Neisseria meningitidis

Gram Stain

• Gram negative diplococci (fastidious)

Clinical Significance

This organism may colonize the nasopharynx in asymptomatic carriers. Carriage prevalence increases throughout childhood from 4.5% in infants to 25% in late teens/early adulthood, decreasing to about 8% in middle age.

This organism causes meningococcemia (acute, chronic bacteremia or fulminant septicemia), meningitis, pneumonia, septic arthritis, osteomyelitis, urethritis, cervicitis, pelvic inflammatory disease, peritonitis, pericarditis, endocarditis, conjunctivitis, and endophthalmitis.

Usual Susceptibility Pattern

Although most strains remain susceptible to penicillin, increasing MICs have been reported secondary to acquisition of a beta-lactamase.

It is generally susceptible to ceftriaxone (rare non-susceptibility has been described), ciprofloxacin, tetracyclines, TMP/SMX, and rifampin.