Faecal peritonitis

A lot of the CICM fellowship questions make use of the post-laparotomy patient as a starting point for management questions. For instance,  Question 18 from the second paper of 2011 asks about antibiotic choices and causes of fever.

The World Journal of Emergency Surgery offers a set of broad guidelines for the management of acute intra-abdominal infections, which seems to refer extensively to the Surviving Sepsis guidelines. Another definitive resource is the IDSA guidelines statement from 2010.

Choice of antibiotics

This specific issue had come up in Question 18 from the second paper of 2011.

Specifically, is there any benefit in the usual "triple therapy" (ampicillin-gentamicin-metronidazole combination), or is a single agent (eg. Tazocin - piperacillin/tazobactam) adequate? There is evidence that single broad agent therapy may be equivalent in its efficacy to the standard multidrug regimen. In 2000, Ledford et al published a review recommending single-agent Tazocin or carbapenem therapy. Another recent (2010) single centre study also did not find much difference in efficacy between single-drug, double-drug or triple-drug combinations (all were around 60%); however apparently only combination therapy with vancomycin achieved adequacy rates higher than 80%. The gradual increasing trend in ESBL colonisation (and probably the effect of people following the advice above) has given rise to an increasing rate of Tazocin-resistant eneterobacteria, and if risk factors for ESBL colonisation are present, meropenem seems to be the appropriate choice.

Certainly, single-agent cephalosporin therapy seems to be universally viewed as useless; enterococci are intrinsically resistant, and enterobacteriaceae frequently have acquired resistance. Aminoglycosides are also sub-optimal, as they fail to penetrate collections (and in acidic environments their efficacy is poor).

What to make of all this? When in doubt, turn to the Sanford Guide. They settle on Tazocin for "mild-moderate" infection, and for anything "severe" (defined as "the patient is sick enough to be in ICU") they recommend meropenem as the first choice. The IDSA, on the other hand, have meropenem and tazocin ranked on the same level (both indicated for high risk or severity patients)

When to add the antifungals

There is no role for prophylactic antifungals, according to the

You should cover for Candida species in the following scenarios:

• Repeated surgery
• Necrotising pancreatitis
• Post-transplantation
• The intraoperative cultures have a high amount of Candida
• There is candidaemia

You should think about antifungals if bowel perforation is the cause of the catastrophe.

A classical 1989 article from the Lancet discusses the clinical significance of Candida in the abdominal surgical patient. Pretty much all the clinically significant infections occurred in patients whose bowels had perforated, as well as in the pancreatitis group.

The IDSA recommend that in the critically ill patient, an echinocandin is indicated as the first choice (instead of fluconazole). However, the grade of recommendation is low (III-B, based on the opinions of respected authoritis, and with only moderate evidence).

What to do with the post-operative abdominal collection

Interesting recommendations from the WJES statement include:

• In the absence of peritonism, post-op intraabdominal collections are best drained percutaneously.
• In the presence of peritonism, urgent surgery is indicated.