Difference between revisions of "Actinobacillus species"
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===''Actinobacillus lignieresii''=== | ===''Actinobacillus lignieresii''=== | ||
| − | *Commensal in the mouth of sheep | + | *Pathogenesis and pathogenicity: |
| − | *Penetrates damaged mucosa to cause | + | **Commensal in the mouth and intestinal tract of cattle and sheep |
| − | *Enodogenous, sporadic | + | **Penetrates damaged mucosa to cause chronic granulomatous inflammation of soft tissues, a condition known as Actinobacillosis |
| − | *Lesions in the tongue, cheek, lips and sometimes in the lower gut and lungs from aspiration | + | **Enodogenous, sporadic infection |
| − | *Often spreads from the site of infection to lymphatics | + | **Lesions in the tongue, cheek, lips and sometimes in the lower gut and lungs from aspiration |
| − | *[[Muscles - inflammatory#Wooden tongue|myositis]] and formation of fibrous tissue in the lesions lead to hardening of the tissue, hence the condition is known as 'wooden tongue' in cattle | + | **Often spreads from the site of infection to lymphatics, and may cause pyogranulomatous lymphadenitis |
| − | *In sheep abscesses with thick walls are produced | + | **[[Muscles - inflammatory#Wooden tongue|myositis]] and formation of fibrous tissue in the lesions lead to hardening of the tissue, hence the condition is known as 'wooden tongue' in cattle |
| − | *Feeding is impaired, causing loss of condition | + | **In sheep abscesses with thick walls are produced |
| − | * | + | **Feeding is impaired, causing loss of condition |
| + | **Infection in the oesophageal groove can cause tympany and enlargement of the retropharyngeal lymph node, causing difficulty in swallowing and breathing | ||
| + | **Cutaneous lesions in cattle and sheep | ||
| + | **Contamination of the environment via ulcerating lesions | ||
| + | *Diagnosis: | ||
| + | **Induration of tongue | ||
| + | **Tissue sections may demonstrate pyogranulomatous foci containing club colonies | ||
| + | **Gram negative rods may be present in smears from exudates | ||
| + | **Cultures on blood agar and MacConkey agar, incubated for 24-72 hours | ||
| + | **Blood agar: small, sticky, non-haemolytic clonies | ||
| + | **MacConkey agar: slow lactose fermentation | ||
| + | *Treatment: | ||
| + | **Sodium iodide parenterally, or potassium iodide orally | ||
| + | **Potentiated sulphonamides or a penicillin/streptomycin combination | ||
| + | **Rough feed should be avoided | ||
Revision as of 13:41, 20 December 2007
- Cause peritonitis in horses
Overview
- Mainly pathogens of farm animals
- Commensals of mucosa of upper respiratory tract and oral cavity
- Cannot survive long in the environment, therefore carrier animals are important in their transmission
- Cause granulomatous inflammation
Actinobacillus characteristics
- Small Gram negative coccobacilli
- Oxidase negative
- Do not grow on MacConkey
- Non-motile
- Facultative anaerobes which ferment carbohydrates to produce acid
Actinobacillus lignieresii
- Pathogenesis and pathogenicity:
- Commensal in the mouth and intestinal tract of cattle and sheep
- Penetrates damaged mucosa to cause chronic granulomatous inflammation of soft tissues, a condition known as Actinobacillosis
- Enodogenous, sporadic infection
- Lesions in the tongue, cheek, lips and sometimes in the lower gut and lungs from aspiration
- Often spreads from the site of infection to lymphatics, and may cause pyogranulomatous lymphadenitis
- myositis and formation of fibrous tissue in the lesions lead to hardening of the tissue, hence the condition is known as 'wooden tongue' in cattle
- In sheep abscesses with thick walls are produced
- Feeding is impaired, causing loss of condition
- Infection in the oesophageal groove can cause tympany and enlargement of the retropharyngeal lymph node, causing difficulty in swallowing and breathing
- Cutaneous lesions in cattle and sheep
- Contamination of the environment via ulcerating lesions
- Diagnosis:
- Induration of tongue
- Tissue sections may demonstrate pyogranulomatous foci containing club colonies
- Gram negative rods may be present in smears from exudates
- Cultures on blood agar and MacConkey agar, incubated for 24-72 hours
- Blood agar: small, sticky, non-haemolytic clonies
- MacConkey agar: slow lactose fermentation
- Treatment:
- Sodium iodide parenterally, or potassium iodide orally
- Potentiated sulphonamides or a penicillin/streptomycin combination
- Rough feed should be avoided
Actinobacillus equuli
- Commensal of the equine intestinal mucosa
- Infection at birth causes severe enteritis and septicaemia within 24 hours, known as sleepy foal disease
- In foals that survive neonatal infection the condition progresses to cause joint infections and purulent nephritis
- A. equuli in arthritis of horses
- RTX group cytotoxin present
Actinobacillus suis
- Fatal septicaemia in pigs 1-8 weeks old
- Causes abscesses in joints and lungs of older pigs
- Carried in the nasopharynx of pigs and nose of horses
- Carriage may confer immunity to the more severe pleuropneumonia
Actinobacillus pleuropneumoniae
- Contagious porcine pleuropneumonia
- Endemic in UK
- Most strains are NAD-dependent (grow on Heated Blood agar)
- Positive CAMP reaction
- 12 serotypes causing the same disease
- Different serotypes in different regions, with serotypes 3,6 and 8 the most common in the UK
- Acute disease in susceptible herds with high morbidity and mortality
- Causes pneumonia in pigs
- Carrier herds have some immunity, protecting from acute disease, where lesions are often subclinical, and deaths sporadic
- Lung scarring and pleural adhesions in many recovered animals
- Solid immunity develops in recovered animals to all serotypes
- The disease is spread between herds by carrier pigs
- The bacteria on the palatine tonsil are undetected by serologucal tests and swabbing, and can therefore cause an outbreak in naive pigs
- Killed and bacterin vaccines are available
- Produce one or two RTX group cytolytic toxins
- RTX toxins:
- 'Repeat in ToXin' - named because there are several peptide repeats within the molecules
- Produced by various Gram-negative bacteria
- Possess four contiguous genes, A, B, C and D
- A is the structural gene; B and D are required for secretion; C allows post-translational activation of the gene product of A into a functional product
- ApxI is a strong haemolysin with cytolytic activity
- ApxII is a weak haemolysin
- ApxIII is a cytotoxin
- Different Actinobacillus pleuropneumonia serotypes secrete a particular combination of toxins; American serotypes secrete ApxI and II; European serotypes secrete ApxII and III