Thursday, March 15, 2007

Gastric lavages and guinea pigs

What's the story behind gastric lavages?

The following explanation is given by Dr Carole Reeves, Outreach Historian, the Wellcome Trust Centre for the History of Medicine, University College London.

"The gastric lavage / guinea pig story is as follows: Bronchial and gastric lavage are established methods of obtaining cells and fluid contents for analysis . It's very difficult for children to produce sputum from the mouth by coughing and hawking but they will swallow sputum after coughing. Gastric lavage is therefore the only way that enough sputum (and bacteria) can be collected. The fluid is injected into guinea pigs. If they become infected, then the child still has active disease. Guinea pigs were also used to test resistance to streptomycin.

Bacteriology has moved on from guinea pigs to culture plates. Sputum or other samples are spread on plastic disks impregnated with a growing medium such as a gel. The disks are incubated at high temperature to encourage the growth of bacteria, which is then analysed under the microscope to determine the type of organism."

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