Evaluation of alkaline phosphatase- and digoxigenin-labelled probes for detection of the thermolabile hemolysin (tlh) gene of Vibrio parahaemolyticus

The biochemical identification and enumeration of Vibrio parahaemolyticus a s described in the FDA Bacteriological Analytical Manual is expensive and l abour-intensive. To reduce fort necessary to verify the identity of V. para haemolyticus, the use of a thermolabile haemolysin (tlh) gene probe is prop osed. An alkaline phosphatase (AP)-labelled probe was evaluated for specifi city against 26 strains of V: parahaemolyticus, 88 strains of other Vibrio species and 10 strains of non-vibrio io species, tested, the probe hybridiz ed only with the 26 strains of V. parahaemolyticus, indicating species spec ificity. Two hundred and six suspect V. parahaemolyticus isolates from oyst ers were tested by this probe and API-20E diagnostic strips, there there 97 % agreement between results, A digoxigenin (DIG)labelled probe for detectio n of the tlh gene fragment was prepared by PCR and compared with the AP-lab elled probe. When tested on 584 suspect V. parahaemolyticus results obtaine d with the AP- and DIG-labelled probes, were in 98% agreement. These result s suggest that the probes are equivalent for detection of the V. parahaemol yticus tlh gene.