Tuberculosis

A 13 year old boy presented to his school nurse complaining that his three week old cough had got worse, he was coughing up sputum and he had lost his appetite. She told him to take the rest of the day off and told his mother to take him to their doctor if it got worse. Overnight the boys cough became worse still and he began to cough up blood. His mother and father took the boy to accident and emergency where it became evident he was very ill. The doctor on duty ordered a chest xray that showed areas of consolidation (shadows) in the lungs.

The doctor suspected that the patient had Tuberculosis because of the presentation. Other symptoms that can be expected in TB include fever, chills, weight loss, pallor, and fatigue. TB is an infectious disease caused by mycobacteria (mycobacterium tuberculosis) that can be fatal if left untreated. The disease most commonly attacks the lungs but can also affect other systems such as the central nervous system, the circulatory system and the joints. Approximately, one third of the worlds population has been exposed to TB but not all of these individuals go on to develop active disease. These individuals are described as having latent infection, of which one in ten will go on to develop active TB disease. There has been a recent rise in the number of infections in the developed world due to a combination of predisposing factors, such as HIV infections, the emergence of drug resistant bacteria and immigration from areas where the disease is endemic.

The doctor considered asking the microbiology department to see if they could culture the tuberculosis bacterium from the patients sputum, but had heard that the relatively new ELISPOT test performed by the immunology laboratory gives a more accurate and speedy result. A healthcare scientist in the immunology department performed the test by measuring the response of the patient’s immune system cells to inactive components of the TB microorganism. The test result was positive, confirming the doctor’s suspicion of TB.

The patient was immediately removed from his school and prescribed a course of antibiotic therapy that would last for over six months and assigned a nurse to observe that he took his medication. Several different antibiotics were prescribed so that if the particular strain of bacteria involved in the infection was resistant to one or more of the drugs it would be cleared by the others.  On discussion with the school, it was decided that as the patient had been in school for a few weeks before being diagnosed, the other students may have been at risk so all his classmates and his teacher were tested using the ELISPOT test. All these follow up test were negative.