A fastidious, oxidase-positive, gram-negative coccus from a rectal swab might be?

A fastidious, oxidase-positive, gram-negative coccus from a rectal swab might be?

• A. Neisseria gonorrhoeae
• B. Pseudomonas aeruginosa
• C. Listeria
• D. Branhamella catarrhalis

Answer: (A)

The choice of Neisseria gonorrhoeae is appropriate because it is a fastidious, oxidase-positive, gram-negative coccus that is commonly associated with human infections, particularly sexually transmitted infections. Neisseria gonorrhoeae requires specific nutrients and growth conditions to thrive, which makes it fastidious. In clinical settings, it is often isolated from specimens of mucous membranes, such as rectal swabs, especially in sexually active individuals. Additionally, this organism is characterized by its oxidase-positive reaction, which is a key testing feature that helps differentiate it from other similar bacteria. This characteristic indicates the presence of cytochrome c oxidase, an enzyme involved in the electron transport chain, reinforcing the identification of the organism. While the other organisms listed have distinct characteristics, they do not fit the profile of a fastidious, oxidase-positive, gram-negative coccus as neatly as Neisseria gonorrhoeae does. For instance, Pseudomonas aeruginosa is an oxidase-positive but is a bacillus, not a coccus, and Listeria is a gram-positive rod. Branhamella catarrhalis (now known as Moraxella catarrhalis) is a gram-negative coccus but is

The choice of Neisseria gonorrhoeae is appropriate because it is a fastidious, oxidase-positive, gram-negative coccus that is commonly associated with human infections, particularly sexually transmitted infections. Neisseria gonorrhoeae requires specific nutrients and growth conditions to thrive, which makes it fastidious. In clinical settings, it is often isolated from specimens of mucous membranes, such as rectal swabs, especially in sexually active individuals.

Additionally, this organism is characterized by its oxidase-positive reaction, which is a key testing feature that helps differentiate it from other similar bacteria. This characteristic indicates the presence of cytochrome c oxidase, an enzyme involved in the electron transport chain, reinforcing the identification of the organism.

While the other organisms listed have distinct characteristics, they do not fit the profile of a fastidious, oxidase-positive, gram-negative coccus as neatly as Neisseria gonorrhoeae does. For instance, Pseudomonas aeruginosa is an oxidase-positive but is a bacillus, not a coccus, and Listeria is a gram-positive rod. Branhamella catarrhalis (now known as Moraxella catarrhalis) is a gram-negative coccus but is