Master Neisseria Meningitidis with Picmonic for Medicine

This organism stains negative on Gram stain due to relatively thin peptidoglycan layer in the cell wall.

Diplococci are round-shaped bacteria that typically occur as two joined cells.

Neisseria are fastidious organisms that require nutrient supplementation to grow in laboratory cultures. Specifically, they grow on chocolate agar which is an enriched growth medium containing red blood cells that have been lysed, providing growth factors like NAD and hemin. The agar is named for the chocolate color of the medium and does not actually contain chocolate.

Thayer-Martin media is an agar plate containing vancomycin, polymyxin, nystatin and specific nutrients that facilitate the growth of Neisseria species while inhibiting the growth of other organisms.

Thayer-Martin media is also called VPN agar, standing for vancomycin, polymyxin, and nystatin. These antibiotics along with specific nutrients facilitate the growth of Neisseria species while inhibiting the growth of other organisms.

An oxidase test is used to determine if bacteria produce certain cytochrome c oxidases to help differentiate bacteria. Neisseria are oxidase-positive bacteria.

Neisseria meningitidis can be distinguished from Neisseria gonorrhoeae because N. meningitidis ferments both glucose and maltose while N. gonorrhoeae only ferments glucose.

Neisseria can be distinguished from other gram-negative bacteria because they are glucose-fermenting. Both Neisseria gonorrhoeae and Neisseria meningitidis are glucose fermenting.

Virulence mechanisms include lipooligosaccharide (LOS), also known as endotoxin, within the cell membrane of N. meningitidis, which instigates a systemic inflammatory response with shock and destruction of red blood cells.

LOS is a smaller form of the more common bacterial virulence factor lipopolysaccharide (LPS). LOS is found within the bacterial cell membrane and its function is to maintain membrane stability. LOS is highly antigenic and when released into the bloodstream it causes a systemic inflammatory response.

N. meningitidis virulence mechanisms include a polysaccharide capsule that is anti-phagocytic and aids in the evasion of the host immune response.

An IgA protease is an enzyme that cleaves certain amino acid sequences of proteins including immunoglobulin A. Neisseria meningitidis releases IgA proteases which destroy IgA, leading to increased pathogenicity. Other IgA protease producers include Streptococcus pneumonia and Haemophilus influenzae type B.

This syndrome is defined as adrenal failure due to massive hemorrhage into the adrenal glands caused by overwhelming meningococcemia and disseminated intravascular coagulation.

Sepsis caused by Neisseria meningitidis can lead to massive hemorrhage into one or both adrenal glands, causing rapidly developing adrenocortical insufficiency with loss of cortisol and aldosterone production. This is also called Waterhouse-Friderichsen syndrome.

Petechia are small red or purple spots on the body caused by broken capillary blood vessels. A petechial rash is present in approximately 75% of meningococcal sepsis caused by widespread destruction of blood vessels.

Ceftriaxone is a third generation cephalosporine used in the treatment of N. meningitidis.

Rifampin is an antibiotic commonly used to treat tuberculosis. People who have had close contact with an individual who has meningococcal infection can be offered rifampin to eradicate the bacteria and prevent disease.