Lecture 5 - Pseudomonas and Burkholderia

What are the three Pseudomonas and Burkholderia species?

1. Pseudomonas aeruginosa

2. Burkholderia pseudomallei

3. Burkhoderia mallei

How is P. aeruginosa identified?

Green hue appearance and fruity odor

What is the definitive identification of P. aeruginosa?

-Production of pyocanin and pyoverdine

-Growth at 42C

What is pyoverdin?

Yellowish green siderophore

What is pyocanin?

Bluish green tricyclic redox toxin

What diseases are associated with P. aeruginosa in swine, dairy cows, dogs, sheep, minks, and chinchillas?

-Swine: necrotic pneumonia, enteritis, rhinitis

-Dairy cows: mastitis

-Dogs: suppurative otitis externa, mange

-Sheep: green wool/fleece rot

-Minks and chinchilla: hemorrhagic pneumonia

What are the predisposing factors to P. aeruginosa?

-Parasitic or fungal infections

-Prolonged exposure to antimicrobials (opportunistic infections)

-Poor sanitation

How does P. aeruginosa infect tissues?

Resist phagocytic killing through a slimy capsule, toxins, and antioxidative enzymes

Why are P. aeruginosa and B. pseudomallei intrinsically resistant? Why is this important?

-Have multidrug efflux pumps

-Multiple antibiotic resistant genes

-Low permeability of bacterial cellular envelopes

-Necessary to run sensitivity tests for proper antibiotic therapy

How is P. aeruginosa treated?

Antibiotic that it is not resistant to

How is P. aeruginosa prevented?

-Medical grade honey

-Probiotic prophylaxis

What are the characteristics of Burkholderia pseudomallei?

-Oval, motile, gram (-), facultative aerobe

What disease does Burkholderia pseudomallei cause? What are the symptoms?

-Causes melioidosis

-Pain in chest, bones, or joints, cough, skin infections, pneumonia

-Associated with granulomatous response

Where is B. pseudomallei commonly found? What can it be isolated from? How is it transferred to new environments?

-Areas with high humidity and temperature

-Saprophyte (lives on dead organic materials)

-Isolated from various soil types and surface water

-Transferred with shipment of contaminated animals, soil, or water

How is B. pseudomallei transmitted?

-Opportunistic infection

-Percutaneous inoculation, contamination of wounds, ingestion of soil or contaminated carcass, or inhalation

-Sexual transmission

What are the clinical lesions B. pseudomallei?

-Most subclinical

-Multiple suppurative or caseous nodules in lungs, spleen, liver, and lymph notes

What are the preventive measures for B. pseudomallei?

-Raise animals off the soil

-Provide clean drinking water

-Minimize environmental contamination

What is quorum sensing?

Communication between bacteria used to coordinate virulence expression

What are biofilm formation?

Virulence property that allows attachment to other organisms and prevent degradation by macrophages

What are the advantages of biofilms?

-Antiphagocytic

-Protected from antimicrobials

-Bacteria mutate at a higher frequency and generate better genetic diversity

-Difficult to eradicate

How can biofilms affect water?

-Inaccurate water quality monitoring

-Thick biofilms can block water filters/pipes

-Sugar and organic acid in water medications

-Biofims on the roof can drip into underlying structures

-Biofilms on fans or cooling systems can become aerosolized

What are problems with biofilms in animal farming?

-Inaccurate antibacterial tested

-Microbes more resistant to disinfectants

-Inaccurate water quality monitoring

What are the general characteristics of Pseudomonas aeruginosa?

Gram (-), aerobic but adapted to low O2, motile rod

How is B. pseudomallei diagnosed?

-Isolation for lesions

-Unique colony form and odor on ashdown’s media

-Serological tests

-DNA probes and PCR tests

How is B. pseudomallei treated?

-Expensive, prolonged, and often unsuccessful

-Initial intensive therapy followed by eradication therapy

What are the general characteristics of B. mallei?

-Nonmotile, aerobic coccobacilus

-Cannot persist in nature outside of host

What disease does B. mallei cause? What are it’s characteristics? In what species?

-Causes glander’s but cannot persist outside of host

-Contagious, acute or chronic, fatal disease

-Equidae but zoonotic for humans, cats, and other species

How is glanders in western Europe and US? Where are recent outbreaks?

-Eradicated or effectively controlled in western Europe and US

-Recent outbreaks in middle east

What are the clinical signs of Glanders with acute disease?

-Septicemia with high fever

-Thick, mucopurulent nasal discharge

-Respiratory distress

-Death

What are the three forms of Glanders found with chronic diseases? Which is most common?

1. Nasal

2. Pulmonary

3. Cutaneous (“Farcy”) - most common

How is B. mallei transmitted?

-Ingestion of food or water contaminated with infected discharges

-Inhalation of infectious aerosols

What should you do if there is a glanders outbreak?

-Bury or burn all contaminated bedding and foodstuffs

-Sterilize stalls and harness equipment

-Avoid contact with infected animals

What is B. mallei sensitive to?

Heat, UV light, desiccation, and common disinfectants

How is B. mallei diagnosed?

-Clinical signs

-Mallein test (injection into skin of eyelid and watch for swelling)

-ELISA

-Culture

-PCR

How is B. mallei prevented and treated?

-No vaccine

-Prevention depends on early detection and elimination

-Quarantine and disinfection

-Antibiotic treatment (in endemic areas)