Improvement of the mismatch amplification mutation assay-PCR for discrimination between Streptococcus suis serotypes 2 and 1/2

A mismatch amplification mutation assay (MAMA)-PCR, which detects a single-nucleotide polymorphism contributed to serological difference between Streptococcus suis serotypes 2 and 1/2, is used to discriminate between these serotypes. The present study reports unusual serotype 1/2 isolates untypable by the MAMA-PCR and improvement of the MAMA-PCR for typing such isolates. •S. suis serotype 1/2 untypable by the original MAMA-PCR were isolated.•The MAMA-PCR was modified to correctly typed these unusual isolates.•Modified MAMA-PCR will help discrimination between S. suis serotypes 1/2 and 2.