Development of a multiplex PCR assay to detect Edwardsiella tarda, Streptococcus parauberis, and Streptococcus iniae in olive flounder (Paralichthys olivaceus)

A multiplex PCR protocol was established to simultaneously detect major bacterial pathogens in olive flounder (Paralichthys olivaceus) including Edwardsiella (E.) tarda, Streptococcus (S.) parauberis, and S. iniae. The PCR assay was able to detect 0.01 ng of E. tarda, 0.1 ng of S. parauberis, and 1 ng of S. iniae genomic DNA. Furthermore, this technique was found to have high specificity when tested with related bacterial species. This method represents a cheaper, faster, and reliable alternative for identifying major bacterial pathogens in olive flounder, the most important farmed fish in Korea.

A simple, rapid and economic method for detecting multidrug-resistant tuberculosis

OBJECTIVE: To evaluate multiplex allele specific polymerase chain reaction as a rapid molecular tool for detecting multidrug-resistant tuberculosis. METHODS: Based on drug susceptibility testing, 103 isolates were multidrug-resistant tuberculosis and 45 isolates were sensitive to isonicotinylhydrazine and rifampin. Primers were designed to target five mutations hotspots that confer resistance to the first-line drugs isoniazid and rifampin, and multiplex allele specific polymerase chain reaction was performed. Whole-genome sequencing confirmed drug resistance mutations identified by multiplex allele specific polymerase chain reaction. RESULTS: DNA sequencing revealed that 68.9% of multidrug-resistant strains have point mutations at codon 315 of the katG gene, 19.8% within the mabA-inhA promoter, and 98.0% at three hotspots within rpoB. Multiplex allele specific polymerase chain reaction detected each of these five mutations, yielding 82.3% sensitivity and 100% specificity for isoniazid resistance, and 97.9% sensitivity and 100% specificity for rifampin resistance as compared to drug susceptibility testing. CONCLUSIONS: The results show that multiplex allele specific polymerase chain reaction is an inexpensive and practical method for rapid detection of multidrug-resistant tuberculosis in developing countries.