What is the room temperature stability of liquid Amies (transport medium) media for detecting vaginal pathogens by real-time Polymerase Chain Reaction (PCR)?

Room Temperature Stability of Liquid Amies Media for Vaginal Pathogen Detection by Real-Time PCR

Liquid Amies transport media maintains specimen stability at room temperature for up to 2 days for NAAT/PCR testing of most vaginal pathogens, with specific pathogens showing extended stability up to 7 days.

Stability by Pathogen Type

Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis

• Specimens in laboratory-provided transport devices (including liquid Amies) remain stable at room temperature for 2 days for NAAT testing of these three common sexually transmitted pathogens 1
• This 2-day window applies to vaginal swabs, endocervical swabs, and urine specimens 1
• Some FDA-cleared multiplex NAAT systems allow room temperature storage for up to 7 days for Trichomonas vaginalis detection specifically 1, 2

Herpes Simplex Virus (HSV)

• NAATs for HSV detection allow less strict sample transportation conditions compared to viral culture, which requires refrigeration and transport within 1-2 hours 1
• Specimens for HSV PCR can be stored in laboratory-provided transport devices at room temperature, though specific duration is assay-dependent and requires laboratory consultation 1
• This represents a significant advantage over viral culture, where delayed transport and lack of refrigeration substantially affect test outcomes 1

Bacterial Vaginosis-Associated Organisms

• Swabs for Gram stain (Nugent criteria) placed in transport tubes are stable at room temperature for 12 hours 2
• Real-time PCR detection of BV-related organisms (Gardnerella vaginalis, Mycoplasma hominis, Lactobacillus species) has been successfully performed on frozen stored specimens, demonstrating nucleic acid stability 3
• DNA hybridization probes for G. vaginalis detection allow room temperature storage for 7 days 1

Candida Species

• Specimens for yeast detection by DNA probe or multiplex NAAT can be stored at room temperature for 7 days 1, 2
• This extended stability applies to both C. albicans-specific tests and multiplex panels detecting resistant species 2, 4

Recent Research Evidence on Amies Media Stability

A 2024 study specifically evaluated vaginal samples stored in modified Amies solution (Amies/RNALater) and demonstrated complete preservation of vaginal microbiota composition during room temperature shipping 5:

• Samples shipped at room temperature for an average of 8 days (range 6-11 days) showed no significant differences in bacterial composition compared to immediately frozen samples 5
• Complete concordance (kappa: 1.0) was achieved for community state type classification between shipped and frozen samples 5
• No significant differences were found in taxon-level comparisons or bacterial abundances 5

Critical Practical Considerations

Exceptions Requiring Immediate Processing

• Wet mount microscopy for Trichomonas requires examination within 30 minutes to 2 hours, as motile organisms lose viability and become undetectable 1, 2
• Saline wet mount preparations for immediate microscopy should be submitted in 0.5 mL saline and examined within this narrow window 1, 2

Transport Medium Selection

• Laboratory-provided transport devices are specifically designed for room temperature stability 1, 2
• Universal transport medium (UTM) or viral transport medium (VTM) may be used for HSV specimens 1
• Modified Amies solutions with nucleic acid preservatives (such as Amies/RNALater) provide extended stability for microbiota studies 5

Clinical Algorithm for Specimen Handling

For PCR/NAAT testing of vaginal pathogens:

1. Collect vaginal swab using laboratory-provided collection device 1, 2
2. Place immediately in liquid Amies or appropriate transport medium 1
3. Transport at room temperature within 2 days for standard NAAT panels (CT/GC/TV) 1
4. Extended 7-day room temperature stability is acceptable for specific DNA probe tests and certain multiplex NAAT systems 1, 2
5. Consult laboratory for assay-specific requirements, particularly for HSV testing 1

Critical pitfall to avoid: Do not confuse stability requirements for PCR/NAAT testing with those for viral culture or wet mount microscopy, which require refrigeration and immediate processing respectively 1, 2.