Intra-abdominal Infections

Question 1

What are the three categories of intra-abdominal infections?

Answer 1

Based on risk of treatment failure:

1. Community-acquired of mild-moderate severity
2. Community-acquired of high severity
3. Healthcare associated (focus on candida, enterococcus, and MRSA).

Question 2

After initial evaluation of intra-abdominal infection, what 4 things should happen?

Answer 2

1. Fluid Resuscitation
2. Initiation of abx
3. Source Control
4. Microbiological Samples (if toxic or high risk)

*Good source of test questions

Question 3

What makes a community acquired intra-abdominal infection high severity?

Answer 3

Age > 70
Immunosuppressed
Malignancy
Liver or Kidney dx
Disease specific factors: 
 -High apache score (>15)
 -Healthcare associated infections
 -Delay in initial intervention (>24 hours)
 -Inability to obtain source control

Question 4

Duration of therapy for intra-abdominal infections?

Answer 4

4 days despite current guidelines! (If source control has been obtained).

STOP-IT trial showed that patients with source control who got 4 days of therapy for complicated intra-abdominal infections did just as well. Even if they are septic.

Question 5

Between Avicaz and Zerbaxa, which one is the CRE and which one is the psuedomonas one?

Answer 5

Avicaz (ceftazidime/avibactam) is the CRE one (and pseudomonas)
Zerbaxa (ceftolozane/tazobactam) is the psuedomonas one (not active against KPC isolates which is the most common cause of CRE)
*Neither has anaerobic coverage or enterococcus coverage.
*Both are approved for complicated IAI. Have to give with metronidazole to get anaerobic coverage.

Question 6

What is the magic PMN count for diagnosis of spontaneous bacteria peritonitis?

Answer 6

> 250 cells/mm3 (PMNs = segs) in the ascitic fluid
Remember this number!

This plus a positive bacterial culture from ascitic fluid is diagnostic of spontaneous bacterial peritonitis.

Question 7

When do you start empiric antibiotics for peritonitis?

Answer 7

When the PMNs in the ascitic fluid are > 250 cells/mm3.

Question 8

Infectious Diarrhea: Nontyphoidal salmonella or non-vibrio cholera

Answer 8

No treatment needed.

Non = non-treated

Question 9

What’s first line therapy for H. pylori?

Answer 9

PPI + clarithromycin + amoxicillin (or flagyl for PCN allergic) for 14 days

*3 drug regimen

Question 10

What is alternative therapy for H pylori?

Answer 10

4 drug regimen:
PPI + Bismuth (subcitrate or subsalicylate) + tetracycline + flagyl for 14 days

*useful for pts who previous had clarithromycin based regimen. Or if there’s high resistance rates to macrolides.

Question 11

What is 3rd line H pylori therapy

Answer 11

Triple therapy: PPI + Levaquin + Amoxicillin

*Use rifabutin if quinolone allergic

Question 12

Who should be tested for H. pylori

Answer 12

Anyone with PUD.

Consider in pts taking NSAIDs (increased risk of bleeding)

Question 13

Which patients should be treated for H pylori?

Answer 13

All who test positive.

Question 14

What do you treat Vibrio Cholera with?

Answer 14

First: Doxycycline

Second line: Cipro

Question 15

What is STEC and how do you treat?

Answer 15

Shigella toxin-producing E. coli. S.T.E.C.
Bloody diarrhea that can cause severe illness including hemolytic uremia syndrome (HUR). Kidney injury.

Antibiotics make this worse! Don’t treat!

Question 16

What is the role of Zinc supplements in infectious diarrhea?

Answer 16

In the developing world, it reduces the duration of diarrhea in children 6 mo-5 years of age. Doesn’t help in developed world because we aren’t deficient.

Question 17

When should you use GHD vs NAAT test for c diff?

Answer 17

GDH (glutamate dehydrogenase) tests for C diff antigen. Very specific. Use this first if patient doesn’t have unexplained diarrhea > 3 times in 24 hours. If positive, it may not be toxin producing so test for toxin.

NAAT or EIA (enzyme linked immunoassay): tests directly for toxin (EIA) or toxin gene (NAAT). May detect toxin gene for non-active colonizer. Use this second, or if there’s strong clinical suspicion (unexplained presence of >3 unformed stools in 24 hours)

Question 18

What is the treatment of choice for C diff?

Answer 18

First line:
vancomycin 125 mg QID (severe=500 mg)
OR
fidaxomicin 200 mg BID

Second line: Flagyl 500 mg TID (if non-severe (WBC < 15k, SCr < 1.5))

*Flagyl can be added to vanc in cases of fulminant infection or ileus

Question 19

What is the Duration of therapy for C diff?

Answer 19

10 days

Question 20

What’s the advantage of fidaxomycin?

Answer 20

Reduced recurrencye of c diff when compared to PO vancomycin treatment.

Question 21

What’s the role of bezlotoxumab in c diff?

Answer 21

It binds Toxin B and reduces recurrence rates of c diff. The toxin A binder didn’t prove effective in trials.

Question 22

What to if c diff recurrence?

Answer 22

First recurrence, basically, try something different than what you tried first. Prolonged, tapered, and pulsed vanc can be an option if VAN 125 QID was used initially, but Fidaxomicin is probably better.

For second, or subsequent recurrence, consider Fecal Microbiota Transplant (FMT). May also consider VAN 125 mg QID followed by Rafaximin 400 mg TID for 20 days.

Question 23

When can FMT be considered for c diff?

Answer 23

On second or subsequent recurrence.

Question 24

Can you give Fidaxomicin as extended pulsed therapy to reduce recurrence?

Answer 24

It’s not in the guidelines just yet, but yes you can. There’s good data on it. Most likely for patients who have already had a recurrence, this could be considered.

Question 25

Should you order another c diff test within 7 days of a positive result?

Answer 25

No. And do not do perform a “test of cure.”

Question 26

Should you screen pateints for c diff at admission?

Answer 26

No, too many asymptomatic carriers. Not rec’d.

Question 27

Should you recommend probiotics for pts with c diff?

Answer 27

No by the guidelines. There’s no good evidence that it’s helpful.

Question 28

Should you stop the inciting abx when a patient tests positive for c diff?

Answer 28

Yes, if possible.

Question 29

Should you recommend longer-than-recommended C. diff treatment if a patient is continued on the inciting antibiotic?

Answer 29

No, give standard duration of therapy.

Question 30

Should you restart the c diff treatment if the patient has to take more systemic abx later as a precaution?

Answer 30

No, don’t do that.

Question 31

Should you stop PPI’s in patients who test positive for c diff?

Answer 31

No.