Bronchopulmonary candidiasis (bronchopulmonary candidiasis) is an infectious disease of the lower respiratory tract caused by Candida. The incidence of candidiasis has increased significantly in the last 20 years due to the increase in the number of immunosuppressed people and the excessive clinical use of immunosuppressive agents and broad-spectrum antimicrobials. According to the Centers for Disease Control and Prevention (CDCP) and the Hospital Infection Surveillance Network, in the early 1980s, Candida ranked 7th among the common pathogens of hospital-acquired infections, and from 1980 to 1989; hospital-acquired candidemia increased by 219% to 500%; between 1990 and 1992, Candida has risen to the 6th among the pathogens of hospital-acquired infections and the 4th among the pathogens of bacteremia. Fourth. The prognosis is poor because the disease often occurs in people with severe underlying disease. Candida belongs to Cryptococcus family in the fungal world, the body can be round, oval, cylindrical, elongated and irregular, through budding reproduction, most of them form pseudomycelium, and very few of them can also form thick-walled spores and true mycelium. There are more than 150 kinds of Candida, including Candida albicans (C. Albicans), Candida tropicalis (C. Tropicalis), Candida parapsilosis (C. Parapsilosis), Candida krusei (C. Krusei), Candida glabrata (C. Glabrata), Candida stellatoidea (C. Stellatoidea), Candida gigantea (C. G. Stellatoidea), and Candida spp. Stellatoidea), Candida Guilliermondi (C. Guilliermondi), Candida Lusitanine (C. Lusitanine), and Candida Rugosa (C. Rugosa). Candida albicans was the most common, accounting for 50-70% of cases, followed by Candida tropicalis, accounting for 12-25%, and Candida smoothus, accounting for 8-11%. Candida klebsiella and Candida smoothis infections occur more frequently in patients treated prophylactically with fluconazole. Candida albicans is widely present in nature and is also a frequent resident of the oropharynx and digestive tract. Candida albicans has a high pathogenicity due to its strong adhesion to tissues. The body’s defense against Candida depends on the normal skin mucosal barrier and the cellular immune function involving neutrophils and lymphocytes. Candida is a conditional pathogen, and it is susceptible to deep candidiasis only when the skin mucosa is damaged and the number of phagocytes, chemotaxis and bactericidal power are reduced. Common predisposing factors include broad-spectrum antimicrobials, application of antitumor chemotherapy and immunosuppressive agents, trauma and major surgery (gastrointestinal surgery and prosthetic valve replacement), neutropenia, interventional therapy, AIDS and organ transplantation. The route of infection of Candida can be divided into endogenous and exogenous, the former being the infection caused by Candida parasiticus entering the organism of the immunocompromised, and the latter being the infection caused by the germ-bearing hands of medical personnel or contaminated medical devices. Candida proliferates in the infected lung tissue, releasing toxins and hydrolytic enzymes, causing acute inflammation with predominantly neutrophils. Pathological manifestations include tissue congestion, necrosis and abscess formation, and microscopically visible pseudomycorrhizal filaments that invade blood vessels. Acute inflammation caused by Candida does not usually form granulomas. The inflammatory response can be mild in leukocyte deficient individuals, but severe tissue coagulation necrosis can occur. [Bronchopulmonary candidiasis can be caused by invasion of Candida in the oropharynx or can be part of hematogenous disseminated candidiasis, forming a diffuse pneumonia. Clinical manifestations can be: (a), bronchiectasis: symptoms include fever, cough, coughing white mucus sputum or small lumpy sputum, the latter is composed of Candida mycelia and cellular debris, sputum can be with blood. On physical examination, the breath sounds of both lungs become coarse, and variable dry and wet rales can be heard. x-ray chest film shows thick texture of both lungs. (b) Bronchopneumonia: symptoms are more severe, with chills and fever, body temperature can be as high as 39-40℃. Cough, coughing more intense, sputum is sticky jelly-like, there may be blood in the sputum, coughing blood and chest pain. Physical examination may reveal solid lung disease and wet rales, and about half of the patients have pleural effusion. X-rays may show diffuse speckled or small lamellar shadows in both lungs, mainly in the lower lungs, which may fuse to form large lamellar shadows, or solid shadows in lobes and segments of the lungs. In a few patients, there may be lung abscess formation. It may be accompanied by enlargement of hilar and mediastinal lymph nodes and pleural effusion. (C), blood-borne pulmonary candidiasis: the disease is critical, in addition to the clinical manifestations of pulmonary candidiasis, but also often involves the gastrointestinal tract, liver and kidneys and other organs. x-ray chest film shows multiple several millimeter-sized corn-like shadow in both lungs with unclear borders, similar to cornular tuberculosis. The cornular lesions may fuse to form nodular shadows of varying sizes and may form small abscesses. The prognosis is extremely poor. The diagnosis of bronchopulmonary candidiasis depends on microbiological and pathological examinations. Microbiological examination can be done by direct smear, section and culture of sputum, pleural fluid or lung tissue specimens. Direct smear microscopy is simple and quick, and the discovery of budding spores and a large number of pseudomycelia in the specimen has diagnostic value. Candida culture is commonly used in Sandburg medium, and the colonies are smooth or zoule-like, white or brown. The sputum specimen should be gargled with 1:100 mycotoxin before retention to reduce the contamination of Candida in the oropharynx, and should be repeatedly sent for examination several times before the positive result has some diagnostic value. Candidaemia lasts for a short time, and the positive rate of blood culture is low. The pathological changes of pulmonary candidiasis lack specificity, but finding evidence of Candida invading tissue in bronchopulmonary biopsy specimens is of definite diagnostic significance. Immunological tests such as determination of serum Candida antibodies (mainly anti-cell wall mannan antibodies), serum mannan antigen, 47kD antigen and thermally unstable antigen may be useful for diagnosis, but sensitivity and specificity are low and not widely used clinically. The diagnostic significance of measuring Candida metabolites such as arabinose and mannose is still in disagreement and needs further validation. [The treatment of bronchopulmonary candidiasis should first remove the predisposing factors and select antifungal drugs according to the severity of the disease. For severe infections such as hematogenous disseminated candidiasis and severe immunodeficiency, amphotericin B or amphotericin B with 5-fluorocytosine (100-150 mg/kg/d) should be used in combination. See Section I of this chapter for dosing. To reduce the side effects of chills and hyperthermia with amphotericin B, a small amount of glucocorticoid may be used on days 1 to 3 of dosing. For those who cannot tolerate amphotericin B, fluconazole or fluconazole in combination with 5-fluorocytosine may be used. Candida albicans, Candida tropicalis, and Candida subsmoothis are sensitive to fluconazole, whereas Candida smoothis and Candida klebsiella are less sensitive (Table 1). Other antifungal Table 1, Susceptibility of different Candida to fluconazole Candida MIC90 (mg/ml) Candida albicans 0.25 Candida tropicalis 1.0 Candida subsmoothis 1.0 Candida smoothis 16 Candida graminearum 32 Drugs such as ketoconazole and allicin can also be used for the treatment of mild cases. Since Candida is an important pathogen of hospital-acquired infections, avoiding the abuse of broad-spectrum antimicrobials and immunosuppressive agents, reducing interventional treatments such as tracheal intubation, hand washing by medical personnel before and after patient contact, and prophylactic use of antifungal drugs in high-risk patients are all important in preventing pulmonary candidiasis.