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M. genitalium
is associated with nongonococcal urethritis in men attending an
urban STD clinic in New Orleans, Louisiana.
Mycoplasma
genitalium infections in asymptomatic men and men with
urethritis attending a sexually transmitted diseases clinic in New
Orleans.
Mena L, Wang X, Mroczkowski TF, Martin
DH.
Clin Inf Dis. 2002;35:1167-73
Summary:
Question
Is M. genitalium infection, detected with a modified polymerase
chain reaction assay (PCR), associated with urethritis in men who attended
an urban STD clinic in New Orleans?
Design
This study describes the results of M. genitalium detection by a
PCR assay in men with urethritis and in asymptomatic control subjects at
an STD clinic in New Orleans.
Participants
Ninety-seven men attending the City of New Orleans' STD clinic, aged 16-54
years, who had clinical symptoms or signs of urethritis were tested.
Urethritis was diagnosed if the patient experienced discharge, dysuria, or
penile irritation and if there were greater than 3 polymorphonuclear
leukocytes (PMNL) per oil-power microscopic field in a urethral smear.
Subjects were excluded if they had urinated less than one hour before
testing or had received antibiotic treatment during the 3 months prior to
testing. Control subjects were 184 men not reporting symptoms of
urethritis, who were attending the same clinic for reasons including
contact with women who had STDs (44%), for a screening examination (45%),
or for symptoms of other STDs (12%). Both case and control groups
consisted of >90% African American patients. There were no significant
demographic differences between the men with urethritis and the control
group. The mean age was 26 years.
Description of Tests and Diagnostic
Standard
Two urethral swab samples and approximately 30 mL of first void urine were
collected from each case subject; only urine was collected from the
controls. One swab was used to make a smear on a glass slide, which was
evaluated for PMNL, and was then tested for C. trachomatis and N.
gonorrhoeae by the Gen-Probe PACE 2 assay. The urine samples, which
were stored at 4oC, were tested for C. trachomatis and N.
gonorrhoeae using the ProbeTec strand displacement DNA amplification
assay according to the manufacturer's instructions (Becton-Dickinson). An
internal amplication control was used for all specimens. The second swab,
a thin wire Dacron-tipped swab that was placed in a dry tube and stored at
room temperature, and the urine samples were tested for M. genitalium
by PCR.
The High Pure PCR Template Preparation
Kit (Boehringer Mannheim) was used to extract DNA from half of each swab
sample and from the pellet obtained from 1 mL of each urine sample,
according to the manufacturer's instructions. Five µL of each 45 µL DNA
sample were added to the M. genitalium PCR reaction. The PCR
primers, MgPaW1 and MgPaWR1, targeted a 495 bp fragment of the adhesion
gene. The PCR products were electrophoresed in agarose gel, transferred to
a nylon filter, and hybridized with a biotinylated M. genitalium
DNA probe that was detected using a chemiluminescent substrate. Positive
samples were identified by the presence of a 495 bp band. For all positive
specimens, a second sample aliquot was processed and amplified. A specimen
was considered positive for M. genitalium only if both the first
and second aliquots were positive.
Main Outcome Measures
The prevalence of M. genitalium, N. gonorrhoeae, and C.
trachomatis in men with urethritis and in asymptomatic control
subjects was determined.
Main Results
The M. genitalium infection rate in men with urethritis in relation
to C. trachomatis and N.gonorrhoeae infections is shown in
table 1. In this analysis, M. genitalium infection was defined as a
positive test result for either the swab or the urine specimen. The
sensitivities of PCR of urine and swab specimens for the detection of M.
genitalium were 87% and 91%, respectively. Seventy-four (76%) of 97
men with urethritis were infected with at least one organism, several were
infected with more than one.
The organisms identified in urine samples
from men with urethritis and from asymptomatic controls are show in table
2. When patients with other infections were excluded, M. genitalium
was detected in 8 (25%) of 32 men with urethritis and in 10 (7%) of 142
asymptomatic men (P = .006).
| Table 1. M.
genitalium infection rates in men with urethritis in relation to
C. trachomatis and N. gonorrhoeae infections |
| Chlamydial
and gonococcal test result |
M.
genitalium infection rate,
number of subjects with results/
number tested (%) |
| C.
trachomatis positive |
7/20 (35) |
| N.
gonorrhoeae positive |
4/29 (14) |
| C.
trachomatis and N. gonorrhoeae positive |
3/16 (19) |
| C.
trachomatis and N. gonorrhoeae negative |
9/32 (28) |
| Total |
23/97 (24) |
Table 2. Organisms identified in 97 men
with urethritis and in 184 asymptomatic control subjects
| Organism |
Urethritis
(number, %) |
Asymptomatic
(number,%) |
P-value |
| M. genitalium |
20 (21) |
14 (8) |
<.002 |
| N. gonorrhoeae |
45 (46) |
15 (8) |
<.001 |
| C. trachomatis |
36 (37) |
32 (17) |
<.001 |
| None |
23 (24) |
132 (72) |
<.001 |
Authors' Conclusions
M. genitalium is associated with
nongonococcal urethritis in men attending an urban STD clinic in New
Orleans. There was a high rate of M. genitalium infection among
symptomatic men with chlamydia infection. The data presented validate the
use of urine samples for detection of M. genitalium by PCR.
Source of funding:
None given
For correspondence: David
H. Martin, Section of Infectious Diseases, Louisiana State University
Health Sciences Center, 1542 Tulane Ave., New Orleans, LA 70112. E-mail
address: dhmartin@lsuhsc.edu.
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