Tuberculosis - jfrieljfriel.wikispaces.com/file/view/Tuberculosis.pdf/555587885/...symptoms, no development of disease, not able to spread to others o May still receive treatment to

TuberculosisMichelle Bromagem

Krista Kaufman

Etiological Agent

● Tuberculosis is caused by a bacteria called Mycobacterium tuberculosis. ● Size, shape, motility, staining characteristics.

o Bacilli or rod shapedo Cluster arrangemento 2-4 micrometerso Acid fasto Gram stain is not used because of the mycolic acid and waxy wall.o Non motileo Obligate aerobe

Ancient History of Mycobacterium tuberculosis

● Tuberculosis (TB) is an ancient disease. ● It has been found in the spines of Egyptian

mummies thousands of years old.● TB was common in ancient Greece

and Imperial Rome.● Without modern drugs, many died

from the infectious disease.

Modern History of Mycobacterium tuberculosis

● TB cases started to rise in the US around 1985o Increases in prison populations, homelessness, crowded housing, increases in populations

in long-term care facilities, increased immigration of people coming from countries where TB was an epidemic, HIV/AIDS epidemic, increase in multidrug-resistant TB.

● TB epidemic in New York City, early 1990so Cost nearly $1 billion to control

● TB cases have declined worldwide and in the US due to scientific advanceso Discovery of Mycobacterium tuberculosiso Development of new drugso Development of Bacille Calmette-Guerin

vaccine (vaccine against TB)

Modern History of Mycobacterium tuberculosis

● Rate of TB cases has been fairly steadily declining in the US since 1992

● Rate of death due to TB dropped 45% between 1990 and 2013 worldwide

● However, TB is still one of the leading deadly infectious diseases worldwide

TB Facts

● TB occurs in every part of the world● ⅓ of world population is infected with TB (does not mean they all develop the

disease)● In 2013, 9 million people worldwide developed TB disease. There were

approximately 1.5 million TB-related deaths.● TB is the leading killer of people who have HIV, responsible for ¼ of all HIV-related deaths .● There are many types of TB such as primary, secondary, extrapulmonary, and

even bovine (milk) or avium (birds) TB.

Tuberculosis Statistics

● 9,582 TB cases reported in the US in 2013o 3.0 cases per 100,000 peopleo Decrease from 2012

● 426 TB cases between 2006 and 2010 in Oregon ● 74 TB cases reported in Oregon in 2011● 73 TB cases reported in Oregon in 2013● Approximately 5% of people in Oregon have

positive skin or blood test for TB. Latent TB infection is more common than TB disease

● Number of TB cases in Oregon continues to decrease and is lower than the national average (1.9 cases per 100,000 people).

Example Case of TB: Sarah

Sarah (age 35) works as a certified nursing assistant (CNA). She was working regularly with a patient that had undiagnosed TB. The patient sneezed, coughed, and talked while Sarah was nearby. M. tuberculosis traveled through the air, and Sarah breathed in the microbes. Sarah has diabetes, and therefore is at higher risk of developing TB disease if infected. After breathing in the microbes at work, she became infected and developed TB disease.

First, she developed mild symptoms (coughing, fatigue). Her symptoms progressed, and she started experiencing a bad cough, pain in her chest, coughing up sputum, feeling weak and tired, losing weight, chills, fever, and sweating at night. Sarah could not participate in any active activities and stayed in bed all day and night. Sarah went to see her doctor, and she was diagnosed with TB disease after results came back from a chest x-ray and acid-fast staining that identified M. tuberculosis.

The nurse carefully described her treatment plan. Sarah would be taking several different drugs for six weeks. The nurse emphasized that it was essential Sarah took the drugs exactly as the doctor prescribed, and that she continued taking the drugs until completion.

Example Case of TB: Sarah Continued

TB can be fatal, but Sarah followed the directions of her health care providers, and she started feeling better after about a month of treatment. She continued taking her antimicrobial medications for the full six months. The antimicrobial drugs killed off all of the bacteria, and Sarah has not had a recurrence of TB.

While sick with TB, Sarah infected two other people. Sarah’s grandmother and uncle took care of her while she was sick. During this time, she sneezed and coughed when they were nearby. The bacteria went into the air when she sneezed and coughed, and both the grandmother and uncle breathed in the bacteria.

Though the uncle was infected, he did not develop TB disease. He had latent TB infection. The TB bacteria lived in his body, but his immune system was strong enough to prevent it from growing, so he did not have any symptoms or develop the disease. He also could not spread the disease to anyone else. The grandmother’s immune system was not as strong, and the bacteria grew in her body. She developed TB disease.

Pathophysiology

● Tuberculosis is an infection that occurs mainly in the lungs, but can be found other places such as the kidney and liver.

● The dosage is as little as 10 bacterial cells.● Once they enter the body, they get engulfed by phagocytes and multiply.● The generation time is very slow. It takes 15-20 hours of incubation to grow one

single bacterium. To make an entire colony, it takes 6 weeks.● If these bacteria multiply and grow, they will fill the tubercles in the lungs with

masses and cause drainage into bronchial tubes and other areas of the respiratory tract.

