Facts About Pneumonia
Pneumonia is caused by an infection or injury to the lower respiratory tract
resulting in inflammation. Infectious agents or injury caused by aspiration
of dust or chemical agents causes fluid to enter the alveolar spaces. The
symptoms of pneumonia include chills, fever, cough, chest pain, laboured
breathing, fatigue, anorexia, headache, leucocytosis, and bloody sputum.
Pneumonia can also result from the aspiration of gastric contents, water,
or other irritants.
Infectious pneumonia is common in the US with about 2-3 million cases
being diagnosed each year resulting in 40,000 to 70,000 deaths. Mortality
is estimated at 14% for patients requiring hospitalisation. Risk factors
include upper respiratory infections, advanced age, alcoholism, cigarette
smoking, institutionalisation, malnutrition, immune system compromise,
and illnesses such as cancer, liver or kidney disease, congestive heart
disease, and cerebrovascular disease. Pulmonary defence mechanisms such
as the cough reflex, mucocilliary action, and immune responses, normally
prevent infections but pneumonia results when the pathogen gets past these
mechanisms. Virulence and severity of the pneumonia depends on the health
of the individual, the particular microorganism, and the size of the inoculation.
Respiratory support, if needed, and antibiotics are the treatments of
choice for most infectious pneumonias. Rarely antiviral drugs are used.
Pneumonia in adults is most commonly caused by bacterial agents. It is
a frequent respiratory infection in industrialized cities, lower socio-economic
groups or in cases of crowded living quarters. The incidence of bacterial
pneumonia increases in winter and spring in temperate zones.
Most infectious pneumonia is caused by bacteria and 60-80% of all bacterial
pneumonia is caused by Streptococcus pneumoniae. These organisms are routinely
found in the upper respiratory tract of healthy persons. It is when they
are drawn into the lower respiratory tract of susceptible individuals
that they cause infection. Pneumococci are spread by droplets or direct
contact with an infected person. Bacterial pneumonia has an incubation
period of 1-3 days. Antibiotic therapy with penicillin or erythromycin
makes the patient non-infective and generally results in a rapid recovery.
A vaccination that confers 90% protection is available and recommended
for those (except infants less than 2 years old) at highest risk of fatal
infection. Vaccination of people older than age 65 is recommended with
a booster every 6 years thereafter. The influenza vaccine is recommended
at yearly intervals and can be administered at the same time as the pneumococcal
Mycoplasma pneumoniae causes pneumonia, particularly in older children
and young adults, of gradual onset that lasts for a few days to weeks.
The symptoms of this type of pneumonia are headache, malaise, sore throat,
cough, and leucocytosis. Diagnosis is by finding antibodies in the blood.
Infection occurs 14-21 days after droplet inhalation or direct contact
with an infected individual. Antibiotic treatment with tetracycline or
erythromycin is effective. Penicillin is completely ineffective because
mycoplasmas do not have cell walls, which this antibiotic targets.
Chlamydia trachomatis is a sexually transmitted disease that may also
cause pneumonia and bronchitis. It usually is a subacute infection of
early infancy producing a sudden cough and eosinophilia without fever
that lasts from 1-3 weeks, but it may occur in adults too. It is transmitted
to infants at birth from the cervix of an infected mother. Adults having
chlamydial pneumonia are usually immune compromised, with the infection
spreading from the eye (conjunctival) to the respiratory tract via the
nasolacrimal duct. Diagnosis is by isolation of the organism and by finding
antibodies in the blood. Erythromycin and tetracycline are effective therapies.
Pneumocystis carinii is an organism of mixed fungal and protozoal character
that causes an acute, often fatal, respiratory infection in infants or
immune compromised patients. Symptoms are laboured or difficult breathing,
cyanosis and heavy infiltrates in the alveolar spaces. Diagnosis is by
finding the organism in mucous smears or by biopsy of lung tissue. Treatment
is by the use of trimethoprim-sulfanethoxazole or pentamidine isothionate.
When treated, 60-90% of patients survive. If untreated it is uniformly
Viral agents causing pneumonia include adenoviruses, parainfluenza, respiratory
syncytial virus, measles, chicken pox, and influenza. Viral infections
in adults are usually mild and limited. Such infections in children are
associated with greater severity and may be fatal. Symptoms of acute upper
respiratory disease include fever, chills, headache, malaise, anorexia,
and general aches. Symptoms usually subside in 2-5 days but may progress
to pneumonia in susceptible individuals if the infection spreads to the
lower respiratory system. Of greater concern is damage to the respiratory
membranes that allows secondary bacterial infections. Sometimes antiviral
drugs are used to treat viral pneumonia.
Alternative Names :
Bronchopneumonia, Community-acquired pneumonia , Pneumonitis
Pneumonia is an inflammation of the lungs caused by a bacterial, viral,
or fungal infection.
- Cough with mucus-like, greenish, or pus-like sputum
- chills with shaking
- easy fatigue
- chest pain
- sharp or stabbing
- increased by deep breathing
- increased by coughing
- loss of appetite
- nausea and vomiting
- general discomfort, uneasiness, or ill feeling (malaise)
- joint stiffness (rare)
- muscular stiffness (rare)
Additional Symptoms that May be Associated with this Disease:
- shortness of breath
- excessive sweating
- clammy skin
- nasal flaring
- coughing up blood
- rapid breathing
- anxiety, stress and tension
- abdominal pain
Causes, Incidence, and Risk Factors
Pneumonia is a very common, often serious illness that affects about 3-4
million people each year in the United States. Many different organisms
can cause pneumonia, including bacteria, viruses, and fungi. Bacterial
pneumonias tend to be the most serious. In adults, bacteria are the most
common cause, and of these Streptococcus pneumoniae (pneumococcus) is
the most common.
Respiratory viruses are the most common causes of pneumonia in young
children, peaking between the ages of 2 and 3. By school age, the bacterium
Mycoplasma pneumoniae becomes more common.
In some people, particularly the elderly and those who are debilitated,
pneumonia may follow influenza.
Pneumonia is classified according to a number of different systems.
One classification system divides pneumonia into "community-acquired"
(pneumonia contracted outside of a health-care institution) and "hospital-acquired"
(acquired in a hospital or other long-term health care facility). S. pneumoniae
is the most common form of community-acquired pneumonia.
Hospital acquired pneumonia tends to be more serious because the patient's
defense mechanisms against infection are often impaired when someone is
hospitalized, due to the condition that initially required treatment .
In addition, there is a greater possibility of infection with bacteria
that are resistant to antibiotics.
Other Classifications of Pneumonia Include:
- aspiration pneumonia
- atypical pneumonia
- bacterial pneumonia
- CMV pneumonia
- hospital-acquired pneumonia
- Legionella pneumonia
- Mycoplasma pneumonia (walking pneumonia)
- necrotizing pneumonia
- pediatric pneumonia
- Pneumocystis carinii pneumonia
- pneumonia in immunocompromised host
- pneumonia with lung abscess
- pyogenic pneumonia
- viral pneumonia
If the cause is bacterial, the goal of treatment is to cure the infection
with antibiotics. However, if the pneumonia is caused by a virus, antibiotics
will NOT be effective.
Supportive therapy includes oxygen and respiratory treatments to remove
secretions, if needed.
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