Acute Abdomen May Be Symptom of C. difficile

ESTES PARK, COLO. — One of the major diagnostic challenges in community-acquired Clostridium difficile–associated disease is that it can present without diarrhea or a history of recent antibiotic use—and with symptoms closely mimicking acute appendicitis.

“I have actually seen a patient go to appendectomy when in fact the problem was unrecognized community-acquired C. difficile–associated disease,” Dr. Mary Bessesen said at a conference on internal medicine sponsored by the University of Colorado.

“C. difficile tends to preferentially involve the cecum, so patients can present with very typical right lower quadrant pain, tenderness, leukocytosis, and look for all the world like appendicitis,” explained Dr. Bessesen, chief of infectious diseases at the Denver VA Medical Center.

Abdominal imaging is extremely useful in making the distinction in these patients without diarrhea.

This is a high-stakes diagnostic dilemma. Patients with community-acquired C. difficile–associated disease (CDAD) who present without diarrhea are at the severe end of the disease spectrum. Moreover, if they present with ileus they can't produce a specimen for diagnostic testing. “These are the most difficult and lethal cases because the CDAD is not recognized and the patients are so ill,” she noted.

The ileus can range in severity from mild to toxic megacolon requiring surgery. Under the latter circumstances, rectal vancomycin can be colon-saving. It is given by inserting a Foley catheter into the rectum, inflating the balloon, instilling 500 mg of intravenous vancomycin in 100 cc of normal saline, then clamping the catheter. This is repeated every 6 hours.

The negative predictive value of most lab tests for C. difficile is so poor that often the best strategy when suspicion runs high is to treat empirically for the infection while waiting 5-7 days for the results of culture, the most sensitive test available.

Some encouraging recent developments in lab testing may make it possible to avoid empiric therapy. In a not-yet-published study, a C. difficile glutamate dehydrogenase assay had a sensitivity approaching that of culture (negative predictive value above 98%), and a turnaround time of an hour or less. And a commercially available C. difficile real-time PCR assay developed by BD GeneOhm had negative predictive values of 97% and 99% in two recent studies (J. Clin. Microbiol. 2009;47:373-8; J. Clin. Microbiol. 2009;47:1276-7).

“We haven't adopted the PCR assay at our hospital because it costs about $80. If the cost comes down it might become an excellent system,” Dr. Bessesen said.