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Pneumonia is
an inflammation of the lower
respiratory tract caused by acute
infection. It affects the
alveolar (air sac) spaces and the
interstitial space (area in between
cells). Pneumonia is
classified in two distinct ways. First, is
the area or part of the
lung affected. Secondly, by the organism that
causes infection. Pneumonia can
be caused by a myriad of bacterium (strep, staph,
klebsiella, H.influenza), dozens of
different viruses, including influenza A and B,
and by certain types of fungus.
The categorization of pneumonia,
including its diagnosis, is defined
by location or distribution in the
lung.
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Lobar
pneumonia: affects a section
(lobe) of one lung
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Lobular
pneumonia: occurring in one
lobe or part of a lung
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Bronchopneumonia:
patches of lung are infected in both
lungs
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Interstitial
pneumonia: involves the
interstitial, or connective tissues
of the lung
Bacteria are the most
common cause of pneumonia
in adults, with
Streptococcus pneumoniae
being the most common pathogen.
Walking pneumonia is most common
among young adults, and is caused by
the bacteria-like organism, Mycoplasma
pneumoniae. The major cause of
pneumonia in children and infants is Respiratory Syncytial virus,
or RSV.
Individuals who are immunocompromised are more likely to
get pneumonia from a fungus, or less
well-known (atypical) bacteria or virus. [1]
Because of the
difficulty in ascertaining which
infectious agent actually caused the
infection, pneumonia is classified
into two separate classifications,
both used to define origin of
location.
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Community
Acquired Pneumonia: This
type of pneumonia is also defined as
an infection contracted outside of
the hospital. Affecting nearly
4 million Americans every year, this
type of pneumonia is most prevalent
following a viral respiratory
infection.
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Hospital-acquired,
or nonsocomial
pneumonia: Contracted during a
hospital stay, this type of
pneumonia is considered far more
dangerous than the community-based
variety. Individuals in
hospital have weekend immune system
response. This immunological
compromise is often due to certain
illnesses which adversely affect
natural defense mechanisms. In
addition, organisms encountered in a
hospital are considered more
dangerous than those in the
community.
Typical symptoms
of pneumonia include cough,
fever, and sputum production. The
onset is usually insidious. In many
cases pneumonia will develop
after a URI. In severe cases
individuals will have pleurisy, or
painful breathing. This may be due
to excessive coughing or irritation
of the lung tissue by the infection. The sputum may,
in severe cases, be blood tinged. Systemic symptoms such
as muscle aches and pains, arthralgia (joint pain), loss of
appetite, nausea, vomiting, and
sweating, can also occur. [2]
Diagnostic signs
include an increased respiratory rate,
'crackling' in the breath sounds, and
x-rays, typically used to show a consolidation
pattern, and are dependant upon type
of pneumonia. [3]
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In the US there are
an estimated 4 million cases of
pneumonia each year, with
Streptococcus pneumonia causing
over 500,000 cases alone.
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Pneumonia is
the 5th leading cause
of death in the US. It is the 3rd
leading cause of death in children
under the age of 5.
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Each year between
70,000 and 90,000 individuals in
the US will die from pneumonia,
with an estimated 3.5 million
deaths occurring worldwide each year.
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African Americans
are 3 times as likely to die, Native Americans are 5-10 times
likely to die from pneumonia than
whites. [4]
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Pneumonia |
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