Objectives Review basic categories of intra-abdominal infection and their

respective treatments Community acquired intra-abdominal infection Mild/Moderate Severe

Acute biliary tract infections Nosocomial intra-abdominal infection

Consider other abdominal processes associated with antibiotic use

Spontaneous bacterial peritonitis Pancreatitis with and without necrosis Infectious diarrhea

Mention of prevention of surgical infections during colorectal surgery

Useful guidelines1. IDSA complicated intra-abdominal infection guideline1

2. IDSA infectious diarrhea guideline2

3. AASLD ascites guidelines3

4. ACG pancreatitis guideline4

5. IDSA SHEA surgical prophylaxis guideline5

6. ISPD peritoneal dialysis infection guideline6

7. AGA diverticulitis guidelines11,12

Intra-abdominal infection Enteric contents enter the peritoneal cavity leading to abscess or

peritonitis

Obtaining adequate early source control is the rule

Localized- Appendicitis, diverticulitis, cholecystitis with or without perforation Contained perforation without hemodynamic instability Carefully selected patients with appendiceal perforation OCCASIONALLY

treated medically without an open or percutaneous source control procedure Trend to non-operative management of perforated diverticulitis utilizing

percutaneous drainage only Trend to percutaneous transhepatic cholecystostomy (PTC) in severe

cholecystitis with delayed >72h duration of symptoms or unacceptable surgical risk32-33

Diffuse peritonitis- after perforation THESE PATIENTS ARE SICK AND NEED TO GO TO THE OR

“High risk” infection1

Treatment Mild-moderate severity: perforated appendicitis, diverticulitis,

intra-abdominal abscess. Cefazolin 1-2g iv q8h plus metronidazole 500mg iv q8h

If local cefazolin E. coli susceptibility <90% consider ceftriaxone 2g

High-risk severity: hemodynamic instability, advanced age, immune-compromised state (Table 1 on prior slide) Piperacillin/tazobactam 3.375g iv q8h over 4h, or

Cefepime 1g iv q6h plus metronidazole 500mg iv q8h

Healthcare-associated Use high-risk regimen

Can consider empiric addition of vancomycin but RARELY NEEDED

Metronidazole dosing T1/2 = 8h (similar to ceftriaxone)

Concentration dependent killing

Some institutions use q24h dosing when using IV 1g – 1.5g IV q24h in adults1,7

30 mg/kg/day IV q24h in children8

When given PO, nausea is limiting so q8h dosing more appropriate

Basic points Cultures not mandatory for mild-moderate infections

Do not use ampicillin/sulbactam, clindamycin, aminoglycosides, or cephamycins Suboptimal E. coli and/or B. fragilis activity

Empiric enterococcus therapy not needed for mild-moderateinfections but favored for severe infections If recovered in culture in severe or healthcare-associated infection

then treat

Empiric antifungal therapy is not recommended Give fluconazole if recovered in culture until identified

Patients to be treated non-operatively for low-risk infections should typically be on a low-risk regimen with plans for early PO conversion

Biliary infections These are UPPER GI flora No anaerobic coverage required for non-severe disease

unless pre-existing biliary-enteric anastomosis is present

Mild-moderate Cefazolin (or ceftriaxone if E. coli susceptibility <90%)

Severe Piperacillin-tazobactam, or Cefepime plus metronidazole

De-escalation and alteration of initial regimen

Low-risk patients with adequate source control who are improving DON’T have to be broadened if untreated pathogens are later reported in culture

In high risk or persistently ill patients, try to optimize regimen to predominant flora and generally avoid narrowing

Duration of therapy Stomach or proximal jejunal perforation repaired within 24h and with

adequate source control Cefazolin prophylaxis x24h then discontinue If on PPI or malignancy, give high-risk regimen x4-7d

Penetrating/blunt or iatrogenic perforation repaired within 12 hours Treat for ≤24h

Acute appendicitis without perforation Treat ≤24h

Acute cholecystitis without perforation Treat ≤24h after cholecystectomy Treat ≤7 days if treated non-operatively with percutaneous cholecystostomy31

Complicated established infection with adequate source control 4 – 7 days

Recent duration-of-therapy literature

Acute grade II cholecystitis9

WBC >18, Mass in RUQ, >72h symptoms, or gangrenous/pericholecystic abscess/emphysematous/local peritonitis

≤4 days of therapy after surgery as effective as >4 days Rx

STOP-IT trial10

NEJM 2015 518 patients with complicated intra-abdominal infection Randomized to fixed 4 day Rx vs. 10 days or “clinical

resolution” Results: intervention group got 4 days, control 8 days Equivalent 21% recurrence rates

Acute uncomplicated diverticulitis Antibiotics may not be needed after all!? If no perforation or sepsis

AGA guidelines allow for “selective” use11,12

Several new studies show no difference in acute resolution, possible reduced recurrence with antibiotics13-

16

Too early to know what to recommend, but argues for less-aggressive trend to current approach

