In ICU patients with abdominal pain, work-up forC. difficilecolitis should ideally be
performed prior to abdominal surgery. Diagnosis can be made by the less sensitive (67%)
rapid enzyme immunoassay or a more sensitive (90%) but slower tissue culture assay (106).
The finding of pseudomembranes on sigmoidoscopy is also diagnostic and can negate the need
for exploratory laparotomy. Optimal therapy ofC. difficilediarrhea/colitis depends on severity
of disease and the need for ongoing antimicrobial therapy. Antiperistaltic agents should be
avoided. If feasible, the offending antibiotic should be discontinued. In mild cases this may
suffice, and specific antibiotic therapy forC. difficilemay be unnecessary.
For many years, oral metronidazole was the agent of choice for most patients requiring
treatment. A recent study demonstrated that using oral vancomycin is more effective in
seriously ill patients (107). Consequently, it is now recommended that any patient requiring
intensive care should be treated with enteral vancomycin if she has leukocytosis15,000
cells/mm^3 or a creatinine level1.5-fold more than the level prior to the onset of theC. difficile
infection (personal communication). Metronidazole is the only agent that may be efficacious
parenterally (108); vancomycin given intravenously is not secreted into the gut. In especially
severe cases, patients can be treated with the combination of high-dose intravenous
metronidazole and nasogastric or rectal infusions of vancomycin. Although therapy with
other agents such as intravenous immunoglobulin and stool enemas has been promulgated,
this approach has not been compared directly to other standard regimens.
ANTIBIOTIC-RESISTANT SUPERINFECTIONS
In the ICU, the use of antibiotics can predispose recipients to colonization and infection with
methicillin-resistantStaphylococcus aureus, vancomycin-resistantEnterococcusspecies (mostly
E. faecium), multidrug resistant gram-negative bacilli, and fungi. Detailed discussion of these
superinfections is beyond the scope of this chapter.
SUMMARY
Antibiotics are commonly used in the ICU. Adverse effects are regularly encountered and
must be anticipated. The multiplicity of medications and underlying conditions in ICU
patients affect the presentation and management of adverse reactions. When possible, the
intensivist should employ the fewest number of antibiotics necessary, choosing those least
likely to interact with other drugs and cause adverse reactions.
ACKNOWLEDGEMENT
Previous versions of this chapter were published in earlier editions ofInfectious Diseases in
Critical Care Medicineand in Critical Care Clinics (2008; 24:421–442). The authors gratefully
acknowledge intensivists Lori Circeo, Thomas Higgins, Paul Jodka, and especially Gary Tereso
for helping us identify the most important adverse reactions and drug interactions affecting
critically ill patients and Pauline Blair for her excellent assistance preparing this review.
Dr. Brown is on the speaker’s bureaus of Merck, Ortho, Pfizer, and Cubist
pharmaceuticals.
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