Diagnosis | From Gum To Bum

Clostridioides (Clostridium) difficile infection – enterocolitis

Usually Toxin A and B are both presents but there has been cases reported with only toxin B. Recently in 2005, a new strain with a third toxin (referred to as binary toxin CDT, on top of A and B toxin) was discovered, but does not appear to have a damaging effect by itself but can potentiate the damage from A&B.

Stool sample

-Enzyme immunoassays (EIAs) tests detect toxins A and B produced by the organism, providing rapid results with high specificity; however, sensitivity can be impacted by specimen handling.

-Nucleic acid amplification tests (NAAT), such as PCR and loop-mediated isothermal amplification, offer sensitivity comparable to toxigenic culture by detecting the gene that encodes the toxin. While NAAT confirms the presence of a toxigenic C. difficile strain, it does not indicate whether the toxin is actively produced in the patient.

-glutamate dehydrogenase (GDH) antigen test, detects an enzyme produced in large quantities by both toxigenic and nontoxigenic strains of C. difficile as well as other clostridial species. The GDH test is highly sensitive and serves as an effective screening tool with a high negative predictive value . However, a positive GDH test requires further confirmation of a toxigenic strain through either NAAT or enzyme immunoassay (EIA), as false negatives can occasionally occur. Therefore, additional testing is recommended if clinical suspicion remains high.

F2.large — Clostridioides difficile bacteria, showed in Photomicrograph. Many have assumed an endospore morphology. This is from a blood agar impression smear incubated for 72 hours anaerobically. From the US Centers for Disease Control and Prevention, Dr. Gilda Jones; Public Domain; Available at: https://phil.cdc.gov/phil/details.asp?pid=3876

Endoscopy:

Not all the cases form pseudomembranes, however when present, it is very suggestive of CDI. The pseudomembrane is composed of inflammatory and cellular debris, forming distinct yellow or gray patches of exudate that cover the underlying mucosa. In early stages, small punctate ulcerations of about 1 to 2 mm may be visible. On gross examination, the pseudomembranes appear as ovoid plaques, typically 2 to 10 mm in diameter, interspersed with areas of normal or reddened (hyperemic) mucosa. Histologically, these pseudomembranes emerge from central ulcerated areas of the epithelium, erupting from intestinal or colonic crypts in a characteristic “volcano-like” pattern. In more severe cases, ulcerated areas and pseudomembranes can merge to cover large sections of the mucosa, sometimes resembling a coating of liquid stool.