Molecular Detection and Genotyping of Azithromycin Resistance

Molecular detection and genotyping of azithromycin resistant Treponema pallidum using conventional PCR and DNA sequencing.

Swab, cerebrospinal fluid (CSF), whole blood or fresh tissue.  Minimum of 0.5 mL of CSF, minimum of 0.5 mL of whole blood, 1-5 g of tissue. For other specimen types, please call or email prior to shipping.

Specimens may be subject to rejection if they are not the appropriate sample type, have insufficient volume, or are not accompanied by relevant patient information.

Use appropriate swab, such as Rayon or Dacron swabs to obtain specimens from ulcers.

Swabs can be shipped dry or in appropriate transport medium, such as viral transport medium.  Store samples refrigerated or frozen until shipped for testing.  Ship frozen samples on dry ice, and refrigerated samples on wet ice.

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.

Suspected of syphilis infection.

Completed Sexually Transmitted and Opportunistic Infections requisition form, including sender laboratory name, address, and telephone number. Patient identifier (specimen reference number), date of birth, and sex. Date collected and test requested.

Specimens that are positive by molecular detection using conventional PCR are genotyped to determine if they are resistant to azithromycin.

Conventional PCR procedures are performed on clinical specimens targeting genes specific to Treponema pallidum including tp47, polA, and bmp (1,2,3). ß-globin is amplified alongside the targets to assess specimen adequacy, verify DNA extraction quality, and confirm successful PCR amplification (4). Specimens positive by conventional PCR are subsequently genotyped to detect mutations associated with azithromycin resistance.

20 calendar days.

1. Burstain JM, Grimprel E, Lukehart SA, Norgard MV, Radolf JD. Sensitive detection of Treponema pallidum by using the polymerase chain reaction. J Clin Microbiol. 1991 Jan;29(1):62-69. doi:10.1128/jcm.29.1.62-69.1991.
2. Liu H, Rodes B, Chen CY, Steiner B. New tests for syphilis: rational design of a PCR method for detection of Treponema pallidum in clinical specimens using unique regions of the DNA polymerase I gene. J Clin Microbiol. 2001 May;39(5):1941-1946. doi:10.1128/JCM.39.5.1941-1946.2001.
3. Pietravalle M, Pimpinelli F, Maini A, Capoluongo E, Felici C, D'Auria L, Di Carlo A, Ameglio F. Diagnostic relevance of polymerase chain reaction technology for T. pallidum in subjects with syphilis in different phases of infection. New Microbiol. 1999 Apr;22(2):99-104.
4. Keller GH, Manak MM, editors. DNA Probes: Background, Applications, Procedures. New York: Stockton Press; 1993.