Exam 4: Intra-Abdominal Infections (IAI)

Question 1

What are the 2 types of primary peritonitis?

Answer 1

Peritoneal Dialysis Related Peritonitis

Spontaneous Bacterial Peritonitis (no known cause)

Question 2

What are the types of secondary peritonitis?

Answer 2

*Diverticulitis
*Appendicitis
*Intra-abdominal abscess

Cholecystitis
Cholangitis
Necrotizing Pancreatitis

Question 3

What is an uncomplicated infection?

Answer 3

Confined to one organ or space, does not extend to peritoneum

Question 4

What is a complicated infection?

Answer 4

Extends beyond a single organ into the peritoneal space and is associated with peritonitis

Question 5

What criteria must be met for an infection to be considered “community acquired”?

Answer 5

Occurs within 48 hours of hospital admission

No healthcare exposure

-Caused by normal intra-abdominal flora

Question 6

What criteria must be met for an infection to be considered “healthcare-associated”?

Answer 6

Occurs after 48 hours of hospital admission
or
Healthcare exposure in the last 12 months

Question 7

What is the source of contamination for Spontaneous Bacterial Peritonitis?

Answer 7

No obvious source of contamination

Question 8

Who is at highest risk for spontaneous bacterial peritonitis (SBP)?

Answer 8

Hepatic failure and ascites (alcoholic cirrhosis)

Continuous ambulatory peritoneal dialysis (CAPD)

Question 9

What is the most common pathogen in spontaneous bacterial peritonitis (SBP)?

Answer 9

E. coli

Question 10

How do we diagnose spontaneous bacterial peritonitis (SBP)?

Answer 10

Ascitic Fluid Analysis

-Low ascitic fluid protein (<2.5 g/dL)
*Absolute neutrophil count > 250/mm^3

Question 11

How do we calculate absolute neutrophil count?

Answer 11

Total Nucleated Cells (TNC) x Bands/Neutrophils %

ex:
TNC= 705
Bands/Neutrophils= 96%

705 x 0.96= 676 (high)

Question 12

What is the drug of choice for Spontaneous Bacterial Peritonitis empiric therapy?

Answer 12

Ceftriaxone 102 g IV q 24 h

Question 13

What are other empiric options for Spontaneous Bacterial Peritonitis besides Ceftriaxone?

Answer 13

Cefepime IV
Piperacillin/Tazobactam IV
Meropenem IV

Question 14

If S aureus/ Coagulase negative staphylococci are present in Spontaneous Bacterial Peritonitis or if there is a risk for MRSA what drugs can be added to the treatment?

Answer 14

Vancomycin IV
Linezolid IV
Daptomycin IV

Question 15

If we need anaerobic coverage in Spontaneous Bacterial Peritonitis what drugs can we add to the treatment regimen?

Answer 15

Beta-lactam/ Beta -lactamase inhibitor

Carbapenem

Metronidazole

(ex of anaerobes: bacteroides, legionella, C diff, peptococcus)

Question 16

When is it appropriate to transition to oral therapy in Spontaneous Bacterial Peritonitis?

Answer 16

Once clinical stability is achieved

Question 17

How long does treatment for Spontaneous Bacterial Peritonitis last?

Answer 17

In patient with cirrhosis and ascites: 5-7 days

Continuous Ambulatory Peritoneal Dialysis: 14-21 days

Question 18

Who should receive secondary prophylaxis with Spontaneous Bacterial Peritonitis?

Answer 18

Patients with cirrhosis and ascites

Question 19

What drugs can we use for secondary prophylaxis in Spontaneous Bacterial Peritonitis?

Answer 19

TMP/SMX DS po once daily
or
Ciprofloxacin 500 mg po once daily

Question 20

What is the most common pathogen in secondary peritonitis?

Answer 20

E. coli

Question 21

What makes secondary peritonitis therapy complicated?

Answer 21

It is normally polymicrobial

Question 22

What bacteria could possibly cause secondary peritonitis but are not common?

Answer 22

Staphylococcus aureus (MRSA is uncommon)

Pseudomonas

Question 23

What makes intraabdominal infections unique?

Answer 23

Multiple organ systems are affected

Bacterial synergy

Question 24

What are signs that the GI tract has an infection?

