Written by- Dr. Aditi Nanda

Penicillin was the first antibiotic to be used for clinical use in the year 1941. Ever since, there’s been a vast variety of antibiotics being produced and used. These drug work by multiple mechanisms; some inhibit cell wall synthesis (penicillin, cephalosporins), some damage the cell membrane (Amphotericin B, Nystatin), others inhibit protein synthesis (tetracycline, erythromycin), and there are others that inhibit DNA function (rifampicin) and interfere in metabolism (sulphonamides).

Antibiotics can be bacteriostatic (sulphonamides, tetracycline) or bactericidal (penicillin, cephalosporins, rifampicin). They can be narrow (penicillin) or broad spectrum (tetracycline).

Success and failure

The success of antibiotic therapy depends upon attainment of sufficient concentration of the drug at the site of infection and sensitivity of the drug to the infectious microorganism.

Antibiotics have now been long used, or I should say overused. This has led to a major problem of failure of antibiotics treatment due to acquired resistance of the drug by the microorganism. This occurs by change in DNA (mutation). This can be prevented by limiting the use of antibiotics to only when required, selecting the correct choice of antibiotic, its dose and duration of intake. Combinations of antibiotics can be used in severe infections to delay the development of resistance.

General considerations

There are some general considerations while choosing an antibiotic. Not all drugs can be given to all age groups. For e.g., sulphonamides are contraindicated in new born because they displace bilirubin from its binding site, which then reaches the brain due to weak blood brain barrier and causes kernicterus. Similarly, tetracyclines are to be avoided in renal and hepatic failure because there is increased risk of drug toxicity due to poor drug metabolism.

Chemoprophylaxis

Antibiotics aren’t given only when there’s an infection. In many cases, where there is a high chance of an infection being developed, antibiotics are used prophylactically. For e.g., pre and post-surgery, post-exposure to infection (syphilis), in immunocompromised patients (HIV-AIDS), in patients receiving anticancer drugs (reduced immunity), in areas of disease endemic (malaria), in patients with valvular heart disease (because they are at increased risk of bacterial endocarditis), in doctors to prevent nosocomial infections (hospital induced), etc.

Superinfections

Superinfections means appearance of new infections due to use of antibiotics. Antibiotics, especially broad spectrum alter the normal microflora of the body as well, what we call the ‘good’ bacteria. Due to this reduced competition for nutrition, the opportunistic bacteria flourishes.

Probiotics

Probiotics are the products that contain viable, non-pathogenic bacteria, the ‘good’ microbes. These are usually advised to reduce the chances of superinfections. Some of the commonly used probiotics are lactobacillus, enterococcus, Bifidobacterium etc. Some of the foods rich in probiotics are yogurt, cheese, buttermilk, green peas, olive pickles, etc.