166. Infectious Diseases of GI tract

Question 1

Primary Peritonitis (SBP)

• define
• etiology
• pathogenesis
• dx
• tx

Answer 1

Bacterial peritonitis w/o inciting event, in setting of ascites (cirrhosis)
Monomicrobial: E Coli, klebsiella pneumo, strep pneumo, enterococci
PGen: hematogenous, lymphatogenous, translocation, women - from vagina via fallopian tubes
cirrhosis (complement deficiency, neutrophil dysfx)
Dx: PARACENTESIS (HIGH NEUTROPHILS >250), cultures may be false negative
Tx: ABx for GNR (ceftriaxone, ciprofloxacin)

Question 2

Secondary Peritonitis

• define
• etiology
• pathogenesis
• dx
• tx

Answer 2

Bacterial Contamination of peritoneum as result of spillage of intestinal flora (inciting event!)

• due to loss of integrity of mucosal barrier (perforation due to appendicitis, diverticulitis, neoplasm, ulcer, trauma(
• average 4.5 organisms
• PGen: chemical (no bacteria) increases infection risk, high risk with higher microbial load (colon > small intestine > stomach), causing diffuse peritonitis/local abscess = ileus, sepsis, shock
• dx: Xray ILEUS, CXR FREE AIR (NEED IMAGING - CT/US)
• tx: broad spectrum Abx, surgery/drainage

Question 3

CAPD Peritonitis

• pathogenesis
• CP
• tx

Answer 3

Continuous Ambulatory Peritoneal Dialysis gets infected
Pgen: contamination by skin pathogens (Staph epidermidis, staph aureus), forming biofilms
CP: cloudy dialysate, abd pain
Tx: Abx via dialysate

Question 4

Intraperitoneal Abscess

• what is it
• etiology
• dx
• tx

Visceral Abscess

• define
• etiology

Answer 4

Infection with viable organisms/neutrophils w/in fibrous capsule (WALLED OFF)
Etiology: polymicrobial, usually with B. fragilis - cell surface capsular polysaccharide complex stimulates abscess formation
Dx: CT scan, US, MRI
tx: drainage + ABx

Complicate underlying organ injury (infarction/pancreatitis)
E: monomicrobial if hematogenous, polymicrobial if communicates with GI lumen
tx: drainage, Abx, surgical debridement of necrotic tissue
Splenic Abscess: 100% hematogenous, and fatal if untx

Question 5

Appendicitis

• pathogenesis
• dx
• tx

Answer 5

Obstruction of appendiceal lumen (fecalith, lymphoid follicular hyperplasia, fibrosis/neoplasm), high luminal pressure = thrombosis/lymph stasis = inflammation, swelling, ischemia = necrosis, perforation

sx: McBurney’s point! 1/3 from ASIS to umbilicus
dx: CT scan!!!! (swollen, thick appendix)
tx: appendectomy, broad-spectrum abx if rupture, if abscess delay surgery and drain,

Question 6

Diverticulitis

• pathogenesis
• tx

Answer 6

Perforation of diverticulum, erosion due to increased intraluminal pressure/inspissated food particles
Tx: monitor if mild, Abx if systemic sx, prevention with high fiber