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Sexually Transmitted Infections

This chapter explores the various bacterial and viral urogenital infections, including gonorrhea, syphilis, chancroid, granuloma inguinale, bacterial vaginosis, chlamydial infections, genital herpes, and human papillomavirus (HPV). Learn about their causes, symptoms, and transmission methods.

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Sexually Transmitted Infections

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  1. Sexually Transmitted Infections Chapter 24

  2. 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

  3. 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

  4. 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

  5. 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)

  6. 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

  7. Syphilis • Congenital syphilis • Vasculitis, necrosis, fibrosis, and generalized tissue destruction • Manifest in the first 2 years of life • Late stage manifestations occur near puberty

  8. 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

  9. Chancroid

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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

  21. Sexually Transmitted Parasitic Infections • Trichomoniasis • Caused by Trichomonas vaginalis • Anaerobic, unicellular, flagellated, parasitic protozoan • Adheres to and damages squamous epithelial cells • 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

  22. Sexually Transmitted Parasitic Infections • Scabies • Caused by the adult female itch mite, Sarcoptes scabiei • Transmission of scabies requires prolonged close skin-to-skin contact • Typically occurs between family members or sexual partners • Burrowsthoughthe horny layer of the stratumperday • New larval forms appear in about 10 days • Classic symptom is intense pruritus

  23. Scabies

  24. 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

  25. Pediculosis Pubis

  26. Sexually Transmitted Gastrointestinal Infections • Shigellosis and Campylobacter enteritis • Giardiasis and amebiasis • Hepatitis B

  27. Sexually Transmitted Systemic Diseases • Epstein-Barr virus • Acquired immunodeficiency syndrome • Cytomegalovirus

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