Experiment 244 Serological Identification of Enteric Organisms

In addition to culture identification techniques, antibody reagents are available to detect O and H antigens of gram-negative enteric bacilli (usually Salmonella and Shigella species and Escherichia coli). The antibodies are used in a simple bacterial agglutination test in which an unknown organism isolated in culture is mixed with the antibody reagent (antiserum). If the antibodies are specific for the organism's antigenic makeup, agglutination (clumping) of the bacteria occurs. If the antiserum does not contain specific antibodies, no clumping is seen. A control test in which saline is substituted for the antiserum must always be included to be certain that the organism does not clump in the absence of the antibodies.

In this exercise, you will see how a microorganism can be identified by an interaction of its surface antigens with a known antibody that produces a visible agglutination of the bacterial cells.


To illustrate identification of a microorganism by the slide agglutination technique


Glass slides

70% alcohol

Saline (0.85%)

Capillary pipettes

Heat-killed suspension of E. coli or Salmonella

E. coli or Salmonella antiserum

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Bacterial Vaginosis Facts

Bacterial Vaginosis Facts

This fact sheet is designed to provide you with information on Bacterial Vaginosis. Bacterial vaginosis is an abnormal vaginal condition that is characterized by vaginal discharge and results from an overgrowth of atypical bacteria in the vagina.

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