Symptoms

Severe symptoms:❖ Violent coughing❖ Green or bloody sputum❖ Low grade fever❖ Weightloss❖ Extreme fatigue❖ Night sweats❖ Chest pain

Virulence Factors

Virulence factors:o Made up of a waxy wall and mycolic acid which helps to protect the

bacteria from the toxic environment and also to protect it when it is inside of the macrophages.

o Stimulate the cell-mediated immune response which helps with the pathology of the disease.

o Ability to live outside the body for 8 months which aids the virulence factor because it can be exposed to more people.

Mode of Transmission

TB is transmitted:● Nosocomially● Airborne● Injury to the skin● Fomite objects● Insect bites● Infected food products such as milk or dairy

products.

Diagnosis

The 4 types of tests to diagnose TB are:1. Tuberculin testing2. Chest x-ray3. Direct identification of acid-fast bacilli in

sputum or other specimens4. Isolation of the culture and antimicrobial

susceptibility testing

Tuberculin Testing

The test is called the Mantoux test. A purified protein derivative is injected under the skin in the forearm. Two to three days later it is observed for a red, raised wheal and can be diagnosed based on the size of bump.

Chest X-ray

These are typically used to verify the positive reading from the Mantoux test. A positive TB test will show up with radioplaque patches in specific places. It also can show if it is primary or secondary because it will show either swollen lymph nodes or infiltration in the upper lungs and bronchi.

Acid-Fast Staining

This test will verify both a positive reading from the Mantoux test and a chest x-ray. It is done by inoculating either sputum or other specimens. After the slide has been stained, it will be viewed through a microscope to verify a positive diagnosis.

Treatment

● Latent TB infection (LTBI)o Bacteria in body but not growing due to immune defenses. No

symptoms, no development of disease, not able to spread to otherso May still receive treatment to prevent the disease from developing

and to help control TB in the US. o Because there is less bacteria present, it is easier to

treat. o Treatment consists of antimicrobial drugs

Medications include isoniazid (INH), rifampin (RIF), rifapentine (RPT)

Treatment

● TB Diseaseo Patient take several drugs for 6-9 months.

Initial phase: 2 months Continuation phase: 4 or 7 months 10 drugs approved by FDA for treating TB Core of treatment includes isoniazid (INH),

rifampin (RIF), ethambutol (EMB), pyrazinamide (PZA)o Very important that patient takes medications exactly as prescribed

and to completion. o If patient starts to feel better and stops taking drugs before

completion, there may be a small amount of bacteria that can grow and cause a recurrence of the disease. This small amount of bacteria is also more likely to become drug-resistant - a serious problem with M. tuberculosis.

Prevention

● Reduce the spread of TB by coughing and sneezing into elbow● Maintain distance when speaking with a person with TB to avoid

breathing in the bacteria● TB skin tests and blood tests for early

detection● People in healthcare settings are at

higher risk of being infected.o Important to have infection control plano Review procedures for TB control periodically

to ensure consistent practice● Use airborne precautions when

appropriate

Why Fund Tuberculosis Research?

● TB causes more deaths worldwide than any other infectious disease other than HIV/AIDS

● TB is communicable and an airborne pathogen, which makes it more capable of spreading and causing epidemics

● It is more expensive to treat an epidemic than to fund research and prevention● Treatment of TB is complicated by multidrug resistant strains.

o Up to 4% of all TB cases are caused by multidrug resistant strainso In parts of Eastern Europe, almost half of all cases are resistant to at least one first-line

drug● There is a continual arms race between the bacteria that

cause TB and the antimicrobial drugs people create. It is important to fund research so humans can keep up with the quickly evolving microbes.

References

Centers for Disease Control and Prevention (2015) Tuberculosis. Retrieved on July 9, 2015 fromhttp://www.cdc.gov/tb/?404;http://www.cdc.gov:80/tb/pubs/TBfactsheets.htm.

Cowan, M., Bunn, J. & Herzog, J. (2013). Microbiology Fundamentals: A clinical approach. Mcgraw-Hill, New York, NY, USA. National Institute of Allergy and Infectious Diseases (2015) Tuberculosis. Retrieved on July 9, 2015 from

http://www.niaid.nih.gov/topics/tuberculosis/Pages/Default.aspx. Oregon Health Authority (no date) TB Basics. Retrieved on July 9, 2015 from

http://public.health.oregon.gov/DiseasesConditions/CommunicableDisease/Tuberculosis/Pages/basics.aspx. Oregon Health Authority (no date) Tuberculosis Control. Retrieved on July 9, 2015 from

http://public.health.oregon.gov/DiseasesConditions/CommunicableDisease/Tuberculosis/Pages/index.aspx. World Health Organization (2015) Tuberculosis. Retrieved on July 9, 2015 from

http://www.who.int/mediacentre/factsheets/fs104/en/.