Lecture 34 Intra abdominal Infections Flashcards
What organisms are included in “GI strep”?
VGS, S. milleri group
What organisms are included as anaerobic, oral and colonic/GI?
Oral: peptostreptococcus, veillonella, fusobacterium ⇒ easily tx by penicillin, amoxicillin, amox/clav, not always clindamycin
Colonic/GI: B. fragilis, clostridia/clostridiodes, lactobacillus ⇒ usually managed by metronidazole, sometimes by extended beta-lactamases like amox/clav and pip-tazo
When does our ‘good’ GI flora go ‘bad’ and causes infection?
A: Obstruction - blockage causing loss of physiologic flow and nidus formation
B: Translocation/Perforation - inflammation/membrane permeability leading to bacterial penetration into blood OR sterile sites
C: Opportunistic or Exogenous - exogenous bacterial inoculation (ex. food poisoning) or loss of bacterial antagonism/immunity (ex. C. diff)
What is cholecystitis (pathophysiology, pathogens, S&S, how its diagnosed (dx), empiric tx)
Patho - obstruction of the cystic duct (draining the gall bladder) trapping organisms in the gall bladder which can caused nidus formation and inflammation, usually obstructed by gallstones but could be something else as well
Pathogens: enterobacterales (mainly E. coli, Klebsiella), less common streptococcus, enterococcus
Sx - RUQ pain, fever, ab tenderness, lack of jaundice
Dx - clinical, ultrasound
Empiric: ceftriaxone IV F7D
What is ascending cholangitis (patho, pathogens, S&S, how its diagnosed, empiric tx)
Patho - obstruction of common bile duct trapping organisms in the whole biliary tree causing backup of bile into liver, usually caused by gallstones but could be something else as well
Pathogens: enterobacterales (mainly E. coli, Klebsiella), less common streptococcus, enterococcus
Sx - RUQ pain, fever, ab tenderness, jaundice
Dx - clinical, ultrasound, blood cultures
Empiric: Amox/Clav IV F10D, Ceftriaxone IV QD is probably ok as well
What are infections of the pancreas (patho, S&S)
Pancreatitis: Patho - inflammatory condition with multiple causes that ultimately leads to pancreatic enzyme auto-digestion of the pancreas and substantial inflammation
S&S - may include fever, tachycardia, hypotension, systemic leukocytosis, commonly confused for acute infection
none of the causes of acute pancreatitis are bacterial in nature (some are viral), however after an episode a patient may develop complications like pseudocyst, necrotizing pancreatitis ⇒ these foci can become infected and are incredibly difficult to manage
What is a liver abscess (Patho, pathogens, S&S, Dx, Tx, empiric)
Patho: trapping of bacteria in hepatic ducts leading to growth and formation of this that pushes on the liver, can also be from organisms that infect the liver via the bloodstream (rarely)
Pathogens: most commonly E. coli, K. pneumoniae, S. anginosus
if from contaminated water can get Entamoeba histolytica
Sx: indolent course, subacute presentation of fevers, chills, some ab pain +/- jaundice, possible elevated liver enzymes
Dx: CT scan of abdomen for this or drainage, possible culture and sensitivity, serology for Entamoeba
Tx: they need drainage to resolve but if this can’t be done then prolonged antibiotics with imaging and follow-up
Empiric: amox/clav IV to stepdown PO based on aspirate culture if obtainable, minimum of 4 week tx
How are viral, bacterial and parasitic diarrhea differentiated from each other?
