Question

Identify the following image.

• A. Neisseria meningitidis
• B. Neisseria cinerea
• C. Neisseria gonorrhoeae
• D. Neisseria polysaccharea

Hint:

Gram-negative coffee-bean diplococci of the meningococcus genus, the encapsulated meningitis-causing species.

Answer 1

The Correct Option is A

Step 1: The image shows Gram-negative diplococci with the characteristic kidney-bean or coffee-bean shape, lying with their flattened sides together, typical of the genus Neisseria.

Step 2: Neisseria meningitidis (meningococcus) is the encapsulated, aerobic, fastidious Gram-negative diplococcus that causes meningitis and meningococcemia. In CSF or blood it is classically seen as paired bean-shaped cocci, often intracellular within neutrophils.

Step 3: The recall key marks N. meningitidis. N. gonorrhoeae is also a bean-shaped diplococcus, so on morphology alone they overlap; the distinction comes from the clinical/specimen context implied by the image. Given the marked answer and the meningococcal context, the answer is Neisseria meningitidis. N. cinerea and N. polysaccharea are non-pathogenic commensals and are not the intended answer.

Ref: Jawetz Medical Microbiology, 27e, p 287.