Transcript Tuberculosis (TB)

History
 Tuberculosis is nothing new,
from the earliest history of
man, it has been there. The
oldest findings of TB are
found in fossil bones dating
back to a spinal form of TB
from 8000BC. It was also
found in Egyptian
mummies dating back to
2400 BC, a mummified Inca
child from 700 BC, and
mentioned frequently in the
time of Hippocrates and
Aristotle 460-322 BC. It
History
 Despite the commonality of the
disease of TB and it’s presence
throughout history, study of the
disease did not really begin until the
19th century. Finally in 1844, Jakob
Henle proposed that TB was
contagious, but not until 1882 did
Robert Koch ( a student of Henle’s )
produce irrefutable evidence that a
microbe was the fundamental cause
of Tuberculosis.
History
 Not until the middle of the second
world war did an effective treatment
for Tuberculosis arrive via antibiotics
and synthetic anti-TB drugs. Great
efforts were made to eliminate TB
from the U.S. livestock population in
the early to mid 1900’s by mass
slaughter of cattle found to be
tuberculin positive, thus nearly
eliminating gastrointestinal entry of
TB into the human population.
TB Deaths by Year
Case Study of TB
 Patient A is a registered nurse, 40 years of age, working in
southern California at a large medical center. The hospital is
located in an area with a large population of immigrants from
southeast Asia, so she has cared for many of those patients
during her 12 years of work on the surgical floor.
 In December, she got a cold that developed into bronchitis and
seemed to hang on forever. She was often awake at night, either
coughing or having drenching night sweats. Finally, in April, she
went to her family practice physician to have it checked.
 Her chest x-ray showed questionable cavitary lesions in her right
upper lobe. Although Patient A's first panicky thoughts were
cancer, her physician investigated further, ordering a TB skin test
and sputum for acid-fast bacilli. Both tests were positive.
Case Study of TB
 She was started on INH, 300 mg/day, and rifampin, 600 mg/day. She
was shocked by her diagnosis and embarrassed to tell her friends that
she, a nurse who should know good universal precautions technique,
would develop a contagious disease.
 Patient A, however, is the perfect candidate for infection. Working in a
community with a large immigrant population from underdeveloped
countries means she had a greater risk for exposure than other nurses.
Although she worked on a surgical unit, many of the patients were
possibly infected.
 Her healthy immune system most likely quickly suppressed the initial
infection, but when the stressors in her life mounted so high, a
breakdown occurred. She had the death of a parent, change in family
financial status, concern for a child, and a new job to manage. Any of
these alone might have been insufficient to cause the immune system
to fail, but grouped together, it was only a matter of time until the
latent infection re-emerged.
What is TB?
 Tuberculosis (TB) 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. When outside the lungs it is
called extrapulmonary TB. Most TB
infections are asymptomatic and
only about one in ten cases
progress to active diseases if not
treated properly, TB kills more that
50% of those with an active
infection.
TB Details
 Worldwide, two billion people are
currently infected. Humans are naturally
resistant to the bacteria, but it is still
relatively easy to get infected. Only about
5% of those infected actually develop TB
disease. The minimum infectious dose is
around only 10 bacterial cells, while the
immune system macrophages do
phagocytose the bacterial cells they are
not killed and continue to reproduce in
the macrophages. The body responds to
the enlargement of the macrophages by
producing a granuloma composed of
fibroblasts, lymphocytes and
macrophages to surround and isolate the
enlarged bacteria filled macrophages.
This protective wall is what forms the
tubercles from which the name
Tuberculosis comes.
TB Details
 Mycobacterium tuberculosis is an acid fast rod
and is a strict aerobe. There is still debate over
whether or not it is Gram negative or Gram
positive. This very slow growing bacteria
requires 15 to 20 hours to reproduce and a
period of 6 weeks to produce colonies in a
culture media. Some of the virulence factors of
M. tuberculosis are cell walls of this bacteria
are high in lipids giving them their acid fast
properties, making it resistant to drying out
and disinfectants. Additionally as noted by
Koch in the 1880’s, the TB bacterium that form
long serpentine cords are more virulent than
ones that do not. This cord factor seems to be
associated with the lipid component of the cell
wall.
