Peritonitis and Intra Abdominal Infection

Question 1

Peritonitis presentation

Answer 1

Fever, increased HR and RR, nausea and vomiting.
Diffuse abdominal pain thay may be more localised
Rebound tenderness
Abdominal wall rigidity

increased leukocytes

Question 2

Defintion of peritonitis and the three types

Answer 2

Peritonitis: Inflammation of the peritoneum/serosa lining the abdominal cavity. (may be generalised and diffuse or local such as an abcess)

Primary: Spontaeous, rare in that no loss of GI tract integrity. Liver disease.
Secondary: acute infection from loss of GI tract integrity or infected viscera. Most common.
Tertiary: Recurrent infection following adeqaute initial therapy, due to defective immune system

Question 3

Microbial causative agents of peritonitis are usually what? what are they

Answer 3

Polymicrobial: reflective of source.

Enterobacteriaceae: E coli; Klebisella; enterobacter
Anaerobes: GNB: bacterodes fragilis; prevotella: GPC: peptostreptococcus: GPB: clostridium
Enterococci

Question 4

Sources of bacteria in the GI tract

Answer 4

Stomach/duodenum: aerobes and facultative anaerobes
Jejunum/Ileum: More anaerobes
Colon: anaerobes

Question 5

Routes of transmission for peritonitis

Answer 5

Appendicitis (ruptured)**
Diverticulitis(ruptured)**
Stomach/duodenal ulcer*
Viscera infection
PID
Tubo-ovarian infection
necrotising enterocolites
surgery/trauma

Question 6

Peritonitis types and risk factors

Answer 6

Primary: liver disease, portal hypertension
Secondary: Appendicitis/diverticulitis, ulcers; surgery, CAPD
tertiary: immune deficiency

Question 7

Time course of peritonitis infection

Answer 7

• Bacteria enter
• Not cleared, due to necrotic tissue and nutrients such as Hb hiding. Normally phagocytosed and held in a clot
• Bacteria proliferate
• Inflammation: Fluid exudate in peritoneum, diluted antibacterial factors. May causes hypovolaemia
• Abcess formation: e.g bacteriodes fragilis hides in clot. Prevents phagocytosis.

Question 8

Diagnostic methods for infection

Answer 8

Aspirate pus
Gram stain the pus (GN rods, GP cocci, a mix!)
Anaerobic and aerobic cultures from pus, anaerobic transport swabs?

Question 9

Diagnostic test of bacteriodes

Answer 9

Due to fastidiousness:

• Often present in mixed infections (i.e with E coli on Maconkey)
• Requires aseptic aspiration, transporton a medium it will not die on (anaerobic) and cultivate on selective agar, bile aesculin
• Is a gram negative rod
• Can use gas-liquid chromatography (detect volatile fatty acids)
• PCR

Question 10

Synergy of some bacteria in polymicrobial infection

B. fragilis and E. coli

Answer 10

B. fragilis: Antiphagocytic capsule and LPS; elicits fibrin deposition and thus abcess formation; complement degradation by protease; reduced oxygen toxicity (SOD, catalase are iron containing)

E. coli: E. coli haem binding protein, can be intercepted by B. fragilis to reduce O2 toxicity

Question 11

Treatment of peritonitis at level of : symptoms; source; microbial cause in this order

Answer 11

Symptoms: fluids, pain relief. Drainage of pus guided by US
Source: Establish the cause, and control by removing pus by US, removing dead tissue, corrective surgery.
Microbial cause: Broad spectrum antibiotics

Question 12

Antibiotics for the microbial cause

Answer 12

Broad spectrum

• Enterobacteriaceae (E coli): aminoglycoside, 4th gen cephalosporin
• Anaerobe (B fragilis: clindamycin, metronidazole
• Enterococcus: ampicillin

If underlying kidney/liver disease, single therapy

Question 13

Antibiotic treatment and time periods

Answer 13

varies, 1-2 weks or 4-6 weeks until resolved (free of fever, pain, normal WBC count, regular function). One week pus
Danger of getting clostridium difficlie due to broad spec wiping out gut bacteria

Question 14

Prevention:

Answer 14

Prompt diagnosis and treatment of predisposing conditions

Question 15

Metronidazole

Bactericidal, amoebicidal and trichomoncidal

Unsure exact mechanism of action: Inhibition and disruption of ____ ____ ____

Works best against some ____ and some ___:

• _____ Gram negative bacteria: _____ ____ and other; fusobacterium
• _____ gram positive ___: _____, eubacterium, anaerobic streptococci
• Wide range of pathogenic ____: _____ ____, ____ lamblia

Is ineffective against ___ and facultative anaerobic bacteria

Answer 15

Bactericidal, amoebicidal and trichomoncidal

Unsure exact mechanism of action: Inhibition and disruption of nucleic acid synthesis

Works best against some anaerobes and some protozoa:

• Anaerobic Gram negative bacteria: bacteriodes fragilis and other; fusobacterium
• Anaerobic gram positive cocci: clostridium, eubacterium, anaerobic streptococci
• Wide range of pathogenic protozoa: trichomonas vaginalis, giardia lamblia

Is ineffective against aerobic and facultative anaerobic bacteria

Question 16

Perotinitis and lack of bowel sounds

Answer 16

Blockage of GI tract