BERKSHIRE HEALTH SYSTEM LABORATORIES
Berkshire Medical Center
Fairview Hospital
Chlamydia and Gonorrhea
Intended Use
The Gen-Probe Aptima Chlamydia trachomatis and Neisseria gonorrhea Assay
uses Transcription Mediated Amplification (TMA) technology for the direct, qualitative
detection of ribosomal RNA of C. trachomatis or N.gonorrhea in female endocervical
and male urethral swab specimens or in male and female urine specimens from
symptomatic and asymptomatic males and females.
Summary and Explanation of the Test
Chlamydia are non-motile, Gram-negative, obligate intracellular parasites of
eukaryotic cells. They form inclusions in the cytoplasm of the host cell. Chlamydia
trachomatis, one of three chlamydial species, is known to be a major etiologic agent of
urogenital infections associated with salpingitis, ectopic pregnancies and tubal factor
infertility in women as well as nongonococcal urethritis and epididymitis in men 1-3. The
genital site most commonly infected in women is the cervix, but the infection can be
asymptomatic and, if untreated, is likely to ascend to the uterus, fallopian tubes and
ovaries and may result in pelvic inflammatory disease (PID)4. Neonates born of infected
mothers can contract inclusion conjunctivitis, nasopharyngeal infections and pneumonia
due to C. trachomatis 5. Infection by C. trachomatis in men is also often asymptomatic
and, if untreated, may lead to epididymitis, a major complication3.
Gonorrhea is one of the most commonly reported sexually transmitted diseases in
the United States with nearly 700,000 reported cases per year. N. gonorrhoeae is the
etiologic agent of gonorrhea. In men, gonorrhea infection usually results in acute anterior
urethritis accompanied by a purulent exudate1. In women, the infection is most often
found in the cervix, but the vagina and uterus also may be infected. Frequently the
infection is asymptomatic, especially in women. Without treatment, local complication
of gonococcal infection can occur including pelvic inflammatory disease (PID) or acute
salpingitis for women and epididymitis for men1.
Target amplification assays are based on the ability of complementary oligonucleotide primers to
specifically anneal and allow enzymatic amplification of the target nucleic acid strands. The GenProbe TMA reaction replicates a specific region of the 23S rRNA from C. trachomatis and a
specific region of the 16S rRNA from N. gonorrhoeae via DNA intermediates. A unique set of
primers is used for each target molecule. Detection of the rRNA amplification product sequences
(amplicon) is achieved using nucleic acid hybridization (1). Single-stranded chemiluminescent
DNA probes, which are complementary to a region of each target amplicon, are labeled with
different acridinium ester molecules. The labeled DNA probes combine with amplicon to form
stable RNA: DNA hybrids. The Selection Reagent differentiates hybridized from unhybridized
probe, eliminating the generation of signal from unhybridized probe. During the detection
step, light emitted from the labeled RNA: DNA hybrids is measured as photon signals in a
luminometer, and are reported as Relative Light Units (RLU). In DKA, differences in the
kinetic profiles of the C. trachomatis and N. gonorrhoeae labeled probes allow for the
differentiation of signal; kinetic profiles are derived from measurements of photon output
during the detection read time. The chemiluminescent detection reaction for C.
trachomatis signal has very rapid kinetics and has the "flasher" kinetic type. The
chemiluminescent detection reaction for N. gonorrhoeae signal is relatively slower and
has the "glower" kinetic type. Assay results are determined by a cut-off based on the total
RLU and the kinetic curve type.
Specimen Collection and Transport to Test Site
Time and temperature conditions for storage must be adhered to during transport.
Transport to the BHS lab within 24 hours of collection.
For swab specimen collection, use only the Gen-Probe Unisex Swab
Specimen Collection Kit for Endocervical and Urethral Swab Specimens.
Note: Do not use the Large-tipped Cleaning Swab for Specimen Collection.
Endocervical Swab Specimen Collection
1.
Remove excess mucus from the exocervix with the large-tipped cleaning swab
provided in the LCx STD Swab Specimen Collection System and discard.
2.
Insert the small-tipped, specimen swab into the endocervix and rotate the swab for
15 - 30 seconds to ensure adequate sampling.
3.
Verify that all Swab Specimen Transport Buffer is at the bottom of the tube. If
necessary, tap or shake the solution down to the bottom of the tube. Unscrew the
cap of the transport tube, insert the swab into the transport tube and break the
swab at the score line. Replace the cap securely making sure that the swab fits
into the cap and then screw on the cap until it clicks into place.
4.
Label the transport tube with the patient's ID number and date of collection.
Male Urethral Swab Specimen Collection
1.
2.
Insert the small-tipped, specimen swab 2 to 4 cm into the urethra and rotate the
swab for 3 - 5 seconds to ensure adequate sampling.
Verify that all Swab Specimen Transport Buffer is at the bottom of the tube. If
necessary, tap or shake the solution down to the bottom of the tube. Unscrew the
cap of the transport tube, insert the swab into the transport tube and break the
swab at the score line. Replace the cap securely making sure that the swab fits
into the cap and then screw on the cap until it clicks into place.
3.
Label the transport tube with the patient's ID number and date of collection.
Swab Specimen Transport
1.
Swab specimens can be shipped to the laboratory or testing site at ambient
temperature. Swab specimens must arrive at the test site within 24 hours of
shipment.
Urine Specimen Collection and Transport
Urine specimens can be transported to the laboratory at 2to 30C in either the primary collection
device (urine cup) or in the urine specimen transport tube. Urine specimens must be transferred
into the GENPROBE specimen transport tube within 24 hours of collection and before being
assayed. After transfer, urine specimens can be stored at 2to 30C for up to 30 days after
collection.
3. Urine specimens
a. The patient should not have urinated for at least one hour prior to specimen collection.
b. Direct patient to provide a first-catch urine (approximately 20 to 30 mL of the initial urine
stream) into a urine collection cup free of any preservatives. Collection of larger volumes of urine
may result in specimen dilution that may reduce test sensitivity. Female patients should not
cleanse the labial area prior to providing the specimen.
Turnaround Time: 3-5 days
Approved by:
Medical Director: C. Abbott, MD
Approved by:
Technical Director: R. Intres, PhD
Prepared by:
R. Intres, PhD
Bhshlp/LabProc/OP/MB/GC-Chlam
Adopted: 5-25-06
Revised:
Reviewed: 1-27-12 RI