Two ways to have TB
 Latent TB Infection
 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, they
are not infectious and cannot spread TB bacteria to
others. However, if TB bacteria become active in the
body and multiply, the person will go from having
latent TB infection to being sick with TB disease.
Two ways to have TB
 TB Disease
 TB bacteria become active if the immune system can't stop them
from growing. When TB bacteria are active (multiplying in your
body), this is called TB disease. People with TB disease are sick,
they may be able to spread the bacteria to people they spend
time with every day.
 Many people who have latent TB infection never develop TB
disease. Some people develop TB disease soon after becoming
infected (within weeks) before their immune system can fight
the TB bacteria. Other people may get sick years later when their
immune system becomes weak for another reason.
 For people whose immune systems are weak, especially those
with HIV infection, the risk of developing TB disease is much
higher than for people with normal immune systems.
How does TB spread?
 TB is spread through the air from one
person to another. The TB bacteria are put
into the air when a person with TB disease
of the lungs or throat coughs, sneezes,
speaks, or sings. People nearby may
breathe in these bacteria and become
infected. Since the pasteurization of milk
was begun, transmission of the TB
bacterium is almost exclusively by fine
droplets of respitory mucus suspended in
the air. Living conditions are the most
significant factor of the epidemiology of
TB. Close living quarters , confined work
spaces, compromised immune system and
inadequate nutrition are all significantly
affect the spread of TB.
TB Symptoms
 Symptoms of TB disease
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include:
a bad cough that lasts 3 weeks
or longer
pain in the chest
coughing up blood or sputum
weakness or fatigue
weight loss
no appetite
chills
fever
sweating at night
TB testing.
 There are two kinds of tests that are
used to detect TB bacteria in the
body: the TB skin test and TB blood
test. These tests can be given by a
health care provider or local health
department. These tests detect
latent TB while a diagnosis of active
TB is confirmed by a chest X-ray
usually done after other symptoms
are reported (cough, night sweats,
fever and weight loss are most
common). It is vital to have close
personal contacts evaluated for TB if
a patient is diagnoses with an active
case of TB diease.
Treatment for TB
 Treatment for Latent TB Infection
 If you have latent TB infection but
not TB disease, treatment will stop
the disease from becoming active.
Treatment of latent TB infection is
essential to controlling and
eliminating TB in the United States.
 Treatment for TB Disease
 TB disease can be treated by taking
several drugs, usually for 6 to 9
months If you do not take the drugs
correctly, the germs that are still alive
may become resistant to those drugs.
Drug resistant TB strains are
becoming more common every year.
Treatment for TB
 Some commonly used antituberculosis drugs are
cycloserine (Seromycin), ethambutol (Myambutol),
ethionamide (TrecatorSC), isoniazid (Nydrazid, Laniazid),
pyrazinamide, rifabutin (Mycobutin), and rifampin
(Rifadin, Rimactane).
 Because people may neglect to take their medication for
tuberculosis, it is common to have tuberculosis centers
develop a program of Directly Observed Therapy (DOT.) In
these programs, patients come to the hospital or clinic, and
take their medication in front of an observer. These
programs may be annoying to the patients, but are justified
by the risks to public health if tuberculosis germs which
have become resistant to drugs were to be spread.
References
 http://www.thebody.com/content/art6109.html?ic=sabottom A
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website focusing on health issues in the gay community.
http://www.modernmedicalguide.com/antituberculosis-drugs/
An online medical guide.
http://www.ssb.no/english/magazine/fig-2009-08-04-01-en.gif
A Norwegian website that compiles health statistics.
Cowan, M. K., & Bunn, J. (2013). Microbiology Fundamentals, A
Clinical Approach. McGraw Hill. Our textbook.
Cornwall, J. (1997). Tuberculosis: A Clinical Problem of
International Importance. The Lancet, 601-674. A journal article
in “The Lancet”, a well respected journal.
http://www.cdc.gov/tb/events/WorldTBDay/resources_global.ht
m The Center for Disease Control website.