Which organism is a gram-negative cocci that is oxidase positive but does not ferment glucose, maltose, sucrose, or lactose?

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Multiple Choice

Which organism is a gram-negative cocci that is oxidase positive but does not ferment glucose, maltose, sucrose, or lactose?

Understanding how these bacteria are identified hinges on two quick tests: whether they are gram-negative cocci, and how they metabolize common sugars. Oxidase positivity plus a diplococcal appearance points you toward Neisseria species. To tell them apart, labs look at which sugars they can ferment. - One Neisseria type ferments glucose only. - Another ferments glucose and maltose. - Another ferments glucose, maltose, and lactose. - A fourth pattern may show glucose and maltose (with lactose and other sugars variable). If you’re told the organism is oxidase positive, gram-negative cocci, and does not ferment glucose, maltose, sucrose, or lactose, that combination doesn’t match the typical patterns for the Neisseria species listed. In practice, a nonfermenter for these four sugars is more characteristic of Moraxella species, not Neisseria. The key learning is that pairing oxidase status with a sugar-fermentation profile lets you narrow down the genus and species, and when the fermentation pattern doesn’t fit, consider other genera or look for atypical results.

Understanding how these bacteria are identified hinges on two quick tests: whether they are gram-negative cocci, and how they metabolize common sugars. Oxidase positivity plus a diplococcal appearance points you toward Neisseria species. To tell them apart, labs look at which sugars they can ferment.

  • One Neisseria type ferments glucose only.

  • Another ferments glucose and maltose.

  • Another ferments glucose, maltose, and lactose.

  • A fourth pattern may show glucose and maltose (with lactose and other sugars variable).

If you’re told the organism is oxidase positive, gram-negative cocci, and does not ferment glucose, maltose, sucrose, or lactose, that combination doesn’t match the typical patterns for the Neisseria species listed. In practice, a nonfermenter for these four sugars is more characteristic of Moraxella species, not Neisseria. The key learning is that pairing oxidase status with a sugar-fermentation profile lets you narrow down the genus and species, and when the fermentation pattern doesn’t fit, consider other genera or look for atypical results.

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