4. Do not eat or drink in the laboratory.

5. The pipettes graduated or Pasteur, should be operated

with rubber teats, and should always be plugged at the

mouthpiece with cotton wool.

6. Do not use tongue to moisten gummed labels,

envelopes, etc.

7. Discarded cultures and contaminated material should

be placed in disinfectant for 24 hours or autoclaved

before the containers are washed.

8. Wrapping from contaminated material should also

be placed in disinfectant and not in the waste paper

basket.

9. A bowl of strong disinfectant should be readily

available on the working bench, so that supernatant

fluids, etc. may be poured there rather than into the

sink.

10. Wire loops should be sterilized before and after use

and the mouths of tubes and bottles should be passed

through the flame on opening and closing.

11. While working, there should not be any current of

breeze, hence fans should be off and windows shut.

Specimen Collection

As far as possible obtain specimens before the

commencement of therapy. This is important especially for

CSF cultures. Often a purulent CSF will reveal no bacterial

pathogens on smear or culture when an antibiotic has been

given within the previous 24 hours. A patient with enteric

fever may show a negative stool culture if the specimen has

been collected while the patient was receiving suppressive

antibiotics. Another important factor for the successful

isolation of organisms is the stage of the disease at which

the specimen is collected for culture, enteric pathogens

are present in much greater numbers during the acute

or diarrheal stage of intestinal infections and they are

more likely to be isolated at that time. Specimens should

be inoculated as soon as possible. If it is not possible

then refrigerate the specimens at 4–6°C. Swabs from

wounds, urogenital tract, throat, rectum and samples of

feces or sputum can be refrigerated for 2–3 hours after

procuring them without appreciable loss of pathogens.

Urine specimens may be refrigerated for 12 hours without

affecting the bacterial flora. On the other hand, cloudy

CSF from a patient with purulent meningitis should be

examined immediately. Gastric washing, for culture of

Mycobacterium tuberculosis should be processed soon

after delivery as the Mycobacteria die quickly in gastric

washing. Specimens submitted for isolation of viruses

should be frozen immediately. Specimens of hair scrapings

may be submitted for isolation of fungi may be kept at

room temperature before inoculation. Sputum, bronchial

secretions, bone marrow and purulent material from

patients suspected of having a systemic fungal infection

should be inoculated to appropriate media as soon as

possible.