My Science School

Special drugs called antibiotics are used to treat diseases caused by bacteria. Early antibiotics were made from moulds and fungi, but today they are produced artificially from chemicals. Antibiotics work by breaking down the cells of the bacteria. There is some concern that the continued use of antibiotics could create problems for the future because the bacteria are becoming resistant to the drugs.

Any substance that inhibits the growth and replication of a bacterium or kills it outright can be called an antibiotic. Antibiotics are a type of antimicrobial designed to target bacterial infections within (or on) the body. This makes antibiotics subtly different from the other main kinds of antimicrobials widely used today:

• Antiseptics are used to sterilise surfaces of living tissue when the risk of infection is high, such as during surgery.


• Disinfectants are non-selective antimicrobials, killing a wide range of micro-organisms including bacteria. They are used on non-living surfaces, for example in hospitals.

Of course, bacteria are not the only microbes that can be harmful to us. Fungi and viruses can also be a danger to humans, and they are targeted by antifungals and antivirals, respectively. Only substances that target bacteria are called antibiotics, while the name antimicrobial is an umbrella term for anything that inhibits or kills microbial cells including antibiotics, antifungals, antivirals and chemicals such as antiseptics.

Most antibiotics used today are produced in laboratories, but they are often based on compounds scientists have found in nature. Some microbes, for example, produce substances specifically to kill other nearby bacteria in order to gain an advantage when competing for food, water or other limited resources. However, some microbes only produce antibiotics in the laboratory.

Antibiotics are used to treat bacterial infections. Some are highly specialized and are only effective against certain bacteria. Others, known as broad-spectrum antibiotics, attack a wide range of bacteria, including ones that are beneficial to us.

There are two main ways in which antibiotics target bacteria. They either prevent the reproduction of bacteria, or they kill the bacteria, for example by stopping the mechanism responsible for building their cell walls.

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Some people may be more at risk from disease than others. in many developing countries, people may be short of food or may not have access to clean water. In such circumstances, they are at risk from nutritional diseases such as scurvy and rickets, as well as those that thrive in areas with poor sanitation, such as cholera and hepatitis. In industrialized nations, the population may have an increased risk of cancer and heart disease, brought about by high-fat diets and unhealthy lifestyles.

Some groups of people appear to be at higher risk of more complicated or severe illness, including:

• Pregnant women;


• Infants and young children particularly under age 2;


• people of any age with certain chronic health conditions (including asthma or lung disease, heart disease, diabetes, kidney disease or some neurological conditions);


• People with severely compromised immune systems.

Currently, people age 65 or older are the least likely to be infected with the pandemic influenza, but those who do get sick are also at high risk of developing serious complications, just as they are from seasonal flu.

Who recommends that pregnant women, or others at higher risk of severe illness and their caregivers, be vaccinated against pandemic influenza and take all the necessary precautions, including hygiene measures, to prevent the spread of illness.

Vaccination against the pandemic influenza is prudent for everyone to reduce chances of infection.

Hepatitis C Virus (HCV) is spread primarily by contact with blood and blood products. Blood transfusions and the sharing of used needles and syringes have been the main causes of the spread of HCV in the United States. With the introduction in 1991 of routine blood screening for HCV antibody and improvements in the test in mid-1992, transfusion-related hepatitis C has virtually disappeared. At present, injection drug use is the most common risk factor for contracting the disease. However, there are patients who get hepatitis C without any known exposure to blood or to drug use.

Those individuals most at risk for hepatitis C infection are:

• People who had blood transfusions, blood products, or organ donations before June, 1992, when sensitive tests for HCV were introduced for blood screening.


• Health care workers who suffer needle-stick accidents.


• Injection drug users, including those who may have used drugs once many years ago.


• Infants born to HCV-infected mothers.


• Other groups who appear to be at slightly increased risk for hepatitis C are:


• People with high-risk sexual behavior, multiple partners, and sexually transmitted diseases.


• People who snort cocaine using shared equipment.


• People who have shared toothbrushes, razors and other personal items with a family member that is HCV-infected.

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People can he protected from certain diseases by being given a weakened version of the germ that causes a disease. This is called immunization. A successful immunization programme has completely eliminated the disease of smallpox. Immunization programmers are especially important for developing countries.

When you get sick, your body makes antibodies to fight the disease to help you get better. These antibodies stay in your body even after the disease is gone, and protect you from getting the same illness again. This is called immunity. However, you don’t have to get sick to develop immunity. You can gain immunity against disease through immunization.

Immunization (or vaccination) protects people from disease by introducing a vaccine into the body that triggers an immune response, just as though you had been exposed to a disease naturally. The vaccine contains the same antigens or parts of antigens that cause the disease, but the antigens in vaccines are either killed or greatly weakened. Vaccines work because they trick your body into thinking it is being attacked by the actual disease.

Immunity through immunization happens without the consequence of being ill and without the risk of potential life-threatening complications from the disease. Once a person is immunized, specific immune cells called memory cells prevent re-infection when they encounter that disease again in the future. However, not all vaccines provide lifelong immunity. Vaccines such as the tetanus vaccine require booster doses every ten years for adults to maintain immunity.

At any age, vaccination provides the longest-lasting, most effective protection against disease. Vaccine-preventable diseases can be serious, and in some cases can cause life-threatening complications that can lead to hospitalization. This is especially a concern for infants and young children, who are particularly more vulnerable. Having children vaccinated on time is important and helps ensure that they receive the protection they need as early as possible to fight off diseases before they are exposed to them.

Immunization is important not only in childhood, but in adulthood as well, to help promote healthy aging. This is because childhood immunization does not provide lifelong immunity against some diseases such as tetanus (lockjaw) and diphtheria. Adults require helper, or booster, shots to maintain immunity. Adult vaccinations may also be recommended to protect against disease common in adulthood such as shingles.

Adults who were not adequately immunized as children may be at risk of infection from other vaccine-preventable diseases. They can also infect others. For example, adults who become ill with measles, mumps or pertussis (whooping cough) can infect infants who may not yet be fully immunized.

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