Bordetella and Moraxella Bacteria

Bacteriology & Mycology

• Week 5 bacteria covered: Bordetella, Moraxella, Ornithobacterium, Pasteurella, Mannheimia, Bibersteinia, Histophilus, Glaeserella, Actinobacillus, Avibacterium

Bordetella

• Gram-negative rods
• Strict aerobes (need oxygen)
• Slow-growing bacteria
• Affinity for ciliated respiratory epithelium
• Usually commensals of the upper respiratory tract (URT)
• Poor survival in the environment
• Transmission occurs via inhalation
• Young animals are more susceptible
• High morbidity, low mortality
• Contagious but not typically fatal

Bordetella Virulence Factors

• Adhesins: contribute to adherence and colonization
• Dermonecrotic toxin (DNT): involved in lesion formation

Bordetella bronchiseptica

• Important species in veterinary medicine
• Causes disease in dogs (kennel cough), pigs, rabbits, and other animals
• Causes atrophic rhinitis in pigs
  • Infected during first weeks of life
  • DNT inhibits osteoblasts, hindering bone formation
  • Results in snout deformities and turbinate atrophy
• Progressive forms of the disease are permanent
• Non-progressive forms may resolve

Bordetella in Other Species

• Guinea pigs: highly susceptible to severe pneumonia, often resulting in high mortality.
• Cats: transmission can occur between dogs and cats, and kittens can have life-threatening respiratory illnesses.

Bordetella avium

• "Bordetellosis," "Turkey coryza," "Infectious coryza"
• Highly contagious URT disease in poultry
• Turkeys are the natural host
• Can also infect chickens and ducks
• Primarily affects 2-8 week old birds
• High morbidity (often 100%)

Bordetella parapartussis

• Mild form of whooping cough in humans and non-progressive pneumonia in lambs
• Ovine and humans cannot transmit the disease to each other

Moraxella

• Gram-negative rods/cocci
• Non-motile
• Resistant to environmental stressors
• Typically diplococci or short chains
• Associated with cow eye infections

Moraxella bovis

• Commensal of bovine mucous membranes
• Reservoir in the conjunctiva and nasopharynx
• Bos taurus (cattle) more susceptible to disease than Bos indicus (zebu cattle)
• Transmission is via direct contact or flying insect vectors
• More prevalent in the summer months

Moraxella bovis - Virulence Factors

• Type IV pili: role in attachment
• Cytotoxin MbxA: hemolytic properties, contributes to ocular damage

Ornithobacterium rhinotracheale

• Gram-negative pleomorphic rods
• Facultative anaerobe
• Capnophilic (grows best in elevated CO2)
• Primarily affects chickens and older birds
• Usually a coinfection with other pathogens
• High mortality can occur in large poultry operations

Pasteurellaceae

• Mostly opportunistic
• Distributed worldwide
• Wide host range
• Commensal bacteria of the respiratory tract (RT)
• Can be found in the oral cavity and gastrointestinal tract (GIT)

Pasteurella

• Gram-negative rods/coccobacilli
• Facultative anaerobes
• Able to survive in oxygen-deficient environments
• Fastidious (specific growth requirements)
• Commonly encapsulated
• Often non-hemolytic colonies in blood agar
• Most important species is Pasteurella multocida

Pasteurella multocida

• "Many killing" — highly pathogenic
• Usually enters via respiratory tract (inhalation)
• Endogenous - commensal becomes pathogenic
• Exogenous - pathogenic, contacted from another animal
• Can cause serious infections in a variety of animals

Pasteurella multocida: in different animal species

• Pigs - progressive atrophic rhinitis, often found in young animals, damages bones in the nasal cavity
• Swine - secondary causative agent in pneumonia. Associated with, but not always the primary cause in swine pneumonia, but often in co-infection with other pathogens.

Mannheimia

• Gram-negative rods/coccobacilli
• Commensal of nose, tonsils, and nasopharynx
• Pathogenic in domestic and wild ruminants
• Mannheimia haemolytica is the most important species

Mannheimia haemolytica

• Commensal in sheep and goats. Low antimicrobial resistance.
• Relatively easy to treat.
• Cause of severe disease in lambs and cause of gangrenous mastitis
• Contributes to shipping fever in cattle

Mannheimia haemolytica: Pathogenesis

• Stress (transport, environmental changes, viral infection) can cause the multiplication of Mannheimia haemolytica.
• Excretion of high numbers of the organism.
• Lung (aspiration of upper airway droplets)
• Fibronecrotic bronchopneumonia
• Acute pneumonia in the finest manifestations.
• Shipping fever (bovine respiratory disease (BRD)).

Bibersteinia trehalosi

• Pathogenic to cattle and sheep Causes septicemia in weaned lambs, usually within 5-12 months of age
• Contributes to pulmonary disease in cattle

Haemophilus-like Bacteria

• Gram + rods
• Fastidious
• Capnophilic (likes CO2) bacteria
• Facultative anerobe
• Non-motile
• Host-specific

Glaesserella parasuis

• Causes Glässer’s disease
• Polyserositis and meningitis in young pigs
• Arthritis and pneumonia in older pigs

Histophilus somni

• "Sleeper's Disease."
• Infectious thromboembolic meningoencephalitis in cattle
• Meningeal and Respiratory disease
• Genital tract infections (e.g. mastitis)

Actinobacillus

• Gram-negative coccobacilli
• Facultative anaerobes
• Fastidious
• Capnophilic (likes CO2).
• Often causes pneumonic disease.
• Non-motile

Actinobacillus pleuropneumoniae

• Commensals of the URT in healthy pigs
• Main cause of outbreaks of fatal pneumonia
• Necrotizing-fibrino-hemorrhagic pneumonia

Actinobacillus suis

• Commensals of the URT and vagina
• Opportunistic pathogen
• Expresses Apxl & ApxII toxins, often cytotoxic and hemolytic
• Can be treated with penicillins

Actinobacillus equuli

• Opportunistic pathogen in horses
• Main cause of pneumonia
• Can occur in adult horses
• Causes meningitis and abortion

Actinobacillus lignieresii

• Commensal of ruminant URT
• Often causes granulomatous inflammation of the tongue
• Pus-filled ulcers on the tongue, but no unusual smells
• Inoculated into mucous membranes through abrasive feed

Actinobacillus seminis

• Causes problems in the male and female reproductive tracts of small ruminants

Avibacterium paragallinarum

• Causes infectious coryza (infectious respiratory disease) of poultry, that often manifests as respiratory diseases
• Subacute cases usually cause coinfections with other viruses and bacteria
• Chronic cases typically result in complications like low growth and decreased egg production

Practice Questions

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