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Klebsiella
pneumoniae, (known as Friedlander’s bacillus), is a short, encapsulated,
gram-negative bacillus that cause a necrotizing lobar pneumonia.
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This
organism also causes 10% of all infections acquired in hospital,
including pneumonia and infections of the urinary tract, biliary
tract, and surgical wounds.
Carriers are a special hazard among
hospital personnel, especially when resistant strains
of K.
pneumoniae colonize their mouths, throats, and intestines.
Predisposing factors are indwelling catheters and endotracheal tubes,
old age, alcoholism, immunosuppression, diabetes, congestive heart
failure, obstructive pulmonary disease, and other debilitating
conditions.
Furthermore, secondary Klebsiella pneumonias may
complicate
influenza or other viral infections of the respiratory
tract.
The combined mortality rate of primary and secondary Klebsiella
pneumonias is about 50%,
because the necrotizing pneumonia is itself dangerous and because
those stricken tend to be chronically ill or otherwise debilitated.
Clinically,
the pneumonia has a sudden onset, characterized by fever, pleuritic
pain, cough, and thick mucoid
sputum when infection is
severe these symptoms progress to shortness of breath, cyanosis, and
death in 2 to 3 days.
Visit:
Bronchopneumonia
;Pneumocystis Pneumonia
Pneumonia
develops when the bacilli invade and multiply within the alveolar
spaces.
The pulmonary parenchyma becomes consolidated, and the mucoid
exudates that fills the alveoli is dominated by macrophages, fibrin,
and edema fluid.
Neutrophils are inhibited by a neutral polysaccharide
in the capsule of K. pneumoniae, and are not a significant part
of the early exudates.
Numerous encapsulated gram-negative bacilli
appear free in the exudates and in alveolar macrophages.
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As the
exudates accumulates the alveolar wall become compressed and then
necrotic.
Numerous small abscesses may coalesce and lead to cavitation.
The
pneumonia, or other infections by K. pneumoniae, may be
complicated by a fulminating, often fatal, septicemia, even without
disseminated lesions in other tissues.
Diagnosis is
made by culture.
Both an aminoglycoside and a cephalosporin are recommended
for treatment.
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