Abstract
We identified 6 sucrose-fermenting Vibrio vulnificus strains and examined their virulence characteristics. They were all encapsulated, motile, capable of producing toxins and utilizing transferrin-bound iron, cytotoxic to cultured cells, and virulent enough to kill mice. They could be definitely identified only by genetic identification methods such as PCR, and not by conventional culture-based identification methods such as API 20E (bioMérieux, France). These results indicate that it is essential to adopt genetic approaches as early as possible in order to avoid misdiagnosis of such strains, especially in clinical situations.
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Table 1.
Characteristics | Y-1 | Y-2 | Y-3 | Y-4 | Y-5 | Y-6 | M06-24/O |
---|---|---|---|---|---|---|---|
Source | E | E | C | E | E | E | C |
TCBS | Y | Y | Y | Y | Y | Y | G |
API20E∗ | 5147025 | 5047025 | 5047125 | 5247025 | 5147025 | 5047125 | 5247105 |
vvhA | P | P | P | P | P | P | P |
16S rDNA (%)† | 100 | 99.8 | 99.9 | 100 | 99.9 | 99.9 | 100 |
Colony | O | O | O | O | O | O | O |
VvpE | ++ | ++ | ++ | ++ | ++ | ++ | ++ |
VvhA | ++ | ++ | ++ | ++ | ++ | ++ | ++ |
Swarming | ++ | ++ | +‡ | ++ | +‡ | ++ | +++ |
TBI utilization | ++ | ++ | ++ | +‡ | +‡ | +‡ | +++ |
Cytotoxicity (%)§ | 101±5 | 41 ±4‖ | 78±4‖ | 15 ± 2‖ | 32 ± 2‖ | 101±3 | 109±7 |
Mouse lethality (hr)¶ | 2.7±0.2 | 15.8±6.9‖ | 2.4±0.3 | 19.5 ± 1.4‖ | 18.8 ± 0.0‖ | 18.7 ± 0.0‖ | 2.0±0.0 |
‡ P<0.05 in ANOVA on ranks; §Mean ±SE from triplicate experiments; ‖P<0.05 in one way ANOVA; ¶Mean time required for killing the five mice.
Abbreviations: E, environmental; C, clinical; TCBS, thiosulfate citrate bile salts sucrose; Y, yellow; G, green; O, opaque; TBI, transferrin-bound iron; vvhA, Vibrio vulnificus cytolysin/hemolysin gene; P, positive PCR band with the expected molecular size; +, weak positive; ++, moderate positive; +++, strong positive.