Category:Pseudomonas and Burkholderia species


Overview

  • Organisms found in soil and water worldwide
  • Burkholderia mallei causes glanders; rodents act as reservoir of infection
  • Burkholderia pseudomallei causes meliodosis
  • Pseudomonas aeruginosa, found on skin, mucous membranes and in faeces, causes opportunistic infections

Characteristics

  • Gram-negative rods
  • Obligate aerobes
  • Oxidase and catalase positive
  • Pseudomonas species and Burkholderia pseudomallei motile by polar flagellae
  • Burkholderia mallei non-motile


Pseudomonas aeruginosa

Burkholderia mallei

  • Causes glanders, a contagious disease of Equidae
  • Nodules and ulcers in respiratory tract and on skin
  • Largely eradicated but sporadic cases in Middle East, India, China
  • Pathogenesis:
    • Transmited by ingestion of food/water contaminated by nasal discharge of infected Equidae; occasionally via inhalation or skin wounds
    • Organism invades nasopharyngeal mucosa and spreads to other tissues via lymphatics
    • Presence of B. mallei in host causes hypersensitivity reaction
  • Clinical infections:
    • Acute septicaemic form with fever, mucopurulent nasal discharge and respiratory signs; death within weeks
    • Chronic disease more common:
      • Nasal form: rhinitis; ulcerative nodules develop on mucosa of nasal septum and lower part of turbinates; purulent blood-stained nasal discharge; regional lymphadenitis
      • Respiratory form: respiratory distress; granulomatous lesions throughout lungs
      • Cutaneous form (farcy): lymphangitis; nodules along lymphatic vesselsof limbs; ulcers develop and discharge pus
      • May die after several months or recover and shed organisms from respiratory tract or skin
    • Carnivores may contract disease by eating infected carcasses
  • Diagnosis:
    • Specimens include discharges from lesions and blood for serology
    • Grows on media containing 1% glycerol; most strains are non-lactose fermenters on MacConkey agar
    • Complement fixation and agglutination
    • Serology
    • Mallein test: mallein injected intradermally below lower eyelid; local swelling and discharge indicates positive reation
  • Treatment/control:
    • Test and slaughter policy where disease exotic
    • Disinfection of contaminated areas using formalin or an iodophor

Burkholderia pseudomallei

  • Causes melioidosis - endemic in Asia and Australia
  • Primarily infects rodents
  • Pathogenesis:
    • Infection via ingestion, inhalation or skin wounds from environment
    • Exotoxin, dermonecrotic protease and lecithinase implicated in pathogenicity
    • Strain virulence and host immunosuppression important
  • Clinical infections:
    • Opportunistic infection with stress and immunosuppression predisposing to disease
    • Abscesses develop in many organs including lungs, spleen, liver, joints, CNS, upper respiratory tract
    • Chronic, debilitating, progressive disease with long incubation period
    • Many animal species susceptible
    • Referred to as pseudoglanders in horses
  • Diagnosis:
    • Specimens: pus from abscesses, affected tissues, blood
    • Fluorescent antibody technique on tissue smears
    • Blood agar and MacConkey agar plates, incubated aerobically
    • Colonies have musty smell
    • Lactose fermentation on MacConkey
    • Slide agglutination
    • ELISA, complement fixation and indirect haemagglutination tests for serum antibodies
  • Treatment/control: slaughter of infected animals where exotic

Pages in category "Pseudomonas and Burkholderia species"

The following 5 pages are in this category, out of 5 total.