Microbiology

• Campylobacter


  Curved Gram-negative bacilli motile with a polar flagellum, non-sporing, capsulate, some species show optimal growth at 42°C require microaerophilic atmosphere containing 5% of O2, 10% of CO2 and 85% of H2 or N2. They do not grow in air.
• Campylobacter species


  • Campylobacter jejuni
  • C. coli
  • C. lari
• Campylobacters


  • They have a characteristic morphology
  • They grow on selective media in a microaerophilic at 42°C
  • Several selective media are available for culture of the organism, including Skirrow's medium which contains the antibiotics vancomycin, polymyxin B and trimethroprim
  • Colonies are colourless or grey with a metallic sheen
  • They are oxidase and catalase positive
• Campylobacter cell walls contain endotoxin
• Cytopathic extracellular toxins and enterotoxins have also been demonstrated in Campylobacter
• Campylobacter infections


  Acute enteritis, rarely complicated by septicaemia
• Laboratory diagnosis of Campylobacter

  1. Culture of stool samples on selective media at 42°C for 42-72 hrs

  2. Serology may be undertaken but detection of serum antibodies to Campylobacters is rarely used in practice
• Campylobacter treatment


  • Antibiotics often not required, erythromycin for severe cases particularly in the elderly
  • Most Campylobacter strains are susceptible to erythromycin, tetracycline and the quinolones
  • Erythromycin, ciprofloxacin are the drugs of choice for Campylobacter enteritis
  • Gentamicin is the drug of choice for Campylobacter septicaemia
• Helicobacter pylori


  • The most important aetiological agent of chronic active gastritis and peptic ulcer disease
  • Fastidious, microaerophilic, oxidase and catalase positive, spiral-rod shaped, Gram-negative bacterium
  • Possesses multiple unipolar or bipolar flagella for motility under optimum growth at 37°C
• Incidence and prevalence of H. pylori

  • 60%-70% of children in developing countries are positive for antibody against H. pylori
  • 2.35% prevalence of this organism in Lagos (Coker and Akande, 1989)
  • 27.8% prevalence rate in Western Nigeria (Smith et al, 1999)
  • 20%-50% prevalence in Europe and North America
  • 50% of infants and 90% of 5 years old were positive for H. pylori from the Gambia
  • In India 60% of children aged 3-10 years were found to be infected
• Acquisition and transmission of H. pylori


  • The route of acquisition and transmission of the bacterial infection is not yet well understood
  • Natural infection is limited to humans and monkeys
  • The faeco-oral or oral-oral route is strongly suggested because they have been detected in saliva, dental plaque and less often in the faeces of patients with gastritis
• Colonization of H. pylori

  • The human gastric mucosa is the major habitat of the H. pylori
  • The organism is able to survive and multiply in the acidic stomach environment because they possess the ability to provide urease in abundance that help the organism to hydrolize urea to ammonia and carbon dioxide
  • The ammonia provides a transient neutralization of the gastric acid, thereby providing the bacterium time to safely transverse the mucous layer and colonize the surface of the epithelium
• Pathogenesis of H. pylori

  • Majority of the bacterial clinical isolates have been shown to express a cytotoxin called VACUOLATING CYTOTOXIN or VacA toxin that causes the formation of vacuoles in mammalian cells
  • The urease activity is considered to stimulate inflammatory responses that is characterized with recruitment of leukocytes, induction of pro inflammatory cytokines and triggering off oxidative burst of neutrophils
  • The CagA protein (120-140KDa) is found in organisms isolated from peptic ulcer patients and stimulates interleukin-8 production
  • The organism also expresses lipase, haemolysins and the vacuolating cytotoxin VacA
• Examination and detection of H. pylori

  1. H. pylori can be examined directly from biopsies that have been carefully mixed (not homogenised) and Gram-stained

  2. They can also be detected in histological sections stained by haemotoxylin and eosin method

  3. The presence of H. pylori can also be detected indirectly by utilizing the ability to the organism to liberate ammonia in commercially produced kits, such as the CLO (Campylobacter-like-organism)
• Culture isolation and identification of H. pylori

  1. H. pylori is highly fastidious and isolation therefore requires enriched culture media in broth and solid forms

  2. Most often they contain selective growth inhibitory substances against possible contaminants e.g. Brain heart infusion Brucella, columbia media

  3. Inoculated media are incubated microaerophilically for 3-5 days at 37°C

  4. Presumptive identification of isolates depend on cell morphology oxidase and urease tests

  5. Accurate identification and typing of strains depend on molecular techniques

  6. Primary isolation of the organism was performed on Dent's medium
• H. pylori treatment


  • Antimicrobial agents that demonstrate inhibitory effects on H. pylori in-vitro may not show similar effects on the organism in-vivo because of the acid environment of the stomach
  • Generally a 14 day triple regimen is recommended for effective treatment
  • Bismuth, metronidazole and amoxicillin have been used with success
  • Follow-up at 28 days post-treatment is suggested for eradication of the organism
  • A combination of antibiotics and a proton pump inhibitor (triple therapy) appears to be most successful e.g. amoxicillin, metronidazole and omeprazole
  • Reinfection with H. pylori can occur
• Latest H. pylori treatment

  • Pariet 20mg 2ce daily for 7 days
  • Clarithromycin 500mg 2ce daily for 7 days
  • Ciprofloxacin 500mg 2ce daily for 14 days
• Treatment of choice for H. pylori

  • PPI in standard dose + clarithromycin 500mg b.d. orally + Amoxicillin 1000mg b.d. orally x 7 days
  • PPI in standard dose + clarithromycin 500mg b.d. orally + metronidazole 400-500mg b.d. orally x 7 days
  • Ranitidine bismuth citrate 400mg b.d. orally + clarithromycin 500mg b.d. orally + Amoxicillin 1000mg b.d. orally x 7 days
  • Ranitidine bismuth citrate 400mg orally + Clarithromycin 500mg b.d. orally + metronidazole 400-500mg b.d. orally x 7 days
  • If Clarithromycin is not available: PPI in standard dose + Amoxicillin 1000mg b.d. orally + Metronidazole 400-500mg b.d. orally x 7 days OR Colloidal bismuth subcitrate 120mg b.d. orally + metronidazole 400-500mg b.d. orally + Tetracycline 500mg qds orally x 14 days
• Treatment for H. pylori failures

  • PPI in standard dose b.d. orally + Colloidal bismuth subcitrate 120mg qds orally + Metronidazole 400-500mg tds orally + Tetracycline 500mg qds orally x 7 days
• Proton pump inhibitors (PPI) in standard dose

  • Eosomeprazone 20mg b.d. orally
  • Lansoprazone 30mg b.d. orally
  • Omeprazole 20mg b.d. orally
  • Pentoprazole 40mg b.d. orally
• This is a Gram-negative curved bacillus
• The ability to survive in the gastric environment is due to the production of a powerful urease enzyme, which breaks down urea to create an alkaline microenvironment
• Diagnosis of H. pylori infection

  • The rapid urease test or culture are the tests most commonly used on biopsy material to establish specific diagnosis
  • Non-invasive methods of diagnosis of infection are serology and the urea breath test
• Though many people are infected only a minority develop ulcers
• Antibiotic treatment is indicated only when ulceration is present