Toxin Testing - PCR

PCR-based testing of Vibrio cholerae for ctx, vhlyA, rtx.

Isolate from urine, stool, blood, environmental, food, other.

Isolate provided on culture medium.

Send as growth on culture medium or in transport medium. Organisms should be sent as cultures.

Shipping of specimens shall be done by a TDG certified individual in accordance with TDG regulations. For additional information regarding classification of specimens for the purposes of shipping, consult either Part 2 Appendix 3 of the TDG Regulations or section 3.6.2 of the IATA Dangerous Goods Regulations as applicable.

Gastroenteritis, septicemia, infection, other.

Completed Enteric Diseases Program requisition form.

ctx – Cholera toxin; a major virulence factor; causes severe diarrhea; indicative of toxigenic Vibrio sp.

vhlyA – Hemolysin A is a pore-forming exotoxin; widely thought to enhance virulence of V. cholerae (accessory toxin)

rtx – repeat/accessory toxin; associated with toxin transportation

PCR-based identification of genes encoding toxins and virulence factors based on the following references and Standard Operating Procedures.

7 calendar days (unless prior notification that the sample is urgent)

1. Paton, A.W. and Paton, J. C. 1997. Detection and Characterization of Shiga Toxigenic Escherichia coli by using Multiplex PCR Assays for stx1, stx2, eaeA, Enterohemorrhagic E.coli hlyA, rfb0111, and rfb0157. J. of Clin. Micro. 36: 598 - 602.
2. Clark, C. G., A. N. Kravetz, C. Dendy, G. Wang, K. D. Tyler, and W. M. Johnson. 1998. Investigation of the 1994-5 Ukrainian Vibrio cholerae epidemic using molecular methods. Epidemiol. Infect. 121:15-29.
3. Sethabutr, O., M. Venkatesan, G. S. Murphy, B. Eampokalap, C. W. Hoge, and P. Echeverria. 1993. Detection of Shigellae and Enteroinvasive Escherichia coli by Amplification of the Invasion Plasmid Antigen H DNA Sequence in Patients with Dysentery. J. of Infect. Dis. Jan 167; 458-461.