Sexually transmitted infections

The term "sexually transmitted infections" (STIs) refers to a group of infections that are mainly transmitted via sexual intercourse. The most common symptoms of STIs are pain in the suprapubic and genital area, urethral or vaginal discharge, and genital lesions, which may or may not be painful. Some STIs (e.g., HPV) may induce or predispose to malignant changes. The majority of STIs are asymptomatic, and therefore easily spread. If a patient is already infected with an STI, they are predisposed to coinfections with further STIs. There are various treatment options for each STI, with simultaneous treatment of the partner often necessary to prevent recurrent infections. In some cases, health care providers are required by law to report cases of STIs to county and health state departments (e.g., HIV, hepatitis B).

Pathogens		Localized disease	Management
Viral	Human papillomavirus (HPV)	Condylomata acuminata Bowenoid papulosis (condylomata plana)	Local cytotoxic therapy (e.g., with 5-fluorouracil) Cryotherapy Operative management: curettage (surgical excision), laser surgery, or electrosurgery
	Herpes simplex virus type 2 (HSV-2)	Genital herpes	Acyclovir PO for episodic or suppressive treatment
	HIV	None	Systemic antiretroviral therapy: HAART/cART
	Hepatitis B	None	Systemic antiviral therapy PO (e.g., entecavir) Interferon (immune modulating, antiviral, and antiproliferative agent) injected SC or IM
Bacterial	Chlamydia trachomatis D-K	Urogenital chlamydia infections ♀: Urethritis, vulvovaginitis, cervicitis, salpingitis, tubo-ovarian abscess, pelvic inflammatory disease (PID) ♂: Urethritis, epididymitis, prostatitis	Drug of choice: doxycycline or azithromycin PO Alternative: fluoroquinolone (e.g., ciprofloxacin, moxifloxacin)
	Chlamydia trachomatis L1-L3	Lymphogranuloma venereum
	Klebsiella granulomatis	Granuloma inguinale
	Haemophilus ducreyi	Chancroid	Ceftriaxone IM single dose Plus azithromycin PO single dose
	Neisseria gonorrhea	Gonorrhea ♀: Urethritis, Bartholin gland cyst, salpingitis, tubo-ovarian abscess, pelvic inflammatory disease, cervicitis ♂: Urethritis, epididymitis
	Treponema pallidum	Syphilis Chancre Condylomata lata	Penicillin G IM Alternatives if allergic to penicillin: tetracycline, macrolides or cephalosporin
Fungal	Candida albicans	Vulvovaginal candidiasis (yeast infection)	Local antimycotic agent (e.g., clotrimazole, nystatin) Alternative: fluconazole PO single dose
Parasitic	Trichomonas vaginalis	Trichomoniasis (cervicitis)	Metronidazole PO
	Phthirus pubis	Pediculosis pubis (pubic lice, crab louse) Irritated skin in the pubic hair region; tiny brown lice droppings detectable	Permethrin 1% lotion (insecticide)

References:^{[1][2][3][4][5][6][7][8][9][10][11][12][13][14]}

	Pathogen	Clinical features	Diagnosis
Painless lesions	Human papillomavirus	Condylomata acuminata Single or multiple skin-colored papular eruptions (1–5mm) ; smooth or verrucous Usually painless Located on internal and external genitalia Bowenoid papulosis Single or multiple small papules (may coalesce into larger plaques) Pigmented, with a flat-to-verrucous surface Most commonly on the penis shaft or external female genitals	Clinical exam and biopsy
	Klebsiella granulomatis	Granuloma inguinale Large (5–10 mm), beefy-red, expanding suppurative ulcers ; Painless; bleed easily Often malodorous because of bacterial coinfection Commonly located in skin folds	Clinical exam and biopsy (Donovan bodies)
	Chlamydia trachomatis L1-L3	Lymphogranuloma venereum Transient painless, small papule, or shallow ulcer Rapid spontaneous healing without scarring ♂: foreskin, glans, and scrotum ♀: posterior vaginal wall, cervix, and vulva Possibly concurrent discharge, cervical/adnexal/testicular tenderness, and painful inguinal lymphadenopathy	PCR detects Chlamydia trachomatis RNA or DNA
	Treponema pallidum	Chancre Singular red, round, and raised painless ulcer with elevated edges Heals spontaneously within 4–8 weeks Manifests mainly on the glans penis, or vulva and cervix Possibly concurrent regional adenopathy Condylomata lata Painless, warty erosions on the genitals in the secondary phase of syphilis that are velvety, moist, and broad-based Resolve spontaneously after weeks to months	Dark field microscopy (spirochetes) Serum antibody test
Painful lesions	Herpes simplex virus type 1 and 2 (mostly HSV-2)	Genital herpes Multiple grouped, painful vesicles (1–3 mm) on an erythematous ground Possibly concurrent malaise, myalgias, and fever Reactive painful inguinal lymphadenopathy common External female genitalia and cervix , or glans and penis shaft	Clinical exam Best initial test: Tzanck smear (multinucleated giant cells)
	Haemophilus ducreyi	Chancroid Single or multiple painful papules or pustules (10–20 mm); yellowish-greyish exudate in the center Affects the glans, penis shaft, and scrotum, or vulva and perineal area Possibly concurrent painful inguinal lymphadenopathy and abscess formation	Clinical exam and culture

References:^{[15][16][17][18][9][10][11][12][13]}