Ozena - Causes and Pathogenesis

The reason for the development of ozena is still unclear. There are many theories about its origin:

• alimentary - one of the most common theories, people who live in poor sanitary and hygienic conditions and eat poorly are more likely to get sick;
• avitaminosis theory - a lack of vitamins A and D, according to other data - K and group B;
• anatomical - based on the structural features of the skull, sinus cavity and nasopharynx;
• hereditary;
• infectious - the main role is played by a variety of microflora, sown from the nasal mucus of patients with ozaena (Corynebacterium, Proteus), but Klebsiella pneumoniae ozaenae is most often sown; which is assigned a leading role in this pathology;
• non-infectious (neurodystrophic) - in the development of ozena, the main role is played by a disorder of the autonomic and endocrine systems or sympathetic innervation, which leads to dystrophic processes in the nasal cavity; trophic disorders subsequently lead to osteomalacia, bone resorption and epithelial metaplasia.

Since the end of the 19th century, the infectious theory has become dominant. In 1885, Lowenberg discovered a capsular diplococcus in patients with ozena, and in 1893, Abel isolated this microorganism in pure culture, studied its properties and called it Bacillus mucosas ozaenae. At present, the infectious theory and the role of Klebsiella pneumoniae ozaenae can be considered proven.

Pathogenesis of ozena

The process begins with the entry of Klebsiella pneumoniae ozaenae onto the surface of the mucous membrane of the nasal cavity, sometimes other parts of the upper respiratory tract. The microorganism has a capsule and is located only on the surface of the mucous membrane, causing its inflammation. The inflammatory process in the first, rather long, period has a catarrhal form and is characterized by a significant amount of liquid mucous secretion up to 4 liters per day. Then mucopurulent discharge appears with a large number of leukocytes and lymphocytes, as well as the capsular bacteria themselves.

Subsequently, the secretion becomes thick, viscous, sticky, which causes it to be retained in the nasal cavity and crusts to form, since nasal breathing is not yet impaired during this period.

At the same time, virulent strains of Klebsiella pneumoniae ozaenae synthesize a large amount of capsular polysaccharide on the surface of the mucous membrane, which causes a trophic disorder due to the effect on the vessels (their walls become inflamed, the lumen narrows).

Subsequently, Klebsiella pneumoniae ozaenae causes dysbacteriosis in the nasal cavity, a slow deterioration in the nutrition of bone tissue and mucous membrane, leading to the progression of the dystrophic process, accompanied by dryness, difficulty in nasal breathing, expansion of the nasal cavity, a large number of crusts with an unpleasant odor characteristic only of ozena (fetid, sweetish, nauseating).

Oena is characterized by atrophy of all tissues of the nasal cavity walls, thinning of the mucous membrane and blood vessels. With ozena, metaplasia of the columnar epithelium is sharply expressed, it completely degenerates into flat, desquamates and forms the basis for crusts. Keratinized epithelium is impermeable to liquid, therefore, even in the presence of a large number of glands, the mucous membrane is not softened with mucus. In the subeliteial layer around the glands and blood vessels, pronounced leukocyte infiltration is observed. The number of glands decreases, they are replaced by connective tissue. Cavernous tissue becomes empty, a process resembling obliterating endarteritis is observed in the vessels. The bone layer of the nasal conchae contains a large number of osteoclasts - cells that dissolve bone. The bone base of the conchae dissolves and is replaced by connective tissue. The destruction of proteins is accompanied by the formation of indole, skatole and hydrogen sulfide, which determines the foul odor from the nose.

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