Bacterial Overgrowth



Bacterial Overgrowth





DEFINITION:



  • Increased number of bacteria in areas of the GI tract that usually do not provide the environment for colonization/proliferation of bacteria


EPIDEMIOLOGY:



  • Depends on cause; See Factors influencing bacterial overgrowth below under Pathophysiology


ETIOLOGIES:



  • Also consider in the DDX: Fructose and Lactose intolerance


PATHOPHYSIOLOGY:



  • Usual bacterial presence in GI Tract: Stomach <104/ml; Jejunum <105/ml; Ileum <106/ml; Colon <1010/ml



    • Proximal to cecal valve: nearly all aerobes; Distal to the cecal valve: nearly all anaerobes


  • In health: small bowel bacteria resemble oropharyngeal flora with gram-positive, aerobic organisms


  • In Bacterial Overgrowth: bacteria are mostly gram-neg (including E. coli), and anaerobic (including Clostridia, Bacteroides)


  • Factors influencing Bacterial Overgrowth: structural lesions, motility, excessive bacterial load, deficiency in host defenses



    • Structural (obstruction to outflow): Surgical anastomosis, Webs, Adhesions, Strictures, Surgical diversions/blind loops, Diverticula


    • Motility (intestinal delay or stasis): Diabetes, Scleroderma, Pseudo-obstruction syndromes, Ileus, Acute enteric infection


    • Excessive bacterial load: Absence or incompetence of IC valve, Enteric fistulas (i.e. Crohn’s)


    • Deficient host defenses: Acid suppression (medications/surgery), Hypochlorhydric disorders (Pernicious anemia), Immune (IgA deficiency), Malnutrition

Tags:
Aug 24, 2016 | Posted by in GASTROENTEROLOGY | Comments Off on Bacterial Overgrowth

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