Reliability of PCR Methods for the Detection of Flavobacterium psychrophilum

We compared the sensitivity and specificity of PCR methods targeting 16S rDNA, DNA gyrase subunit genes (gyrA, gyrB) and peptidyl-prolyl cis-trans isomerase C gene (ppiC) for the detection of Flavobacterium psychrophilum using 82 bacterial isolates and 55 washings of fish gills. To identify F. psychrophilum among the bacterial isolates, the PCRs targeting 16S rDNA, gyrB and ppiC exhibited the same sensitivity and specificity but some false-positive results were found in the PCR targeting gyrA. The PCR targeting 16S rDNA was more sensitive than the other PCRs in detecting the bacterium from gill washings but occasionally gave false-positives. To avoid the false-positive result in gill washings, the PCRs targeting gyrB and ppiC seem to be preferable.