GI pharmacology and therapeutics

GI pharmacology and therapeutics: H.pylori + c.difficle

Intended learning outcomes:

Demonstrate an understanding of, and describe the pathogenicity, epidemiology, management and prevention of urinary tract infection, H pylori-associated gastrointestinal disease, viral and bacterial skin and eye infections and viral and bacterial respiratory tract infections
Describe how pathogens cause disease and how they overcome the innate host defence

Core Concept ILOs

Explain the role of Helicobacter pylori in causing gastrointestinal disease including gastritis and peptic ulcer disease
Describe how Helicobacter pylori infection is diagnosed
Discuss the management of Helicobacter pylori associated gastrointestinal disease
Explain how the use of antibiotics and proton pump inhibitors is associated with the development of Clostridioides difficile
Discuss how this Clostridioides difficile is treated

Helicobacter pylori (H.pylori)

Gram negative bacteria which causes persistent infection in the gastroduodenal mucosa
The infection always causes gastritis (which is inflammation of the GI tract)
H.pylori is transmitted through gastro-oral and face-oral route
The elderly are more prone to infection by H.pylori
H.pylori is the most common cause of peptic ulcer disease, as it host co-factors that are critical to the development of the ulcer

Peptic Ulcer disease (PUD)

Open sores that develop on the inside lining of the oesophagus, stomach or upper portion small intestine
Complication of PUD can include upper GI bleed
Symptoms:
- Upper abdominal discomfort
- Heartburn
- Bloating
- Early satiety
- Heaviness
- Flatulence
- Nausea/ vomiting
Diagnosis:
- Is pain in a specific place (patients can often point to location)
- Mid- epigastric pain
- Constant pain
- Gastric - relieved by food
- Duodenal - pain 2-3 hours after eating
ALARMS:
- Anaemia
- Non intentional loss of weight
- Unexplained loss of appetite
- Recent onset of symptoms
- Blood in stools or vomit
- Dysphagia
- Severe debilitating pain
- Persistent vomiting
- Pain awakens a person at night

H.pylori testing:

Who should be tested:
- Proven peptic ulcer where status is uncertain
- Uncomplicated dyspepsia and no alarm symptoms
- GI symptoms considered to be high at risk of H.pylori infection
- Untested patients with history of peptic ulcer/bleeds
- Prior to initiating NSAID in patients with prior history of peptic ulcer/bleeds
- Unexplained iron- deficiency anaemia
H.pylori produces an antibody response which is detectable in serum, saliva or urine and antigen detectable in stool
Testing:
- Urea breath test kits
- Stool helicobacter antigen test
- Mucosal biopsies
- Lab based serology
Antibiotics - may supress H.pylori growth and give false negative results
Achlorhydria leads to false positive results as it affects the acidity of stomach
Treatment should not within 4 weeks of antibacterial or 2 weeks with PPI

H.pylori treatment:

Treatment should be: simple, well tolerated, easy to comply with and cost effective
Triple therapy: 7 days, twice daily course of PPI plus to antibiotics
Previous antibiotics exposure needs to be checked to rule out potential resistance
Patient adherence is key
Generally start treatment for h.pylori straight away but if patient has also been on a NSAID which has caused the ulcer then the focus is on treating the ulcer first before the eradication treatment
First line treatment:
- Full dose of PPI twice daily
- Amoxicillin 1 g twice daily
- Clarithromycin 500mg twice daily or metronidazole 400 mg twice daily
First line if penicillin allergy:
- Full dose of PPI twice daily
- Clarithromycin 500mg twice daily
- metronidazole 400 mg twice daily
Alternative regimes:
- PPI full dose twice daily
- Two or more of the following
- Bismuth subsalicylate
- Tetracycline
- Quinolone e.g ciprofloxacin, levofloxacin
- Metronidazole
- Clarithromycin
Important interaction to make patients away of
Clarithromycin inhibits the enzyme which breaks down stain in the body, leading to more statin in body so there is increased side effect of the statin
Metronidazole interferes with how alcohol is broken down in the body, which can lead to side effects of nausea, vomiting and Gi pain

Clostridioides difficle

Anaerobic gram positive bacteria
Found in 2-3% of the adult population who display no symptoms
Infection occurs when normal gut microbiota are supressed so C.difficile to grow unchecked, and also allows the toxin in some strain of c.difficile to reach high levels
Toxin damages the lining of the colon and causes diarrhoea, biggest cause of infectious diarrhoea in hospitalised patients
In severe causes the toxin can lead to severe inflammation of the bowel

Risk factors of C.difficile infections

Most common in patients who are currently taking or have recently taken antibacterial
Antimicrobials associated with infection are: clindamycin, cephalosporins, fluoroquinolones and broad spectrum penicillin's
Continuing a patient on antibiotics for longer than necessary can increase risk of patient getting c.difficile infection
Acid suppressing medications change the environment in the gut which favours c.difficile
With age gut microbiome changes
Hospitalisation increase risk as bacteria spreads easily

C.difficile diagnosis

Symptoms
- Diarrhoea - tends to have a specific smell
- Abdominal pain
- Raised temperature
Assessment:
- C.difficle toxin test
- Abdominal imaging
- Blood tests
- Signs of sepsis

C.difficile management

Treatment