B. bronchiseptica and transfer infection to piglets
B. bronchiseptica invades initially and causes a mild, transient form of the disease
* B. bronchiseptica: dermonecrotoxic exotoxin and osteotoxin

Secondary invasion by toxigenic P. multocida (type D) results in a more severe and progressive form of disease (osteolytic)
* P. multocida dermonecrotic toxin

Question 9

Diagnosing bordatella infections

Answer 9

Canine Cough
* Often a presumptive diagnosis

Tracheobronchitis and/or Pneumonia
* B. bronchiseptica is NOT part of normal flora of URT; so nasopharyngeal swabs may be OK (but not as good) if this pathogen is suspected
* Samples can be cultured or multiplex PCR
* If suspect other pathogens (e.g., Enterobacterales) collect samples from lower respiratory tract

Atrophic Rhinitis
* Clinical signs and lesions usually sufficient
* Swabs of the nasopharynx and culture for isolation of B. bronchiseptica and P. multocida
* ELISA and multiplex PCR for detection of toxigenic strains of P. multocida (type D

Question 10

treatment of kennel cough

Answer 10

Canine Cough is usually a self limiting infection & resolves by 4-7 days; so antibiotics may not be indicated
* But, antibiotic therapy may reduce length of time of coughing and help prevent secondary complications
* Treat if you suspect bronchopneumonia

Not predictably susceptible so should do culture and susceptibility testing if:
* not responding to therapy
* if dogs are very ill (other bacteria involved often have widespread resistance)
* or if a cat is involved; their isolates as have more resistance

Question 11

pseudomonas

Answer 11

**Gram negative rods **
Obligate Aerobes
Highly motile (but not as motile as Proteus!)
Has “classical” colony morphology on blood agar (metallic sheen, hemolysis)
Oxidase positive (helps differentiate from Entrobacteriales)
ONLY one species has significant veterinary importance
* Pseudomonas aeruginosa

involved in superinfections

Question 12

Where does pseudomonas aeurginosa come from?

Answer 12

Pseudomonas aeruginosa is UBIQUITOUS in the environment
* Saprophyte; lives in soil and water
* Loves moist conditions!
* Also occurs transitorily in feces, skin and mucus membranes of normal animals

Can survive in “weird places”
* Old disinfectants, mastitis preparations, semen extenders, soap etc
* Supposedly “sterile” water for injection
* Medical equipment e.g., bronchoscopes, endoscopes

Question 13

Pseudomonas aeruginosa virulence factors

Answer 13

Pili : Adherence to host cells
Exotoxins: Kills cells especially phagocytes
Endotoxin
Pyocyanins and Fluoroscein
* kills cells and damages tissues
* Causes green coloration of colonies

Collagenase, Elastase
* Breaks down collagen (melting ulcers)
* Damages blood vessels, skin, etc

Biofilm Production: Aids colonization, resist phagocytosis & antimicrobial tolerance

Question 14

Pseudomonas aeruginosa pathogenesis

Answer 14

Environmental exposure is constant (they’re ubiquitous)
Therefore infections are secondary to compromised host tissues
Need underlying injury or damage to get disease e.g. damage to eye with sand, mud, thorns etc.
Therefore, Pseudomonas aeruginosa is an:
OPPORTUNISTIC PATHOGEN: needs SIGNIFICANT host comprimise

Question 15

what are superinfections

Answer 15

Disease due to P. aeruginosa often (not always) involves SUPERINFECTIONS!
1. First some underlying disease/predisposing factor causes tissue damage (=devitalised/compromised tissues)
1. This will disrupt the normal flora and allow other (good) pathogens to cause an infection (=primary infection)
1. The bacterial infection is diagnosed and treated with (often prolonged) antimicrobial therapy & which may kill the 1°bacteria
1. But underlying disease/predisposing factor NOT addressed in therapy and so still have compromised/damaged tissues
1. AND P. aeruginosa, although a weaker pathogen, has widespread antibiotic resistance, so it can survive in the face of antibiotic therapy, & therefore can invade & cause 2°infection at this time

Question 16

What bacteria can cause superinfections

Answer 16

Pseudomonas aeruginosa
Nocardia spp
Klebsiella pneumoniae

Question 17

What diseases does pseudomonas aeruginosa
cause?

Answer 17

Corneal Ulcers (Keratitis) – many animal species

Dermatitis “Green Wool” – sheep

Wound Infections
* All species
* Especially burn wounds
* As it “LOVES” moist environments and burn wounds have lots of exudation