Final answer:
The characteristic sign that can help distinguish Klebsiella pneumoniae from other kinds of pneumonia is the presence of "currant jelly sputum" caused by the bacterium's thick polysaccharide capsule.
Step-by-step explanation:
One characteristic sign that can help distinguish between Klebsiella pneumoniae and other kinds of pneumonia is the presence of a thick polysaccharide capsule produced by the bacterium. This capsule causes the sputum produced by Klebsiella pneumoniae infection to have a characteristic appearance known as "currant jelly sputum." This is because the sputum consists of clumps of blood, mucus, and debris from the capsule.