Brucellar uveitis is a bacterial inflammation of the vascular membrane of the eye caused by microorganisms of the genus brucella. The main symptoms of the disease are conjunctival hyperemia, photophobia, decreased visual acuity, the appearance of “floating opacities” and “flies” in front of the eyes. Biomicroscopy, ophthalmoscopy, non-contact tonometry, visometry, ultrasound and laboratory tests (IFR, PCR, Burne test) are used for diagnosis. Etiotropic treatment is reduced to the appointment of local and systemic antibiotic therapy. Symptomatically, antihypertensive drugs, NSAIDs and glucocorticosteroids are used.
Brucellar uveitis is an inflammatory process that develops directly in the uveal membrane. In 1886, the English scientist David Bruce discovered a previously unknown group of bacteria – brucella, and also described the symptoms of their infection of the main organs and systems. Eye damage in brucellar is observed in 26% of patients. Pathology is widespread everywhere, but the incidence rate is highest in agricultural regions. About 74% of patients indicate contact with animals, 70% – consumption of fresh milk, cheese or liver. In 38% of cases, there is a positive family history of brucellar uveitis.
The etiology of the disease is associated with direct infection of the vascular membrane of the eyes with bacteria of the genus brucella. Representatives of microorganisms of this class are small gram-negative aerobic coccobacteria. Due to the ability to intracellular reproduction, pathological agents persist in the body for a long time. The optimal temperature of microbial activity is 37 ° C. Bacteria are very demanding to the conditions of the nutrient medium. The causative agents of the disease are considered to be three main pathogenic types of brucella for humans: Maltese (Brucella melitensis), bovine (Brucella abortus), pork (Brucella suis).
Brucella is characterized by a high penetrating ability. They pass through the conjunctiva and cause damage to the membranes of the anterior segment of the eye with a direct transition to the chorioretinal zone. Also, bacteria penetrate through areas of microtraumatization of the skin and even intact mucous membranes of the respiratory and digestive systems. Further, with the flow of lymph, they spread throughout the body and settle in the lymph nodes. Subsequent hematogenic dissemination of microorganisms causes infection of the vascular membrane without primary inflammation of the conjunctiva.
Brucella can be located inside phagocytes and inhibit the fusion of phagosomes with lysosomes. Bacteria form L-forms, persist in the body for a long time, which leads to the formation of granulomas. With the reverse transition to the original form, a relapse of brucellar uveitis occurs. The disease is characterized by pronounced delayed hypersensitivity. With brucellar uveitis, all structures of the eyeball can be involved in the pathological process, the greatest danger is the development of panuveitis. The morphological substrate of the disease is granulomatous inflammation with a tendency to form multiple choroid exudates.
The clinical picture of the disease largely depends on the type of pathogen. When infected with Maltese brucella, the pathology is characterized by a severe prolonged course with a high probability of chronization. Other types of microorganisms cause milder forms of inflammation of the vascular membrane of the eyeball. With isolated brucellar uveitis, pathological changes are detected on the one hand. After a certain period of time, a similar lesion is found in the area of the second eye. If the disease develops against the background of generalized brucellosis, the symptoms are always symmetrical.
With anterior uveitis, patients complain of discomfort and soreness in the periorbital region, redness of the eyes, pronounced photophobia and lacrimation. In the case of intermediate localization of the process, the main symptoms of the disease are “blurring” of vision, the appearance of “flies” and “floating opacities” in front of the eyes. The progression of the disease leads to a decrease in visual acuity. With a complicated course of brucellar uveitis, unnatural dark spots appear in the field of vision. Due to severe pain, patients close their eyelids and close their eyes with their hands. Bright light potentiates the enhancement of clinical symptoms.
In the anterior form of uveitis, ribbon-like dystrophy of the iris and keratopathy are often noted, posterior synechiae are formed. Increased intraocular pressure (IOP) causes ophthalmic hypertension. With violation of intraocular hydrodynamics, the risk of secondary glaucoma increases significantly. With concomitant damage to the lens, posterior capsular cataract progresses. The most formidable complication of brucellar uveitis is exudative retinal detachment. In some patients, brucellar uveitis is combined with severe reactive inflammation of the vitreous body and edema of the macular area of the retina. The spread of the pathological process to all structures of the uveal tract leads to panuveitis (iridocyclochorioiditis).
