Evaluation of an Indirect Immunoperoxidase Test for Identification of Acholeplasma and Mycoplasma

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Abstract
Four Acholeplasma, 11 animal Mycoplasma (mostly bovine) and 7 human Mycoplasma types were examined using the indirect immunoperoxidase (IP), indirect immunofluorescence (IF) and growth inhibition (GI) tests to compare the sensitivity and specificity of these tests for the identification of Mycoplasmatales. The IP and IF tests were applied to unfixed colonies on agar blocks. Colonies of A. laidlawii, A. modicum, M. agalactiae and M. bovis showed a bright yellow autofluorescence in the IF test making it inapplicalbe in these cases. The IP test was as specific as the GI test and more specific than the IF test. In the IP test, cross-reactions were only found between M. agalactiae and M. bovis strains, 2 types originally considered to be related to each other. Cross-reactions between these organisms were not seen in the GI test. With 1 exception, the IP test was also found to be more sensitive than the GI test and as sensitive as the IF test; thus for 2 A. axanthum antisera the IP test was inferior to the IF and GI tests with A. axanthum strains. A close relationship was found in the IP and IF tests between M. mycoides strain Gladysdale and the unclassified bovine group 7 strain N29. The results of the IP test were much easier to read than those of the IF tests. Thus colonies treated with homologous antiserum became dark brown and, in mixed cultures, could be readily distinguished from heterologous colonies using a light microscope. All controls were negative and strains isolated from cattle, cell cultures [human, KB], humans and monkeys were easily identified.