Viral (MOST COMMON, norovirus, rotavirus (peds), astroviruses, calciviruses, influenza, etc): Time of Year ⇒ Winter epidemic (Sept > Feb) more than summer
Sick Contacts ⇒ + for these (+/- outbreak associated)
Diarrhea ⇒ mild-moderate, watery, acute
Other Sx ⇒ +/- URTI, fever, myalgias, weakness, fatigue
Bacterial (LESS COMMON, C. perfringens, E. coli, Shigella, C. jejuni, S. aureus, C. diff, etc): Time of Year ⇒ Summer months > winter
Sick Contacts ⇒ - for these, but multiple pt sick simultaneously, contaminated food/water
Diarrhea ⇒ watery/explosive/mucus/bloody, mild-severe, ACUTE
Other Sx ⇒ fever
Parasitic (VERY UNCOMMON, Giardia, Entamoeba, etc): Time of Year ⇒ perhaps during times of travel
Sick Contacts ⇒ - for these, unless simultaneously sick, contaminated water/food
Diarrhea ⇒ chronic/atypical/recurrent/relapsing-remitting course >2 weeks, in immunocompromised
Other Sx ⇒ lack of improvement on other tx
What is gastroenteritis (patho, pathogens, sx, empiric tx)
Patho: stomach/intestine inflammation, can be viruses/food poisoning
Pathogens: Viral (rota/noravirus), rarely S. aureus, B. cereus, Salmonella, Campylobacter
Sx: N/V/D, ab upset/discomfort
Empiric: usually no antibiotic required, watch and wait, if severe/bloody and likely bacterial ⇒ ciprofloxacin F3-5D
What is diverticulosis (patho, pathogens, Sx, Dx, empiric tx)
Non-Infectious: Patho - out-pouching of colonic mucosa into small pockets, may be due to chronic constipation, obesity, smoking, use of NSAIDs, steroids, opiates, can be hereditary
Sx - asymptomatic in most, rarely bleed or inflamed
Dx - colonoscopy, CT scan or MRI
Infection of this: Patho - feces/debris/bacteria trapped overgrow in this instead of being normally passed and cause inflammation/infection
Pathogens - enterobacterales, anaerobic gram - (ex. B. fragilis)
Sx - often LLQ pain (can be anywhere), fever, pain, palpable sigmoid colon, can rupture into peritoneum causing peritonitis, form intra-abdominal abscess
Dx - clinical especially if known non-infectious, CT scan
Empiric - amox/clav PO/IV or Ceftriaxone + metronidazole F5-7D
What is appendicitis (tx involved)?
surgical problem when vermiform this becomes inflamed usually due to obstruction of this lumen most often due to hardened feces but may also be from local lymphadenopathy ⇒ leads to overgrowth of bacteria ⇒ inflammation, irritation, and often perforation with spillage into the peritoneum ⇒ Tx: antibiotics may be warranted if a non-operative approach was taken but surgical management is DEFINITIVE
What is peritonitis (classes, who it happens to, sx, pathogens, empiric tx)
Primary: fluid already in this (ascites) gets infected
Who - patients with liver disease predominantly
Pathogens - involves often a SINGLE pathogen (dominantly enterobacterales)
Sx - ad pain (guarding, ab tenderness, rigid), fever
Empiric - Ceftriaxone IV F5-7D, direct against aspirate culture
Secondary: rupture of GI-tract spills into sterile peritoneum
Who - severe appendicitis, perforated bowel/ulcers, intra-abdominal surgery, ruptured diverticulitis
Pathogens - polymicrobial
Sx - ad pain (guarding, ab tenderness, rigid), fever
Empiric - amox/clav IV, may have to broaden depending on drain cultures
This-Dialysis-Related: the dialysate becomes infected via catheter
Pathogens - often skin organisms infected catheter
Sx - cloudy effluent, > 50% PMNs in effluent
Empiric - IP cefazolin + gentamicin QD and catheter/effluent exchange, may only need 5 days, can use IV cefazolin as well
What defines an episode of spontaneous bacterial peritonitis, and what are risk fx for it?
bacteria seen in paracentesis AND PMNs (neutrophils) >/= 250 (0.25 x 10^9/L)
Risk Fx: cirrhosis, low hepatic synthetic fxn, UGIB, low ascitic protein conc, hx of prior episode(s)
When might prophylaxis of spontaneous bacterial peritonitis be indicated, and what antibiotics might be used?
episode of an acute UGIB ⇒ prophylaxis indicated, typically Ceftriaxone 1 g IV QD F5-7D
ongoing high risk or recurrences, such as increased bilirubin, SCr, Child-Pugh (9+), decreased platelets, ascitic protein conc, Na+ ⇒ consider secondary prophylaxis, may involve TMP-SMX 1 DS tab PO QD, norfloxacin 400 mg PO QD, ciprofloxacin 750 mg PO QD, maybe rifaximin 550 mg PO BID
