Module 4 (Aeromonas, Francisella, Hemophilus, & Actinobacillus) Flashcards
• These are groups of microorganisms that live in aquatic habitats
• Infections caused are common
among fish and amphibians
AEROMONAS
Species associated with
animal infections Aeromonas
➢Aeromonas hydrophila
➢Aeromonas salmincola
➢Aeromonas shigelloids
Morphology, staining features and
cellular composition of Aeromonas
• Gram-negative
• Short, plump aerobic rods
Growth characteristics of Aeromonas
• Grow in trypticase soy agar at 22 to 25°C
• Heavy turbidity in broth
Reservoir of Infection Aeromonas
• Stools, bile and throat of avian,
cattle, swine and dogs
• Feces and dysenteric stool of swine
and dogs
Transmission of Aeromonas
Ingestion of organism
Diseases associated with Aeromonas species
- Red syndromes
- Furunculosis
Etiologic agent: A. hydrophila
➢ Lethargy, emaciation, ulceration of the skin
Red syndromes
➢ Systemic disease with ulceration (A. salmincola)
• Hemorrhages on the fin, tail muscles, gills and intestinal organs
• Crateriform abscesses that discharge contents to the skin (furuncle)
Furunculosis
Other signs of Aeromonas infection
Fin rot and ulceration of the skin
Virulence Factors of Aeromonas
• Adhesins
• Enterotoxins
Laboratory diagnosis of Aeromonas
Samples: Fish and eggs
Preferred culture media:
Rimler-Shotts Medium
Agent Identification
➢ Bacterial isolation and cultivation (Trypticase soy agar)
➢ DNA primers for PCR
Treatment for Aeromonas
Oxytetracycline (60-75 mg/kg for 21 days)
Control and Prevention for Aeromonas
• Obtain fish and eggs from disease-free sources
• Stress reduction (ensuring well-aerated clean water and good nutrition)
• Human pathogens that occasionally infect domestic animals
FRANCISELLA
Species associated with animal
infections Francisella
➢Francisella tularensis
➢Francisella philomigaria
➢Francisella novicida
Morphology, staining features and cellular composition of Francisella
• Gram-negative coccobacilli
• Fresh cultures possess capsules with high lipid and amino acid content
• Older cultures show pleomorphism
Growth characteristics of Francisella
• Fastidious aerobes that prefer to grow in glucose-cysteine-blood agar
• Survives cold temperature in water, soil
and animal lesions
Reservoir of Infection Francisella
• Rabbits
• Rodents
Transmission of Francisella
• Ingestion of infected prey, feed and water
• Bites of infected blood-sucking
insects
Diseases associated with Francisella species
- Tularemia
Etiologic agent: F. tularensis
• Systemic infection marked by ulcerative inflammatory and necrotic lesions
Tularemia
Virulence Factors of Francisella
• Capsular lipids
Laboratory diagnosis of Francisella
Samples: tissue samples
Preferred culture media: Glucose cystein blood
agar
Agent identification
➢Bacterial cultivation
➢Guinea pig inoculation
➢PCR using primers for pathogenic Francisella
Treatment for Francisella
• Streptomycin
• Tetracycline
• Aminoglycosides
Control and prevention for Francisella
• Limiting tick exposure
and access to contaminated feed and water
➢Organisms require one or both of two growth factors (porphyrins or nicotinamide as X factor) and adenine dinucleotide (NAD, NADP) as V factor
➢Organisms exhibit satellite formation
Hemophilus
Species associated with animal infections Hemophilus
➢Hemophilus parasuis
➢Hemophilus paragallinarum
➢Hemophilus somnus
➢Hemophilus agni
Morphology, staining features and
cellular composition of Hemophilus
• Gram-negative tiny rods that form longer filaments
• Non-sporeforming, non-motile aerobic but some are facultative anaerobes
• Some forms are pleomorphic, capsulated and piliated
• Capsules are composed of polysaccharides
Growth characteristics of Hemophilus
• Organisms do not grow in plain or glycerol-containing agar
• Growth is enhanced by hemin and NAD and chocolate agar
• Turbid in broth
• Grows luxuriantly when a feeder bacterium is cross-streaked (satellism) with the organism
Reservoir of Infection Hemophilus
➢Respiratory tract (sick/carrier animals)
➢Nasopharynx (pigs)
➢Genital tracts (cattle and sheep)
Transmission of Hemophilus
• Airborne
• Direct contact
Diseases associated with Hemophilus species
- Bronchopneumonia in animals
- Glasser’s Disease (Swine influenza)
- Thrombotic meningo-encephalitis of cattle
- Respiratory, mammary, epididymitis and septicemias in sheep
• secondary to viral infections {swine influenza} and other bacterial infections caused by Pasteurella and Mycoplasma spp.
