Intra-abdominal Infections Flashcards
What are intra-abdominal Infections
Presence of microorganisms in normally sterile sites within the abdominal cavity
Name two normally sterile sites in the abdominal cavity
Peritoneum
Hepatobiliary tract
Stomach
NOT GASTROENTERITIS
Except for some anaerobes and candida species, the proximal intestine is relatively free from microorganisms. Why?
Bile inhibits growth
What organism reside in the large bowel?
95-99% anaerobes
Some aerobic bacteria - - enterobacteriaceae (coliforms)
- Gram negativecocci (enterococci)
What are the sources of a intraabdominal infection?
GI contents (lumen)
Blood
External e.g. surgery
What are the mechanisms pf intra abdominal infection?
Transaction of microorganism from GI tract lumen to peritoneal cavity e.g. inter peritoneal infection
Translocation of MO along a lumen e.g. hepatobiliary infection
Translocation of MO from extra-intestinal source e.g. haematogenous spread, penetrating trauma
What are the mechanisms by which infections translocate across a wall?
Perforation e.g. appendicitis, ulcer, diverticulum, cancer
Loss of integrity e.g. ischaemia, strangulation
Surgery e.g. seeding at operation, anastomotic leak
What are the mechanisms by which infection translocate across a lumen?
Blockage e.g. cholecystitis, hepatic abcess
Iatrogenic e.g. instrumentation (ERCP)
How does a perforated appendix cause peritonitis?
Obstruction of lumen of appendix (e.g. faecal matter/enlarged lymph)
Stagnation of luminal contents - bacterial growth
Increased luminal pressure - perforation into peritoneum
- peritonitis
What are the complications of diverticulum?
Diverticulitis
Perforation
Pericolic abcess
How is iscahemia cause in the GI?
strangulation
Arterial occlusion
Post operative e.g. aneurysm repair
What is cholecystitis?
Inflammation of gallbladder wall
What is cholecystitis associated with? What is this mainly caused by?
Obstructed cystic duct
Gallstones mainly, but can be malignancy, surgery, or parasitic worms
What is the presentation of cholecystitis?
Fever, upper right quadrant pain, jaundice
What is empyema of gallbladder and how does it present?
Frank pus in gallbladder
Same as cholecystitis but sepsis (severe pain, high fever, chills/rigor)
Requires removal
What is cholangitis?
Infection/inflammation of biliary tree (hepatic duct and common bile duct)
How is cholangitis caused? How does it present?
Obstruction of common bile duct
Fever, right upper quadrant pain, jaundice
What is a pyogenic liver abcess? What are the main routes by which it is caused?
Pus forming in liver
- Biliary obstruction
- Spread from other intra-abdominal obstruction
- haematogenous - from mesentery or systemic
What is an intra-peritoneal abcess?
Localised area of peritonitis with pus
What are the predisposing factors ofintraperitoneal abcess?
Perforation e.g. ulcer, appendix, diverticulum Cholecystitis Mesenteric bowel infarction Pancreatitis/pancreatic necrosis Postoperative anastomotic leak
What are the clinical presentations of an intraperitoneal abcess?
Nonspecific e.g. sweating, high swinging pyrexia, anorexia
Can show ipsilateral lung collapse with pleural effusion
What are the main causative bacterial organisms?
Aerobic gram - Enterbacteriacae (cloriforms) e.g E coli, Pseudonomas
Anaerobic gram -
Bacteriorides
Aerobic gram +
Enterococcus, Strep milleri
Anaerobic Gram +
Clostridium
Why are liver abcesses usually ‘sterile’?
Polymicrobial - hard to grow anaerobes
What are liver accesses usually caused by?
Not GI flora
From haematogenous spread or trauma
