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Infection means invasion of the body by microorganisms, which are harmful. The most common sources of infection in medical practice are direct contact with a patient’s blood and saliva, consequently instruments and equipment used in the treatment become contaminated. If no action were taken infection may enter the body through skin cuts or abrasions or the eyes, it may also be swallowed. Infection from the contamination would be passed on from patient to patient, from patient to staff and from staff to patient. This involvement is called cross – infection.
Even ancient people taught that body’s first of defense against infection was an intact surface, e.g. the outer layer of skin and the protective outer layer of
mucous membrane. If infection had passed it the second line of defense started its action. It was the liquid secretion produced by the protective surfaces. The mucous membrane and the salivary glands had produced saliva, which neutralized some bacterial poisons and could kill some microorganisms. Tears and sweat had a similar effect. The acidity of gastric juice killed many bacteria in food. The third line of defense is discovered now. It is immunity.
And we also know that if these defense mechanisms fail to prevent infection, the last line of defense is a response by the body called inflammation.
EXERCISE 1. Найдите в тексте эквиваленты следующих слов и словосочетаний:
2.Кровь и слюна пациента
3.Через порезы на коже
5.Наружный слой слизистой оболочки
6.Продуцируемая защитной поверхностью
7.Яды, вырабатываемые бактериями
EXERCISE 2. Процитируйте предложения из текста со следующими словами и словосочетаниями:
EXERCISE 3. Ответьте на следующие вопросы:
1.What are the most common sources of infection?
2.How may infection enter the body?
3.What did ancient people teach?
4.When does the second line of defense start its action?
5.What is it produced by?
6.What can saliva do?
7.What effect do tears and sweat have?
8.When was the third line discovered?
9.What is the last line of defense?
EXERCISE4. Измените предложения в прошедшее совершенное время:
MODEL: They have finished the work (by 5 o’clock yesterday).
They had finished the work by 5 o’clock yesterday.
1.My friend has prepared the report (by last Monday).
2.The students have done the exercises (by the end of the lesson).
3.Mother has cooked supper (by the time I came home).
4.We have not seen our teacher (before the bell rang).
5.Have you done the work (before I called you up)?
6.He has translated the article (by this time yesterday).
7.She has not bought a present for him (when we came to her place).
EXERCISE 5. Составьте 12 вопросов к тексту “Infection”.
EXERCISE 6. Приготовьте пересказ текста “Infection”.
In order to prevent cross – infection it is essential to kill all the microorganisms on infected instruments. This process is known as sterilization and means the killing of all microorganisms: bacteria, spores, fungi, and viruses. It is carried out immediately after completion of treatment so that all instruments are sterile again before use on the next patient.
Countless number of microorganisms lives on the skin and in the mouth, nose and throat. Normally they do no harm to their host as they living on an external surface and not among delicate internal cells. However, they may become harmful if they are introduced inside the body tissues, or are transferred from one person to another. This can occur when the tissues penetrated by contaminated forceps blade, scalper or syringe needle, and may give rise to harmful reaction. After each patient has left the surgery, it is the nurse`s duty to see that all instruments are properly sterilized before being used again for another patient.
As already mentioned, sterilization means killing not only bacteria and fungi, but all other microorganisms, including viruses and bacterial spores. Any method which kills bacteria and fungi but allows some spores or viruses to survive cannot be sterilization. The term used for this restricted range of action is disinfection.