Abstract: Sequence specific DNA amplification and analysis techniques are provided. In some aspects, methods of the embodiments comprise amplifying sequence from two regions of a target sequence in the presence of a blocking oligonucleotide (e.g., such as a phosphorothioate-containing oligonucleotide) that hybridizes to the target sequence between the two regions. In some specific embodiments, a method is provided for detecting bacteria (such as detecting gram-positive or gram-negative bacteria) in a biological sample using polymerase chain reaction (PCR).