Tuberculosis disease: Difference between revisions

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==Diagnosis==
==Diagnosis==
If the patient is experiencing the symptoms described above it is highly likely they will be tested for the presence of <i> Mycobacterium tuberculosis</i> in their body. The evaluation process for a disease as serious as tuberculosis is a daunting one, but physicians need to be absolutely sure to produce a proper diagnosis. The steps for diagnosing a patient presenting with symptoms similar to TB include:
<ul>
<li> <b>Obtaining the patients’ medical history:</b> </li> Health care providers must determine if the patient has been exposed to TB, as well as illnesses that leave the patient immunodeficient. Demographic, such as age and occupation are important factors in determine if the patient is in an at risk group for contracting TB.
<li> <b>A thorough physical examination:</b> </li> This can allow for health care providers to asses overall health and knowledge that will lead to the treatment, if the patient is determined to be infected with <i>Mycobacterium tuberculosis</i>.
<li> <b>Testing for the presence of <i> Mycobacterium tuberculosis</i>:</b> </li> The two most common tests are the Mantoux tuberculin skin test (TST) and the TB blood test. The TST is accomplished by injecting 1/10th of a milliliter (mL) of tuberculin is injected into the patient’s skin, usually in the mid forearm. 48-72 after the injection, a health care provider reads the test and documents the results. If there is no reaction, the test is considered negative, however if redness and swelling occur the presentation of the reaction determines if a test is considered positive or not.
5 mm of hard swelling will be considered positive if the patient:
<ul>
<li> Has been diagnosed with HIV </li>
<li> Is immunodeficient </li>
<li> Has ever had an organ transplant</li>
<li> Has come into contact with someone who has active TB</li>
<li> Has worsening chest X-Rays</li>
</ul>
10 mm or greater of hard swelling will be considered positive if the patient:
<ul>
<li> Has presented with a negative test within 2 years </li>
<li> Has a condition that increases their chances of contracting TB </li>
<li> Is a health care professional</li>
<li> Is an intravenous (IV) drug user </li>
<li> Immigrants from a country with a high rate of TB who moved to the United States less than 5 years ago </li>
<li> Is under the age of four years old </li>
<li> Is exposed to high risk adults, and are infants, children, or teenagers </li>
<li> Is frequently in an area of high TB risk, such as homeless shelters and jails </li>
</ul>
Any test with results 15 mm or larger of hard swelling will be considered positive whether is patient is at risk or not.
<li> <b>Chest X-Ray or more in depth studies if needed:</b> </li> This is not a test that can allow a physician to diagnose a patient with TB, but can rule out pulmonary TB if a patient has presented with a positive TST or blood test.
<li> <b>Culturing of the samples taken from the patient:</b></li>This method of culturing the bacteria is the only definitive way to diagnose a patient with a <i> Mycobacterium tuberculosis </i> infection. All positive results of this test must be reported to the primary care physician and the state.
<li><b> Testing the <i> Mycobacterium tuberculosis</i> for drug resistance, due to possibility of having drug resistant tuberculosis (MDR TB) or worse, extremely drug resistant tuberculosis (XDR TB):</b></li>  This is incredibly important because if the <i>M. tuberculosis </i> strain is resistant, then an appropriate regiment needs to be prescribed to the patient to ensure the best scenario of curing the disease.
</ul>


==Treatment==
==Treatment==

Revision as of 06:59, 22 July 2013

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Mycobacterium tuberculosis under microscope [1]

Etiology/Bacteriology

Taxonomy

Mycobacterium tuberculosis Stain [2]

Kingdom: Bacteria
Phylum: Actinobacteria
Class: Actinobacteria
Order: Actinomycetales
Family: Mycobacteriaceae
Genus: Mycobacterium
Species: tuberculosis

Description

Mycobacterium tuberculosis Stain [3]

Pathogenesis

Transmission

Infectious Dose, Incubation, and Colonization

Epidemiology

Virulence Factors

Clinical Features and Symptoms

Mycobacterium tuberculosis presented via X Ray [4]

