13 Nov

How Do Antibiotics Works

Antibiotics are a type of a powerful drug that are used to treat bacterial infections. It works by either killing the bacteria or by inhibiting its growth. They don’t work for infections against viral agents. Antibiotics are mostly prescribed to treat serious and severe bacterial infections. When an antibiotic is prescribed, it must be taken in required amounts. Antibiotics can be very harmful, when taken in a excess amount.

The term antibiotic is derived from a Greek word ‘’anti’’ meaning ‘’against’’ and ‘’bios’’ meaning life. This term was introduced by a French bacteriologist named Jean Paul. While the first antibiotic, Penicillin, was discovered by Alexander Fleming in 1928.

Antibiotics are used to treat bacterial infections and diseases which include syphilis, tuberculosis, meningitis, salmonella and acne. Antibiotics can be taken in the form of injections, liquids, tablets and capsules. They are also available as ointments, lotions and creams to treat the skin infections caused by bacteria.


There are number of antibiotics that are used to treat different bacterial diseases and bacterial infection. All of them work in a two ways:

A bactericidal antibiotic:

They tend to kill the invading bacteria. Penicillin is a bactericidal antibody. A bactericidal mostly interferes with the formation of the bacterium's cell wall or destroys its cell contents.

A bacteriostatic antibiotic:

It stops bacteria to reproduce and multiply.


Antibiotics are usually prescribed for serious infection and diseases caused by bacteria. Viruses cause many of the infections but an antibiotic will not be of use. Our immune system is strong enough to kills off the bacteria that causes mild infection. But some people having a defective or weak immune system can even not cope that mild infection causing bacteria. That is when antibiotics are prescribed.

However, you will surely need antibiotics if you undergo serious infections caused by bacteria such as meningitis or pneumonia. In these conditions, antibiotics are the only life-saving.

Antibiotics can also be prescribed to treat infections caused by bacteria on the skin. For example, acne, antibiotics can be taken by mouth or applied directly to the skin.


There are many different types of antibiotics. The best antibiotic for your infection will depend on what infection you have and the type of bacteria causing it.

  •     Aminoglycoside antibiotics

Active ingredients used in these:

  •     Amikacin
  •     Gentamicin (aminoglycoside antibiotics)
  •     Neomycin sulfate
  •     Tobramycin (aminoglycoside antibiotics)
  •     Cephalosporin antibiotics

Active ingredients used in these:

  •     Cefalotin
  •     Cefepime
  •     Cefotaxime
  •     Cefoxitin sodium
  •     Ceftaroline fosamil
  •     Ceftazidime
  •     Ceftolozane – tazobactam
  •     Ceftriaxone
  •     Cephalexin
  •     Cephazolin
  •     Macrolide antibiotics

Active ingredients used in these:

  •     Erythromycin
  •     Clindamycin
  •     Gentamycin
  •     Tetracycline
  •     Meclocycline
  •     (Sodium) sulfacetamide
  •     Penicillin antibiotics

Active ingredients used in penicillin antibiotics:

  •     Ampicillin sodium
  •     Benzathine penicillin
  •     Benzylpenicillin sodium
  •     Dicloxacillin sodium
  •     Flucloxacillin
  •     Phenoxymethylpenicillin
  •     Phenoxymethylpenicillin benzathine
  •     Phenoxymethylpenicillin potassium
  •     Piperacillin – tazobactam
  •     Procaine penicillin
  •     Ticarcillin – clavulanic acid
  •     Quinolone antibiotics

Active ingredients used in quinolone antibiotics:

  •     Ciprofloxacin (quinolone antibiotics)
  •     Moxifloxacin
  •     Norfloxacin
  •     Tetracycline antibiotics

Active ingredients used in tetracycline antibiotics:

  •     Minocycline hydrochloride
  •     Tigecycline

Most side-effects of antibiotics are not very serious. Common side-effects include:

  •     soft stools (faeces)
  •     diarrhoea,
  •     mild stomach upset such as feeling sick (nausea).
  •     Fungal infections of the mouth, digestive tract and vagina.

Rare side effects includes:

  •     Formation of kidney stones while using sulphonamides.
  •     Abnormal blood clotting while using  cephalosporins.
  •     Sensitivity to sun while using tetracyclines.
  •     Blood disorders while using trimethoprim.
  •     Deafness while using erythromycin and the aminoglycosides.

The length of treatment depends on what kind of infection you have and its severity. Treatment can be:

  •     For just a few days ('water' infection – urinary tract infection).
  •     For one or two weeks (pneumonia)
  •     For a few months (bone infections)
  •     For many months (acne).
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