Evaluation of the microagglutination test in the diagnosis of Mycoplasma gallisepticum infection in chickens.

The sensitivity and specificity of the microagglutination (MA), serum-plate-agglutination (SP), and hemagglutination-inhibition (HI) test for Mycoplasma gallisepticum (MG) were compared in groups of chickens infected with MG, M. synoviae, or Pasteurella multocida or inoculated with bacterins prepared from Staphylococcus aureus or Erysipelothrix rhusiopathiae. Of the three tests evaluated, the HI test had the highest specificity, but it was the least sensitive. Both the MA and SP tests were more sensitive than the HI test but lower in specificity. The MA test was less sensitive than the SP test in detecting antibodies against heterologous MG strains.