Difference between revisions of "Rhodococcus equi"

From WikiVet English
Jump to navigation Jump to search
Line 1: Line 1:
 
<big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big>
 
<big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big>
 
<big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big>
 
<big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big>
 
*Causes [[Peritoneal cavity - inflammatory#Peritonitis|peritonitis]]
 
*[[Bacterial infections#Rhodococcus equi|Pneumonia]] in foals
 
  
 
===Overview===
 
===Overview===
Line 10: Line 7:
 
*Found in soil and intestinal tract of animals
 
*Found in soil and intestinal tract of animals
 
*Replicates at warm temperatures in soils contaminated by faeces of herbivores
 
*Replicates at warm temperatures in soils contaminated by faeces of herbivores
*Opportunistic respiratory pathogen of foals under 6 months causing suppurative bronchopneumonia
+
*Opportunistic respiratory pathogen of foals under 6 months causing suppurative [Bacterial infections#Rhodococcus equi|bronchoneumonia]]
  
  
Line 36: Line 33:
 
===Clinical infections===
 
===Clinical infections===
  
*Bronchopneumonia and lung abscessation in foals less than 4 months
+
*[[Bacterial infections#Rhodococcus equi|bronchoneumonia]] and lung abscessation in foals less than 4 months
 
*Acute disease in 1 month-old foals: acute fever, anorexia, bronchopneumonia
 
*Acute disease in 1 month-old foals: acute fever, anorexia, bronchopneumonia
 
*Insidious disease in 2-4 month-old foals with coughing, dyspnoea, weight loss, exercise intolerance, loud, moist rales on lung auscultation
 
*Insidious disease in 2-4 month-old foals with coughing, dyspnoea, weight loss, exercise intolerance, loud, moist rales on lung auscultation
 
*Occasionally diarrhoea  
 
*Occasionally diarrhoea  
*Granulomatous ulcerative enterocolitis and mesenteric lymphadenitis in some foals following ingestion of contaminated sputum
+
*Granulomatous ulcerative enterocolitis, mesenteric lymphadenitis and [[Peritoneal cavity - inflammatory#Peritonitis|peritonitis]] in some foals following ingestion of contaminated sputum
 
*Foals over 6 months refractory to pulmonary infection
 
*Foals over 6 months refractory to pulmonary infection
 
*Superficial abscesses in horses over 6 months
 
*Superficial abscesses in horses over 6 months

Revision as of 11:55, 20 July 2008

BACK TO INFECTIOUS AGENTS AND PARASITES
BACK TO BACTERIA

Overview

  • Gram-positive aerobic saprophyte found worldwide
  • Found in soil and intestinal tract of animals
  • Replicates at warm temperatures in soils contaminated by faeces of herbivores
  • Opportunistic respiratory pathogen of foals under 6 months causing suppurative [Bacterial infections#Rhodococcus equi|bronchoneumonia]]


Characteristics

  • Grows on non-enriched media
  • Salmon-pink mucoid colonies due to capsule and pigment production
  • No haemolysis on blood agar
  • Aerobic, non-motile
  • CAMP test-positive
  • Catalase positive, oxidase negative, weakly acid-fast
  • Found as cocci and rods
  • Intracellular pathogen


Pathogenesis and pathogenicity

  • Organism present in faeces or healthy foals as well as adult horses
  • Pastures can become heavily contaminated, leading to outbreaks
  • Transmission via inhalation of dust contaminated with R. equi
  • Virulence associated with specific surface antigens encoded by a large plasmid
  • Capsular polysaccharide and mycolic acids in cell wall prevent phagocytosis


Clinical infections

  • bronchoneumonia and lung abscessation in foals less than 4 months
  • Acute disease in 1 month-old foals: acute fever, anorexia, bronchopneumonia
  • Insidious disease in 2-4 month-old foals with coughing, dyspnoea, weight loss, exercise intolerance, loud, moist rales on lung auscultation
  • Occasionally diarrhoea
  • Granulomatous ulcerative enterocolitis, mesenteric lymphadenitis and peritonitis in some foals following ingestion of contaminated sputum
  • Foals over 6 months refractory to pulmonary infection
  • Superficial abscesses in horses over 6 months
  • Occasional infections in pigs and cattle, causing cervical lymphadenopathy
  • Subcutaneous abscesses and mediastinal granulomas in cats
  • Pneumonia in HIV patients


Diagnosis

  • History of disease on the farm, age of foals affected and clinical signs
  • Auscultation and rediography of thorax confirms pulmonary disease