• marked by sero-fibrinous to fibrino-purulent secretions in the lungs, body cavities and joints
Bronchopneumonia in Animals
Etiologic agent: H. parasuis
➢Common among young weaned pigs raised in stressful conditions
➢Bronchopneumonia secondary to bacterial and viral infections
Glasser’s disease (Swine influenza)
Etiologic agent: H. paragallinarum
➢Catarrhal inflammation of the upper respiratory tract
Coryza in Chickens
Etiologic agent: H. somnus
➢marked by septicemia, meningoencephalitis and motor and behavioral abnormalities
Thrombotic meningo-encephalitis of
cattle
Etiologic agent: H. somnus, H. agni
Respiratory, mammary, epididymitis
and septicemias in sheep
Virulence Factors of Hemophilus
• Capsular polysaccharides (antiphagocytic functions)
• Heat-labile cytotoxins
• Outer membrane proteins (bind transferin –
iron complexes)
• Lipopolysaccharides (initiate release of cytokines IL1 and TNF from macrophages)
• Endotoxin
• Adherence to epithelium, endothelium and immunoglobulins
• Resistance to killing by complement proteins and phagocyte killing
Laboratory diagnosis of Hemophilus
Samples (Nasal secretions, infected tissues or fluids)
Preferred culture media: Chocolate agar
Agent identification
➢Bacterial isolation and cultivation (media that contains substances that provide the X and V factors)
➢Porphyrin test (determines X factor)
➢Serology (Agglutination, Hemagglutination-inhibition tests)
Treatment for Hemophilus
• Penicillin
• Tetracycline
• Ceftiofur
• Tilmicosin
Control and Prevention for Hemophilus
• Immunization of animals at risk
• Elimination of carriers
• Depopulation of infected flocks
➢ Microorganisms are agents of local and septicemic infections of animals
➢ Commensals of mucus membranes
➢ Opportunistic pathogens when integrity of the host’s defenses is compromised
ACTINOBACILLUS
Species associated with animal infections Actinobacillus
• Actinobacillus lignieresii
• Actinobacillus equuli
• Actinobacillus suis
• Actinobacillus capsulatus
• Actinobacillus salpingitis
• Actinobacillus seminis
• Actinobacillus pleuropneumonia
Morphology, staining features and
cellular composition of Actinobacillus
➢ Gram-negative coccobacilli
➢ Capsulated (A. pleuropneumonia) and non-capsulated forms are present
➢ Some are piliated
➢ Contain LPS with adhesive properties to tracheal epithelia
➢ Some produce outer membrane protein that binds transferrin-iron complexes
➢ Produce periplasmic iron-binding protein (AfuA/actinoferric uptake)
➢ Form aggregates or clumps in small cheese-like grayish white sulfur granules
Growth characteristics of Actinobacillus
• Require blood and serum
• Hemolytic forms exist
• Carbohydrate fermenters (no gas
production)
• Reduce nitrates to nitrites
• Produce urease, ortho-nitro-phenyl-beta-D-
galacto-pyranosidase and nitrite
Reservoir of Infection Actinobacillus
• Sick and carrier animals
Transmission of Actinobacillus
• Endogenous infections
Diseases associated with Actinobacillus species
- Pyo-granuloma of ruminants (Wooden tongue)
- Porcine pleuropneumonia (Respiratory septicemia in swine)
- Arthritis of rabbits (A. capsulatus)
- Salpingitis and peritonitis of chickens (A. salpingitis)
- Navel ill/umbilical infection of
newborn foals (A. equuli) - Epididymitis in rams (A. seminis)
Virulence Factors of Actinobacillus
• Adherence to ciliated and alveolar epithelia
• Capsule with antiphagocytic function
• RTX-type hemolysins (ApxI, ApxII and ApxIII pleurotoxin) that kill macrophages and neutrophils
• Pili-mediated adherence to alveolar epithelium
• Lipopolysaccharides (induce inflammatory response and subsequent release of pro-inflammatory cytokines ILI and TNF)
• Outer membrane proteins (bind transferrin-iron complexes)
Treatment for Actinobacillus
• Gentamycin
• Cephalosporins
• Ceftiofur
• Kanamycin
• Trimethoprim-sulfa combination
• Oral administration of iodides for wooden tongue
Prevention and Control for Actinobacillus
• Elimination of infected animals
• Mass medication to eradicate infection
• Avoiding harsh dry feed
• Navel disinfection
