One of the highest-yield mnemonics in microbiology is the one for encapsulated organisms:
“Some Nasty Killers Have Some Capsule Protection”:
- Streptococcus pneumoniae
- Neisseria meningitidis
- Klebsiella pnemoniae
- Haemophilus influenzae
- Salmonella typhi
- Cryptococcus neoformans
- Pseudomanas aeruginosa
Most people know this mnemonic. However, many people don’t realize how many questions they can answer just by memorizing just one sentence.
The following are uses for the above mnemonic:
- If the question presents a patient missing anything needed to kill encapsulated organisms (eg spleen, IgG, C3b, macrophages, etc.), they are at increased risk for infections from the above bugs.
- Diseases that are infamously susceptible to encapsulated organisms:
- anyone who doesn’t have a functional spleen (eg: sickle cell)
- Bruton’s agammaglobulinemia
- If an organism has a capsule, some vaccines are made against the capsule
- H. influenzae type b
- Usually, the capsule is a major virulence factor for the above organisms.
- If the question mentions a positive Quellung reaction, look for one of the above bugs for an answer.
- Big mucoid colonies on blood agar are Klebsiella (from a big mucoid capsule)