THE PHARMACY

The Antibiotic Ladder

When I was learning about antibiotics in school, it fried my brain. I felt like there were too many drugs to remember, especially when picking the correct one. One thing that helped me understand the algorithm behind antibiotics is the antibiotic ladder. It’s a timeline of the discoveries of each antibiotic class. The higher up on the latter, the more narrow their target is. Additionally, the higher up the ladder, the less antibiotic resistance there is.

In this article, I will go through a few diagrams that aided me in school.

Penicillin

Penicillin is at the bottom of the ladder because it was the first beta-lactam discovered (1928). After almost one hundred years, bacteria have grown accustomed to resisting penicillin easily. Nowadays, penicillin has strict coverage over the streptococcus genus. From penicillin, the ladder branches out into gram-positive bacteria. (staphylococcus and streptococcus) and gram-negative bacteria.

Anti-Staphylococcal Penicillins

Next, starting from the left of the ladder, I will discuss bacteria with targeted gram-positive coverage. Since penicillin only covers strep, we need to find an antibiotic class that has staph coverage. The anti-staphylococcal penicillins come into play here. Examples of…