(eSwab)
Swab
2.0 mL
Storage and Transport Temperature: H. ducreyi is a fastidious organism, and maintaining DNA integrity is key for PCR.
Refrigerated (2–8°C): Store and ship refrigerated on cold packs (stable for at least a few days).
Frozen (-20°C or -70°C): If transport is delayed, specimens should be frozen on dry ice for shipping.
Room Temperature: Not recommended for prolonged periods; stability is poor for culture, but PCR samples may be stable for a limited time (e.g., up to 5 days in a specific medium like OneSwab).
Serum or plasma
Frozen
Tue, Thu, Sat
1-5 days
qPCR
Molecular
(RML)
Chlamydia trachomatis L serovar
Genital ulcer
Haemophilus ducreyi
Herpes simplex virus 1
Herpes simplex virus 2
Treponema pallidum
Test
Antiseptics/Disinfectants: Application of these agents to the ulcer before sampling can kill the bacteria and degrade DNA, leading to false negatives. Use only sterile saline for cleaning.
PCR Inhibitors: Certain components in clinical specimens (e.g., blood components, sodium phosphate in some transport media) can inhibit the PCR reaction. Proper sample preparation methods at the lab can help mitigate this.
Inadequate Specimen: Collecting only superficial crusts or failing to collect material from the base of the ulcer can result in a low bacterial load and a false-negative result.
Antibiotic Therapy: Prior or current antibiotic treatment may reduce the number of viable organisms or DNA content, affecting PCR sensitivity.
Specimen Preparation
APTIMA Swab: Place blue swab in swab specimen transport tube, break shaft off at score line, then recap tube.
Swab in Viral Transport Media (VTM): Transfer swab to viral transport media.
Not FDA Cleared: As of recent information, no H. ducreyi molecular assays have been cleared by the FDA for use in the United States, meaning tests are often lab-developed and specific protocols must be followed meticulously.
Clinical History Required: The lab requisition often requires detailed patient clinical history and travel history to endemic areas (e.g., Southeast Asia, Africa) for testing to be performed.
Differential Diagnosis: Genital ulcers can be caused by T. pallidum (syphilis) and Herpes Simplex Virus (HSV). It is recommended to collect additional swabs for syphilis testing (DFA or serology) and HSV culture/PCR simultaneously.
PCR vs. Culture: PCR is more sensitive than culture for H. ducreyi detection (96%-100% sensitivity vs. ~80% for culture). Culture requires highly specific media and ideal conditions (33°C to 35°C in 5% CO2) and must be plated at the bedside or transported rapidly (within 4 hours in Amies media).
Appearance: On Gram stain, H. ducreyi may exhibit a characteristic “”school of fish”” or “”railroad track”” arrangement of gram-negative coccobacilli.
NOT DETECTED
87798
76076-9
