| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4368520 | International Journal of Food Microbiology | 2011 | 5 Pages |
A microbiological survey was conducted to determine the levels of total and pathogenic Vibrio parahaemolyticus (Vp) and Vibrio vulnificus (Vv) in Pacific oysters (Crassostrea gigas) collected from commercial growing areas in the North Island, New Zealand.The survey was intended to be geographically representative of commercial growing areas of Pacific oysters in New Zealand, while selecting the time frame most likely to coincide with the increased abundance of pathogenic vibrio species. Vp was detected in 94.8% of oyster samples examined (n = 58) with a geometric mean concentration of 99.3 MPN/g, while Vv was detected in 17.2% of oyster samples examined with a geometric mean concentration of 7.4 MPN/g. The frequency of Vp positive samples was 1.7 fold greater than reported in a study conducted three decades ago in New Zealand. Potentially virulent (tdh positive) Vp was detected in two samples (3.4%, n = 58) while no trh (another virulence marker) positive samples were detected. 16 S rRNA genotype could be assigned only to 58.8% of Vv isolates (8:1:1 A:B:AB ratio, n = 10). There was a good agreement [98.2% of Vp (n = 280) and 94.4% of Vv (n = 18) isolates] between molecular tests and cultivation based techniques used to identify Vibrio isolates and there was a significant (R2 = 0.95, P < 0.001, n = 18) linear relationship between the MPN estimates by real-time PCR and cultivation. There was no significant correlation between any of the environmental parameters tested and Vp or Vv concentrations.
Research highlights► Vp detected in 94.8% of oyster samples (n = 58), geometric mean concentration: 99.3 MPN/g; two samples positive for tdh, none for trh. ► Vv detected in 17.2% of oyster samples, geometric mean concentration: 7.4 MPN/g; 16S RNA genotype ratio: 8:1:1 (A:B:AB) for 58% of isolates. ► Good agreement between molecular tests and cultivation based estimates. ► The frequency of Vp positive samples 1.7 fold greater than reported three decades ago in New Zealand.
