USE OF DRUGS AGAINST MICRO-ORGANISMS ABBOTTS

VACCINES PAGE 27 Is a suspension of dead, weakened or fragmented germs or their toxins that will stimulate the production of antibodies These antibodies will induce immunity and so give protection against the disease

VACCINES HAVE BEEN DEVELOPED FOR: Polio Mumps Measles Typhoid Cholera Tetanus Influenza Yellow fever Hepatitis A and B Encephalitis Typhus

VACCINATION Is a process of giving a vaccine to a person to make them immune to a disease

HOW DO VACCINES WORK Contain dead or weak germs Injected, scratched, breathed in or taken orally Do not cause disease T lymphocytes produce antibodies [they think they are alive] Individual becomes immune to the germ Antibodies stay in the bloodstream If live germs enter the body they are destroyed straight away

Is there a vaccine to prevent TB? There is a vaccine for TB disease called Bacille Calmette-Gurin (BCG). It is used in some countries to prevent severe forms of TB in children.

ANTIBIOTICS TEXTBOOK PAGE 29 Antibiotics are substances that fight infections caused by bacteria Different antibiotics are developed to treat different infections Antibiotics cannot fight infections caused by viruses (colds, flu, HIV)

What is an antibiotic ? A substance that kills or halts the growth of a micro-organism (typically a bacterium) – cannot destroy viruses Usually made by other micro-organisms (fungi, other bacteria) Examples Pencillin Streptomycin Chloramphenicol

Why don’t antibiotics kill us ? Bacteria and humans share many core processes But there are some things that are completely different bacteria have a peptidoglycan cell wall and we don’t The best (least toxic to us) antibiotics target these “completely different” structures

HOW DO ANTIBIOTICS WORK Bacteria sometimes get past all the body’s defenses because they have reproduced so fast that the immune system cannot deal with the infection Permanent damage could be caused to the body Body needs help from the outside PAGE 29

HOW DO ANTIBIOTICS WORK Antibiotics destroy the bacteria directly Each antibiotic targets a certain part of the bacterium’s cell: Cell wall stop proper wall formation and the bacterial cell bursts Cell membrane damages the membrane which changes the permeability Protein synthesis Blocks the process and causes death

ADVERSE EFFECTS OF ANTIBIOTICS SIDE EFFECTS Nausea, diarrhoea, stomach cramps and vaginal yeast infections ALLERGIES Shortness of breath, itching, swelling of lips, face, tongue or fainting

ADMINISTRATION Antibiotics are either injected, given orally, or applied to the skin in ointment form. Many, while potent anti-infective agents, also cause toxic side effects. Some, like penicillin, are highly allergenic and can cause skin rashes, shock, and other manifestations of allergic sensitivity. Others, such as the tetracyclines, cause major changes in the intestinal bacterial population and can result in superinfection by fungi and other microorganisms.

ANTIBIOTIC RESISTANCE Bacteria can become resistant to antibiotics – they are then not affected by the drug Result is that diseases like tuberculosis are steadily increasing again In hospitals some bacteria are resistant to all known antibiotics – they are called “super bugs”

HOW DO RESISTANT STRAINS DEVELOP? Bacteria breed quickly Populations become enormous Chance mutations occur which produce bacteria which are resistant to antibiotics Resistant bacteria survive Multiply to produce a antibiotic resistant population Caused by overuse of antibiotics

How bacteria become resistant

WHY RESISTANT POPULATIONS DEVELOP ADD TO WORKBOOK Repeated use of antibiotics Every time a person takes antibiotics, sensitive bacteria are killed, but resistant ones are left to grow and multiply Incorrect use of antibiotics Wrong diagnosis – incorrect antibiotic for the bacterium causing the infection Unnecessary prescriptions eg for viral infections Improper use of antibiotics by patients – not completing the course Use of antibiotics as food additives eg in milk to promote growth

DANGERS OF ANTIBIOTIC RESISTANCE ADD TO WORKBOOK Ilnesses last longer More visits to the doctor More expensive and toxic medicines are needed Death!

TO DO TEXTBOOK PAGE 28 LEARNING ACTIVITY 19 HOW ANTIBIOTICS WORK

TYPES OF ANTIBIOTICS Are made from living organisms SYNTHETIC ANTIBIOTICS Originally, an antibiotic was a substance produced by one microorganism that selectively inhibits the growth of another. Synthetic antibiotics, usually chemically related to natural antibiotics, have since been produced that accomplish comparable tasks. NATURAL ANTIBIOTICS Are made from living organisms Process is called biosynthesis Are secreted by fungi: Eg Penicillium which grows on fruit Streptomyces grows in the soil

WHY ANTIBIOTICS DON’T KILL VIRUSES viruses are not living organisms - they have no biological systems to interrupt. viruses invade other cells and subvert the target cells biological functions to replicate more of themselves. if we created an antibiotic which worked against viraly infected cells, we would be creating an antibiotic which worked against our own cells

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