Lecture 26: Peritonitis and intra-abdominal infection

Question 1

Patient presentation with peritonitis?

Answer 1

• Fever
• Tenderness
• Incr. HR and RR
• Nausea and vomiting
• Diffuse abdominal pain (can –> more localised)
• Abdominal wall rigidity
• Increased blood leukocytes

Question 2

Primary peritonitis

Answer 2

• rare

- spontaneous

Question 3

Secondary peritonitis

Answer 3

• more common

- due to infection of GI tract –> loss of integrity –> infection of peritoneum

Question 4

Tertiary peritonitis

Answer 4

-Recurrent

Question 5

Causative agents?

Answer 5

-Polymicrobial
-Enterobacteriaceae:
E coli, Klebsiella, enterobacter
-Anaerobes:
GNB: Bacteroides fragilis, prevotella
GPC: peptostreptococcus
GPB: Clostridium
-Enterococci

Question 6

Sources of bacteria?

Answer 6

-GI tract:
Stomach/duodenum: aerobes
COPY

Question 7

Routes of transmission?

Answer 7

-From GI tract to peritoneum via a perforation:
Appendicitis
Diverticulitis 
stomach ulcer
many others..

Question 8

Risk factors for peritonitis?

Answer 8

• Primary: liver disease, portal vein hypertension, ascities
• Secondary: appendicitis, diverticulitis, ulcers, surgery, CAPD
• Tertiary: Immune deficiencys, previous case

Question 9

pathophysiology?

Answer 9

bacterial invasion
–> proliferation
–> inflammation response; fluid into peritoneal cavity, dilution of antibacterial factors, may lead to hypovolemia
–> abscess formation;
Fibrin deposited traps bacteria, may prevent immune response to bacteria, microbrial growth continues, proteases etc damage tissue

Question 10

diagnostic microbiology?

Answer 10

• Aspirate pus
• Gram’s stain
• Culture bacteria (aerobes and anaerobes)

Question 11

Bacteroides?

Answer 11

• difficult to isolate
• often present in mixed infections
• need to keep anaerobic
• Gram-negative rod
• PCR identifies

Question 12

_______ and ________ are the most common cause of __________ peritoneal infections and use _________

Answer 12

B. fargilis
E coli
polymicrobial
Synergy

Question 13

B. Fragilis

Answer 13

• Antiphagocytic capsule and LPS
• Capsule elicits deposition of fibrin
• Complement degradation by proteases
• Reduced oxygen toxicity - SOD, catalyse

Question 14

Treatment of peritonitis

Answer 14

1. Symptomatic relief:
   Fluids, pain relief, removal of pus
2. Treat source
   establish cause and origin, remove pus, dead tissue, surgical fixation
3. Treat microbial source
   Empiric antimicrobial therapy
   Broad spectrum - recommendations for course vary

Question 15

Metronidazole

Answer 15

- Bactericidal:
Anaerobic gram-ve bacilli
Anaerobic gram+ve cocci
pathogenic protozoa
-amoebicidal and trichomoncidal 
- Pro drug --> bacteria --> gets oxidised --> fucks bacterial DNA synthesis