Lecture 24: Peritonitis Flashcards
Define:
- Primary/spontaneous peritonitis
- Secondary peritonitis
Primary peritonitis:
- Due to bacterial translocation, heamatogenous spread or iatrogenic contamination of the abdomen without a GI tract defect
- Predominantly in those with underlying ascites
- Usually monomicrobial
Secondary
- Due to indirect contamination of the peritoneum from perforation in the GI or urogenital tracts
When it comes to peritonitis what is meant by nosocomial, localised, generalised?
Nosocomial: Post-operative complication usually due to anastomotic leak
Localized: Peritoneal signs limited to one or two abdominal quadrants. Suggests a contained process.
Write some notes on the diaphragm and peritonitis:
The diaphragm is semi permeable and this is exploited in peritoneal dialysis
It has rapid lymphatic action therefore rapid spread
What is the pathophysiology of peritonitis?
- Extension of localised inflammatory conditions (appendicitis, pancreatitis, PID etc) or perforation or a post op anastomotic leak.
- Bacteria enter peritoneum
- Local inflam response
- Greater omentum acts a physical barrier, confines infection & for rapid neutrophil deployment
= Infection may be contained
If unable to be contained, widespread peritonitis -> Systemic inflam repsonse and bacteraemia
What are the potential outcomes of acute peritonitis?
Potential outcomes are spontaneous resolution, confined abscess, diffuse peritonitis.
Systemic inflammatory response and large fluid shifts
What are the likely bacteria of peritonitis?
- Local bacterial flora of the GI tract
-> Polymicrobial
= Generally combination of aerobic gram negative organisms i.e E Coli, Enterobacter spp, anaerobes and enterococci spp
E. Coli is most common isolated gram neg
B Fragilis most frequent isolated anaerobe
Alterations in natural flora change likely cause i.e
- Colonization with an ESBL-producing organism
- Recent antibiotic exposure/hospitalisation
What aspect of a history and exam gives you a suspected peritonitis?
- Clues to initial source of disease (Appendicitis, diverticulitis, cholecystitis, PID, etc)
- Peritonism
= Abdo rigidity, rebound tenderness or guarding
= Is it generalized (all 4 quadrants) or localised
= Is there sepsis
Whats the general management of peritonitis?
- Fluid resus and BP support
- Samples for micro; Blood cultures, surgical samples or aspirate
- Broad-spectrum antibiotics (Meropenem)
- Early source control
- De-escalation of antibiotics based on microbiology
- Gross peritonitis generally 5-7 days antibiotics (10-14 limited evidence)
What does antibiotic choice depend on?
Broad-spectrum antibiotics with good aerobic coverage and good anaerobic coverage ((B. fragilis +/- enterococcal coverage)
i.e
Amoxycillin + Gentamicin + Metronidazolee
or
Cefuroxime + Metronidazole (If not covering enterococci)
Write some notes on gentamicin:
- Aminoglycoside
- Inhibit bacterial protein synthesis
- Rapidly bactericidal
- Poor CSF penetration
What is gentamicin predominantly effective against?
Predominantly active against aerobic gram negative bacilli including enterobacteriaceae, psuedomonas aeruginosa and acinetobacter spp
Require aerobic metabolism to exert an antibacterial effect therefore not active against anaerobes
What are the risks of gentamicin use?
- Nephrotoxicity and ototoxicity/vestibular toxicity common, can occur with single dose, more likely with prolonged exposure
- Rarely neuromuscular blockade
How effective is gentamicin?
- Reduced mortality in those with septic shock
- In intra-abdominal sepsis reduced mortality but didnt influence abscess formation where as clindamycin or metronidazole reduce abscess formation but not effect on peritonitis, bacteraemia or lethality.
