The aim of this work was to construct and test a plasmidial Internal Control (IC) to detect the inhibition in the PCR test for M. tuberculosis and also its contribution for a Public Health Laboratory routine. The IC was a 600-bp of DNA linked to a plasmid with the same primer sites, allowing the amplification with the 245-bp diagnostic fragment. The amplification of the positive samples rendered the IC and the diagnostic fragment; instead negative samples only showed the IC. A total of 149 tuberculosis samples were studied and introduced the IC to monitor. Results showed 3.3% of the samples without amplification of the IC, suggesting the inhibition. These samples showed results in accordance with the clinical results. The objective of the IC was to identify the false negative results.
Polymerase Chain Reaction; tuberculosis; internal control; nucleic acid amplification; uracyl DNA glycosilase
