Antibacterials

"An antibacterial is an agent that kills bacteria or inhibits their growth or replication." 1

**What are some common antibacterials?**


Antibacterials are divided into two groups according to their speed of action and residue production.
 * Group 1 : Those who act rapidly to destroy bacteria, but disappear quickly and leave no active residue behind. Examples: chlorine, alcohol, peroxydes and aldehydes.
 * Group 2 : Leave long acting residues on the surface to be disinfected and therefore have a prolonged action. Examples: triclosan, triclocarban and benzalkonium chloride.

Infectious Organisms
Bacteria, fungi, viruses, yeasts and protozoa are micro-organism that can cause disease. A bacterium consists of a single cell with a cell wall made up of a mixture of proteins, sugars and lipids. Each bacterial cell contains a single chromosome consisting of a strand of deoxyribonucleic acid (DNA). Aerobic bacteria require oxygen and are more likely to infect surface areas such as the skin. Nonaerobic bacteria multiply in oxygen-free or low oxygen areas such as the bowel. Not all bacterias cause disease; in fact some are beneficial.

How do antibacterials work?
Antibacterials can be divided into two groups. The first group of antibacterials attacks a special piece of a germ and destroy it, while the second group destroys multiple cell components at once. There are two main mechanisms by which antibiotics destroy bacteria. **Penicillins** and **cephalosporins** prevent bacteria from making normal cell walls. Here is a short video that rapidly explains how both groups work. media type="youtube" key="gTWiaH_oCCY" height="315" width="420"

When are antibacterials useful?
Antibacterials are useful where the level of sanitation is critical. They are important in hospitals, day care centers and healthcare facilities. At home, they may be needed when there is a sick individual with a specific infection or for those whose immune system has been weakened by a disease.

[[image:Penicillin-G.png width="480" height="258"]]
Penicillin is a group of antibiotics derived from Penicillium fungi. Penicillin antibiotics were the first drugs that were effective against many diseases and infections.

Discovery of Penicillin
Penicillin was discovered by bacteriologist Alexander Fleming in 1928. Fleming was working with cultures of Staphylococcus aureus, a bacterium that causes boils and other types of infections. He left an open petri dish containing one of the cultures. Days later he noticed that mold had developed and had inhabited growth of the bacterium. He discovered that the mold (Penicillium notatum) produced a compound (penicillin) which inhibited the growth of bacteria. However, Fleming did not pursue his discovery. Howard Florey and Ernest Chain overcame the problems associated with isolating and purifying penicillin. They used penicillin to treat a policeman who was dying of septicaemia. They recorded dramatic improvements in his condition. The search to produce penicillin in bulk was on. In the 1950's the structure of penicillin was determined and this allowed chemists to create different types of penicillin and other antibiotics.media type="youtube" key="de5kxwp3vzI" height="315" width="560"

Uses of Penicillin
Penicillin is used to prevent bacteria from growing or to stop it from growing. It is important to know that penicillin ONLY works for bacteria, NOT viruses. Penicillin was a significant breakthrough since it was one of the first antibiotics developed. During World War II penicillin was used to fight infectious disease. Most commonly, this antibacterial is used to fight ear, intestinal, respiratory infections and sexually transmitted diseases. Doctors commonly prescribe penicillin to patients that have stomach ulcers, and abscess in a tooth, a wound infected with gangrene, chlamydia or gonorrhea. Since the discovery of penicillin, other antibacterials have been developed which have made the use and prescription of penicillin go down, yet it it still a very common antibacterial.

Overuse and Resistance to Penicillins
When penicillin became available to doctors, it was used a lot to treat minor illnesses. Certain bacteria became resistant to penicillin and were able to multiply. In the 1940's penicillin was used to treat gonorrhea. Some people got injections of penicillin to prevent the spread of gonorrhea, yet most of the time they were receiving the shot when they were not even sick. So, resistance to penicillin begun developing in these people. Also, in the 1950's penicillin could be purchased by anyone. This contributed to resistance because anyone could buy it, even if they did not need it. The resistance of the bacteria to penicillin is due to the presence of an enzyme called penicillinase, which deactivated the original penicillin. An important discovery about the resistance to penicillins was made by Sergio Filipe Alexander Thomasz in 1980. They discovered two genes that code for branched muropeptides. The bacteria that are resistant have these genes activated. If the genes are inactivated, the bacteria will not be resistant. This discovery opened up the option of creating new antibacterials. 6

Staphylococcus aureus and strains of Mycobacterium tuberculosis are methicillin-resistant. To treat these infections a 'cocktail' of different antibiotics is required to prevent the risk of further resistance developing.

The use of antibiotics in animal feedstocks also contributed to bacteria's resistance to penicillin. Livestocks are regularly injected with penicillin to prevent disease and enhance growth. If a person eats the infected meat, then it will not be easy to cure him/her because the bacteria has already developed a resistance to penicillin.

Allergic Reactions
Penicillin allergy is the most common allergy in the world. There is three types of adverse reactions:

-Nausea -Diarrhea -Rashes
 * Common adverse** (99% of patients who are allergic) :

-Fever -Seizures -Colitis
 * Infrequent adverse** (1% of patients who are allergic) :

**Anaphylaxis** ( very uncommon) -low blood pressure -difficulty breathing, -abdominal pain, -swelling of the throat or tongue

Administration and Side Effects of Antibacterials
There are several ways in which antibacterials can be administered to the patient. The doctor decides how to administer the medicine depending on the severity of the patient's sickness and their ability to take it. The most common way is orally, this is when the antibacterial is taken as a pill and swallowed with liquid, it is used when patients are in a stable condition. When the patient's condition is more critical, the doctor may choose use intravenous administration, where the medicine is put in directly into the blood stream and its effects are quicker. Finally, is the patient is unable to take the antibacterial orally or through an IV, the medicine can be administered topically, through eye drops or ointments.



Side effects can range from mild to severe depending on the amount of antibacterial administered and the individual patient. Usually, the severe side effects are a result of an allergy toward the antibacterial. When patients discover this allergy, many choose to wear a bracelet that says what they are allergic to, so, in case of an emergency doctors know what they cannot use. Mild effects include: Severe effects include:
 * Nausea
 * High fevers
 * Diarrhea
 * Hives
 * Swelling of the throat and mouth tissue
 * Difficulty breathing
 * Rapid pulse
 * Sudden increase in blood pressure

Antibacterial Interactions with Other Commonly Used Drugs
Alcohol: Even though there is no concrete evidence that mixing alcohol with antibacterials exists, doctors still do not recommend the mix of these two. Depending on which antibacterial the patient is taking, the effect of mixing it with alcohol can range from canceling the effect of the antibacterial, to causing nausea, vomiting and shortness of breath. Doctors suggest that if you will be drinking, drink moderately.

Birth Control: Similarly to alcohol, there is not concrete evidence that antibacterials will reduce the effectiveness of birth control pills. The failure rate of contraceptive pills caused by antibacterials is estimated to be 1%. There are certain antibacterials that will reduce the effect of the contraceptive pill, for example rifampicin. In these cases, it is vital for the patient to disclose all details of the medicine he or she takes to their doctor in order to prescribe the correct medicine.