A Sputum Gram Satin is a laboratory test used to detect bacteria in a sputum sample. Sputum is the material that appears from a patient’s air passage when coughed deeply. The Gram stain test is one of the most commonly used methods to identify the cause of a bacterial infection including pneumonia. The bacterial infection can affect your lower respiratory tract. The infection is generally seen in children under the age of five, patients of above 65 years of age and /or people with the weak immune system. The Gram stain test is the most common and preliminary test before a chest X-ray is prescribed for pneumonia or any other chest infection. The test got the name as Gram Stain sputum after its inventor, Hans Christian Gram. The symptoms of this infection include shortness of breath, rapid breathing, chest pain, excessive coughing, fever, nausea, vomiting, and sputum with a colour and odour. Sputum is a mixture of saliva and mucus that you cough up from your respiratory tract.