Exogenous contaminating DNA in Taq polymerases: A method to avoid false-positive results when detecting the bla gene.

In the course of developing an assay to identify genes responsible for antibiotic resistance in gram-negative bacteria, it has been found that standard (not DNA-free) Taq DNA polymerases were contaminated with bla gene fragments that varied in length and quantities. The complete bla gene sequence was either absent or was detected in infinitesimal amounts. We developed an approach to avoid false-positive findings caused by contaminating bla gene sequences in conventional polymerases.