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Inoculation of
modified Columbia agar is a sensitive method for culture of T.
vaginalis from clinical samples in the routine laboratory.
Detection of Trichomonas
vaginalis on modified Columbia agar in the routine laboratory.
Stary A, Kuchinka-Koch A, Teodorowicz
L.
Journal of Clinical
Microbiology 2002;40:3277-3280.
Summary:
Question
How does cultivation of T. vaginalis on modified Columbia agar
(MCA) compare to microscopy and to broth culture (study I) and to
microscopy only (study II) for diagnosis of trichomoniasis?
Design
Two studies were carried out. Study I compared isolation of T.
vaginalis on MCA to identification of T. vaginalis by wet mount
or Gram stain and to culture in a commercially available liquid medium.
Study II compared culture on MCA to identification by direct microscopy
(wet mount vs. Gram stain for symptomatic patients).
Participants
For study I, 889 women attending the Outpatients' Center in Vienna,
Austria for symptoms or signs of genital tract infection, or for contact
tracing were recruited. For study II, 39,585 men and women presenting to
the STD center for routine examinations or for suspected genital tract
infections were included.
Description of Tests and Diagnostic
Standard
For study I, four swabs were collected from the posterior vaginal fornix
of each woman. The first two swabs were used for wet mount and Gram stain,
respectively. Trichomonas medium (Oxoid Ltd., Basingstoke, Hampshire,
England) and MCA (Columbia agar, Oxoid Ltd.) plates were inoculated with
the third and fourth samples, respectively. For study II, vaginal swabs
from women and urethral swabs from men were collected and used for Gram
staining and to inoculate MCA plates. For symptomatic patients (n=111), an
immediate wet mount was also performed. Immediate incubation of inoculated
broth and agar plates, which were held under anaerobic conditions, was
carried out at 37oC for 6 days. Identification of T. vaginalis from
culture was achieved by observation of motile organisms in wet mount
preparations.
Main Outcome Measures
The sensitivity of each diagnostic method, in symptomatic and asymptomatic
individuals, for the detection of T. vaginalis, as determined by
all methods combined was calculated.
Main Results
For study I, a combined total of 63 (7.1%) of 889 women were positive for T.
vaginalis by direct microscopy (wet mount or Gram stain), by culture
in broth, or on MCA. T. vaginalis was observed in 57 (90.5%), 58
(92.1%), and 62 (98.4%) of the 63 positive samples by microscopy, broth
culture, and MCA culture, respectively.
For study II, a combined total of 91
(0.23%) of 39,272 asymptomatic and 111 (100%) of 111 symptomatic men and
women were positive for T. vaginalis by direct microscopy (gram
stain for asymptomatic, gram stain and wet mount for symptomatic patients)
or by culture on MCA. Among asymptomatic patients, T. vaginalis was
detected in 64 (70.3%) and 91(100%) of 91 positive samples by Gram stain
and MCA culture, respectively. Among symptomatic patients, T. vaginalis
was detected in 103 (92.8%), 99 (89.2%), and 108 (97.3%) of 111 positive
samples by wet mount, Gram stain, and MCA culture, respectively.
Authors' Conclusions
Detection of T. vaginalis by culture
on MCA had a sensitivity of 98.5% in a low-risk population comprising
symptomatic as well as asymptomatic patients. It is a highly sensitive,
reliable, and easy-to-handle culture technique for the diagnosis of T.
vaginalis infections.
Source of funding: None given
For correspondence: Angelika Stary,
Outpatients' Center for Diagnosis of Infectious Venerodermatological
Diseases, Franz-Jonas-Platz 8/2/3, A-1210 Vienna, Austria. E-mail address:
angelica.stary@univie.as.at.
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