Intra-Abdominal Infection + C.diff

Question 1

Types of primary peritonitis

Answer 1

1. Peritoneal dialysis related peritonitis
2. spontaneous bacterial peritonitis

Question 2

What group of patients are at highest risk for developing SBP?

Answer 2

pts with hepatic failure and ascites (alcoholic cirrhosis)

Question 3

Is SBP usually mono- or polymicrobial? What is the most common causative agent?

Answer 3

Monomicrobial
E. coli

Question 4

SBP empiric treatment options

Answer 4

1. ceftriaxone
2. cefepime
3. zosyn
4. meropenem

Question 5

SBP treatment duration - patients with cirrhosis and ascites

Answer 5

5-7 days
(secondary prophylaxis is recommended after treatment)

Question 6

SBP treatment duration - patients undergoing CAPD (and preferred route of administration)

Answer 6

14-21 days
intraperitoneal administration preferred

Question 7

Is secondary peritonitis usually mono- or polymicrobial? What is the most common causative pathogen?

Answer 7

Polymicrobial
E. coli

Question 8

How do IAI affect other organ systems?

Answer 8

GI: bowel paralysis

Cardiovascular: hypotension, tachycardia, vasoconstriction due to fluid shifts

Respiratory: Hypoxemia

Renal: decreased renal perfusion -> renal failure

Question 9

What type of bacteria create an optimal environment for anaerobic bacteria and why?

Answer 9

Enterobacterales (i.e. E. coli) because they use up the O2

Question 10

What do anaerobes cause?

Answer 10

Abscess formation

Question 11

Antimicrobial agents generally not recommended if resistance rates exceed ___-___%

Answer 11

10-20%

Question 12

When is Enterococci coverage recommended empirically?

Answer 12

1. high severity IAI
2. History of recent cephalosporin use
3. Immunocompromised
4. Biliary source of infection
5. History of valvular heart disease
6. Prosthetic intravascular material

Question 13

When would you consdier antifungal coverage?

Answer 13

1. pt not improving on appropriate abx therapy
2. esophageal perforation

Question 14

Community-acquired mild-moderate severity empiric options

Answer 14

1. ceftriaxone + metronidazole
2. cefazolin + metronidazole
3. cefoxitin
4. ertapenem
5. tigecycline

Question 15

Community-acquired high severity OR healthcare-acquired empiric options

Answer 15

1. Zosyn
2. Meropenem
3. Cefepime + metronidazole - (may need to add enterococci agent like vanco)

Question 16

Candida albicans treatment

Answer 16

fluconazole 200-400mg IV/PO

Question 17

Candida species (other than albicans) treatment

Answer 17

Micafungin 100mg IV

Question 18

It is common to maintain ____________ coverage even if culture doesn’t have isolates

Answer 18

anaerobic

Question 19

IAI oral antibiotic regimens

Answer 19

1. amox/clav 875/125mg PO Q8H - higher than normal dose!
2. cefpodoxime 400mg PO q12h + metronidazole 500mg PO q8-12h

Question 20

IAI general treatment duration

Answer 20

4-7 days after source control

Question 21

Diverticulitis - moderate/severe treatment duration

Answer 21

5-10 days
(if uncomplicated, no Abx needed!)

Question 22

Diagnosis of SBP

Answer 22

1. s/sx of infection
2. ascitic fluid analysis
   -low ascitic fluid protein (< 2.5g/dL)
   -ANC > 250

Question 23

Diagnosis of IAI

Answer 23

1. s/sx of infection
2. imaging - CT scan or X-ray

Question 24

C.diff microbiological basics

Answer 24

1. Gram-positive, spore-forming, obligate anaerobic bacillus
2. Produces two toxins:
   -TcdA - inflammatory enterotoxin
   -TcdB - cytotoxin

Question 25

C.diff infection risk factors

Answer 25

1. age > 65 years
2. use of PPIs or H2RAs
3. Chemotherapy + immunosuppression
4. GI surgery
5. Healthcare or ABx exposure

Question 26

Which ABx are highest risk for causing C. diff infection?

Answer 26

1. Fluoroquinolones
2. Clindamycin

Question 27

C. diff - non-severe classification

Answer 27

WBC ≤ 15,000
SCr < 1.5

Question 28

C. diff - severe classification

Answer 28

WBC > 15,000
SCr > 1.5

Question 29

C. diff - fulminant classification

Answer 29

Hypotension or shock
Ileus
Toxic megacolon