UTILITY OF AN INTERNAL CONTROL FOR EVALUATION OF A MYCOPLASMA-MELEAGRIDIS PCR TEST

Mycoplasma meleagridis, a turkey pathogen, can be detected by PCR dire ctly from tracheal or genital swabs. However, up to 40% samples may co ntain inhibitory substances. A DNA fragment, that can be amplified wit h M, meleagridis primers and in the same cycling conditions, was const ructed to use as an internal control (IC) to check for these inhibitor s. This IC can easily be distinguished from the M. meleagridis amplico n after agarose gel electrophoresis since it is longer. Use of this IC in PCR amplifications revealed that more than 35% of turkey tracheal swabs and more than 45% of turkey cloacal swabs contained inhibitors. In most cases, dilution (1:100) of swab lysates allowed amplification of the internal control but DNA purification may be necessary to elimi nate inhibitors (20% of tracheal swabs and 5% of cloacal swabs). Use o f this internal control DNA allowed assessment of the efficiency of ea ch individual reaction and ensured that the reaction was not inhibited by interfering substances. (C) 1998 Elsevier Science B.V.