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Sexually Transmitted
Infections
Chapter 24
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Sexually Transmitted Urogenital
Infections
Bacterial infections
Gonorrhea
Caused by microorganisms of the species Neisseria
gonorrhoeae
Aerobic, non–spore-forming, gram-negative, diplococcus
Transmission generally requires contact of epithelial
surfaces
Gonorrhea also crosses amniotic membranes
Humans are the only natural hosts
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Sexually Transmitted Urogenital
Infections
Gonorrhea
Presence of pili helps the microorganisms attach
themselves to the epithelial cells of mucous
membranes
Infections can result in:
Disseminated gonococcal infection (CGI)
Perihepatitis
Ophthalmia neonatorum
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Sexually Transmitted Urogenital
Infections
Syphilis
Treponema pallidum
Corkscrew-shaped, anaerobic bacterium that cannot
be cultured in vitro
Infects any body tissue
Syphilis becomes a systemic disease shortly after
infection.
Maternal-fetal transmission
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Syphilis
Stages
Primary syphilis
Local manifestations
Granulomatous tissue reaction—hard chancre
Microorganisms drain with the lymphatic fluid
Secondary syphilis
Systemic manifestations
Fever, malaise, sore throat, hoarseness, anorexia, joint pain,
skin rash, and lesions (condylomata lata)
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Syphilis
Stages
Latent syphilis
Medical evidence of the infection, but patient is
asymptomatic
Tertiary syphilis
Most severe stage
Formation of gummas
Destructive skin, bone, and soft tissue lesions
Destructive systemic manifestations
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Syphilis
Congenital syphilis
Vasculitis, necrosis, fibrosis, and generalized
tissue destruction
Manifest in the first 2 years of life
Late stage manifestations occur near puberty
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Sexually Transmitted Urogenital
Infections
Chancroid
Typical in underdeveloped or developed tropical
climates
Painful, tender, soft chancre
Acute infectious disease caused by Haemophilus
ducreyi
Gram-negative bacillus
Inguinal buboes
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Chancroid
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Sexually Transmitted Urogenital
Infections
Granuloma inguinale
Chronic, progressive, destructive bacterial
infection
Caused by Klebsiella granulomatis; gram-negative,
non–spore-forming, encapsulated bacillus
Mildly contagious; repeated exposure is required
Concurrent infection with syphilis is common
Does not occur in the United States
Donovan bodies
Bacteria-filled vacuoles within white cells
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Sexually Transmitted Urogenital
Infections
Bacterial vaginosis
Sexually associated condition, but not always an STI
Caused by Gardnerella vaginalis and various other
anaerobes
Manifestations
Gray vaginal discharge, pH > 4.5, odor, presence of “clue” cells on
wet mount
Bacterial catalytic enzymes degrade proteins and elevate the
vaginal pH to produce a fishy odor
Clue cells are vaginal epithelial cells covered with bacteria
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Chlamydial Infections
Chlamydia
Infections caused by Chlamydia trachomatis
Most common STI in the United States
Obligate, gram-negative, intracellular bacterium
Growth cycle (two parts)
Elementary body
Small, resilient, metabolically inert, able to survive
extracellularly
Metabolically active parasite
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Chlamydial Infections
Lymphogranuloma venereum
Caused by Chlamydia trachomatis (invasive
serovars of strains L1, L2, and L3)
Chronic STI
Begins as a skin lesion and spreads to genital and
rectal lymphatic tissue
Inflammation, necrosis, buboes, abscesses, and
infections
Can spread to the CNS
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Chlamydial Infections
Nongonococcal or nonspecific urethritis
Nonreportable STI
Syndrome caused by a variety of microbes
Most common is C. trachomatis
Trichomonas vaginalis, herpes simplex virus,
Ureaplasma urealyticum, and Mycoplasma
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Sexually Transmitted Viral
Infections
Genital herpes
Two serotypes
Herpes simplex virus type 1
Herpes simplex virus type 2
80% of initial and 98% of recurrent infections are type 2
Not a reportable disease
Transmitted through contact with a person who is
shedding the virus in a secretion or from a
peripheral lesion or mucosal surface
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Sexually Transmitted Viral
Infections
Genital herpes
Initial virus replication occurs locally
Virus spreads to contiguous cells and into sensory
nerves
Virus is transported intraaxonally to the dorsal
root
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Sexually Transmitted Viral
Infections
Genital herpes
Virus remains latent until reactivated
Oral infection
Virus resides in the trigeminal ganglion
Genital infection
Virus resides in the dorsal sacral nerve roots
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Sexually Transmitted Viral
Infections
Human papillomavirus (HPV)
120 different types of HPV
30 serotypes are unique to stratified squamous
epithelium
Divided into high-risk and low-risk serotypes
HPV is a nonenveloped, circular double-stranded
DNA virus
Belongs to the Papovaviridae family
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Sexually Transmitted Viral
Infections
Human papillomavirus (HPV)
Condylomata acuminata (genital warts)
Soft, skin-colored, whitish pink to reddish brown
benign growths caused by HPV
Treatment is considered cosmetic, not curative
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Sexually Transmitted Viral
Infections
Molluscum contagiosum
Benign viral infection of the skin
Primarily infects the face, hands, lower abdomen,
and genitalia
Taken into epithelial cells by phagocytosis
Replicates to produce molluscous bodies
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Sexually Transmitted Parasitic
Infections
Trichomoniasis
Caused by Trichomonas vaginalis
Adheres to and damages squamous epithelial cells
Anaerobic, unicellular, flagellated, parasitic protozoan
Urethra, vagina, and Skene and Bartholin glands
Accounts for 25% of infectious vaginitis cases
Often coexists with gonorrhea
Presence confirmed by microscopic examination
of vaginal secretions or urine
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Sexually Transmitted Parasitic
Infections
Scabies
Caused by the adult female itch mite, Sarcoptes
scabiei
Transmission of scabies requires prolonged close
skin-to-skin contact
Burrows though the horny layer of the stratum per
day
Typically occurs between family members or sexual
partners
New larval forms appear in about 10 days
Classic symptom is intense pruritus
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Scabies
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Sexually Transmitted Parasitic
Infections
Pediculosis pubis
Caused by the crab louse Phthirus pubis
Transmitted primarily by intimate sexual contact
or contact with infected bed linens or clothing
A crab louse has a 25- to 30-day life cycle
Stages: egg or nit, three nymphal stages, and an adult
stage
Symptoms
Mild to severe itching, allergic sensitization, and
secondary infections from scratching
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Pediculosis Pubis
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Sexually Transmitted
Gastrointestinal Infections
Shigellosis and Campylobacter enteritis
Giardiasis and amebiasis
Hepatitis B
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Sexually Transmitted Systemic
Diseases
Epstein-Barr virus
Acquired immunodeficiency syndrome
Cytomegalovirus
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