"Some Nasty Killers Have Some Capsule Protection":

that's the mnemonic for bacterias that have capsules:

Streptococcus pneumoniae
Neisseria meningitidis
Klebsiella pnemoniae
Haemophilus influenzae
Salmonella typhi
Cryptococcus neoformans
Pseudomanas aeruginosa

you're prolly thinking...great, i'll just memorize this for the exam then. this is where i show you, that it's also important for you as a diagnostician to remember something as minute as which bacteria is capsulated:

say, you get a patient who is asplenic, or has IgG/C3b/ macrophage deficiency. your patient is at an increased risk for infections from the above bugs because they lack what it takes to kill with encapsulated organisms. so is someone who doesn't have a functional spleen (sickle cell) or a person with Bruton's agammaglobulinemia.

the capsule is a virulence factor for the above organisms and can induce and immune response and the formation of antibodies against it. which means vaccines can also be made against the capsule for bugs such as Pneumococci, Meningococci and H. influenzae type b.

now, how do we know that these bugs are capsulated to begin with? these organisms test positive for the Quellung reaction, where anticapsular antibody binds to the organism's capsule causing it to swell and become more visible, especially under the microscope.

so remember: "Some Nasty Killers Have Some Capsule Protection".