Lecture 26 - Mycobacterium 2

Leprosy
Leprosy, also known as Hansen's disease, is a chronic infection caused by Mycobacterium leprae. It is transmitted through long term contact with an infected individual. Leprosy has a long incubation period of 2-5 years most of the time, but can range from 9 month to 40 years. The two major types of leprosy are tuberculoid and lepromatous. Tuberculoid is the early form of leprosy, have few leprae cells in lesions, and is treated with dapsone and rifampin. The lepromatous form is a severe form of leprosy, and is treated with dapsone, rifampin, and clofazamine.

Diphtheria
Diphtheria is an acute infection caused by Corynebacterium diphteria. It only incubates for 1 to 10 days and forms a false diphtheroid pseudo-membrane in the throat and nasopharynx area that can cause suffocation in the host. The bacteria also releases exotoxins that cause heart damage, which is referred to as atoxemia.

Diagnosis
Corynebacterium diphtheria is a Gram-positive rod that has a palisade arrangement and metachromatic granules. It can be diagnosed with a microscope and with a PCR test.

Transmission
It is transferred by coughing (microaerosol), and can stay in the environment for a long time. Predisposing factors include not being immunized, poor nutrition (most important), and nose/throat operations.

Prevention
One can prevent diphtheria with the most common vaccine DTaP, which covers diphtheria, tetanus, and acellular pertussis. This is an active immunity method because the host's immune system is actively producing the antibodies.

Treatment
To treat diphtheria, one can use DAT (diphtheria antitoxin), which are antibodies extracted from a horse that target the toxins that diphtheria produces. This is a method of passive immunity because the antibodies are not actively being produced by the host. DAT can only be used one because the body treats DAT as an antigen and builds resistance to it.

The second drug is erythromycin, which reduces the amount of toxins, kills the corynebacterium, and prevents the patient from becoming a carrier.