Answer 24

Bowel paralysis -> Abdominal distention

Question 25

What are signs that the cardiovascular system is infected?

Answer 25

Fluid shifts -> hypotension, tachycardia, vasoconstriction

Question 26

What are signs that the respiratory system is infected?

Answer 26

Hypoxemia

Question 27

What are signs that the renal system is infected?

Answer 27

Decreased renal perfusion -> Renal failure

Question 28

What bacterial synergy is commonly seen in intra-abdominal infections?

Answer 28

Enterobacterales (e. coli) create an optimal environment for anaerobic bacteria (they use up all the oxygen) Anaerobes cause abscess formation and have several virulence factors *we need to cover both aerobes and anaerobes

Question 29

How do we diagnose an intra-abdominal infection?

Answer 29

Signs + Symptoms + Imaging (*CT scan* or x-ray)

Question 30

What are the 2 treatment pathways in intra-abdominal infections?

Answer 30

Source Control Antimicrobial Therapy

Question 31

What are examples of source control in intra-abdominal infections?

Answer 31

Repair perforations Resection of infected organs/ tissue Removal of foreign material Drain purulent collections *make sure to obtain cultures*

Question 32

What 3 considerations need to be made when choosing empiric antibiotic therapy for secondary peritonitis?

Answer 32

1. Select agents or combinations that have a high likelihood to cover common organisms *Look at antibiogram* 2. Consider if enterococci coverage is necessary 3. Consider if antifungal coverage is necessary

Question 33

An agent is generally not recommended if resistance exceeds what on an antibiogram?

Answer 33

10-20% (need to have 80-90% efficacy)

Question 34

When is Enterococci coverage not needed?

Answer 34

Mild-Moderate severity community acquired intraabdominal infection

Question 35

Who should receive Enterococci coverage for intra-abdominal infection?

Answer 35

High severity History of cephalosporin use Immunocompromised Biliary source of infection History of valvular heart disease and/or Prosthetic intravascular material

Question 36

When would we consider prophylactic antifungal coverage in an intra-abdominal infection?

Answer 36

If patient not improving on appropriate antibiotic therapy Esophageal perforation

Question 37

What are the possible empiric therapy options for secondary peritonitis/ intra-abdominal infections that are community-acquired and mild-moderate?

Answer 37

Ceftriaxone IV + Metronidazole IV/PO Cefazolin IV+ Metronidazole IV/PO Ciprofloxacin IV + Metronidazole IV/PO Levofloxacin IV + Metronidazole IV/PO Cefoxitin IV Ertapenem IV Tigecycline IV

Question 38

What are the possible empiric therapy options for secondary peritonitis/intra-abdominal infections that are either community acquired with high severity or healthcare-associated?

Answer 38

Piperacillin/Tazobactam IV Meropenem IV Cefepime IV + Metronidazole IV/PO Ciprofloxacin IV + Metronidazole IV/PO Levofloxacin IV + Metronidazole IV/PO *note that cipro and cefe need extra enterococci coverage

Question 39

What are the treatment options if we need antifungal coverage in secondary peritonitis/intra-abdominal infections (candida species)?

Answer 39

Candida albicans: Fluconazole IV/PO Candida others: Micafungin IV

Question 40

What drug is not used in secondary peritonitis/intra-abdominal infections due to resistance?

Answer 40

Ampicillin/Sulbactam

Question 41

Which drug class should we try to avoid if possible?

Answer 41

Fluoroquinolones (do not pick these if other options are available) (ciprofloxacin, levofloxacin)

Question 42

What points are important to remember about anaerobic coverage?

Answer 42

More difficult to isolate in culture Common to maintain anaerobic coverage even if culture does not isolate anerobic bacteria *we will almost always maintain anaerobic coverage*

Question 43

When can we transition to oral therapy?

Answer 43

When clinical stability is achieved

Question 44

What are the possible oral regimens we can use for intra-abdominal infections/ secondary peritonitis?

Answer 44

Amox/Clav PO *q8h* Cefpodoxime + Metronidazole Cephalexin + Metronidazole Cefadroxil + Metronidazole Ciprofloxacin + Metronidazole Levofloxacin + Metronidazole TMP/SMX + Metronidazole

Question 45

How long should general intra-abdominal infections be treated for?

Answer 45

4-7 days after source control