The significance of sputum smear and sputum culture in acute exacerbations of chronic bronchitis COPD is often due to an increase in infection in the patient’s bronchial tubes. Doctors need to identify the cause of the infection as early as possible in order to control the condition of the patient as soon as possible. In COPD patients, the infection is in most cases caused by a single bacterium, or a combination of bacteria. If the type of bacteria that is infected is identified, it makes it easier for the doctor to target the most appropriate antibiotic. To accomplish this, a sputum smear and sputum culture test is given to the patient. A sputum smear, as the name implies, means that sputum is applied to a glass slide for examination. The doctor in the laboratory takes the sputum specimen taken from the patient’s respiratory tract and smears it, then stains it and looks at it under a microscope. If there are bacteria in the sputum they are easily detected and can even be roughly distinguished as to which type or species of bacteria. So sputum smear is a common test in respiratory medicine that is simple and inexpensive and can give preliminary results quickly. And sputum culture is to get exactly what kind of bacteria it is, it is to give it a developmental environment by artificial method to grow and easy to observe. And the drug sensitivity test of bacteria can be done based on the results from the culture to find out the antibiotics that are effective against such germs, avoiding the blind use of antibiotics and enabling patients to get effective treatment earlier. Sputum culture is more accurate and reliable than sputum smear, but it takes a relatively long time, usually about three days. Depending on the needs of the condition, these tests sometimes need to be repeated. If the results of several tests are consistent, they are more representative. Many patients think that they have already taken a chest X-ray and even a CT test, and have made a clear diagnosis of their condition, so they can skip other tests, and a few patients mistakenly believe that this is an abuse of tests by their doctors. In fact, this is not the case. Chest X-ray or CT is only an imaging test to understand the extent and scope of COPD and its complications, but it cannot identify the bacterial type of infection, so it cannot replace sputum smear and sputum culture for bacteriological examination. One very important issue in sputum smear and sputum culture is the collection of sputum specimens. The quality of sputum specimens and the timeliness of their delivery will directly affect their results. Sputum is easily contaminated by bacteria from the oropharynx. Therefore, attention must be paid to: first, try to collect specimens before the use of antibiotics; second, rinse the mouth first, then perform a deep cough, preferably with the second sputum coughed up, and it is best to retain purulent sputum for examination. Because sputum comes out through the upper respiratory tract and mouth, it is certainly susceptible to chemical and bacterial factors in the upper respiratory tract, so it does not necessarily represent the accurate condition of the lower respiratory tract. Otherwise, the culture of the so-called “normal flora”, and lose the value of clinical applications. Third, to send the test as soon as possible, not more than 2 hours. If the specimen to be sent for examination or to be processed exceeds the time, it should be placed at 4℃ for cryopreservation. Do not let the sputum put too long, or wait for the sputum to become dry before sending it for examination, which is meaningless. This is when the laboratory physician will tell the patient to resend the sputum specimen for examination. Sometimes it is necessary to use special methods to collect sputum specimens. For example, sputum is collected by transtracheal suction, but also by protective brushing with a fibrinoscope and alveolar lavage and lung biopsy. However, the latter methods are invasive and difficult for the average patient to accept. It should also be noted that some germs require special culture techniques to be cultured, such as sputum culture to obtain pathogenic bacteria, such as Pseudomonas aeruginosa, also need to do more than two consecutive tests and the same results to be meaningful. Drug sensitivity test results, although suggesting sensitivity to one or several antibiotics, but this is after all the laboratory results outside the patient’s body, not necessarily an accurate representation of the real situation in the patient’s body, but also specific analysis of each case. The doctor will make a comprehensive analysis based on the characteristics of the sputum, the severity of the disease, the efficacy of the antibiotics that have been used, combined with the results of the sputum culture and drug sensitivity test, and so on, to choose the really effective antibiotic treatment.