Antibiotics Types and Side Effects

by Yury Bayarski

What are Antibiotics?

The word "antibiotics" comes from the Greek anti ("against") and bios ("life"). Antibiotics are drugs that either destroy bacteria or prevent their reproduction. Antibiotics that kill bacteria are called "bactericidal" and the ones that stop the growth of bacteria are called "bacteriostatic".

Since penicillin's introduction during the 1940s, scientists developed numerous other antibiotics. Today, over 100 different antibiotics are available. About 90 percent of antibiotics are made from living organisms such as bacteria, others are produced synthetically, either in whole or in part.

Antibiotics classification

Although there are several classification schemes for antibiotics, based on bacterial spectrum (broad, narrow) or route of administration (injectable, oral, topical), or type of activity (bactericidal, bacteriostatic), the most useful is based on chemical structure. Antibiotics within a structural class will generally have similar patterns of effectiveness, toxicity, and allergic potential.

Most commonly used types of antibiotics are: Penicillins, Fluoroquinolones, Cephalosporins, Macrolides, and Tetracyclines. While each class is composed of multiple drugs, each drug is unique in some way.

Penicillins

The penicillins are the oldest class of antibiotics. Penicillins have a common chemical structure which they share with the cephalopsorins. Penicillins are generally bactericidal, inhibiting formation of the cell wall.

There are four types of penicillins:

The natural pencillins are based on the original penicillin-G structure. Penicillin-G types are effective against gram-positive strains of streptococci, staphylococci, and some gram-negative bacteria such as meningococcus. Penicillinase-resistant penicillins are active even in the presence of the bacterial enzyme that inactivates most natural penicillins.

Extended spectrum penicillins which are effective against a wider range of bacteria. Aminopenicillins such as ampicillin and amoxicillin have an extended spectrum of action compared with the natural penicillins.

Penicillins side effects

Penicillins are among the least toxic drugs known. The most common side effect of penicillin is diarrhea. Nausea, vomiting, and upset stomach are also common. In rare cases penicillins can cause immediate and delayed allergic reactions - specifically, skin rashes, fever, and anaphylactic shock. Penicillins are classed as category B during pregnancy.