The purpose of physicians prescribing sputum specimens for culture is to understand the lower respiratory tract bacterial infections, so collecting lower respiratory tract specimens and preventing contamination is key, and if improperly collected and cultured for non-infected bacteria, the value of the culture is not only lost, but treatment is delayed. I. Sources of sputum specimens Lower respiratory tract sputum, tracheal aspirates (TA), bronchopulmonary lavage aspirates, bronchial brushes, endotracheal tubes, lung punctures or biopsies, etc. II. Use of containers Clean, wide-mouth, sterile, capped, sealed, leak-proof, single-use, available from the Laboratory Department. The sputum volume in the early morning is large and the bacteria content is also large, you can use the mouth cleansing solution first, then gargle with cool boiled water or saline to remove the bacteria in the mouth, cough out 1-2 mouthfuls of sputum in the wide mouth sterile bottle after deep inspiration, and the sputum volume is very small, you can use 45℃ 10% sodium chloride solution for nebulized inhalation to induce sputum. If artificial airway has been established, such as tracheotomy or tracheal intubation, sterile gloves should be worn or sterile forceps should be used to take disposable sterile special suction tube, and one end should be inserted slowly into the trachea to the level of the rongeur (lobe bronchus), and one end should be connected to electric suction device and spiral suction to attract sputum. IV. Precautions 1. The second mouthful of sputum in the early morning is preferred. Prevent contamination by saliva and upper respiratory secretions. 2.High value is collected before antimicrobial use. It is better to indicate relevant signs, infection indicators, and premedication. 3.Collected 3 to 4 times consecutively, with collection interval > 24h.