Approach to perforated diverticular abscess

Patients with diffuse fecal peritonitis require emergent surgery

Localized small abscesses <4-6cm may be amenable to antimicrobial therapy alone17,18

Larger abscesses are generally drained by CT guidance percutaneously

Failure to improve with medical or CT drainage after 3 days suggests need for surgery

Patients with successful drainage may require delayed elective sigmoid resection due to high recurrence rates19-22

Spontaneous bacterial peritonitis3

Defined as PMN ≥250 cells/mm3 in ascitic fluid of cirrhotic patient with signs or symptoms suggestive of ascitic fluid infection

Tap and treat if PMN criteria reached

Ceftriaxone 1g iv q12h x5 days Narrow if a single pathogen is isolated in culture Cefotaxime option offers no benefit, limited availability Total daily dose 2g vs. 1g associated with improved outcomes29

Give SBP prophylaxis in patients with GI bleeding Ceftriaxone 1g IV q24h x 7 days

Secondary prophylaxis after 1st SBP episode30 if ascites protein <1 Trimethoprim/sulfamethoxazole DS 1 tab daily Ciprofloxacin 500mg PO daily if tmp/smx not feasible

Acute pancreatitis These patients have high WBC, fever, and tachycardia;

they look septic

Patients with shock need blood cultures and antibiotics4

Without shock, treat as pancreatitis with fluids, NPO etc If antibiotics started, when blood cultures negative and no

other source found abx should be discontinued

Necrotic pancreatitis is not an indication for antibiotics Earlier trials of PROPHYLACTIC antibiotics23,24 have been

disproven25-27

No decrease in infections or sugery, but more RESISTANT organisms when infection develops25

Infected pancreatic necrosis Patients failing to improve or worsening after 7-10 days of

conservative management

CT guided fine needle aspiration (FNA) can be used to diagnose Preferred from stewardship standpoint over empiric abx

Prolonged IV antibiotics if infected Surgery can be avoided in ~3/4 of patients and only ~1/3

required percutaneous drainage28

Cephalosporin plus metronidazole or carbapenem

Infectious Diarrhea2

Fever and blood = dysentery Shigella, campylobacter, sometimes salmonella Await stool culture if stable

If using rapid diagnostics, be sure to submit culture prior to treatment

If septic can give azithromycin 500mg or ciprofloxacin 500mg

Traveler’s diarrhea Entero-toxigenic E. coli (ETEC), shigella, salmonella Empiric ciprofloxacin 500 bid x3d or 750 x1; azithromycin 500 x3d

Blood and NO fever Enterohemorrhagic E. coli (EHEC): NO ANTIBIOTICS

Recent hospitalization, ED visit, or antibiotics CDIFF, CDIFF, CDIFF (which is another talk entirely)

Peri-operative prophylaxis for colorectal surgery

Our protocols mimic our treatment guidelines

Cefazolin 2g (3g if >120kg) plus metronidazole 500mg Immediately prior to incision Can be mixed and given in same bag as “cefanidazole” Cefazolin redosing interval 4h; metronidazole not redosed

Levofloxacin 750mg plus metronidazole if anaphylactic penicillin allergy No redosing

If known MRSA colonized can consider adding vancomycinthough literature supports primarily for orthopedic and cardiac surgery

If already on antibiotics and going to OR

Re-dose based on published intra-operative re-dosing interval5

4h for cefazolin 2h for piperacillin/tazobactam

Using cefazolin/metronidazole is effective, easy, and logistically simple vs. alternative regimens

We do NOT endorse use of ertapenem for prophylaxis Extremely broad , ESBL coverage

If surgeons insist on q24h regimen can use daily dosed ceftriaxone plus metronidazole 1g

References1. Clinical Infectious Diseases 2010; 50:133–64

2. Clinical Infectious Diseases 2001; 32:331–50

3. Hepatology 2009;49:2087-107).

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7. J Chemother. 2007 Aug;19(4):410-6

8. J Pediatr Surg . 2008 June ; 43(6): 981–985

9. J Gastrointest Surg (2013) 17:1947–1952

10. N Engl J Med 2015;372:1996-2005.

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18. Dis Colon Rectum. 2006 Oct;49(10):1533-8

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20. ANZ J Surg. 2016 Apr 8.

21. Ann Surg. 2015 Dec;262(6):1046-53

22. Dis Colon Rectum. 2014 Dec;57(12):1430-40

References23. Surg Gynecol Obstet 1993 ; 176 : 480 – 3

24. Lancet 1995 ; 346 : 663 – 7

25. Ann Surg 2007 ; 245 : 674 – 83

26. Cochrane Database Syst Rev : CD002941

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29. F1000Research 2014, 3:57

30. Ann Pharmacother. 2010 Dec;44(12):1946-54

31. World J Surg (2017) 41:1239–1245

32. The American Journal of Surgery (2013) 206, 935-941

33. Hepatobiliary Pancreat Dis Int2014;13:316-322