Answer:
It is known that the lungs and mouth are associated with a passage known as trachea. At the time of an infection, if there is a passage between the lungs and the mouth, the body makes a fluid known as sputum, also known as phlegm. By coughing the body is in real sense attempting to get rid of this phlegm.
The most general pathogens, which are found in Sputum culture are Haemophilus influenzae, Streptococcus pneumonia, Mycobacterium species, and Staphylococcus aureus. In the given case by observing the symptoms demonstrated by Navin, one can presume that Navin is suffering from Tuberculosis.
The disease is the result of Mycobacterium tuberculosis bacteria. These are the pathogenic bacteria, that comprise a mycolic acid on its cell surface. Due to the presence of this coating, it is tough to determine it with the help of Gram staining. Thus, Acid-fast staining, like Zehl-Neelsen is used.
These bacteria are aerobic in nature and need a huge concentration of oxygen, it mainly infects the respiratory system of the mammals, and generally spreads from infected persons via sneeze, coughing, talks, or laughing. Smoking is also a supplementary element of the condition. The major symptoms of the condition are weight loss, fatigue, severe cough, no appetite, chest pain, and night sweats.