Review Question - QID 101632

Neisseria meningitidis contains lipooligosaccharide in its cell wall and causes a petechial rash by inducing hemorrhage from blood vessels.

N. meningitidis is a Gram-negative cocci that causes severe sepsis (ie. meningococcemia), and can present in a fulminant form, Waterhouse-Friderichsen syndrome, with bilateral adrenal hemorrhage and high mortality. While most Gram-negative bacteria contain lipoPOLYsaccharide (LPS), which acts as a virulence factor for the bacteria (endotoxin), N. meningitidis contains lipoOLIGOsaccharide (LOS), an analogous structure that is responsible for the toxicity of N. meningitidis; LOS levels in the blood correlate with morbidity and mortality. N. meningitidis has its reservoir in the nasopharynx and can also cause meningitis, especially in infants and college students.

Kimmel discusses the prevention of meningococcal disease. About one case in 100,000 cases of N. meningitidis is invasive and associated with severe symptomatology and critical illness. Household and other close contacts should be given prophylaxis with rifampin, ciprofloxacin or ceftriaxone. Vaccinating an affected population is necessary when outbreaks occur, though the majority of cases are sporadic.

Unkmeir et al. discuss the basic science behind lipooligosaccharide and its role in the host inflammatory response. They demonstrated that LOS infection of human dendritic cells induced a strong inflammatory response with release of cytokines TNF-alpha, IL-8 and IL-6, while infection with a mutant serotype B strain without LOS elicited hardly any cytokine release. This emphasizes the role of LOS as a main mediator of the proinflammatory response seen in N. meningitidis infection.

Illustration A shows the appearance of a petechial rash. Note that examiner is placing pressure on the rash using a transparent piece of glass, but it does not disappear. This demonstrates the important point that petechial rashes are non-blanching.

Incorrect answers:
Answer 1: Undercooked beef contaminated with E. coli O157:H7 can cause hemolytic uremic syndrome, characterized by anemia, thrombocytopenia, and acute renal failure. E. coli is a Gram-negative bacillus containing lipoPOLYsaccharide.
Answer 3: Ascending paralysis describes the presentation of Guillain-Barre syndrome, which is associated with Campylobacter jejuni infection. C. jejuni is a Gram-negative bacillus.
Answer 4: History of exposure to rabbit hides is associated with Francisella tularensis, a Gram-negative zoonotic bacteria. F. tularensis causes ulceroglandular tularemia, which presents with a black-colored hole in skin and swollen, painful lymph nodes. Its presentation is similar to that of bubonic plague.
Answer 5: Rice water stools are found in Cholera infection, caused by Vibrio cholerae, a Gram-negative bacillus.