Intra-abdominal Infection (GIT)

Question 1

How are liver abscesses classed, and what are the four types? Give an exmaple for each type.

Answer 1

Classed by causative organisms.

• Pyogenic (bacterial, main)
• Fungal (Candida)
• Helminthic (Hyatid cyst)
• Protozoal (Entamoeba histolytica)

Question 2

What are the three potential routes of infection of the liver?

Answer 2

1. Bile duct (enteric bacteria, most common)
2. Portal vein (from infected organs)
3. Hepatic artery (systemic infection)

Question 3

What are three sources of pyogenic infection.

Answer 3

• Enteric bacteria from biliary tract
• Septic emboli from portal circulation
• Systemic circulation

Question 4

What is the main source of fungal infection, and what is a causative organism?

Answer 4

Main source of fungal infection is via the hepatic artery.

Can be a complication of candidiasis dissemination - causes multiple abscesses from systemic circulation.

Question 5

How do humans acquire hydatid disease, and what does it do?

Answer 5

Hydatid disease is caused by the Echinococcus species of helminths, acquired by humans ingesting eggs in dog poops.

Cysts develop in the liver.

Question 6

What does Entamoeba histolytica cause?

Answer 6

Causes amoebic dysentery (blood and pus in stool).

May also infect the liver and cause abscesses.

Characterised by anchovy sauce pus - draining the abscess gives a foul smelling, anchovy sauce looking pus.

Question 7

How common are splenic abscesses comapred to liver abscesses?

What is the most common cause of them?

Answer 7

SPlenic abscesses are much less common than liver abscesses.

They most commonly occur from microorganisms in systemic circulation, commonly being from endocarditis.

Question 8

Differentiate between cholangitis and cholecystitis.

Answer 8

Cholangitis is infection of the biliary system due to blockage of bile duct by gallstone. Causes bile stasis and growth of bacteria ascending from the duodenum.

Cholecystitis is obstruction of the cystic duct due to gallstone. Causes bile stasis, oedema of the gall bladder and grwoth of bacteria ascending from the duodenum.

Question 9

What is diverticulitis?

Answer 9

Diverticulitis involves sac-like projections from the colonic wall. Common in the elderly.

Diverticulosis is the formation of the projections. Diverticulitis is an inflammatory/infective state of it.

Question 10

What are the sequelae of diverticulitis?

Answer 10

• Perforation of diverticulum resulting in peritonitis
• Leakage of bowel contents
• Abscesses

Question 11

Describe the pathogenesis of appendicits.

Answer 11

Obstruction of lumen causes bacterial overgrowth, resulting in inflammation and ischemia of the appendix wall.

Question 12

Define peritonitis, and the difference between primary and secondary peritonitis.

Answer 12

Peritonitis is inflammation of the peritoneal tissue. Not just infective - can be inflamed by blood, urine, bile. However, infection is hte main cause of peritonotis.

Primary peritonitis = spontaneous bacterial peritonitis. Mostly caused by skin flora, such as in CAPD (continuous ambulatory peritoneal dialysis) contamination.

Secondary peritonitis = post operative, acute (perforation o diverticuli, appendix, gall bladder)

Question 13

What three drugs are recommended for abdominal infections, and why?

Answer 13

Most intra-abdominal infections are caused by bowel flora (Gram negative, positive, anaerobes). Thus, empirical antibiotics are chosen to cover them, unless the bacteria is deemed to be from systemic circulation.

Drugs:

• Gentamicin (Gram negative)
• Amoxycillin (Gram positive)
  Metronidazole (Anaerobes)