August 19, 2014 Grand Rounds

Case # 1. A 35/F presented with 4 month history of fever, diarrhea, vomiting, 30 pound weight loss, and granulomatous ileitis 

1. Several differential diagnoses were brought up including tuberculosis, histoplasmosis, Crohn's disease, sarcoidosis, and lymphoma. A useful article to review the different causes of granulomatous disease is linked to Case # 3 from June, 17, 2014.

2. It is hard to distinguish Crohn's disease from gastrointestinal tuberculosis especially in areas where the prevalence of both diseases is high. A positive anti-Saccharomyces cerevesiae (ASCA) antibody test is common in patients with Crohn's disease while a positive tuberculin skin test (TST) or interferon gamma release assay can be supportive of tuberculosis. Tissue culture remains the gold standard of diagnosing gastrointestinal tuberculosis.

3. Again, it was emphasized (similar to Case # 3 from June 17, 2014) that multiple tissue biopsies and cultures should be obtained to determine the cause of the granulomatous process. Empiric anti-tuberculous treatment may be warranted in some patients if the index of suspicion for tuberculosis is high.

Case # 2. A 7-week old infant presented with 1 day history of irritability, low grade fever, tachycardia, and localized neck cellulitis and adenitis secondary to group B Streptococcus (GBS)

From: http://www.giglig.com/wp-content/uploads/2011/09/Streptococcus.jpg

1. GBS cellulitis-adenitis syndrome is a rare (34 cases in the literature) but well-described late-onset GBS disease in neonates and infants. The median age of onset is 4.5 weeks. It usually presents as fever, increased irritability, and poor feeding followed by the appearance of lymphadenitis that is usually located in the submandibular region. In >90% of cases, GBS is isolated from the blood or from the lymph node.  

Case # 3. A 58/F presented with acute onset fever, nausea, vomiting, diarrhea, leukocytosis to 44,000, enterocolitis on CT scan, and septic shock several weeks after completing levofloxacin treatment for community acquired pneumonia; stool C. difficile toxin test is negative on two occasions

From: https://ndnr.com/wp-content/uploads/2012/01/10045000_m.jpg

1. The sensitivity of Clostridium difficile toxin enzyme immunoassay (EIA) is 63-94% depending on the the commercial test used (read here). The EIA we use for detecting Clostridium difficile toxin in our hospital is called TECHLAB assay. From the package insert, this test, compared to tissue culture cytotoxicity assay which is the gold standard in diagnosing Clostridium difficile, has a sensitivity of 92.2%, specificity of 100%, negative predictive value of 98.6%, and positive predictive value of 100% (read here).

2. The EIA can have as much as 10-20% false negative rate (read here). Thus, in some rare cases when this test is negative, it may be reasonable to continue treatment for Clostridium difficile. Although, in these cases, one should always look for other competing diagnoses such as ischemic bowel disease and other antibiotic-associated enterocolitis (e.g. Campylobacter, Salmonella).