Francisella tularensis pneumonia

　　Francisella belongs to the genus Francisella of the family Francisellaceae. It is a fragile, minute Gram-negative coccobacillus without motility. It has no capsule in culture, but it can appear in the secretions of living organisms. It is difficult to grow on ordinary culture media, and it grows best on culture media rich in serum, sugar, and cysteine. The suitable growth temperature is 36-37°C, pH 6.8-7.2. It is not heat-resistant, but has strong resistance to low temperature. It is generally believed to have endotoxins.

　　Francisella pneumonia often complicates with bacteremia, which involves the pleura and causes pleural effusion. Bacteremia refers to the entry of bacteria from the outside through the entry of the body surface or the entry of infection into the blood system, where they multiply in the human blood and spread throughout the body with the blood flow. The consequences are very serious. Generally, catheters or surgical openings on the body surface are prone to cause bacteremia. Patients with bacteremia often develop acute metastatic infections in multiple organs and various acute infection symptoms. Once suspected, blood tests should be taken immediately, and once diagnosed, immediate treatment for the infecting bacteria should be carried out without delay. Bacteremia is mostly caused by bacteria entering the blood from local lesions, with no systemic toxic symptoms, but bacteria can be found in the blood. It mainly occurs in the early stage of inflammation, and macrophages in the liver, spleen, and bone marrow can form a defense line to clear bacteria.

　　Francisella pneumonia often occurs in the first 2-3 weeks of the course, with symptoms such as cough, expectoration of white sputum or blood-stained sputum, chest pain, and shortness of breath. Patients often have fever and the formation of localized ulcerative granulomas. Primary pneumonia caused by inhalation, in addition to cough and shortness of breath, occasionally involves the pleura, causing pleural effusion.

　　The diagnosis is based on the patient's history of contact with animals in the epidemic area or history of insect bites by arthropods in the epidemic area, with symptoms such as fever, skin lesions, and tender, swollen lymph nodes. It should be highly suspected of tularemia. If cough, shortness of breath, chest pain, and other symptoms occur, and X-ray confirms lung involvement, the etiological diagnosis can be performed by direct fluorescent antibody staining and serum agglutination test.

　　To prevent Francisella pneumonia patients from paying attention to the following points in daily life:

　　1. When in contact with animals in the epidemic area, attention should be paid to self-protection, such as wearing gloves; wear protective clothing or spray insecticides to prevent contact and transmission.

　　2. Strengthen the monitoring of the source of the epidemic, strengthen international quarantine and traffic quarantine, and strictly quarantine vehicles, ships, and airplanes coming from the epidemic area.

　　3. Sputum and excrement of patients should be thoroughly disinfected or incinerated. Pay attention to the environmental hygiene of the living space, actively eliminate mosquitoes and flies, pay attention to dietary hygiene, do not drink unboiled water, and do not eat uncooked meat and eggs and other food; wash hands frequently and develop good personal hygiene habits.

　　It is difficult to find the pathogenic bacteria in the sputum and pleural effusion of Francisella tularensis pneumonia patients by Gram staining and culture, but direct fluorescent antibody staining is positive, and the double-serum agglutination test is very helpful for etiological diagnosis, that is, the double serum of acute and convalescent periods, the antibody titer has a 4-fold or more increase, if the antibody titer of a single serum in the convalescent period exceeds 1:160, it should be highly suspected that there is an active focus in the body, antigen skin test is also helpful for diagnosis, but the preparation of the antigen is not easy.

　　During the initial 2-4 hours of fever, X-ray findings may not be abnormal, and then pulmonary infiltration foci and hilar lymph node enlargement may occur, which may involve the pleura, causing pleural effusion. The X-ray changes of this disease are not proportional to the signs, that is, disseminated bronchopneumonia, unilateral or bilateral pleural effusion, but the signs are relatively mild. The central oval dense shadow, which was once used as a characteristic sign, is now rarely found.

　　For Francisella tularensis pneumonia patients during the fever period, it is best to have light semi-liquid diet with small and frequent meals. In daily life,Eat more fruits with the effect of clearing heat, stopping cough, and resolving phlegm, such as pears and oranges, and ensure adequate water intake to prevent the aggravation of poisoning symptoms. Give the patient. High-protein, high-calorie, high-vitamin, easily digestible diet to increase nutrition, improve the overall weakness, enhance resistance and repair ability. Eat more millet, wheat, beans, corn, and various fresh vegetables and dried and fresh fruits such as lily, tremella, longan, walnut, chestnut, jujube, white sesame, watermelon, orange, apple, pear, cucumber, cabbage, lotus root, etc.; various high-protein foods such as chicken, lean pork, lean beef, eggs, and various marine fish, etc..

　　Penicillin is ineffective against Francisella tularensis pneumonia, and aminoglycosides, tetracyclines, and chloramphenicol are sensitive. Streptomycin is the first-line drug, administered intramuscularly, 2.0g/d, and changed to 1.0g/d after 3 days, for a total of 7-10 days. Gentamicin is another effective drug, with a dose of 1mg/kg, administered intramuscularly, once every 8 hours. Tetracycline or chloramphenicol are also effective for this disease, suitable for patients who cannot tolerate aminoglycosides.