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Lecture notes, cheat sheets
Детские инфекционные заболевания. Бруцеллез (конспект лекций)
Directory / Lecture notes, cheat sheets Table of contents (expand) Lecture number 9. Brucellosis Brucellosis is an acute or chronic disease of livestock transmitted to humans mainly by four types of brucella - from cows, goats, pigs and dogs. Etiology. There are six known species of Brucella that can cause disease in humans: B. abortus (source: cow), B. melitensis (source: goat), B. suis (source: pig), B. canis (source: dog), V. ovis (sources: sheep and hare) and B. neotome (source: wood rat). The causative agents of brucellosis are small gram-negative, immobile, aerobic rods that do not form spores and capsules, characterized by slow growth on nutrient media. Epidemiology. Human disease with brucellosis is caused by direct contact with sick animals. People caring for livestock most often fall ill. Sources of infection can be raw milk of sick animals, butter, cream, cottage cheese, ice cream. The pathogen can enter the eye, nasopharynx, and genitals, but intact healthy skin is impermeable to it. Brucella remains viable when infected products are stored in a refrigerator for 3 weeks and during the production (smoking) of ham. They die during pasteurization and boiling. Brucellosis epidemics usually occur when eating unpasteurized milk, sour cream, butter, cheese, ice cream containing B. abortus. Children rarely get brucellosis. When conducting mass serological studies, antibodies to B. canis were found in 67,8% of healthy individuals, antibodies to B. canis in 5,7% of newborns came through the placenta. A significant stratum of the population with antibodies to B. canis indicates the prevalence of this infection in humans. Despite the fact that brucellosis pathogens are excreted in the urine of patients, human-to-human transmission has not been reported. Cases of congenital disease are also unknown. Pathogenesis and pathomorphology. Brucella is an intracellular parasite. After penetration into the human body, they are phagocytosed by leukocytes and macrophages, spreading into the reticuloendothelial tissue. Pathogens can multiply in different cells, including red blood cells. Infection with brucellosis is accompanied by the development of delayed-type hypersensitivity to the brucellosis antigen. The patient's body reacts to a brucellosis infection by producing antibodies, among which are agglutinins, bacteriolysins, opsonins, precipitins and complement-fixing antibodies. Reproduction of the pathogen in the body is mandatory for the development of immunity. Specific IgM appear first, and then IgC antibodies, the titer of which gradually becomes dominant. Serum or plasma of healthy individuals and patients in the acute phase of the disease, when complement is added, has a pronounced non-specific bactericidal activity against Brucella. In chronic forms of infection, specific antibodies appear that prevent the action of the "serum-complement" system, act as opsonins and increase the phagocytic activity of polymorphonuclear and mononuclear cells, due to which Brucella quickly disappear from the blood of patients with a high antibody titer, but remain in the cells, in which the action of antibodies is not manifested. The most virulent smooth strains of Brucella continue to multiply in the cells of even individuals immune to brucellosis. Smooth and intermediate strains of Brucella contain endotoxin, which plays a role in the course of the disease and the results of treatment. All types of Brucella cause granulomatous changes detected by histological examination of the liver, spleen, lymph nodes and bone marrow. There are signs of central lobular necrosis and cirrhosis of the liver. Granulomatous inflammation develops in the gallbladder, there are signs of interstitial orchitis with scattered areas of fibrous atrophy. Endocarditis with thickening of the aortic valve and atrioventricular orifice is also commonly found, and granulomatous changes in the myocardium, kidneys, brain, and skin have been described. Clinical manifestations. The incubation period varies from several days to several months. The disease most often begins unnoticed, but acute sudden development of clinical signs of infection is possible; in endemic areas, the disease in children usually proceeds unnoticed. Prodromal symptoms are weakness, fatigue, anorexia, headaches, myalgia and constipation. As the disease progresses, there is an increase in body temperature in the evening, which soon reaches 41-42,5 °C. Chills, profuse sweating, nosebleeds, abdominal pain and cough appear. Often, body weight decreases significantly. Physical examination reveals an enlarged liver and spleen, hyperplasia of the cervical and axillary lymph nodes. Wheezing may be heard in the lungs, in which case changes in them are visible on chest radiographs. Chronic forms of brucellosis are difficult to diagnose and are often interpreted as a fever of unknown origin. Patients complain of fatigue, muscle and joint pain, sweating, nervousness and lack of appetite. Cases of depression and psychosis have been described. A maculopapular (more rarely, morbilliform) rash may appear. Brucellosis is often accompanied by the development of uveitis, endocarditis, hepatitis, cholecystitis, epididymitis, prostatitis, osteomyelitis, encephalitis and myelitis. The number of leukocytes in the peripheral blood may increase, decrease, or remain within the normal range. Relative lymphocytosis and anemia are often observed. Diagnosis. Diagnosis of the disease is carried out on the basis of anamnestic data, epidemiological history, an objective examination of the patient, as well as a number of laboratory tests, including: 1) serological research methods (Wright and Huddleson reactions - the main methods for diagnosing brucellosis, CSC, RPHA, antiglobulin test to detect incomplete antibodies (Coombs), etc.); 2) intradermal allergic test Burne, characterized by high sensitivity. Differential diagnosis. In the acute period, brucellosis is differentiated from tularemia, typhoid, rickettsiosis, influenza, tuberculosis, histoplasmosis, coccidioidomycosis and infectious mononucleosis. Chronic forms of brucellosis are differentiated from lymphogranulomatosis and other neoplastic diseases. Accounting for anamnestic information, the results of serological and radiographic studies, the isolation of the culture of the pathogen help to correctly establish the diagnosis. In some cases, a diagnostic tissue biopsy may be required. Complications. The nature of complications of brucellosis is determined by the localization of infectious lesions. The most common complications include osteomyelitis, predominantly purulent spondylitis, accompanied by damage to the intervertebral disc and adjacent vertebrae. Purulent arthritis often develops, but joint destruction is rare. Neurological complications of brucellosis may appear sooner or later and are expressed in acute or subacute meningitis or encephalitis. Cases of adhesive arachnoiditis have been described. Myocarditis and endocarditis are among the most serious complications, often leading to death. In the initial period of treatment, signs of the Herxheimer reaction are often observed. Treatment. Patients with brucellosis are prescribed bed rest and an easily digestible high-calorie diet. Treatment with tetracycline is carried out for 3-4 weeks. Relapses of the disease occur in 50% of patients. In these cases, increase the dose of tetracycline and add streptomycin for a period of 2 weeks. During the 2nd week, the initial dose of drugs is halved. It is also recommended to prescribe rifampicin in combination with trimethoprim-sulfamethoxazole or moxalactam. Other third-generation cephalosporins have been reported to have an effect on Brucella in vitro, but clinical studies are not yet available. Limited abscesses must be opened and drained. Corticosteroids may be useful only in the initial period of treatment to prevent the Herxheimer's reaction. Forecast. Without appropriate treatment, death occurs in 3% of cases. Most untreated patients survive, but the recovery process is delayed by about six months. With antibiotic treatment, the prognosis is good. With late diagnosis, the treatment time is delayed. Prevention. Prevention of brucellosis involves eliminating human contact with sources of the disease. Infection in domestic animals with which humans are in constant contact can be prevented by vaccination. Along with the vaccination of animals and the pasteurization of milk, it is necessary to periodically carry out agglutination reactions with the blood and milk of animals, which makes it possible to identify infected animals. The latter are to be slaughtered. Eating unpasteurized milk and products from it should be excluded. Author: Muradova E.O. << Back: Infections caused by pathogens of the Pseudomonas group (Pseudomonas infection. Diseases caused by other strains of Pseudomonas) >> Forward: yersiniosis (Plague. Diseases caused by Y. enterocolitica and Y. pseudotuberculosis)
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