The diagnosis is carried out by an infectious disease specialist and an ophthalmologist, based on anamnestic information, physical examination data, results of instrumental and laboratory diagnostics. Additionally, palpation of the lymph nodes, ultrasound of the abdominal organs and chest radiography are performed to exclude the generalized form of brucellosis. The following research methods are assigned:
- Immunofluorescence reaction (IFR). The pathological material is treated with special fluorochrome-labeled antibodies. If brucella antigens are present in the smear, they bind to antibodies. When examining a smear through a fluorescent microscope, a characteristic glow is revealed.
- Cultural research. Blood is seeded on nutrient media. The growth of brucella colonies indicates the presence of these bacteria in the body. It is possible to confirm the diagnosis by the cultural method only 50-70% of cases.
- The skin-allergic test Byrne. In case of sensitization of the body, an intradermal allergic test with brucellin is positive. At the site of the allergen injection, an oval-shaped red painful papule appears, towering above the skin level.
- Polymerase chain reaction (PCR). This is a serological diagnostic method that allows detecting brucella DNA in biological material by amplification of nucleic acids. The reliability of the result reaches 98-100%.
Hyperemia and puffiness of the anterior part of the eyes, maceration of the skin in the ocular region are visually determined. In a unilateral process, anisocoria is observed due to a narrowing of the diameter of the pupillary opening on the affected side. The following methods of instrumental diagnostics are used to confirm specific changes in brucellar uveitis:
- Ophthalmoscopy. When examining the fundus, signs of edema of the optic nerve disc and the inner shell are visible. Chorioretinal foci of inflammation with clearly defined boundaries are found in the peripheral parts. With pronounced exudation, retinal detachment is noted.
- Inspection of the anterior segment. During biomicroscopy of the eye, pericorneal injection, granulomatous foci of the iris and posterior synechiae are visualized. The cellular reaction of the vitreous body is determined. With a chronic course, local thickening of the iris is visible.
- Visiometry. With a mild course of the disease, visual acuity corresponds to the reference values. Severe forms of brucellar uveitis are characterized by pronounced visual dysfunction, the type of clinical refraction corresponds to a high degree of myopia.
- Measurement of intraocular pressure. There are uveitis with hypo- or hypertension. Tonometry is performed in a non-contact way. The value of intraocular pressure directly depends on the patency of the trabecular network. In case of violation of the circulation of watery moisture, intraocular pressure increases significantly.
- Ultrasound of the eyes. Ultrasound examination is used when the optical media of the eyeball are clouded and it is impossible to perform ophthalmoscopy. In the AV scan mode, edema of the uveal tract structures, cellular suspensions in the vitreous cavity are detected.
- Inspection of the front camera. Gonioscopy is performed with an increase in intraocular pressure. Anterior synechiae, signs of neovascularization of the iris and the angle of the anterior chamber are visually determined. With a prolonged course, foci of organized exudate are visible.
Therapeutic tactics depend on the characteristics of the course of the disease. Etiotropic therapy is based on the appointment of antibiotics from the group of tetracyclines and aminoglycosides. To achieve the desired effect, in addition to these drugs, drugs capable of penetrating into cells are used – sulfonamides (netilmycin). The most effective treatment regimen is considered to be a combination of doxycycline and netilmycin. The duration of the course is 21 days. Further, for 1 week, only the tetracycline antibiotic is indicated.
If there is no effect from the prescribed therapy, the administration of drugs from the reserve group is recommended. These include the following representatives of the class of fluoroquinolones: ciprofloxacin hydrochloride, norfloxacin, ofloxacin. These medications are used alone or in combination with doxycycline. Additionally, local nonsteroidal anti-inflammatory drugs are included in the treatment package. In severe cases, instillations of glucocorticosteroids are indicated. Systemic administration of hormonal drugs is justified only with a pronounced allergic reaction (urticaria, Quincke’s edema). With the development of symptoms of ophthalmohypertension, instillation of hypotensive drops is added to the treatment program.
Prognosis and prevention
The prognosis for brucellar uveitis is doubtful. Chronization of the process is accompanied by the formation of dense connective tissue granules on the structures of the uveal tract, which cause a persistent decrease in visual acuity. After healing, unstable immunity is formed, reinfection is possible after 3-5 years. For the purpose of specific prevention of the population at risk, a special vaccine has been developed, but it is effective only for 10-12 months, therefore, repeated vaccination is shown every year. Non-specific preventive measures are reduced to washing hands with soap or treating with antiseptics before touching the ocular area. It is recommended to drink pasteurized or boiled milk, consume heat-treated meat.