Antibiotics

What are they

The term antibiotic refers to a group of compounds that can prevent the development of bacteria.

To indicate them, two other terms are used, sometimes indistinctly: antibacterial and chemotherapeutic.

Antibacterials of natural origin – the first to be discovered – are molecules that other microorganisms, mostly certain types of microscopic fungi (belonging to the mold group), produce to defend themselves from bacterial infections.

A historical example of this group is penicillin, identified in 1928 by Alexander Fleming and so called because it is produced by a fungus of the genus Penicillium.

Since then, starting from the original molecules, compounds have been derived, through modifications of the chemical structure specifically designed to increase their effectiveness, which, precisely because of their “mixed” origin, are defined as semi-synthetic antibiotics.

How they work

The now numerous molecules available inhibit the development of bacteria through different mechanisms of action, which however essentially aim at two objectives:

• destroy the outer protective envelope of the bacterial cell;
• interfere with the biochemical reactions that allow it to survive and reproduce.

Depending on the final effect on the bacterial cell, the various drugs are then divided into:

Depending on the chemical structure and mechanism of action, each molecule is selectively effective on individual species or groups of bacteria or simultaneously on a wide range of bacteria.

Antibacterials of this second type are called “broad-spectrum”.

When and how to use them

The intake of antibacterial drugs is appropriate only in infections caused by bacteria, while it is useless and inappropriate in the course of diseases caused by different infectious agents (viruses, fungi, protozoa), unless there is a risk that these are complicated by the overlapping of bacterial infections.

The use of broad-spectrum antibacterials is indicated for infections in which the identity of the bacteria responsible is not known and which can be caused by many different bacteria.

The use of a more selective antibacterial is obviously the best choice: it is possible in the case of diseases of which the most probable infectious agent is known and especially when, by analyzing a sample of infected organic material (secretions of the respiratory tract, vaginal mucus, urine, blood, etc.), it is possible to accurately identify the bacterial strain involved and even to test its sensitivity to different drugs (through a defined examination bacterial culture with antibiogram).

Antibacterial drugs should only be used on doctor’s prescription and it is important that they are taken for the time and at the prescribed doses.

The problem of resistance

In the last century, pharmaceutical research has made numerous antibacterial molecules available, pursuing the goal of creating more and more specific, more effective and less toxic ones.

At the same time, bacteria have put in place the biological countermeasures they are equipped with (genetic modifications, biochemical adaptations) to reduce their susceptibility to the effect of drugs.

Currently, this phenomenon, called drug resistance, represents one of the biggest obstacles in the control of bacterial infections and consequently one of the major health emergencies.

Among the main causes of the development of forms of resistance by bacteria is the improper use of antibiotic drugs: when not necessary, at doses other than those prescribed, with inappropriate intake methods, for insufficient or too prolonged periods of time, etc.