Disease description: Candidiasis is a primary or secondary infection caused by Candida spp, mainly Candida albicans, which can involve the skin, mucous membranes, etc. and even appear as a systemic infection. Candida is the normal flora of human gastrointestinal tract, genitourinary tract and skin, when the systemic or local immunity is reduced, such as after the application of a large number of antibiotics, glucocorticoids, immunosuppressants, etc. can cause disease through endogenous or exogenous pathways. Medical contamination can also lead to the occurrence of the disease. Clinical manifestations can be divided into mucosal lesions, skin lesions, systemic infections, and allergic disorders caused by Candida. Treatment should remove all the causative factors related to the occurrence of the disease, actively treat the underlying concurrent diseases, as well as the systematic or local application of antifungal treatment. Causes: Candida albicans is the main pathogenic bacteria of this disease, which is ovoid under normal circumstances and is in a symbiotic state with the organism and does not cause disease. When certain factors disrupt this balance, such as endogenous infection caused by damage to the normal defense function of the body, trauma, antibiotic application and cytotoxic drug use to dysbiosis or mucosal barrier function changes, corticosteroid application, nutritional disorders, immune function defects, etc., Candida albicans will be converted from yeast phase to mycelial phase, in the local mass growth and reproduction, causing skin, mucous membrane and even systemic infection. The cells of this bacteria are round or ovoid, very much like yeast, 3-6μm in diameter, 5-6 times larger than staphylococcus, gram-positive, but uneven coloring. Germinating mode of reproduction. In the focal material common fungal cells germinate to generate pseudomycorrhizae, pseudomycorrhizae vary in length, and not branched, pseudomycorrhizae contraction break and become budding fungal fine. In the Sabo weak glucose agar medium can grow cheese like, light gray moist colonies, soon formed dendrites into the agar. Microscopic examination of colonies can be seen on the surface layer of ovoid budding cells, the bottom layer has more pseudomycorrhizal. If inoculated on corn agar medium, it can produce characteristic round thick film spores of Candida albicans. In addition, there are a few other pathogenic bacteria in the genus Candida, such as Candida graminearum, Candida asteroids, Candida tropicalis, etc. Pathogenesis: The pathogenesis of candidiasis is complex and is influenced by three factors. ① Organismal aspects: firstly, cellular immune deficiency, which is manifested in unresponsiveness to Candida antigen skin test, low lymphocyte conversion rate and reduced synthesis or lack of macrophage mobile inhibitory factor after stimulation by Candida antigen in vitro. This was followed by a decrease in the number of phagocytes, loss of chemotaxis, and a decrease in phagocytosis and bactericidal capacity. In addition, myeloperoxidase deficiency, reduced transferrin and elevated serum iron, zinc ion deficiency, hyperglycemia, vitamin A deficiency and skin damage can all induce candidiasis. ②Candida spore wall: Candida albicans spore wall is mainly composed of glycogen, mannan, etc. The latter can strengthen the adhesion ability of Candida albicans and cause infection. The experiment proves that Candida albicans with budding tube is stronger than simple budding adhesion. Secondly, Candida albicans is often in the tissue as mycelium, compared with spores, it is not easy to be engulfed, so its pathogenicity is increased, other Candida form mycelium ability is weak, so the pathogenicity is also weak. In addition, Candida may also produce high molecular weight and low molecular weight toxins and some hydrolytic enzymes, which damage the body tissue and induce infection. ③Medicinal aspects: such as broad-spectrum antibiotics, adrenal corticosteroids (hormones), immunosuppressants, radiotherapy and chemotherapy applications; catheters, infusions (especially parenteral hypernutrition therapy), surgery (especially gastrointestinal and prosthetic valve surgery), burns, etc. can reduce the body’s defense function or create conditions for germs to invade and increase the chance of infection. Pathophysiology: superficial skin lesions, the primary damage can appear similar to impetigo or subcutaneous pustulosis, sometimes sponge-like changes, only a small amount of fungi exist in the stratum corneum, as Candida albicans