Final answer:
Meningitis with petechial hemorrhages is typically caused by the bacterium Neisseria meningitidis. This serious infection rapidly progresses and can lead to shock, convulsions and coma. Immediate antibiotic treatment and preventive measures for close contacts are essential.
Step-by-step explanation:
Meningitis with petechial hemorrhages on the chest and legs is a distinctive feature of infection by the bacterium Neisseria meningitidis, which is a gram-negative, bean-shaped diplococcus. This bacterium causes meningococcal meningitis a form of bacterial meningitis that can progress rapidly and be very serious. The characteristic petechial rash that appears soon after disease onset is a response to virulence factors released by the bacteria.
These virulence factors include LOS endotoxin and lead to disruption of endothelial cells in capillaries and small veins, resulting in blood leaking into surrounding tissue. If the infection progresses, it can lead to shock, convulsions, coma and even death. Rapid treatment with appropriate antibiotics is crucial, and vaccination and prophylaxis may be recommended for those in close contact with an infected person.