Case 1:

I. Tuberculosis -Tuberculosis is caused by a bacterium called Mycobacterium tuberculosis. The bacteria usually attack the lungs, but TB bacteria can attack any part of the body such as the kidney, spine, and brain. TB is generally classified as being either latent or active. • Latent TB TB bacteria can live in the body without making you sick. This is called latent TB infection. In most people who breathe in TB bacteria and become infected, the body is able to fight the bacteria to stop them from growing. People with latent TB infection do not feel sick and do not have any symptoms. People with latent TB infection are not infectious and cannot spread TB bacteria to others. • Active TB is contagious and is the condition that can make you sick with symptoms.

II. Mycobacterium tuberculosis Occasionally, mycobacteria are visible on a Gram stain as gram-positive or gram-variable curved, beaded bacilli in a sputum sample when tested using the Ziehl Neelsen Technique.

III. Ziehl Neelsen Technique -With the Ziehl-Neelsen stain, the appearance of Mycobacterium tuberculosis bacilli as red bacilli on a blue background indicates that they are acid fast. Many organisms are curved and some are beaded. In general, mycobacteria range from coccobacilli to long, slender, curved rods that may have beads or bands within them. To distinguish among mycobacteria on the basis of their microscopic appearance is difficult, although some species are often thicker, longer, shorter, or more coarsely beaded than is M. tuberculosis.

IV. Langerhans’ Cell -Langerhans cell is a specific kind of white blood cell. Found largely in the epidermis, as well as in lymph nodes, Langerhans cells are an important element of the immune system. They are classified as dendritic cells because they grow projections called dendrites as