VOL: 100, ISSUE: 19, PAGE NO: 32
- Alexander Fleming discovered the antibacterial effect of penicillin in 1929.
- The phenomenal success of penicillin led to a search for other antibiotic-producing micro-organisms.
- Several hundreds of compounds with antibiotic activity have been isolated from micro-organisms. However, only a few are clinically useful because they must be highly effective and also have minimal toxicity to humans.
- Antibiotics are used to treat infections caused by bacteria.
- Some can be used to treat a wide range of infections and are known as ‘broad-spectrum’ antibiotics.
- Others are only effective against a few types of bacteria and are called ‘narrow-spectrum’ antibiotics.
- Some antibiotics work against aerobic bacteria and others against anaerobic bacteria.
- Antibiotics can also be use as a prophylactic to prevent an infection occurring, for example before orthopaedic surgery and to prevent secondary meningococcal meningitis, but this practice should be limited to clinically essential situations.
MODE OF ACTION
- Penicillins, cephalosporins, and vancomycin are bactericidal. They work by interfering with the cell wall of the bacteria.
- Sulphonamides, trimethoprim, quinolones, and nitroimidazoles are ‘bacteriostatic’. They work by stopping bacteria multiplying.
- Diarrhoea and nausea are common side-effects. Fungal infections of the mouth, digestive tract, and vagina can also occur.
- Rare but more serious side-effects include kidney stones with the use of sulphonamides, abnormal blood clotting with some cephalosporins, increased sensitivity to the sun with the tetracyclines, blood disorders with trimethoprim, and deafness with erythromycin and aminoglycosides.
- Antibiotic treatment can cause a type of colitis in older people leading to severe diarrhoea.
RISKS AND PRECAUTIONS
- Some people are allergic to antibiotics, particularly penicillins, therefore sensitivity should be checked before prescribing or administering this medication.
- Some antibiotics are contraindicated during pregnancy or when breastfeeding.
- Antibiotics can reduce the effectiveness of oral contraceptives - women should be advised to take additional contraceptive precautions.
- The repeated or continued use of antibiotics favours the growth of antibiotic-resistant mutants.
- Antibiotic resistance is not a recent phenomenon, it was recognised soon after the natural penicillins were introduced for disease control.
- In some cases there has been the emergence of pathogenic strains that show multiple resistance to a broad range of antibiotics such as methicillin-resistant Staphylococcus aureus (MRSA).
- Best practice principles of treatment have been developed to help reduce the emergence of resistant strains.
PRINCIPLES OF TREATMENT
- Only use when there is likely to be a clear clinical benefit.
- Do not use antibiotics for viral sore throats, simple coughs, and colds.
- Use simple generic antibiotics first whenever possible.
- Ensure that the dose and course duration is adequate for the nature of the infection.
- The use of new and more expensive antibiotics (for example quinolones and cephalosporins) is inappropriate when standard and less expensive antibiotics remain effective.
- Avoid the widespread use of topical antibiotics (especially those agents that are also available as systemic preparations).
- Where a ‘best guess’ therapy has failed or special circumstances exist, microbiological advice should be obtained.
Health protection agency: ‘www.hpa.org.uk/infections/topics_az/antimicrobial_resistance/guidance.htm