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Category:Actinobacillus species (view source)
Revision as of 11:13, 10 May 2010
, 11:13, 10 May 2010Created page with '===Overview=== *Mainly pathogens of farm animals *Commensals of mucosa of upper respiratory tract and oral cavity *Cannot survive long in the environment, therefore carrier anim…'
===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 [[Chronic Inflammation - Pathology#Granulomatous Inflammation|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
**[[Muscles Inflammatory - Pathology#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
**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
**[[Bacterial skin infections - Pathology#Bacterial granulomatous dermatitis|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 pleuropneumoniae''===
*Contagious porcine pleuropneumonia especially of pigs under 6 months
*Endemic in UK
*12 serotypes causing the same disease
*Different serotypes in different regions, with serotypes 3,6 and 8 the most common in the UK
*Pathogenesis and pathogenicity:
**Virulent strains possess capsules which are antiphagocytic and immunogenic
**Fimbriae allow the bacteria to attach to cells of the respiratory tract
**Damaged [[Neutrophils - WikiBlood|neutrophils]] in the lungs produce lytic enzymes
**The sustained inflammatory response causes tissue necrosis
**Lungs consolidated and necrotic with fibrinous pleuisy at post mortem
**Produce three cytotoxins which belong to the repeats-in-structural-toxin (RTX) cytolysin family
**RTX toxins:
***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
***Toxins introduce pores into cell membranes
*Clinical signs and epidemiology:
**Acute disease in susceptible herds with high morbidity and mortality (up to 50%)
**In acute outbreaks, pigs may be dyspnoeic, pyrexic or anorexic
**Blood-stained froth surrounding nose and mouth
**Cyanosis
**Pregnant sows abort
**Causes [[Respiratory Bacterial Infections - Pathology#Actinobacillus pleuropneumoniae|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
*Diagnosis:
**Haemorrhagic consolidation close to the main bronchi and fibrinous pleuritis may be suggestive
**Specimens are cultured on chocolate agar and blood agar in 5-10% carbon dioxide for 2-3 days
**Small colonies surrounded by clear haemolysis
**No growth on MacConkey agar
**Positive CAMP reaction with [[Staphylococcus spp.|''Staphylococcus aureus'']]
**Most strains are NAD-dependent (grow on Heated Blood agar)
**Immunofluorescent- or PCR-based techniques
**The bacteria on the [[Tonsils - Anatomy & Physiology#Palatine|palatine tonsil]] may remain undetected by serological tests and swabbing, and can therefore cause an outbreak in naive pigs
*Treatment:
**Antibiotics depending on the strain of bacteria
**Prophylactic antibiotics for in-contact pigs
*Control:
**Killed and polyvalent bacterin vaccines as well as a subunit vaccine are available
**Improve ventilation, avoid chilling and overcrowding
===''Actinobacillus equuli''===
*Commensal of the equine intestinal and reproductive tract
*Pathogenesis and clinical signs:
**Foals infected ''in utero'' or or after birth via the umbilicus
**Infection at birth causes severe enteritis and septicaemia within 24 hours, known as sleepy foal disease
**Foals become pyrexic and recumbent
**Death usually occurs within 1-2 days
**In foals that survive neonatal infection the condition progresses to cause joint infections and purulent nephritis, enteritis or pneumonia
**''A. equuli'' in [[Joints Inflammatory - Pathology#In Horses|arthritis of horses]]
**Abortion, septicaemia and [[Peritoneal Cavity Inflammatory - Pathology#In horses|peritonitis in horses]]
*Diagnosis:
**Specimens cultured on blood agar and MacConkey agar and incubated aerobically for 1-3 days
**Sticky colonies with variable haemolysis on blood agar
**Lactose-fermenting colonies on MacConkey agar
*Treatment and control:
**Antimicrobials ineffective unless early in course of disease
**Blood trasfusion and administration of colostrum
**Good hygiene
**Consider prophylactic antibiotics for new-born foals
**Bacteria susceptible to streptomycin, tetracyclines and ampicillin
*In other animals:
**Septicaemia in piglets
**Arthritis and enteritis in pigs
**Enteritis in calves
**RTX group cytotoxin present
===''Actinobacillus suis''===
*May be present in upper respiratory tract of sows
*Pathogenicity and clinical signs:
**Infection of piglets via aerosol or possibly skin abrasions
**Fatal septicaemia in piglets 1-8 weeks old
**Mortality up to 50% in some litters
**Fever, respiratory distress, prostration and paddling of forelimbs seen in piglets
**Petechial and ecchymotic haemorrhages in many organs
**Interstitial pneumonia, pleuritis, meningoencephalitis, myocarditis and arthritis
**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
*Diagnosis:
**Specimens cultured on blood agar and MacConkey agar for 1-3 days
**Sticky haemolytic colonies
**Pink, lactose-fermenting colonies on MacConkey agar
*Treatment and control:
**Bacteria usually susceptible to ampicillin, carbenicillin, potentiated sulphonamides and tetracyclines
**Disinfect contaminated pens
*Other animals:
**Septicaemia and pneumonia in foals
**Pneumonia in pigs and horses
===''Actinobacillus seminis''===
*Epididymitis in young rams (4-8 months)
*Polyarthritis in lambs
*Organism found in prepuce
*Opportunistic infection causing abscesses in epididymides
*May be purulent discharge onto scrotal skin
