هليكوبتر

• Helicobacter species


  • Spiral, curved, or fusiform rod-shaped Gram-negative bacteria

  
• Hosts of Helicobacter species

  • Dogs
  • Cats
  • Pigs
  • Cattle
  • Other domestic and wild animals
• Groups of Helicobacter species

  • Helicobacter species that primarily colonize the stomach (gastric helicobacters)
  • Helicobacter species that colonize the intestines (enterohepatic helicobacters)
• H. pylori


  Associated with antral gastritis, duodenal (peptic) ulcer disease, gastric ulcers, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue (MALT) lymphomas
• Helicobacter species


  • Motile and have single and/or multiple monopolar flagella that are typically sheathed and can vary greatly in their flagellum morphology

  
• Culture sensitivity


  May be limited by delayed specimen transport and processing, prior antimicrobial therapy, and contamination with other mucosal bacteria
• Culturing Helicobacter


  1. Use special transport media to maintain viability during transport

  2. Incubate at 37°C in a microaerophilic and humid atmosphere for 3-6 days, up to 14 days if negative

  3. Homogenize biopsy specimen prior to streaking onto agar plate

  4. Use enriched agar media supplemented with blood and/or blood products or antibiotic-containing media to suppress overgrowth by other bacterial flora

  
• Helicobacter colonies


  • Varying appearance on blood agar ranging from gray to translucent, 1-2 mm in diameter

  
• H. pylori


  • Oxidase positive, catalase positive, characteristic Gram-stain morphology
  • Motile and strong producer of urease
• H. pylori


  Able to survive in the acidic environment of the stomach and establish lifelong colonization of the gastric mucosa in the absence of antimicrobial treatment
• H. pylori


  Grows optimally at pH 6.0-7.0, but would be killed or not grow at the pH within the gastric lumen (pH 1-3)
• Factors contributing to H. pylori's ability

  Overcome the acidic environment of the stomach, contributing to colonization, inflammation, changes in gastric acid production, and tissue destruction
• H. pylori utilizes its urease activity

  To neutralize the gastric acid after entering the stomach
• Intracellular urease activity as well as urease located on the bacterial surface contribute to H. pylori's ability to survive in the acidic gastric environment
• تركابوكيليلها ةيباوبلا


  Helicobacter pylori
• While H. pylori grows optimally at a pH of 6.0–7.0, it would be killed or not grow at the pH within the gastric lumen (pH 1–3)
• تركابوكيليلها ةيباوبلا


  • Several factors contribute to the organism's ability to overcome the acidic environment of the stomach, contributing to colonization, inflammation, changes in gastric acid production, and tissue destruction
• Urease


  • Intracellular urease activity as well as urease located on the bacterial cell surface allow for the breakdown of urea into ammonia and CO2; NH3 is converted to ammonium (NH4+) and extruded from the bacterial cell leading to neutralization of the gastric acid
• ةيربتخملا تاصوحفلا


  Laboratory tests
• The diagnosis of gastritis and H. pylori infection can be made histologically; this approach is generally more sensitive than culture
• Since H. pylori organisms adhere to the gastric mucosa, the bacteria cannot be recovered from stool specimens like other gastrointestinal pathogens
• Testing modality


  • Histology
  • Urease detection in tissue
  • Microbiologic culture
• Histology


  • Allows for detection of organism and assessment of the extent of tissue damage (eg, ulceration)

  
• Urease detection in tissue

  • Rapid test, with most positive results being obtained within 2 hours
• Microbiologic culture


  • Allows for antimicrobial susceptibility testing
• Invasive Testing


  • Histology
  • Urease detection in tissue
  • Microbiologic culture
• Noninvasive Testing


  • Serology
• Serology


  • Noninvasive; inexpensive; "rapid" turn-around-time for results; Useful for epidemiologic purposes and evaluation of symptomatic patients
• Serology provides no assessment of tissue damage/pathology. Not suitable to assess completion of antimicrobial therapy. Usually cannot differentiate between acute and past infection
• Requires several days for results

  • Slow growth of organisms
  • Requires special and careful specimen processing
  • False-negative results due to prolonged specimen transport and processing in suboptimal conditions
• Noninvasive Testing


  Tests that do not require invasion of the body
• Serology


  Testing of blood serum
• Noninvasive testing


  • Does not require invasion of the body
  • Inexpensive
  • Rapid turn-around-time for results
• Useful for


  • Epidemiologic purposes
  • Evaluation of symptomatic patients
• Noninvasive testing


  • Provides no assessment of tissue damage/pathology
  • Not suitable to assess completion of antimicrobial therapy
  • Usually cannot differentiate between acute and past infection
• Urea breath test

  • Relatively non-invasive and rapid
  • Valuable for assessment of therapy (eradication of infection)
• Urea breath test


  • Requires expensive instrumentation for testing
  • Less convenient than serology
  • False-negative when patient receives PPI therapy
  • Provides no assessment of extent of tissue damage/pathology
• Stool antigen test


  • Relatively non-invasive, convenient, rapid, and inexpensive
  • Most valuable for assessment of response to antimicrobial therapy
• Stool antigen test


  • Not useful to assess the extent of tissue damage/pathology
• Antibodies


  Serum antibodies specific for H. pylori