Laboratory tests for fungal infections

Laboratory tests for fungal infections include direct microscopy and culture methods, pathology methods, serological methods, and molecular biology methods. During the examination, please consult the history of trauma and surgery, the time of injury, the location, the treatment after the injury, the onset time, the development of the disease, and the history of vaccination against tetanus; for female patients, the history of childbirth or abortion should be consulted; For newborns, the history of childbirth and umbilical cord management should be asked. There were a few cases with no history of injury and no obvious wounds. Basic Information Specialist classification: Infectious disease inspection and classification: pathogenic microorganism inspection Applicable gender: whether men and women apply fasting: not fasting Analysis results: Below normal: Normal value: no Above normal: negative: A negative test result indicates that the body should be free of bacterial infection. Positive: A positive test indicates a possible bacterial infection. Tips: Pay attention to personal hygiene and avoid eating foods that are very irritating to the skin. Normal value Negative, that is, no pathogenic bacteria grow. Clinical significance Abnormal results When fungi invade the human body, doctors will divide them according to their invasion of the human body. Therefore, fungi can be divided into two major categories: shallow fungus and deep fungus. Shallow fungi mainly cause superficial infections such as skin and mucous membranes; deep fungi can invade systemic organs and tissues, such as severe sepsis, endocarditis, meningitis and other fatal diseases. The fungi causing these diseases include Candida albicans, Cryptococcus neoformans, and Candida tropicalis. The person in need of examination has a patient suspected of having fungal infection symptoms. Positive results may be diseases: urinary tract fungal infection, head seborrheic dermatitis, pigmented purpuric mossy skin disease, fungal urinary tract infection, burn infection, malignant small sweat gland spiral adenoma considerations Contraindications before inspection: Pay attention to personal hygiene and avoid eating foods that are very irritating to the skin. Requirements for inspection: 1. Inquire about the history of trauma and surgery, the time of injury, the location, the treatment after injury, the onset time, the development of the disease, and the history of vaccination against tetanus; for female patients, the history of childbirth or abortion should be consulted; For newborns, the history of childbirth and umbilical cord management should be asked. There were a few cases with no history of injury and no obvious wounds. 2, check the injured part, the wound situation, the muscles around the wound are sputum and twitching, paying special attention to whether the rectus abdominis is strong. If there is exudate or exfoliated tissue block in the wound, bacteriological examination (including smear and anaerobic culture) and pathological examination should be performed. 3, to observe whether the patient has closed teeth, paroxysmal convulsions, sneer, angulation, generalized tonic and paroxysmal spasm, pay special attention to whether the airway is smooth, with or without throat. After the patient is quiet, check for pulmonary complications and necessary auxiliary examinations. Inspection process First, direct microscopy and culture Direct microscopy and culture examination are the basic methods of morphological examination. Direct microscopy is the most classic method of mycological examination, and it is fast and simple. However, the positive rate is low, the rate of missed diagnosis by direct smear method is as high as 45%, and the cumulative positive rate of direct microscopic examination is up to 99%. Therefore, the negative result can not rule out the diagnosis, and can be diagnosed by combining with culture examination. . The culture inspection method can further improve the positive rate of pathogen detection, verify the results of direct microscopic examination, and determine the type of pathogenic bacteria. The parasitic morphology of some fungal infections is characteristic and important for diagnosis. For example, Candida infection can simultaneously detect yeast cells and pseudohyphae in the tissues: Cryptococcus infection can be seen with yeast cells with capsule: Aspergillus infection It can be seen that the five-color, 45° branch-separated hyphae: Mucor infection can be seen in large undivided hyphae with a right-angled branch; yeast cells in tissue cells often suggest histoplasma or Penicillium marneffei infection: brown hyphae and / Or spores often suggest dark fungal infections. Fungal cells can be more clearly displayed by special staining such as iodic acid-Schaffer staining PAS and silver staining. Second, histopathological examination Histopathological examination is important for determining the pathogen's ability to parasitize within the tissue and to understand the host's response, and once the fungal hyphae and/or spores are found in the tissue section, this is a strong evidence of diagnosis. The results, combined with direct microscopy and culture, have a greater impact on diagnosis. In addition to the commonly used fungal pathogen staining methods, immunohistochemical specific antibody staining can make a specific diagnosis of common pathogenic bacteria in clinical practice. Ma Lei et al. used microwave Envision immunohistochemical two-step method to determine the specimens of 34 patients with deep mycosis with formalin fixation, paraffin-embedded sections for PAS staining, and microwave Envision immunohistochemical labeling. The results showed that 16 cases of immunohistochemical staining were positive for 14 cases of suspected Aspergillus infection; 11 cases were all positive for suspected cryptococcal infection; 7 cases were positive for 7 cases of Candida infection. The cells are stained clearly without background. Therefore, the microwave Envision immunohistochemical two-step method has the characteristics of high sensitivity, low background, fast and simple detection for deep fungal infection detection, and has good application value in the clinicopathological diagnosis of fungal diseases. Some scholars have pointed out that the immunohistochemical method can specifically diagnose Candida albicans, Cryptococcus neoformans and Aspergillus infections compared with the PAS method. Not suitable for the crowd The test is a non-invasive test with no specific contraindications. Adverse reactions and risks The test is a non-invasive test that does not cause serious complications or other hazards.