mycelium and ovoid spores. Candidal granuloma shows obvious papilloma-like hyperplasia and hyperkeratosis, and inflammatory infiltration of dense lymphocytes, neutrophils, plasma cells and multinucleated giant cells can be seen in the dermis, which can penetrate into the dermis to the subcutaneous tissue. Mycelia and spores are seen around the inflammatory cells. Visceral damage pathologically can be manifested as extensive masses composed of spores and mycelia, and inflammatory manifestations can be mild. Clinical manifestations: 1.Multiple groups: Candida is a conditional pathogen, when the normal defense function of the body is impaired leading to endogenous infection, trauma, antibiotic application and cytotoxic drug use causing dysbiosis or mucosal barrier function change, corticosteroid application, nutritional disorders, immune function defects, etc., may cause local or systemic infection. 2, disease symptoms: according to the different sites of infection, the clinical classification of the disease into three categories: mucosal lesions, skin lesions, systemic infections, and Candida-induced allergic disorders. (1) Mucosal lesions: ① Oral candidiasis: thrush is the most common. The surface of the oral mucosa can be seen as gray-white membranous spots with a moist, slightly red base, which can be macerated. Neonatal oral pH is low, which is conducive to the growth of Candida and causes the disease, or infection occurs during delivery through the birth canal. Adults present similarly to children without a clear history of long-term glucocorticoid, antibiotic, or immunosuppressive use, and attention is given to finding evidence of HIV infection, such as enlarged lymph nodes, leukopenia, or positive serum antibodies. Localized scattered erosions may occur in the presence of Candida labyrinthitis. ②Vaginitis or glansitis: Candida albicans is a normal flora of the vagina, and overgrowth can cause severe itching and increased leucorrhea. According to statistics, 70% of adult women have Candida vaginitis at least once in their lifetime. Diabetes, application of antibiotics and pregnancy are predisposing factors for this disease. Erythema and maceration of the labia may be seen, tofu-like discharge is visible in the vagina, and the cervix is congested, swollen and eroded. Candida glans or penile circumcision is usually transmitted by a spouse with Candida vaginitis. Light red vesicles and thin-walled pustules are seen on the glans and coronal sulcus, and microscopic examination and culture results are often negative. Bronchial and pulmonary candidiasis: Patients may have cough, sputum, and rales may appear at the base of the lungs. X-rays may show widening of the hilar and bronchial shadow, or imaging manifestations such as corn-like tuberculosis. Primary pulmonary candidiasis is less common, often caused by other foci of dissemination or sepsis, and sputum smear is easy to find Candida. ④Gastrointestinal candidiasis: Esophageal candidiasis often develops from oral candidiasis. Candida enteritis sometimes has an “allergic colitis”-like appearance. Infantile thrush often leads to perianal lesions with pruritus and mild intestinal symptoms. (2) Skin lesions: ①Candida rubra: most commonly found in the axilla, groin, under the breast, umbilicus, etc., with vesicular oozing on the basis of erythema, with fan-shaped edges and peripheral blisters and pustules. ② nail fungus and nail fungus chronic nail fungus: nail fungus redness and pain or finger (toe) nail thickening, hardening, brownish, with streaks. ③ diaper dermatitis: often caused by not changing diapers, or secondary to perianal and oral candidiasis in infants. It occurs on the skin and may appear as scaly erythema with pinpoint to corn-like blisters. (4) Lichen planus-like cutaneous candidiasis: It is common in infants and children and occurs in non-friction areas such as the neck and back of the shoulders, with mild itching and sometimes scaly papule-like damage, similar to lichen planus. The fungal examination is often positive. Candida granulomatosa: The lesions are vascular papules with a thick brownish-yellow crust that adheres to the skin. The face is the preferred site and is often associated with immunodeficiency and lymphopenia. (3) Systemic infections: various diseases caused by invasion of Candida into internal organs or blood, such as urinary tract infection, endocarditis, meningitis and sepsis, etc. These should be differentiated from internal diseases and bacterial infectious diseases. (4) Candida-induced metabolic disease: the metabolic