The Effect of Temperature on Generation Time

1. How does a person usually acquire tuberculosis?

Since tuberculosis is an airborne transmitted disease, people can acquire the disease by

inhalation of bacterium when a person with active pulmonary disease coughs, sneezes,

spits or sings. Aerosol droplets of M. tuberculosis cells can penetrate the respiratory

tracts of those with a compromised immune system. Typically the disease affects those

most associated with crowded conditions or poor ventilation, often in urban areas or

ghettos where malnutrition is prevalent. The bacteria enters the alveoli of the lungs

where pathogenesis occurs. Macrophages then respond to the infection by ingesting the

bacilli. The bacilli are engulfed by white blood cells called phagocytes, but not

destroyed. Lymphocytes and fibroblasts surround the mass in the lungs, then forming

what is called a tubercle (a hard nodule), henceforth the name tuberculosis.

2. What physical property of Mycobacterium tuberculosis makes it acid fast?

Once stained, the organisms are classified as acid fast due to their impermeability of their

waxy barrier around the cell (mycolic acid) by certain dyes and stains. The bacteria also

resists de-colorization and most aqueous dyes, which include gram stains. High lipid

concentration within the cell wall prevents the acceptance of those dyes.

3. Why does Mycobacterium tuberculosis require long-term drug therapy?

Mycobacterium tuberculosis is a stubborn disease that consumes most body tissues and

the respiratory tract. Over the years, the bacterium has been known to showcase the

development of antibiotic resistance. The first line of defense includes drugs such as

isoniazid and rifampin. Other drugs such as ethambutol, pyrazinamide, and

streptomycin are used to delay resistant strains from emerging. If that does not work, a

second line of defense includes drugs such as fluoroquinolones and kanamycin which still

battle the multi-drug resistant tuberculosis (MDR-TB). As a last resort, antimicrobial

drug therapy is being used to fight off the bacteria over a six to nine month period, since

the