Pseudomonas & Burkholderia

What is the typical cell morphology and size of Pseudomonas and Burkholderia species?

They are medium-sized Gram-negative rods measuring 0.5-1.0 x 1-5 um

What oxygen requirement category do Pseudomonas and Burkholderia fall into?

They are obligate aerobes that utilize oxidative metabolism.

Which two biochemical tests yield positive results for both Pseudomonas and Burkholderia?

The oxidase test and the catalase test.

Where is Pseudomonas aeruginosa typically found as a commensal organism?

It is a commensal on the skin and mucosal surfaces.

In which specific geographical region is Burkholderia pseudomallei considered a common soil dweller?

It is a soil dweller in tropical regions.

Approximately how long does Burkholderia mallei persist in the environment?

It persists for approximately 6 weeks.

What is the primary physical characteristic used to differentiate Pseudomonas and B. pseudomallei from B. mallei?

Motility, as B. mallei is the non-motile exception.

Describe the specific structure used for motility in Pseudomonas species.

They utilize polar flagella.

According to the diagnostic flow, what is the suspected identity of a non-motile Gram-negative rod from an equine host?

The suspected organism is Burkholderia mallei.

Which temperature and pigment profile confirms the presence of Pseudomonas aeruginosa?

Growth at $42^{\circ}C$ combined with the production of blue-green pigment.

How is the colony morphology of Burkholderia pseudomallei described after growth at 42C?

The colonies appear wrinkled with a musty or earthy odor.

Describe the unique odor associated with Pseudomonas aeruginosa cultures.

It has a fruity or grape-like odor.

How does the colony morphology of P. aeruginosa differ from B. pseudomallei?

P. aeruginosa produces large, flat colonies with serrated edges, while B. pseudomallei produces wrinkled, rough, yellow-brown colonies.

What is the characteristic appearance of Burkholderia mallei colonies on agar?

They are white and smooth, eventually becoming granular.

Under what condition does Burkholderia mallei show optimal growth on MacConkey agar?

It grows best when the medium is supplemented with glycerol.

Which species is unique in its ability to produce the blue-green pigment known as Pyocyanin?

The unique producer is Pseudomonas aeruginosa.

What is the pathogenic function of Pyocyanin in Pseudomonas aeruginosa infections?

It acts as an iron scavenger and is toxic to the host.

Name the fluorescent pigment found in the Pseudomonas aeruginosa 'pigment arsenal'.

The fluorescent pigment is Pyoverdin.

List the two red or dark pigments produced by Pseudomonas aeruginosa.

The pigments are Pyorubin and Pyomelanin.

How does Exotoxin A contribute to the virulence of Pseudomonas aeruginosa?

It inhibits host protein synthesis, leading to cell death.

What is the role of the biofilm (slime layer) in Pseudomonas infections?

It facilitates persistence on surfaces and acts as an anti-phagocytic barrier.

Which enzymes produced by P. aeruginosa are primarily responsible for host tissue damage?

Proteases and elastase.

What condition in sheep is caused by Pseudomonas aeruginosa after prolonged rain?

Fleece rot, characterized by green wool discoloration.

What is the typical clinical manifestation of P. aeruginosa infection in canines?

Chronic otitis externa (ear infection).

Which animal species experiences high mortality sepsis and hemorrhagic pneumonia due to P. aeruginosa?

Farmed mink.

With what common source is bovine mastitis caused by Pseudomonas often associated?

It is associated with contaminated wash water or antibiotic tubes.

What is the primary host profile for Burkholderia mallei?

It is an obligate pathogen of Equidae, including horses, mules, and donkeys.

How is Glanders typically transmitted among equine populations?

Through the ingestion of food or water contaminated by nasal discharges.

Describe the 'nasal form' of Glanders.

It involves ulcerative nodules, purulent discharge, and stellate (star-shaped) scarring.

What are the hallmarks of the 'pulmonary form' of Glanders?

Respiratory distress and the formation of tubercle-like lesions in the lungs.

What is the common name for the cutaneous form of Glanders?

The cutaneous form is known as Farcy.

Describe the clinical presentation of 'Farcy' in horses.

It involves lymphangitis and ulcerating nodules along the lymphatic vessels.

What diagnostic agent is used in the field for the Mallein test?

A glycoprotein extract derived from B. mallei.

Where is the Mallein antigen injected during an intradermopalpebral inoculation?

It is injected into the skin of the eyelid.

What constitutes a positive reaction in a Mallein test for Glanders?

The presence of edema and discharge 24 hours after injection.

Which two laboratory tests are used to confirm a positive field Mallein test?

Complement Fixation Test (CFT) and ELISA.

What is the causative agent of the disease Melioidosis?

The causative agent is Burkholderia pseudomallei.

What are the primary environmental reservoirs for Burkholderia pseudomallei?

Soil and surface water, particularly in rice paddies.

How does B. pseudomallei typically enter the host?

Through percutaneous inoculation (cuts), inhalation, or ingestion.

Why is Melioidosis often referred to as 'The Great Mimicker'?

Because its chronic abscesses in various organs can mimic Glanders (Pseudoglanders) or Tuberculosis.

In which organs are visceral abscesses commonly found during Melioidosis?

Common sites include the lungs, spleen, liver, joints, and CNS.

Contrast the primary virulence strategy of Pseudomonas ('The Brute') with Burkholderia ('The Stealth').

Pseudomonas relies on extracellular tissue destruction and biofilms, while Burkholderia uses intracellular survival and cell-to-cell spread.

What mechanism does Burkholderia use for cell-to-cell spread within the host?

It utilizes actin-based motility, similar to Listeria.

Name four intrinsic resistance mechanisms shared by these Gram-negative rods.

Low outer membrane permeability, multi-drug efflux pumps, chromosomal beta-lactamases, and biofilms.

What is the recommended therapeutic protocol for Pseudomonas aeruginosa infections?

A combination of an aminoglycoside (e.g., Gentamicin) and a beta-lactam, following mandatory susceptibility testing.

Why is the treatment of Melioidosis considered particularly challenging?

It requires expensive, long-term therapy, and relapses are common.

What is the mandatory control strategy for Glanders in non-endemic areas?

A 'Test and Slaughter' policy.

How is Pseudomonas mastitis controlled in bovine herds?

Through environmental control, specifically the sterilization of water lines.

What is the primary method for preventing sepsis in farmed mink populations?

The use of autogenous bacterins.

Which Burkholderia species is categorized as a Category B Bioterrorism agent?

The non-motile species Burkholderia mallei.

How does the genome of B. mallei compare to that of B. pseudomallei?

The B. mallei genome is smaller because it is host-adapted to Equidae.

Which species acts as a significant environmental reservoir for Melioidosis in tropical regions?

Wild rodents.

Describe the 'Farcy' lesions seen in the cutaneous form of Glanders.

Thickened lymphatic vessels with ulcerating nodules draining yellowish purulent material.