Læknablaðið - 15.07.1995, Blaðsíða 16

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LÆKNABLAÐIÐ 1995; 81
Table I. Performance ofPCR compared with culture on cervical specimens from 88females, 33 (38%) ofwhom were considered
infected.
Results of culture Results of PCR
No No of positive No of negative No of positive No of negative
Infected 33 29 4’) 31 22>
Not infected 55 0 55 0 55
Total 88 29 59 31 57
1) Initial culture results were inconclusive on three specimens because of the cytopathogenisity of the specimen and one was a false negative.
21 One specimen was PCR negative on initial testing but was positive when the test was repeated on the same specimen. The other remained negative on
repeating.
Table II. Performance ofPCR compared with culture on 91 urine specimens and urethral swabsfrom males, 47 (53%) ofwhom
were considered positive.
Results of culture Results of PCR on urine Results of PCR on swabs
No No positive No negative No positive No negative No positive No negative
Infected 47 33 14 45 2 19 28’>
Not infected 44 0 44 3 41 0 44
Total 91 33 58 48 43 19 72
1) The results were positive in 13 instances when the test was repeated on the same specimen.
collected first on a Culturette® swab that was
used for culture of N. gonorrhoea, U. ure-
alyticum and M. hominis. If the patient had no
discharge this specimen was taken last. Two
urethral specimens were collected for the de-
tection of C. trachomatis. Specimens for cul-
ture and PCR were collected in an alternating
sequence. The sample intended for culture was
collected on a cotton swab (Medical wire Co)
and put in 1.0 ml of 0.2 M sucrose phosphate
buffer, antibiotics and 10% foetal calf serum
and cooled with ice. One sample was collected
with collection kits supplied by Roche. A first
void urine sample was collected after swab
specimen collection. Specimens were deliver-
ed to the laboratory within three hours. Speci-
mens for culture and Amplicor® were either
processed right away or frozen at -70°C until
processing.
Test procedures: Specimens for culture of C.
trachomatis were agitated with glass beads and
0.6 ml of the buffer was added to two tubes
with a monolayer of McCoy cells. The cells
were centrifuged for one hour at 5000 g at
35°C. The supernatant was aspirated and re-
placed with maintenance media containing cy-
cloheximide. The tubes were incubated at 35°C
for 48-72 hours and the slide from one of the
tubes was examined stained with Fluorescent
Antibody (Syva MicroTrak FA). If the slide
was conclusively positive or negative the slide
from the second tube was stained. If the exam-
ination of the first tube was inconclusive the
second was subcultured and the procedure re-
peated.
The Amplicor® assay was performed on a
Perkin Elmer thermocycler supplied by Roche
Molecular Systems for the study. The test was
performed according to manufacturer’s in-
structions. When discrepancy occurred, the
leftover Amplicor® specimen was retested by
Roche with Amplicor® and a primer for the
Major Outer Membrane Protein (MOMP)
gene.
Results
Results from 179 patients were evaluated in
the study, 88 females, 15 to 35 years of age with
the median age of 20, and 91 males 17 to 36
years of age with the median age of 23. Of
those 179 patients, 80 (45%) were considered
to be infected. None of the patients had Go-
norrhoea. A patient was considered infected,
even if culture was negative, when two types of
tests were positive, for example two tests with
different primers. The prevalence of infection
in the 88 females was 38% (table I). The sensi-
tivity of culture and PCR in females was 88%
and 94% respectively and specificity of both
methods was 100%. Of the 91 males 48 were
considered positive, a prevalence of 53% (ta-
ble II). Thirty two had signs or symptoms of