Etiology and pathogenesis
The causative agents of yersiniosis are Yersinia enterocolitica and Yersinia pseudotuberculosis bacteria, which are genetically related to the plague pathogen and are intracellular parasites that destroy cells using specific enzymes. The main natural reservoirs and sources of infection are rodents and cats, and transmission occurs via the fecal-oral route, with children being affected more frequently. In the Russian Federation, the Far East is an endemic focus, but sporadic cases are registered everywhere.
The portal of entry for the infection and the primary lesion site are often the tonsils, which at onset may present with the clinical picture of tonsillitis or pharyngitis. Subsequently, the pathogen spreads through the digestive tract, targeting the terminal ileum and cecum as the main target organs.
Clinical and morphological forms
In the pathological anatomy of yersiniosis, three main clinical and morphological forms are distinguished:
- Abdominal form — characterized by catarrhal or catarrhal-ulcerative gastroenteritis, gastroenterocolitis, and terminal ileitis. The intestinal wall is infiltrated with neutrophils, lymphocytes, plasma cells, and a small number of eosinophils. Hyperplasia and ulceration of Peyer's patches are observed in the lymphoid apparatus.
- Appendicular form — represents a combination of acute appendicitis, terminal ileitis, and mesenteric lymphadenitis.
- Generalized form — develops against the background of immunodeficiencies, anemias (especially iron-deficiency anemia), and kidney pathology. It is characterized by the appearance of vasculitis, thrombovasculitis, and rash, with a fatality rate reaching up to 50%.
Morphology of lymph nodes and granulomas
Regional lymph nodes are involved in the inflammatory process in yersiniosis (mesenteric lymphadenitis): they are infiltrated by leukocytes, mat together into single clusters, microabscesses may form within them, and the spleen undergoes hyperplasia.
Sometimes, specific yersinial granulomas (pseudotuberculosis) form in the intestinal mucosa against the background of catarrhal or catarrhal-erosive inflammation with diffuse eosinophilic infiltration. In their structure, they resemble tuberculous granulomas — they contain epithelioid cells, macrophages, sometimes Langhans giant cells, and have a necrotic center with karyorrhexis. The main difference from tuberculosis is that yersinial granulomas undergo suppuration with abscess formation, resulting in the formation of small scars.
Complications and prognosis
The pathological process can be accompanied by various complications, among which are:
- Intestinal bleeding and intestinal wall perforation;
- Bacterial infections of the respiratory tract and middle ear;
- Dysbiosis.
In most cases, the prognosis for yersiniosis is considered favorable, ending in recovery, although relapses and a transition to a chronic course are possible. The generalized form of the infection has an unfavorable outcome.
Briefly: answers to topical questions
What macroscopic changes occur in regional lymph nodes in yersinial mesenteric lymphadenitis?
In yersinial mesenteric lymphadenitis, regional lymph nodes are infiltrated by leukocytes and matted together into clusters. Microabscesses are possible.
What local intestinal complications can develop in severe yersiniosis?
In the abdominal form of yersiniosis, local intestinal complications may develop: intestinal bleeding, ulceration, necrosis, and perforation of the small and large intestine, peritonitis, diverticulitis, toxic megacolon, and ileocecal intussusception. Dysbiosis and intestinal wall perforation are also listed among the complications of yersiniosis.
What extraintestinal immunopathological complications are characteristic of yersiniosis?
Extraintestinal non-suppurating complications and secondary focal clinical variants have been described for yersiniosis. According to sources, these manifestations include Reiter's syndrome, erythema nodosum, arthritis, arthralgia syndrome, exanthema, and post-viral fatigue syndrome. In the scarlet fever-like variant, cases of acute interstitial nephritis and hemolytic-uremic syndrome have been described.
What morphological changes develop in the liver in the generalized form of yersiniosis?
In the generalized form of yersiniosis, inflammatory and purulent-destructive processes develop in the liver. Macroscopically, hepatomegaly (enlargement of the liver) is determined. Abscesses form in the organ tissue. The development of yersinial hepatitis, which occurs predominantly in an anicteric form, is also characteristic. A more detailed description of microscopic morphological changes in the liver is absent in the sources.
Yersiniosis hits the Ileum (terminal ileitis) and Lymph nodes (mesenteric lymphadenitis with matted clusters), and its granulomas are easily distinguished from tuberculosis by their tendency to suppuration.
Class and exam questions
Which microorganisms cause yersiniosis?
The causative agents are Yersinia enterocolitica and Yersinia pseudotuberculosis, which are intracellular parasites and are related to the plague bacterium.
Which organs are the main targets in yersiniosis?
The main target organs are the terminal ileum and cecum, as well as regional lymph nodes.
How do yersinial granulomas differ from tuberculous ones?
Unlike tuberculous granulomas, yersinial granulomas invariably undergo suppuration with the formation of abscesses.
What else to study on this topic
- Epidemiology and sources of infection in the Russian Federation
- Features of the abdominal form of ileitis
- Morphological picture of mesenteric lymphadenitis
- Differences between pseudotuberculous granulomas and tuberculosis
- Pathogenesis and causes of the generalized form
Master the entire topic in the "Pathological Anatomy" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Yersiniosis" and 4,414 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 153 video lessons on the subject
Other topics in "Chapter 16. Infectious and Parasitic Diseases"
Free video lessons: pathological anatomyShort lessons with study notes — no registration required.
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.