Causes and clinical presentation
The development of the pathology is directly linked to the excessive proliferation of Clostridium difficile. Typically, this process is triggered following a course of broad-spectrum antibiotics, when the normal intestinal microflora is disrupted. The bacteria release toxins that damage tissues.
Endoscopically, the disease manifests as the formation of yellowish plaques on the inner surface of the bowel. These plaques consist of dead and sloughed mucosal cells that coalesce to form a so-called pseudomembrane.
Clinically, patients complain of diarrhea, accompanied by fever (pyrexia) and elevated blood leukocyte levels. It is important to remember that colitis can take a fulminant course. In such cases, deep tissue necrosis develops, which can lead to organ perforation—a life-threatening condition.
Radiological signs
Plain abdominal radiography may provide initial clues, although its diagnostic value is limited. The images frequently reveal a pattern of generalized ileus (intestinal obstruction).
A specific radiological marker is the "thumbprinting" sign (thumbprinting). It is visualized in the transverse colon and occurs due to pronounced mucosal edema, which resembles thumb impressions on the radiogram. Nodular thickening of the colonic haustra may also be observed.
CT and ultrasound diagnostics
Computed tomography is a more detailed method, although the findings can sometimes be nonspecific. The main CT signs are associated with inflammation of the intestinal wall layers:
- Wall thickness: pronounced thickening is observed, predominantly of a nodular nature.
- Mucosal changes: marked contrast enhancement of the mucosa is characteristic.
- Submucosal layer: extensive areas of low attenuation are visualized, which clearly indicate intense submucosal edema.
- Specific patterns: the combination of edema and thickening forms a pronounced target sign, which in this context is more commonly referred to as the "accordion sign" (accordion sign).
- Surrounding tissues: inflammatory changes in the adjacent adipose tissue (pericolic stranding) are usually minimal.
- Ascites: free fluid in the abdominal cavity is detected in approximately 40% of patients.
Ultrasound also visualizes significant thickening of the colon wall and its haustral folds, correlating with CT findings.
Differential diagnosis
The described imaging signs are highly typical of Clostridium difficile infection, but they are not entirely unique. A similar picture with pronounced edema and wall thickening can be observed in:
- AIDS-associated colitis.
- Ischemic colitis.
- Severe intestinal wall edema developing against the background of liver cirrhosis.
Additionally, this condition should be distinguished from neutropenic colitis (typhlitis). In typhlitis, which frequently occurs after chemotherapy, wall thickening is less pronounced, the process is usually localized on the right (in the cecum), often accompanied by pneumatosis intestinalis and small bowel involvement, and mesentery stranding is more pronounced.
Briefly: answers to topical questions
Which specific groups of antibacterial drugs most frequently provoke the development of pseudomembranous colitis?
Pseudomembranous colitis is most frequently provoked by lincosamides, as well as penicillins, cephalosporins, and fluoroquinolones.
- Lincosamides (clindamycin, lincomycin) — use of this group is most strongly associated with the development of pseudomembranous colitis.
- Penicillins — provoking group.
- Cephalosporins — provoking group.
- Fluoroquinolones — provoking group.
Overall, the disease is usually a consequence of broad-spectrum antibiotic therapy.
Which specific Clostridium difficile toxins cause damage to the intestinal mucosa?
Damage to the mucosa and wall of the colon is caused by toxins A (TcdA) and B (TcdB) produced by Clostridium difficile.
- Toxin A (TcdA), according to traditional understanding, disrupts the mucosal-epithelial barrier.
- Toxin B (TcdB) penetrates enterocytes and the lamina propria, exerting a toxic effect.
According to modern data, both toxins are capable of damaging the colonic wall by directly destroying epithelial cells and tight junctions. The pathogen itself is non-invasive; its virulence is driven by toxins A and B, as well as enzymes.
To remember the imaging findings, use the "Dactyloscopist Musician" mnemonic: due to severe edema, the bowel leaves "thumbprints" on the radiograph, and folds into an "accordion sign" on the tomogram.
Class and exam questions
Does CT always show pathology in pseudomembranous colitis?
No, the imaging findings can be nonspecific. According to statistics, in 39% of patients with this disease, CT results remain within normal limits.
What causes areas of low attenuation in the intestinal wall on CT?
These areas form exclusively due to pronounced edema of the submucosal layer of the intestinal wall.
What is the pseudomembrane found during endoscopy composed of?
It consists of yellowish plaques formed from dead and sloughed cells of the intestinal mucosa.
What else to study on this topic
- Toxic megacolon: radiological presentation and transmural inflammation
- Neutropenic colitis (typhlitis): CT findings in chemotherapy
- Acute appendicitis: graded compression ultrasound
- Parasitic colitides (trichuriasis, strongyloidiasis, Chagas disease)
- Radiation enteritis: MRI diagnostics
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