Diagnosis

Treatment

There are multiple treatments for tuberculosis, because the patient could be diagnosed with a latent TB infection or TB disease. Only if the risk of TB outweighs those of the antibiotics is a patient treated. If it is decided that action is needed TB is treated with the antibiotics isoniazid (INH), rifampin (RIF), and rifapentine (RPT). There are four different treatment routines that include isoniazid daily for nine months, isoniazid daily for six months, isoniazid and rifapentine once a week for three months, or rifampin daily for 4 months. The regiment of isoniazid and rifapentine is one that is to be taken along with directly observed therapy (DOT), due to the high risk of liver damage and death. Due to the tragic side effects, the grouping of isoniazid and rifapentine is strongly discouraged and rarely prescribed. Tuberculosis disease is treated with the four antibiotics isoniazid (INH), rifampin (RIF), ethambutol (EMB), and pyrazinamide (PZA). The treatment for pulmonary TB has two steps, starting with a combination of isoniazid, rifampicin, pyrazinamide, and ethambutol once a day for two months. The next four months of treatment consist of the patient taking only isoniazid and rifampicin for another four months. Extrapulmonary TB is treated with the same antibiotics used for pulmonary TB; INH, RIF, EMB, and PZA. The length of time needed to cure this form of TB is longer, therefore, antibiotics are prescribed to be taken during a twelve month span. If M. tuberculosis is to colonize in the patient’s brain, a corticosteroid will be prescribed for approximately a month in addition to the antibiotic regiment. This corticosteroid is prescribed to control the swelling around the brain as a result of the TB. It is crucial that patients take every dose of antibiotics as instructed for the indicated amount of time to be sure all the bacteria is killed and resistance does not occur.

Prevention

There is currently a vaccine, Bacillua Calmette-Guerin (BCG), which aims protect certain groups from the disease, although is 100% effective. The criteria for this vaccine varies depending on the country one resides. In the United States, a vaccine is not given until the set guidelines have been met and the patient has been seen by a doctor considered an expert with the TB disease. The guidelines broken down into two categories for the United States are:
Children

  • An accredited hospital has recorded the patient is TB positive, through the reading of a skin test
  • The child must remain in contact with persons diagnosed with TB that are not or inadequately treated for the disease
  • The child must remain in contact with persons that were infected with Mycobacterium tuberculosis that is resistant to the antibiotics isoniazid and rifampin

Health Care Workers The consideration for this vaccine is only on an individual basis, in which the person

  • Is in contact with a large population of TB patients infected with Mycobacterium tuberculosis that is resistant to isoniazid and rifampin
  • Drug-resistant TB is being transmitted between health care workers
  • Widespread preventative measures against the spread of TB have been implemented, but deemed unsuccessful

Most patients vaccinated with the BCG vaccine will proved a positive TB skin test, due to their immunological memory and the exposure of Mycobacterium tuberculosis.


In most cases the prevention of TB is related to how the disease is controlled. There are many different measures that need to be controlled when a TB prevention plan is put into effect.

Host Immune Response

Tuberculosis acts in a two-step mechanism that begins with a primary infection and as the host deteriorates the secondary disease can occur. When infected with the Mycobacterium tuberculosis a healthy individual with a strong immune system presents asymptomatically or with mild flu like symptoms. Due to being of low to no risk, most patients are left with these bacteria growing and colonizing within their body. Pulmonary tuberculosis infections begin with the Mycobacterium tuberculosis invading and reproducing within the macrophages residing in the infected alveoli. As immune cells make their way to the lymph nodes, the adaptive immune response is initiated by T cells. At this point multiple sites of the body are experiencing the process of inflammation. Not much is known about the immune system and how Mycobacterium tuberculosis effects it.

References

1 Conway, Tyrrell. “Genus conway”. “Microbe Wiki” 2013. Volume 1. p. 1-2.

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