C h a p t e r 4 1
Sexually Transmitted Infections
1055
usually requires a medical appointment to confirm the
presence of vaginal candidiasis. Recurrent vulvovagi-
nal candidiasis, defined as four or more mycologically
confirmed episodes within 1 year, affects approximately
5% of women and is difficult to manage. Maintenance
therapy with oral fluconazole often is required for long-
term management of this problem.
16–18
Trichomoniasis
Trichomoniasis affects an estimated 120million people in
the United States and is the most prevalent nonviral sex-
ually transmitted infection worldwide.
4
Trichomoniasis
vaginalis
infections are commonly associated with other
STIs and are therefore a marker for high-risk sexual
behavior. Although the infection is commonly transmit-
ted by sexual contact, it can occur via fomites and the
organism has been shown to survive in swimming pools
and hot tubs.
2
The manifestations of infection with
T. vaginalis,
the
causative agent of trichomoniasis, are primarily observed
in women, and range from asymptomatic presentation
to a copious, frothy, malodorous green or yellow dis-
charge.
19–21
There often is erythema and edema of the
affected mucosa, with occasional itching and irritation.
Sometimes, small hemorrhagic punctations, called
straw
berry spots
, appear on the cervix. Men can present with
urethritis, prostatitis, and discharge, but most men are
largely asymptomatic.
21
Trichomoniasis vaginalis
is an anaerobic protozoan
that is shaped like a turnip and has three or four ante-
rior flagella (see Fig. 41-3B, C). Trichomonads can reside
in the paraurethral glands of both sexes. This extracel-
lular parasite feeds on the vaginal mucosa and ingests
bacteria and leukocytes. Trichomonads attach easily to
mucous membranes. It may reduce the chorioamnionic
membrane strength and predispose pregnant women to
premature rupture of membranes and premature birth.
19
Trichomoniasis vaginalis
infection has emerged as a
cofactor for HIV transmission. Potential mechanisms for
increased susceptibility include recruitment of HIV tar-
get cells, weakening of structural integrity of epithelial
cells and their defense against HIV invasion, and creation
of punctate microhemorrhages in mucosal genital tissue
that serve as a portal of HIV entry.
19,20
Trichomonads
may serve as vectors for the spread of other organisms,
carrying pathogens attached to their surface into the fal-
lopian tubes; infection has been associated with acute sal-
pingitis and postpartum endometrial infection.
21
In men,
it is a common cause of nongonococcal urethritis and is a
risk factor for infertility, altering sperm motility and via-
bility. It has also been associated with chronic prostatitis.
Diagnosis is made microscopically by identification
of the motile protozoan on a wet-mount slide prepara-
tion. The pH of the discharge usually is greater than 6.0.
Newer point-of-care tests include an antigen-based diag-
nostic test (OSOM
Trichomonas
Rapid Test), a DNA
probe test (Affirm VP III), and a PCR-based test. The
OSOM and DNA probes have greater sensitivity than a
vaginal mount and results can be available in less than
an hour.
4,19
Because the organism resides in other uro-
genital structures besides the vagina, systemic treatment
is recommended. Metronidazole and tinidazole, which
are the treatments of choice against anaerobic protozo-
ans, can cure
T. vaginalis
.
19
Systemic treatment is pre-
ferred over topical application to achieve adequate drug
concentrations in nonvaginal sites.
19
Because the organ-
ism responds to only one class of medication, mild drug
resistance has been noted against metronidazole but not
tinidazole.
24
Although metronidazole is considered safe
for use during pregnancy, data on tinidazole use in preg-
nancy are limited. Sexual partners should be treated to
avoid reinfection, and abstinence is recommended until
the full course of therapy is completed.
Bacterial Vaginosis
Bacterial vaginosis is a polymicrobial infection charac-
terized by lack of hydrogen peroxide–producing lac-
tobacilli and an overgrowth of anaerobic organisms.
It is the most prevalent vaginal disorder in women of
reproductive age.
2
Bacterial vaginosis is associated with
multiple male or female sex partners, a new sex partner,
lack of condom use, and douching.
4,22–24
Sexual activity
is believed to be a catalyst rather than a primary mode
of transmission, and endogenous factors may play a role
in the development of symptoms.
The predominant symptom of bacterial vaginosis
is a thin, grayish-white discharge that has a foul, fishy
odor. Burning, itching, and erythema usually are absent
because the bacteria have only minimal inflammatory
potential. Because of the lack of inflammation, the term
vaginosis
rather than
vaginitis
is used to describe the
condition. The organisms associated with bacterial
vaginosis may be carried asymptomatically by men and
women.
The pathogenesis of bacterial vaginosis remains
poorly understood. It is a complex disorder character-
ized by a shift in the vaginal flora from one dominated
by hydrogen peroxide–producing lactobacilli to one
with greatly reduced numbers of
Lactobacillus
species
and an overgrowth of facultative anaerobic organisms,
including
Gardnerella vaginalis
,
Mobiluncus
species,
and
Mycoplasma hominis
.
2,22,24
The massive overgrowth
of vaginal anaerobes is associated with the production
of proteolytic enzymes that break down vaginal amines,
which become volatile and malodorous in a high pH.
The amines are associated with increased vaginal secre-
tions and squamous epithelial cell exfoliation, creating
the typical discharge. In conditions of elevated pH, the
vaginal anaerobes more efficiently adhere to the exfoli-
ating epithelial cells, creating what are called
clue cells
(Fig. 41-4).
In addition to causing bothersome symptoms, bac-
terial vaginosis is associated with an increased risk of
pelvic inflammatory disease (PID), adverse pregnancy
outcomes including premature rupture of membranes,
preterm labor, preterm birth, and postpartum endometri-
tis linked to the organisms associated with bacterial vagi-
nosis. Postoperative infections, including postabortion
