Yersinia Enterocolitica Workup

Updated: Oct 20, 2015
  • Author: Zartash Zafar Khan, MD, FACP; Chief Editor: Mark R Wallace, MD, FACP, FIDSA  more...
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Workup

Approach Considerations

The following tests can be used in the diagnosis of Y enterocolitica infection (see the image below):

  • Stool culture - This is the best way to confirm a diagnosis of Y enterocolitica [2, 3] ; the culture result is usually positive within 2 weeks of onset of disease
  • Tube agglutination
  • Enzyme-linked immunosorbent assays
  • Radioimmunoassays
  • Imaging studies - Ultrasonography or computed tomography (CT) scanning may be useful in delineating true appendicitis from pseudoappendicitis
  • Colonoscopy - Findings may vary and are relatively nonspecific
  • Joint aspiration - Synovial fluid contains 500-60,000 WBCs/µL, with a predominance of polymorphonuclear cell; cultures are sterile; testing synovial fluid for bacterial antigens may be of some use in difficult cases
    Gram stain of Yersinia enterocolitica.
Gram stain of Yersinia enterocolitica.
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Stool Culture

Stool samples tested for leukocytes usually produce positive results, but Y enterocolitica is difficult to distinguish from other invasive pathogens. Stool samples from infected patients should be handled carefully to avoid infecting others.

When Y enterocolitica infection is suspected, instruct the microbiology laboratory to use cefsulodin-Irgasan-novobiocin (CIN) agar, which is a differential selective medium with increased yield for Y enterocolitica. It requires 18-20 hours of incubation at 25°C to create unique colony morphology, representing 0.5- to 1-mm colonies with a red "bull's-eye" and a clear border. Use of this media allows differentiation between Y enterocolitica and Y enterocolitica– like isolates.

When using conventional enteric media, MacConkey agar incubated at 25°C for 48 hours produces the best results. [51]

Recovery of organisms from otherwise sterile samples, such as blood, cerebrospinal fluid (CSF), and lymph node tissue, is usually faster than recovery from stool samples. Isolation of Y enterocolitica from stool is hampered by slow growth and overgrowth of normal flora.

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Serodiagnosis

Serodiagnosis is possible with various methods, including tube agglutination, enzyme-linked immunosorbent assays, and radioimmunoassays. However, carefully interpret the serotest results for Y enterocolitica infection if a positive stool culture result is absent. Cross-reactions with other organisms can occur—including with Brucella, Morganella, and Salmonella —and a background seroprevalence rate among different populations may confound the diagnosis by acting as a false-positive result.

Agglutinin titers typically increase 1-2 weeks after infection and peak at 1:200. However, elevated levels can be found for years after infection, which also limits the usefulness of serodiagnosis.

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DNA Microarray

Advanced experimental techniques for diagnosis of Y enterocolitica infection include polymerase chain reaction (PCR) assay, immunohistochemical staining, and DNA microarray. Diagnostic DNA microarray for pathogenetic organisms is a comparatively new technique that is used to identify multiple genes from different kinds of pathogens, allowing it to be used to detect different species, biotypes, and/or toxins of pathogenic organisms in the same specimens. This is the major advantage over the conventional PCR assay technique, which is used to identify only 1 gene from a hybridization. DNA microarray is also more sensitive and accurate than the multiplex PCR. [52]

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Colonoscopy

Typically, in patients with Y enterocolitica infection, the cecum contains aphthoid lesions and the terminal ileum has small, round elevations and ulcers (as seen in the image below). An exudate may be present. The left side of the colon is typically unaffected, but case reports have described left-sided colitis with serotype O:8.


Yersinia enterocolitis in a 45-year-old white wom Yersinia enterocolitis in a 45-year-old white woman who presented with chronic diarrhea.
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Histologic Findings

Histologic findings in Y enterocolitica infection are consistent with acute and chronic inflammation. Yersiniosis does not produce unique histologic findings. Epithelial cell granulomas with suppuration of the centers of the granulomas (central microabscesses) have been reported. These granulomas were composed of numerous histiocytes with or without epithelioid cell features, along with scattered small T-lymphocytes and plasmacytoid monocytes. [53]

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