A. Antibiotics - A natural substance, or derivative of a natural substance, which, when taken in small doses, will either kill or prevent the growth of a microorganism, but will not seriously harm the person taking it. This definition is based on the "principle of selective toxicity" in which it was proposed that drugs could be developed that would be toxic to microorganisms, but not to humans, i.e., selectively toxic.

B. History - In 1928, Sir Alexander Fleming discovered a mold contaminant on his culture plates of Staphylococcus aureus. Sir Fleming noted that the bacterium, Staphylococcus aureus, in the vicinity of the mold was destroyed. This remarkable discovery was the beginning of the antibiotic revolution which changed the course of modern medicine. There is probably no other class of medicinal agents which has so effectively prolonged life and increased the average life expectancy as antibiotics. There are very few individuals in the world today whose lives have not been affected by antibiotics.

A. Signs and symptoms of infectious disease - Most infectious diseases are apparent due to the development of symptoms such as fever, presence of sores or lesions, coughing, diarrhea, nausea, vomiting, inflammation, redness, pus formation, etc. Each of the symptoms will contribute information that is useful in helping to establish the cause of the infection so that an appropriate antibiotic may be selected for treatment.

B. Site of infection - The location of the infection is important since some antibiotics can reach certain parts of the body while others cannot. This is an important consideration in the selection of the appropriate antibiotic.

C. Cause of the infection - Most infectious diseases which are treatable with antibiotics are caused by bacteria, although fungi, protozoa, and rickettsia also cause such diseases. Viral diseases are not cured by antibiotics. Since different types of microorganisms respond differently to antibiotics, the identification of the microorganism that causes the disease is the single most important factor in the selection of the best antibiotic to cure the disease.

D. Treatment of the infection - The cure of an infectious disease will depend primarily on the proper choice of the most effective antibiotic for the disease. Not only must all of the above factors be considered in this choice, but the properties of the antibiotics themselves are among the most important information which contributes to the correct therapy for an infectious disease. Other factors which must also be considered are the general health and age of the patient, other medication which the patient may be taking and COSTS OF MEDICATION.

A. Penicillins - The first antibiotic to be used in medicine, penicillin G, is still one of the most useful and important antibiotics. It is considered to be the safest drug available. However, penicillin G suffers from certain shortcomings. For example, when taken orally, it is not very reliable because it is destroyed in the stomach. It is also easily destroyed by certain microorganisms, making it ineffective. In addition, it is effective against only a very small group of bacteria. In order to overcome some of these shortcomings, a number of penicillin derivatives were prepared by slight modification of the chemical structure of penicillin G. These newer penicillin antibiotics (semisynthetics) differ slightly from penicillin G in their chemical structures, their stability, and their range of antibiotic activity. There are now about twenty penicillin antibiotics which are used clinically. Some examples of penicillin antibiotics include penicillin V (PENVEE K, V-CILLIN) ampicillin (POLYCILLIN, OMNIPEN), and amoxicillin (AMOXIL). They are used to treat such common infections as strep throat, urinary tract infections, boils and carbuncles, as well as some very serious infections such as meningitis, pneumonia, and typhoid fever. While the penicillin antibiotics are generally very safe, about 15% of the population is allergic (usually a rash) to this class of antibiotics.

B. Cephalosporins - Cephalosporins are very similar to penicillins in their chemical structures. They are usually effective against a broader range of bacteria than the penicillins. However, most clinicians agree that the cephalosporins should be saved for cases in which the penicillins cannot be used or are not effective. Cephalosporins are also effective in infections such as respiratory tract infections and urinary tract infections.

C. Tetracyclines - The tetracycline antibiotics, like the penicillins, are among the most useful and important antibiotics. They are effective against a wide variety of bacteria and rickettsia. For this reason, they are called "broad spectrum" antibiotics. The tetracyclines should not be taken by pregnant women or by children less than 8 years old because they will discolor (darken) the developing teeth of the infants and children. Most tetracyclines should not be taken with food or milk because their effectiveness will be greatly diminished. Also, people taking some tetracyclines (especially demeclocycline, Ò Declomycin) should avoid sunlight (natural or artificial) since it makes the skin more sensitive, causing a very severe sunburn. Tetracyclines are used to treat a variety of sexually transmitted diseases (STD) and are often used in rape victims to prevent the development of STDís. In addition, the tetracyclines are used to treat Rocky Mountain Spotted Fever, acne, and the plague. Examples of tetracyclines, in addition to tetracycline itself, include doxycycline (VIBRAMYCIN), minocycline (MINOCIN), and demeclocycline (DECLOMYCIN).

D. Erythromycin - Erythromycin is probably the second safest antibiotic after penicillin G. In fact, it is used much like penicillin G and is a good alternative for people who are allergic to penicillins. Erythromycin (E-MYCIN, ILOTYCIN) is used for infections such as diphtheria, pneumonia, strep throat, Legionnaire's disease, and whooping cough.

E. Aminoglycosides and Polypeptides - The aminoglycoside antibiotics are used almost exclusively in hospitalized patients for serious life threatening infections. Polypeptide antibiotics are too toxic to be used generally in the body. However, they are not toxic if used topically, or on the surface of the body. There are a few of each of these types of antibiotics that are incorporated into creams and ointments for the treatment of skin infections that usually result from relatively minor cuts and abrasions. Examples of preparations that include combinations of aminoglycoside and polypeptide antibiotics include NEOSPORIN and POLYSPORIN.

F. Antifungal Antibiotics - When a fungus infects humans, it usually is a localized, contained infection that is slow to spread, but also takes longer to cure. Examples of fungal infections are athlete's foot, ringworm, jock itch, and vaginal yeast infections. These are usually treated by the application of antifungal drugs to the affected area. The antifungal antibiotic nystatin is included in MYCOLOG, which is used to treat vaginal yeast infections. Another antifungal antibiotic is griseofulvin (GRISACTIN, FULVICIN) which is taken orally for fungal infections of the fingernails and toenails. There are many synthetic antifungals on the market that are very effective against topical fungal infections but there are very few drugs available to effectively treat systemic infections which are often present in immune compromised patients like those suffering from AIDS.

A. Dosage and duration of therapy - Take all medication as prescribed for the full time prescribed. This is a very important point which cannot be overemphasized. The dosage and length of time prescribed is based on a knowledge of the infection and how long and how much antibiotic will be required to completely cure the infection. Failure to comply with the prescribed dose and duration of therapy will often result in a relapse and may lead to a more resistant strain of the bacterium that is more difficult to kill.

B. Follow the labeled directions - The pharmacist will provide special instructions for certain antibiotics and these should be followed exactly. For example, some antibiotics should be taken with meals and some should not.. Some antibiotics are available in liquid form, but must be shaken well in order to obtain the correct amount of antibiotic for the prescribed dose. It may be necessary to refrigerate some antibiotic preparations in order to keep them from degrading. All of this type of information, if it is applicable, will be provided by the pharmacist. If they don't provide the information, ask! It is very important to follow these directions in order to get the maximum benefit of the antibiotic. The most important point is to take the antibiotic as prescribed. If there is any antibiotic remaining at the end of the prescribed therapy, throw it away. DO NOT SAVE IT AND ATTEMPT TO USE IT ANOTHER TIME. Many antibiotics will degrade over time and often the outdated or old material can cause unwanted side effects or simply will not be effective.

1. Choose the most appropriate antibiotic based on the identification of the microorganism which causes the infection.

2. Use antibiotics with as narrow a range of effectiveness as possible.

3. Use a dosage which will cure the infection, but use the antibiotic for the shortest possible time which will effect a cure.

4. The patient should follow the labeled directions exactly.