Chapter 41
Sexually Transmitted Infections
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External Infections
• Condylomata
• Herpes
• Chancroid
• Granuloma
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Condylomata (Genital Warts)
• Human papillomavirus (HPV)
• Transient or persistent
• May be asymptomatic
• Associated with genital cancers
• Vaccine recently developed
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Question
Tell whether the following statement is true or false:
The HPV vaccine is currently available for both males and
females.
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Answer
False
The FDA has approved the vaccine for girls (optimal age is
9 to 12 years old). The vaccine is a series of three
shots/injections. Clinical trials are currently underway
evaluating the efficacy of the vaccine in males, but the
vaccine won’t be available for males until the trials are
complete and the FDA approves it.
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Genital Herpes
• Herpes simplex virus 2 (related to chickenpox
and cold sores)
• Causes genital ulcers
• Grows in neurons
• Can remain dormant in neurons for years
• Can reactivate and spread back down neuron
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Bacterial Diseases of External Genitalia
• Chancroid
– Haemophilus ducreyi
• Granuloma inguinale (genital ulcers)
– Calymmatobacterium
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Vaginal Infections
• Candidiasis
• Trichomoniasis
• Bacterial vaginitis
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Normal Bacterial Flora
• Many species of bacteria normally live in the vagina
• Lactic-acid-producing bacteria dominate
– Acid helps control growth of other bacteria
• Species composition of flora varies
– Between individuals
– Between ethnic groups
(Zhou, et al., [2004]. Characterization of vaginal microbial communities in adult healthy
women using cultivation-independent methods. Microbiology,150, 2565-2573. Retrieved
September 22, 2005, from http://mic. sgmjournals.org/cgi/content/full/150/8/2565.0)
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Candidiasis
• “Yeast infection” or “thrush”
• Causes include:
– Decreased normal bacterial flora (antibiotics)
– Increased estrogen/progesterone levels
– Decreased immune system activity
• Results in:
– Inflammation
– Thick odorless discharge
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Trichomoniasis
• Inflammation
• Frothy, malodorous, green or yellow discharge
• Associated with tubular infertility or pelvic
inflammatory disease
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Bacterial Vaginosis
• Nonspecific: may be caused by many different
bacteria
• Imbalance of normal vaginal bacterial flora
• Thin discharge with fishy odor
• Usually treated only if symptomatic or associated
with other risk conditions (pregnancy,
hysterectomy)
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Question
Which vaginal infection is associated with suppressed
immune function?
a. Candidiasis
b. Trichomoniasis
c. Bacterial vaginitis
d. Chancroid
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Answer
a. Candidiasis
Candidiasis (yeast infection/thrush) is associated with
diminished immune function. When the normal flora is
decreased, Candida albicans has room to thrive.
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Urogenital-Systemic Infections
• Chlamydia
• Gonorrhea
• Syphilis
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Chlamydia
• Intracellular parasites
– Signs at site of infection: hypertrophy, drainage
– Signs of urinary tract infection: urinary frequency,
dysuria, discharge, postcoital bleeding
– Signs of upper genital tract infection: irregular
uterine bleeding, abdominal/pelvic discomfort
• Complications include infertility and ectopic pregnancy
• May cause conjunctivitis
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Gonorrhea
• Bacterium Neisseria gonorrhoeae
• May be asymptomatic
• May cause pain and discharge
• May cause conjunctivitis
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Syphilis
• Spirochete Treponema pallidum
• Primary syphilis
– Chancre at site of exposure
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Syphilis (cont.)
• Secondary syphilis
– Disseminates to other organs
– Skin rash
– Mucosal lesions
• Tertiary syphilis
– Gumma lesions develop in organs
– CNS and heart often affected
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Question
Which of the following STDs may cause conjunctivitis?
a. Chlamydia
b. Gonorrhea
c. Syphilis
d. a and b
e. All of the above
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Answer
d. a and b
Certain STDs affect other body systems - chlamydia
(caused by an intracellular parasite/virus) and
gonorrhea (caused by a bacteria) may both result in
conjunctivitis.
Syphilis is affects the skin, organs, and CNS.
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