Bacteriological sampling of fish

Lesson 15

1. Read the words:

searing

sterile loop

incubate

bacterial fish

pathogens

gastrointestinal

2. Master the active vocabulary. Cover the left column and translate the Russian words back into English.

swab physiological saline Bunsen burner medicine

тампон физиологический раствор горелка Бунзена медицина

3. Word formation.

g) Analyze the meaning of the prepositions: un-, pre-, in-.

h) Find words formed with these prepositions in the text and translate them.

i) Give your own examples.

Step 1. Examination and direct inoculation of solid media.

Before examining a fish internally, the external body surface, including gills, tail and fins should be examined for the presence of any lesions. Observations should always be recorded on paper. Samples from these sites can be taken by searing the surface with a hot scalpel blade followed by insertion of a sterile bacteriological loop or swab.

Material from the loop/swab is then plated out onto suitable agar medium by the spread plate technique.

Once external examination or sampling has been carried out, the body surface is opened to expose the internal organs. Care must be taken not to puncture the gastrointestinal tract. In the absence of any visible internal lesions a sample of kidney is taken and inoculated onto suitable agar medium. The surface of the kidney (or other organ) should be seared with a hot scalpel blade before insertion of the sterile loop.

Agar plates containing the streaked out samples should be incubated and examined daily for any evidence of growth. The majority of bacterial fish pathogens will grow on Tryptone Soya Agar (TSA) within seven days. Media such as Marine Agar or TSA plus 1.5% salt (NaCl) can be used for marine pathogens.

Step 2. Kidney smears.

Direct examination of Gram stained kidney smears may give an indication of bacterial septicemia and is especially useful in the examination of fish for Bacterial Kidney Disease (BKD).

A small portion of kidney is emulsified in a loopful of sterile physiological saline on a microscope slide, allowed to air dry then fixed by passing the slide through a Bunsen flame several times.

Direct observation of the slide is carried out using the X40 and X100 (oil immersion) objectives after being stained using Gram's method.

Step 3. Bacteriology plates or swabs can be dispatched to the lab for investigation but must be clearly identified and labeled. A written note regarding the history and clinical appearance or the fish and samples taken is important.

4. Put down the nouns. Translate the words.

Model: to write – writer; писать - писатель

To carry - _____________; ______________ - ______________

To use - _______________; ______________ - _____________

To record - _____________; _______________ - ____________

To fix - ________________; _______________ - ____________

5. Combine the given adjectives (A) with the proper nouns (B).

A	B
clinical gastrointestinal bacteriological suitable hot Direct	scalpel loop observation appearance tract agar

6. Put down the English for:

метод окрашивания по Граму - _________________________

желудочно-кишечный тракт - __________________________

внешняя поверхность тела - ____________________________

эмульгированный - ___________________________________

мазок для микроскопических исследований почек - ________

Дата добавления: 2014-12-26