(eSwab)
Swab
2.0 mL
Collection Technique: The lesion should be gently abraded with a sterile swab to collect serous fluid/exudate; avoid drawing blood. The swab tip is immediately placed into the transport medium.
Storage and Transport Temperature:
Refrigerated (2–8°C): This is the ideal condition for shipping and storage, with stability typically up to 14 days.
Room Temperature (2–30°C): Stability varies by medium; some (e.g., Aptima) are stable for up to 21 days, while others (e.g., M4/VCM) may be unacceptable.
Frozen (-20°C or -70°C): Specimens can be frozen if transport is delayed for more than 48 hours, or for long-term storage.
Handling: The swab shaft must be broken off at the score line, the cap screwed on tightly, and the tube labeled with the specimen source.
CSF or other body fluids.
REFRIGERATED
Mon-Sat
Next Day
qPCR
Molecular
(RML)
MHA-TP
Syphilis Antibody by MHA
Syphilis TPPA
T pallidum TPPA
T. pallidum Antibody by MHA
TP-PA
Treponema Pallidum AB, Particle Agglutination
Treponema pallidum Particle Agglutination Assay
Test
Antiseptics and Disinfectants: Cleaning the lesion with antiseptics or disinfectants before swabbing can kill the bacteria and degrade DNA, leading to false-negative results. Use sterile saline to clean the area if necessary.
Incorrect Swab Type: Cotton or calcium alginate swabs with wooden sticks may contain substances that inhibit the PCR reaction and are generally unacceptable.
Excessive Blood: Swabs contaminated with large amounts of blood should be avoided, as blood components can inhibit PCR amplification.
Commensal Treponemes: Sampling oral or anal lesions has a higher risk of false-positive results due to the presence of non-pathogenic Treponema species in normal flora, unless the lab uses highly specific PCR assays targeting unique T. pallidum genes (like tpp47 or polA).
Antibiotic Therapy: Recent or current antibiotic treatment can reduce the bacterial load in the lesion, potentially resulting in a false-negative test.
Specimen Preparation
Separate serum or plasma from cells ASAP or within 2 hours of collection. Transfer 1 mL serum or plasma to an ARUP standard transport tube. (Min: 0.4 mL)
Clinical Context: PCR results should be interpreted alongside the patient’s clinical presentation (e.g., visible chancre) and serological test results for accurate diagnosis.
Specimen Priority: Lesion swabs are generally much better than blood for detecting T. pallidum DNA by PCR, especially in the primary stage.
T. pallidum Cannot Be Cultured: Because the bacterium cannot be grown in artificial media, direct detection methods like PCR and dark-field microscopy are essential for primary diagnosis.
Testing Limitations: Commercial T. pallidum PCR tests are not as widely available as serological tests and are often laboratory-developed tests, so specific collection protocols must be followed precisely.
NEGATIVE: =1.1 INDEX
87798
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