18 – Actinobacillus Flashcards
Microbiological characteristics
- Gram-negative rods or coccobacilli
- Facultative anaerobes
- Biocontainment level 2
- Some are fastidious and difficult to grow
- Presence of sulfur granules and pyogranulomatous inflammation seen with A. lignieresii
Actinobachillus suis: pure culture microbial characteristics
- Pleomorphic ‘morse code’ morphology: combination of cocci and rods
Natural host or habitat
- Host associated microbes
o A. pleuropneumoniae infections are contagious
o Others originate from animals endogenous organism - Found in upper respiratory tract and mouths of animals and people
- Found in GIT
- *do NOT survive well in environment
NAD dependent (“V-factor”)
- Dependence can be detected with supplementation or co-culture with S. aureus which overproduce V-factor
- *only grow close to S. aureus growth
Virulence factors of A. pleuropneumoniae
- Type 4 fimbriae: adhesion
- Capsule: anti-phagocytic
- Apx toxin
- RTX toxin
- Proteases
Apx toxin
- Cytotoxin which is within the RTX superfamily of toxins
o Pore forming cytotoxins which affect porcine neutrophils
RTX toxin
- Found in A. equuli
- Shown to be toxic to equine ganulocytes
APP (A. pleuropneumoniae) in pigs
- Very important, economically damaging disease
- Spread between pigs through DROPLETS (requires close contact)
o Chronic, subclinical carriers maintain in herd
o Inflammation stimulates coughing=spread - Variable incubation period
- Outbreaks in 2-4month old piglets (wan of maternal immunity)
- Disease prevention varies with age, herd health state, environmental conditions
APP peracute disease (pigs)
- High fever
- May have diarrhea/vomiting
- Fibrinous/necrotizing pneumonia and fibrinous pleuritis
- Respiratory disease followed by circulatory collapse
- Animals become cyanotic
- Mouth breathing shortly before death
- Death as quick as 4hrs (up to 36hrs)
APP acute disease (pigs)
- More widespread in barn
- Inappetent, wont drink
- Respiratory signs (cough, mouth breathing)
- Respiratory and circulatory failure
- Can see spectrum of outcomes within herd (recovery -> death)
APP chronic disease (pigs)
- Following resolution of acute signs or without prior acute disease
- Lethargy, exercise intolerance
o Fibrinous pneumonia - Decreased production even with antimicrobials
Management/prevention of APP (pigs)
- Chronic/subclinical infections=persistent problems
- Transmits between herds by introduction of carries (AIAO)
- Buying replacement stock from specific pathogen free herds
- Maintaining a healthy herd (those with influenza=predisposed)
- Vaccination
APP similar disease syndrome with A.suis, but other body systems also involved
- Sepsis
- Meningitis
- Abortion
Actionbacillus lignieresii
- Normal member of oral and rumen microbiota
- Disease tends to be sporadic: when animals eat abrasive food
Actinobacillus lignieresii: wooden tongue (cattle), signs
- Glossal actinobacillosis
- Animals salivate excessively (may have difficulty eating)
- Tongue=swollen and hard
- Painful
- May have nodules develop on tongue which typically contain purulent material (nodules may be ulcerated)
- *infections at other sites can occur
Actinobacillus lignieresii: wooden tongue (cattle), purulent material is NOT
- Malodorous
o *may help differentiate from other infections
Actinobacillus lignieresii: wooden tongue (cattle), management factors for avoiding disease
- High quality feed: avoid thistles , foxtails
Actinobacillus lignieresii: in sheep, lesions
- Occur on face and lips
- Large nodules may ulcerate
- Reportedly implicated in cases of cud-dropping: green staining of lips
Actinobacillus equuli (horse)
- Found in reproductive and intestinal tracts of horses
- Acute and potentially fatal sepsis of neonatal foals
- Ascending infections from umbilicus?
Actinobacillus equui: acute and potentially fatal sepsis of neonatal foals
- In foals <2 years old, most commonly recovered in blood or respiratory infections
- Sepsis associated with embolic spread and subsequent
o Nephritis
o Pneumonia
o Lymphoid necrosis
o Hepatic necrosis
o Septic arthritis
Actionbacillus equui: animals are predisposed if
- Failure of passive transfer
- Concurrent infections
Actinobacillus equui: treatment
- Anitmicrobials
- Supportive care
Actionbactillus suis (pigs)
- Can be difficult to differentiate from A. equuli phenotypically
- Only reported to affect pigs
- Opportunistic pathogen that affects ‘high health farms’
Actinobacillus suis: piglets
- Septicemia
- Arthritis
Actinobacillus suis: older pigs
- Pleuropneumonia
- Meningitis
- Abortion
Specimens to collect
- Purulent materials
- Exudates
- Biopsies from lesions
- Lung samples
- Tissues collected on necropsy
Sample handling
- Do NOT freeze
Lab ID
- Culture possible
- Growth on blood and MacConkey
- Some require chocolate agar
- Carboxyphilic (5-10%)
- Microscopy very useful
- Club colonies can also be seen on histopathological sections
- PCR useful
Zoonotic/interspecies transmission
- Not a major zoonotic concern: narrow host range
- Have been cases of humans infections with various Actinobacillus sp. Following BITES
- Needle-stick injuries
Treatment options
- Antimicrobial susceptibility test methods for APP
- No guidelines for other organisms
Actinobacillus lignieresii: treatment options
- Oral iodine solutions (topical)
- Sulfoamides
- Penicillins
Actinobacillus equuli: treatment options
- Septic foals need to be treated aggressively
- Consult an equine med book (must be away of certain antimicrobials in neonates)