reaction caused by Candida is called Candida rash, often sterile clusters of blistering damage, located between the fingers or other parts of the body, the metabolic product-induced metabolic reaction can also be manifested as eczema, asthma, gastritis, etc., and even allergic colonic syndrome and telecentric erythema multiforme. Diagnosis and differentiation: 1. Diagnosis: (1) Mycological diagnosis: All patients must have positive fungal culture results to confirm the diagnosis. Direct microscopic examination of specimens found a large number of mycelia and clusters of spores have diagnostic significance. If only budding spores are seen, especially in sputum or vaginal secretions may belong to normal carriage. It has no clinical significance. The presence of mycelium indicates that Candida is in pathogenic state. (2) Pathological diagnosis: The primary damage of skin lesions may appear similar to impetigo or subcutaneous pustulosis, sometimes sponge-like changes, and only a small amount of fungi exist in the cuticle as Candida albicans mycelia and ovoid spores. Candidal granuloma shows obvious papilloma-like hyperplasia and hyperkeratosis, and inflammatory infiltration of dense lymphocytes, neutrophils, plasma cells and multinucleated giant cells can be seen in the dermis, which can penetrate into the dermis to the subcutaneous tissue. Mycelia and spores are seen around the inflammatory cells. The visceral damage may appear pathologically as an extensive mass of spores and hyphae, and the inflammatory manifestations may be mild. Histological examination can identify Candida, but the strain cannot be determined. (3) Serological diagnosis: Candida spore wall is mainly composed of glycogen, mannan, etc., and the latter is hydrolyzed to form mannose, which is continuously shed to form metabolites. The use of ELISA or AB-ELISA method to determine serum Candida polysaccharide antigen is more timely and accurate for the diagnosis of partial systemic and disseminated candidiasis. (4) Clinical diagnosis: When clinical manifestations cannot be explained by other diseases, and there are also predisposing factors and positive fungal examination (referring to routine fungal examination), the possibility of candidiasis should be considered and further examination should be performed. In addition, the appearance of thrush in adults marks the early manifestation of deep-seated candidiasis and should not be ignored, and attention should be paid to the screening of HIV infection and other potential diseases. 2. Differential diagnosis: Neonatal thrush needs to be differentiated from leukoplakia, lichen planus, and stage III syphilis. Candida vaginitis needs to be differentiated from trichomonas vaginitis. Systemic infections should be differentiated from other infectious diseases and tumors, etc. Treatment: Try to remove all the causative factors related to the occurrence of the disease, such as broad-spectrum antibiotics, glucocorticoids, immunosuppressants, etc., and actively treat the underlying disease, as well as active anti-Candida treatment. 1, local treatment: (1) oral candidiasis: oral mycobacterium tablets, 0.25-0.5g each time, 2-3 times a day; (2) skin candidiasis: topical application of 1% bifenbendazole cream, etc., with red prickly rash of papular candidiasis can also be applied externally containing mycobacterium sulfur glycolate lotion, 4-6 times a day. Between rubbing rash can be added with puff powder. (3) Candida vaginitis: Mycobacterium suppositories (50,000-100,000 U each), once a night, for 1 or 2 weeks. 2, systemic treatment: mainly for systemic candidiasis = infection, or part of the serious, stubborn skin mucosal candidiasis. (1) mycobacterium: 2 million to 4 million U daily, divided into 4 oral doses, children 50,000 to 100,000 U/kg?d. The drug is rarely absorbed in the intestine, mainly for gastrointestinal candidiasis. (2) Ketoconazole: 0.2g, once daily. The duration of treatment depends on the type of infection and the patient’s response. Use with caution in patients with abnormal liver function. (3) Itraconazole: 200mg once daily for more than 4 weeks. (4) Amphotericin B: 0.5-1mg/kg?d, intravenous drip, combined with oral 5-fluorouracil (150-200mg/kg?d), may have a certain synergistic effect to improve the efficacy. In addition, fluconazole and miconazole can be used, and transfer factor and IFN can be used simultaneously in patients with immunodeficiency. Recently, it has been found that patients with iron deficiency are often treated with serum lactoferrin to enhance the efficacy.