a method for detecting in a biological sample the presence of lyme - disease causing spirochetes using the polymerase chain reaction . this method includes the steps of : isolating dna from the biological sample ; amplifying the isolated dna under hybridizing conditions with a primer pair that targets portions of extrachromosomal linear plasmid gene encoding outer surface protein a or outer surface protein b of the lyme - disease causing spirochetes , probing the amplified dna under hybridizing conditions with a labeled gene probe ; and detecting the labeled gene probe that hybridized to the amplified dna of the lyme - disease causing spirochetes .