Antibiotics

Overview of antibiotics

An antibiotic is an antibacterial agent aimed to kill or to stop the growth of bacteria causing infections in humans or animals. Antibiotics are used to treat or to prevent various diseases. This type of medication can be administrated orally, intravenously, by injection or topically (for example, in the form of eye drops or ear drops).

Since the discovery of penicillin in 1928, pharmacology has come a long way to producing antibacterial medication from the different recourses. Nowadays, antibiotics of organic origin (like aminoglycosides), synthetic origin (e.g. quinolones) and semisynthetic origin (for example, cephalosporins) are used all together. Common side effects include allergic reactions, diarrhea and gastrointestinal reactions caused by damaging intestinal flora, vaginal candidiasis caused by affecting vaginal flora, interaction with alcohol, birth control pills and other medications.

One of the most important problems of modern medicine is growing bacteria resistance to antibiotics. Bacteria tend to adapt themselves to the action of the antibiotics. There are several ways to protect humanity from growing antibiotic resistance. Those include limitation of antibiotic use in animal husbandry, development of new antibiotic classes, limitation of prophylactic use, checking the correct dosage depending on patient’s weight and prior history of medication use, administering full course of treatment without leaving untreated strains of infections and combination therapy with 2 or more antibiotics used together.

Classification of antibiotics

There are many ways to classify antibiotics, depending on their coverage, mechanism of action or chemical structure. Broad-spectrum antibiotics like aminoglycosides aim wide range of bacteria, while narrow spectrum antibiotics like vancomycin target a certain group of bacteria. Antibiotics’ mechanisms of action include such ways as:

1. binding to the bacteria ribosomes and blocking synthesis of proteins essential for bacterial growth,
2. blocking bacteria DNA transcription,
3. inhibiting bacterial cell wall division and synthesis,
4. binding to bacteria membrane and causing its rapid depolarization,
5. producing toxic free-radicals that disrupt bacterial DNA and proteins etc.

There are various types of antibiotics in modern world. Each type has its own unique area of impact, features of work and limits of effectiveness. In certain cases, prolonged treatment is necessary, in other cases, a timely change of the drug is necessary to achieve the optimal result. The most common and important groups of antibiotics are the following:

• aminoglycosides (including kanamycin, streptomycin, tobramycin, neomycin, gentamicin),
• carbapenems (including doripenem, imipenem),
• penems (including faropenem, ritipenem),
• cephalosporins (including cefcapene pivoxil, cephazolin, ceftriaxone),
• quinolones (including ciprofloxacin, levofloxacin, ofloxacin),
• glycopeptides (including teicoplanin, vancomycin),
• macrolides (including azithromycin, clarithromycin),
• penicillins (including amoxicillin, flucloxacillin),
• sulfonamides (including sulfamethizole, sulfasalazine),
• tetracyclines (including doxycycline, tetracycline),
• antibiotics targeting mycobacteria (antileprotic, antituberculotic – including isoniazid, ethambutol, rifampicin, clofazimine).

 Remember that antibiotics should not be abused, as this leads to the development of resistant bacterial strains. Consult with a specialist before you start medication to find best possible options.