Neisseria gonorrhoeae and meningitidis

A 28-year-old woman presents with acute urethritis and purulent urethral discharge. Gram stain of urethral exudate shows gram-negative diplococci within polymorphonuclear leucocytes. Which investigation is most appropriate to confirm the diagnosis of gonococcal urethritis?

A 28-year-old woman presents with acute meningitis (CSF: pleocytosis with PMN predominance, low glucose, elevated protein). Blood cultures grow Gram-negative diplococci that are oxidase-positive. A second patient, a 22-year-old man, presents with acute urethritis (purulent discharge, dysuria). Urethral smear shows Gram-negative diplococci within neutrophils. Both organisms are oxidase-positive. Which clinical and microbiological feature BEST distinguishes the meningitis isolate from the urethritis isolate?

A 28-year-old woman presents with acute urethritis and purulent urethral discharge. Gram stain of urethral exudate shows gram-negative diplococci within polymorphonuclear leukocytes. Which investigation is most appropriate to confirm the diagnosis of gonorrhea?

A 19-year-old male student presents with sudden-onset fever (39.5°C), severe headache, neck stiffness, and a petechial rash on the trunk and extremities. Cerebrospinal fluid (CSF) analysis shows pleocytosis (WBC 850/μL, predominantly neutrophils), elevated protein (120 mg/dL), and low glucose (28 mg/dL). Gram stain of CSF reveals gram-negative diplococci. Which is the most specific investigation to confirm Neisseria meningitidis meningitis?

Neisseria meningitidis is an obligate human pathogen that produces a polysaccharide capsule. Which serogroup is most commonly associated with epidemic meningitis in sub-Saharan Africa?