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Understanding Antibiotics

Understanding Antibiotics

December 10, 2012


Despite their widespread use all over the world antibiotics still remain the most misunderstood medicines. I have seen two typical parental reactions when it comes to antibiotics usage in children. One group is of parents who look at these medicines as some kind of miracle drugs and expect them to be prescribed by the doctor for every possible illness.  The other group is of parents who look so suspiciously at any antibiotic prescription as if it is a page flown out of some dreaded ‘conspiracy theory’!

Both these extremes are wrong and what is needed is a sensible ‘middle path’ where antibiotics are used when necessary and avoided when unnecessary. So let’s examine facts and eliminate fictions about antibiotics!

What are antibiotics?

Since the time when Alexander Fleming discovered penicillin –the first ever antibiotic- way back in 1940, antibiotics have occupied a pride of place in modern medicine. Thanks to them, millions of lives have been saved from deadly infections.

When are they necessary?

Antibiotics are useful in bacterial infections. Common infections of various body organ systems are caused mostly either by viruses or by bacteria. In children, almost 90-95% of such infections are viral in origin. Antibiotics are unnecessary in viral infections as they don’t have any effect on viruses.

Through clinical examination and laboratory tests, the doctors can mostly differentiate viral from bacterial infections. Sometimes even in a viral infection, antibiotics are given to prevent subsequent likely bacterial invasion. 

Severe suggestive symptoms at very young ages, urinary infections, pneumonias, middle ear infections and CNS infections usually warrant antibiotics.

What is a spectrum of an antibiotic?

The types of bacteria against which an antibiotic is mostly effective constitutes its spectrum and that is taken into consideration before starting treatment. For most infections, ‘Broad spectrum’ antibiotics which are effective against a wide variety of different types of bacteria are used.

Why there are so many types of antibiotics?

Thanks to the continuous research and advancement of medicine, there are plenty of groups of antibiotics and each of that group has a number of members. Most commonly used antibiotic groups are Penicillins (Benzylpenicillin, Amoxycillin, Cloxacillin, Ampicillin), Cephalosporins (Cefadroxil, Cefaclor, Cefotaxime, Ceftriaxone, Ceftazidime), Macrolides (Erythromycin, Clarithromycin, Azithromycin), Fluoroquinolones (Ciprofloxacin, Norfloxacin) and Aminoglycosides (Gentamicin, Amikacin).

The main aim in development of any new antibiotic is to improve its activity, broaden its spectrum and lessen its side-effects. But beware that not all new antibiotics are better than their age-old predecessors and in terms of money they are usually costlier.

Why sometimes many antibiotics are used together?

In severe infections like septicemia, multiple antibiotics are used to launch a multi-pronged attack on bacteria. By augmenting each other’s action, by working on the same infective organism through different routes, by broadening the treatment spectrum these combinations eradicate infections.

Combination antibiotics like Amoxycillin-Clavulanate and Sulfa-trimethoprim which are also used very commonly even for milder infections also work on same principles.

What are the side-effects of antibiotics?

  • Gastro-intestinal disturbances (nausea, vomiting, diarrhea) and skin rashes are the commonest side-effects and can be seen to a more or less degree with almost any antibiotic.
  • Penicillin injection and occasionally oral penicillin can cause severe anaphylactic allergic reactions.
  • Aminoglycosides can cause adverse effects on kidney and hearing.
  • Tetracyclines cause a permanent yellow staining of teeth.
  • Chloramphenicol can cause bone marrow depression and a drop in blood counts.
  • Sulfa drugs can lead to a severe reaction called Steven-Johnson syndrome.
  • Quinolone group of antibiotics can cause joint affection.
  • Long term antibiotic therapy can cause pseudomembranous colitis – an inflammation of colon.


Many of these antibiotics like sulfa drugs, quinolones, tetracyclines, chloramphenicol and penicillin are avoided whenever possible in children.

Then what is wrong with rampant antibiotic usage?

The most important problem associated with repeated use of antibiotics is the development of bacterial resistance. Bacteria might become ‘used to’ the antibiotics and then develop mechanisms to resist its action in future. The commonest factor aiding the bacteria to develop such resistance is the tendency of people to use incomplete, inadequate antibiotic courses.

What is the ideal duration of antibiotic course?

The duration of antibiotic therapy is determined by the chosen antibiotic and the site, type and severity of infection. Most common infections need a course of 3-7 days whereas serious infections like septicemia, meningitis and pneumonia could need courses of 2-4 weeks. Urinary tract infections and middle ear infections also usually need 10-14 days of antibiotics.

What is ideal dosage schedule for antibiotics?

The doses of antibiotics for children are calculated as per their body weight. The doses for various antibiotics are different and so are their strengths. There is little sense in comparing ‘10mg of this’ with ‘100 mg of that’ antibiotic.

What is the ideal antibiotic strategy for parents?

  • Never start antibiotic on your own.
  • Never demand an antibiotic prescription from your doctor.
  • Ask the doctor ‘Why’ and ‘Which’ about the antibiotic prescription.
  • Discuss about side-effects and any relevant queries.
  • Costlier, newer antibiotics are not always the best choices. Ask the doctor if alternative is possible.
  • Follow the dosage/ duration of antibiotic schedule as advised.

Remember antibiotics are not ‘monsters’. They really are ‘miracle medicines’ but only in situations where they are absolutely necessary!


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