Which Neisseria species produces acid from glucose and maltose but not from sucrose or lactose?

• A. Neisseria meningitidis
• B. Neisseria lactamica
• C. Neisseria gonorrhoeae
• D. Neisseria sicca

Answer: (A)

Carbohydrate fermentation patterns are used to distinguish Neisseria species in the lab. The key idea is which sugars the organism can ferment to acid. Neisseria meningitidis typically ferments glucose and maltose, producing acid in those substrates, but does not ferment lactose or sucrose. This combination sets it apart from other Neisseria: gonorrhoeae ferments glucose only; lactamica ferments glucose, maltose, and lactose; sicca is more variable. In the test, acid production is detected by a color change in the sugar medium. Therefore, the observed pattern of acid from glucose and maltose—but not from lactose or sucrose—best identifies Neisseria meningitidis.