*Specimens cultured on blood agar and incubated aerobically for 1-3 days produce pin-point haemolytic colonies which are catalase-positive; no growth on MacConkey agar
===''Actinobacillus actinomycetemcomitans''===
*Epididymitis in rams
[[Category:Bacteria]]
*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 [[Chronic Inflammation - Pathology#Granulomatous Inflammation|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
**[[Muscles Inflammatory - Pathology#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
**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
**[[Bacterial skin infections - Pathology#Bacterial granulomatous dermatitis|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 pleuropneumoniae''===
*Contagious porcine pleuropneumonia especially of pigs under 6 months
*Endemic in UK
*12 serotypes causing the same disease
*Different serotypes in different regions, with serotypes 3,6 and 8 the most common in the UK
*Pathogenesis and pathogenicity:
**Virulent strains possess capsules which are antiphagocytic and immunogenic
**Fimbriae allow the bacteria to attach to cells of the respiratory tract
**Damaged [[Neutrophils - WikiBlood|neutrophils]] in the lungs produce lytic enzymes
**The sustained inflammatory response causes tissue necrosis
**Lungs consolidated and necrotic with fibrinous pleuisy at post mortem
**Produce three cytotoxins which belong to the repeats-in-structural-toxin (RTX) cytolysin family
**RTX toxins:
***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
***Toxins introduce pores into cell membranes
*Clinical signs and epidemiology:
**Acute disease in susceptible herds with high morbidity and mortality (up to 50%)
**In acute outbreaks, pigs may be dyspnoeic, pyrexic or anorexic
**Blood-stained froth surrounding nose and mouth
**Cyanosis
**Pregnant sows abort
**Causes [[Respiratory Bacterial Infections - Pathology#Actinobacillus pleuropneumoniae|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
*Diagnosis:
**Haemorrhagic consolidation close to the main bronchi and fibrinous pleuritis may be suggestive
**Specimens are cultured on chocolate agar and blood agar in 5-10% carbon dioxide for 2-3 days
**Small colonies surrounded by clear haemolysis
**No growth on MacConkey agar
**Positive CAMP reaction with [[Staphylococcus spp.|''Staphylococcus aureus'']]
**Most strains are NAD-dependent (grow on Heated Blood agar)
**Immunofluorescent- or PCR-based techniques
**The bacteria on the [[Tonsils - Anatomy & Physiology#Palatine|palatine tonsil]] may remain undetected by serological tests and swabbing, and can therefore cause an outbreak in naive pigs
*Treatment:
**Antibiotics depending on the strain of bacteria
**Prophylactic antibiotics for in-contact pigs
*Control:
**Killed and polyvalent bacterin vaccines as well as a subunit vaccine are available
**Improve ventilation, avoid chilling and overcrowding
===''Actinobacillus equuli''===
*Commensal of the equine intestinal and reproductive tract
*Pathogenesis and clinical signs:
**Foals infected ''in utero'' or or after birth via the umbilicus
**Infection at birth causes severe enteritis and septicaemia within 24 hours, known as sleepy foal disease
**Foals become pyrexic and recumbent
**Death usually occurs within 1-2 days
**In foals that survive neonatal infection the condition progresses to cause joint infections and purulent nephritis, enteritis or pneumonia
**''A. equuli'' in [[Joints Inflammatory - Pathology#In Horses|arthritis of horses]]
**Abortion, septicaemia and [[Peritoneal Cavity Inflammatory - Pathology#In horses|peritonitis in horses]]
*Diagnosis:
**Specimens cultured on blood agar and MacConkey agar and incubated aerobically for 1-3 days
**Sticky colonies with variable haemolysis on blood agar
**Lactose-fermenting colonies on MacConkey agar
*Treatment and control:
**Antimicrobials ineffective unless early in course of disease
**Blood trasfusion and administration of colostrum
**Good hygiene
**Consider prophylactic antibiotics for new-born foals
**Bacteria susceptible to streptomycin, tetracyclines and ampicillin
*In other animals:
**Septicaemia in piglets
**Arthritis and enteritis in pigs
**Enteritis in calves
**RTX group cytotoxin present
===''Actinobacillus suis''===
*May be present in upper respiratory tract of sows
*Pathogenicity and clinical signs:
**Infection of piglets via aerosol or possibly skin abrasions
**Fatal septicaemia in piglets 1-8 weeks old
**Mortality up to 50% in some litters
**Fever, respiratory distress, prostration and paddling of forelimbs seen in piglets
**Petechial and ecchymotic haemorrhages in many organs
**Interstitial pneumonia, pleuritis, meningoencephalitis, myocarditis and arthritis
**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
*Diagnosis:
**Specimens cultured on blood agar and MacConkey agar for 1-3 days
**Sticky haemolytic colonies
**Pink, lactose-fermenting colonies on MacConkey agar
*Treatment and control:
**Bacteria usually susceptible to ampicillin, carbenicillin, potentiated sulphonamides and tetracyclines
**Disinfect contaminated pens
*Other animals:
**Septicaemia and pneumonia in foals
**Pneumonia in pigs and horses
===''Actinobacillus seminis''===
*Epididymitis in young rams (4-8 months)
*Polyarthritis in lambs
*Organism found in prepuce
*Opportunistic infection causing abscesses in epididymides
*May be purulent discharge onto scrotal skin
*Specimens cultured on blood agar and incubated aerobically for 1-3 days produce pin-point haemolytic colonies which are catalase-positive; no growth on MacConkey agar
===''Actinobacillus actinomycetemcomitans''===
*Epididymitis in rams
[[Category:Bacteria]]