Invasive Meningococcal Disease results from bacterial infection with Neisseria meningitidis, a gram-negative aerobic organism that is usually a commensal in humans; 5-25% of adults are asymptomatic carriers. 8 Meningococci that cause invasive disease develop a capsule that protects the organism from host defence mechanisms. IMD may present with a clinical spectrum that ranges from acute meningitis, with neck stiffness, photophobia and a bulging fontanelle (all symptoms may not be present), to rapidly progressive meningococcal septicaemia with a non-blanching rash, reduced conscious level, shock and multiorgan failure. Less common manifestations of IMD include pneumonia, conjunctivitis, otitis media, epiglottitis, arthritis, and pericarditis. .
