A Patient With Klebsiella pneumoniae Infection

A patient in the hospital develops pleuritic chest pain, shortness of breath, fever, chills, productive cough, and colored sputum after 3 days of being in the hospital for major surgery.
Physical examination shows tenderness to palpation without any areas of increased tactile fremitus. Blood and sputum cultures confirm gram-negative rods that ferment lactose, have a large mucoid capsule, and form viscous colonies.
The patient subsequently dies from her infection. Which of the following is most likely to be found at autopsy?

(A) Acute inflammatory infiltrates from bronchioles into adjacent alveoli
(B) Congestion, red hepatization, gray hepatization, and resolution
(C) Diffuse, patchy inflammation localized to the alveolar wall interstitium
(D) Intra-alveolar hyaline membranes without alveolar space exudates
(E) Predominantly intra-alveolar exudate resulting in consolidation.

Answer And Discussion:


The correct answer is A. Acute inflammatory infiltrates from bronchioles into adjacent alveoli
The characteristics of the microorganism indicate infection with Klebsiella species, while the physical exam points to a bronochopneumonia rather than a lobar pneumonia.
K. pneumoniae is a gram negative rod that ferments lactose and has a mucoid capsule. Bronchopneumonias are characterized by acute inflammatory infiltrates from bronchioles into adjacent alveoli. Pneumonia resulting from infection by this bacterium is often caused by aspiration, so that it is often seen in people with a loss of consciousness (ie, alcoholics). It is also more common in patients with diabetes.

Answer B is incorrect. Lobar pneumonia, most frequently due to Streptococcus pneumoniae,
morphologically evolves through four stages without treatment: congestion, red hepatization, gray hepatization, and resolution. S.pneumoniae is an encapsulated gram-positive coccus. It is known for causing rust-colored sputum.

Answer C is incorrect. Interstitial pneumonias from mycoplasma and viruses, are characterized
by diffuse patchy inflammation localized to interstitial areas at alveolar walls.

Answer D is incorrect. Interstitial pneumonias from mycoplasma and viruses, are characterized by diffuse patchy inflammation localized to interstitial areas at alveolar walls. They also have no exudates in alveolar spaces, but have intra-alveolar hyaline membranes.

Answer E is incorrect. Lobar pneumonia, most frequently due to Streptococcus pneumoniae,characteristically has predominantly intra-alveolar exudates, resulting in consolidation.