Infectious diseases

Question 1

H. Pylori gram stain and appearance

Answer 1

Gram negative, spiral

Question 2

How does the urease enzyme facilitate colonisation of the stomach?

Answer 2

Urease neutralises stomach acid and enables penetration through gastric mucous. Patient produces more acid which allows it to further survive

Question 3

What is VacA?

Answer 3

All pylori contain this gene which codes for a passive urea transporter and stimulates IL-8 –> inflammatory response causing the gastritis and inflammation

Question 4

Disease associations for H. Pylori

Answer 4

• duodenal ulcer
• gastric ulcer
• gastric ulcer
• gastric lymphoma (MALT)

Question 5

Ulcer pathogenesis from pH to Hp

Answer 5

• increased gastric secretion
• gastric metaplasia of duodenum
• stimulate immune response
• impairs mucosal defence

Question 6

Therapy for H. Pylori eradication

Answer 6

1. PPI
2. Amoxicillin
3. Clarithromycin

Question 7

What would you give for H. pylori eradication if patient was allergic to penicillin or clarithromycin?

Answer 7

Metronidazole

Question 8

Which antibiotics can be reused?

Answer 8

• Amoxicillin
• Bismuth
• Tetracycline

Question 9

Which A/B should only be used once?

Answer 9

• Clarithromycin
• Metronidazole
• Quinolones
• Rifamycines

Question 10

Most common cause of liver abscesses

Answer 10

Pyogenic - bacterial is most common (enteric bacteria)

Biliary tract is most common

Question 11

Pathogenesis of pancreatitis

Answer 11

Typically inflammatory, from the blockage of pancreatic duct by a gall stone or chronic alcohol abuse. Pancreatic enzymes self digest organ - necrosis

Question 12

Which of the viral hepatitis infections can cause chronic disease in humans?

Answer 12

B, C, D

Question 13

Which hepatitis viruses are spread through blood and which through faecal-oral?

Answer 13

Blood - B, C, D

F-O - A, E

Question 14

Markers of successful treatment of HBV

Answer 14

• HBeAg seroconversion to antiBeAb
• suppression of the HBV DNA
• Settling of the raised ALT

Question 15

Nucleoside and nucleotide analogues

Answer 15

Nucleoside - lamivudine, entacavir

Nucleotide - tenofovir

Question 16

Investigations for liver abscesses

Answer 16

• neutrophilia
• raised ALP
• Blood cultures positive 50%

Question 17

What does hepatic bile contain?

Answer 17

–  water,
–  bile acids,
–  bile salts (formed by the conjugation of bile acids with taurine or
glycine),
–  bilirubin (end product of heme degradation),
–  cholesterol,
–  phospholipids,
–  excreted hormones and drugs

Question 18

Epidemiology of cholethiasis

- what the stones consist of

Answer 18

• GS present in 10-20% adult population
• 20% will develop biliary colic or other
complications

Essentially consist of:
– Cholesterol
– Bilirubin
– Calcium salts

Question 19

Classification of gall stones

Answer 19

Classification based on amount of cholesterol in stones
– Cholesterol (>50% crystalline cholesterol monohydrate)
– Pigment (black or brown) – bilirubin calcium salts

Question 20

Factors commonly associated with cholesterol gall stones

Answer 20

*women, reproductive age, pregnancy, HRT, OCP, obesity, rapid weight loss, drugs Iprednisolone, cyclosporine, azathioprine…, ethnic groups