Bacteriological Laboratory

In spite of immunization and effective treatment by modern drugs infectious diseases are still a major cause of illness and death worldwide. Recognizing microorganisms responsible for diseases is an essential step in the diagnosis and treatment of infectious illnesses. Tests to identify microorganisms play an increasingly important role in medicine today. All traditional tests performed in the bacteriological laboratory can be divided into two main groups: direct and indirect. The first method is microscopy, in which highly magnified images of microorganisms are produced so that they can be detected. Microscopy can be performed on any type of samples from the body, such as blood, urine, sputum or any other material withdrawn from the patient. Different microscopes are used to reveal different microorganisms. Bacteria are usually identified with light microscope. Viruses, which are much smaller than bacteria, are examined with a more powerful electronic microscope.

Sometimes test samples are taken and investigated immediately during the surgery, for example, to reveal bacteria causing the patient’s condition.. However, a sample often contains so few organisms that they cannot be identified easily. In such cases the microorganisms may be grown (cultured) to increase their number before microscopy.

Most samples are stained before a microscopic investigation to demonstrate the microorganisms they contain (for example, with Gram stain). When the samples are prepared different types of microorganisms can be recognized by their size, shape and color.

If the direct identification is impossible serologic methods are used. They are usually applied when a rapid diagnosis is needed or for diagnosing persistent infections (e.g. HIV infection), or to confirm the patient still has the immunity to a previous infection (such as rubella). This test is based on the reaction with antigen and antibody. Antigens and antibodies cannot be observed separately, but when they join together they form a large clump that can be seen by naked eye. The sample that is to be tested is added to the antibody-coated beads. If the suspected microorganism is present in the patient`s sample his antibodies will attach to the antigens beads, producing visible clumping.

Although the clumps of antigen and antibody may be seen without a microscope, the test may be made more sensitive by adding a fluorescent or radioactive marker to either the antigens or the antibodies before testing.

Words for better understanding:

In spite of – несмотря на

sample – проба, небольшое количество, взятое для образца

clump – слипаться в комок

suspect - подозревать

b) Answer the questions:

1.Why are bacteriological tests administered by doctors?

2.What equipment is needed to perform a bacteriological test?

3.What is the difference between direct and indirect bacteriological methods?

4.What kind of samples may be used for testing?

5.How is it possible to improve examining samples and identification of a pathogenic agent?

6. What is the basis of serological methods?

7. When are serologic methods used?

8. In what cases is it necessary to stain samples?

9. How can a serological test be made more sensitive?

2. Complete the sentences:

1.All common bacteriological tests can be divided......

2.The bacteriological tests can be performed on any......

3.To increase the number of detected microorganisms....

4.Testing for antibodies is used when.....

5.Antigen tests may be made more sensitive.......

6.In spite of effective immunization and vaccination…

7. The type of a microscope used to identify bacteria is…

8. Viruses can be seen only with … because…

9. Sometimes a serological test is necessary to confirm …

10. Visible clumps are produced when …

8. Translate into English:

1. В стационарном отделении больницы пациенты остаются на лечении несколько дней или недель.

2. Пациенты приходят в амбулаторное отделение, чтобы получить консультацию врача или какую-то процедуру.

3. При госпитализации в присемном отделении медсестра записывает общую информацию о пациенте в его историю болезни.

4. Медсестры также фиксируют основные признаки жизнедеятельности организма госпитиализируемого больного и передают их врачу.

5. Принимающий врач осматривает пациента, доставленного скорой помощью, и решает, в какое отделение (службу) больницы он должен быть доставлен.

6. Больные в критическом состоянии получают немедленное лечение.

7. Медсестры работают посменно, чтобы всегда быть в пределах досягаемости больного.

8. Медсестры больницы делают инъекции, ставят капельницы, берут желудочный сок для анализа.

9. Различные анализы крови, мочи и другие помогают врачу поставить правильный диагноз.

10. Во время своего обхода палат врачи измеряют давление и пульс у пациентов с заболеваниями сердца.

11. УЗИ позволяет контролировать деятельность органов брюшной полости.

12. Этому больному сделали ЭКГ и обнаружили у него увеличение правого желудочка сердца.

9. Read the list of various tests given below and explain why a doctor has ordered them. Try to give more reasons

Model: X-ray– Doctor ordered X-ray of lungs to exclude pneumonia in the patient.

X-ray, CT, ultrasound scan, MRI, digestive juice test, blood test, urine test, ECG

Дата добавления: 2015-10-31