Which organism is commonly found in the mouth and upper respiratory tract of humans?

Which organism is commonly found in the mouth and upper respiratory tract of humans?

• A. Escherichia coli
• B. Eikenella corrodens
• C. Klebsiella pneumoniae
• D. Pseudomonas aeruginosa

Answer: (B)

Normal flora of the mouth and upper airways includes Eikenella corrodens, a Gram-negative rod that commonly colonizes dental plaque and gingival crevices. Because it is a typical resident of this region in healthy people, it’s the best fit for “commonly found in the mouth and upper respiratory tract.” The other organisms come from different habitats: Escherichia coli is mainly associated with the intestinal tract; Klebsiella pneumoniae is also primarily GI-associated and not a standard oral inhabitant; Pseudomonas aeruginosa is an environmental opportunist and not a normal resident of the mouth. So Eikenella corrodens best matches the description.

Normal flora of the mouth and upper airways includes Eikenella corrodens, a Gram-negative rod that commonly colonizes dental plaque and gingival crevices. Because it is a typical resident of this region in healthy people, it’s the best fit for “commonly found in the mouth and upper respiratory tract.” The other organisms come from different habitats: Escherichia coli is mainly associated with the intestinal tract; Klebsiella pneumoniae is also primarily GI-associated and not a standard oral inhabitant; Pseudomonas aeruginosa is an environmental opportunist and not a normal resident of the mouth. So Eikenella corrodens best matches the description.