Sexually Transmitted Infections
Ceftriaxone-plus-doxy, the syphilis staircase, and PID's complications
Gonorrhea and chlamydia
Shared features. Neisseria gonorrhoeae and Chlamydia trachomatis cause urethritis and cervicitis, often coexist, and are diagnosed by nucleic acid amplification testing (NAAT) of first-catch urine in men or a vaginal swab in women, adding rectal and pharyngeal swabs according to exposure. Gonorrhea tends to produce purulent discharge; chlamydia is often asymptomatic.
| Feature | Gonorrhea | Chlamydia |
|---|---|---|
| Organism | Gram-negative diplococci | Obligate intracellular bacterium, serovars D–K |
| Treatment | Ceftriaxone 500 mg IM once (1 g if ≥150 kg); add doxycycline if chlamydia is not excluded | Doxycycline 100 mg twice daily for 7 days; alternative azithromycin 1 g once |
| Pregnancy | Ceftriaxone | Azithromycin; tetracyclines stain fetal teeth and bone |
| Beyond the genitals | Disseminated infection: tenosynovitis, pustules, migratory arthralgia or septic arthritis | Serovars L1–L3 cause lymphogranuloma venereum; reactive arthritis |
Partners and retesting. Expedited partner therapy (EPT) gives the patient treatment for sexual partners without a prior exam, preventing reinfection. Retest the index patient at about 3 months to detect reinfection, not as a test of cure; true test of cure is reserved for pharyngeal gonorrhea and for chlamydia in pregnancy.
Complications in men. Epididymitis in young sexually active men is usually gonococcal or chlamydial (ceftriaxone plus doxycycline); enteric gram-negative rods predominate in older men (levofloxacin) and join gonorrhea and chlamydia after insertive anal sex (ceftriaxone plus levofloxacin). Disseminated gonococcal infection needs IV ceftriaxone.
Syphilis
- Primarysingle painless, indurated chancre with painless regional nodes; heals on its own
- Secondaryweeks later: diffuse maculopapular rash including palms and soles, condylomata lata, lymphadenopathy
- Latentasymptomatic seropositivity; early latent within 1 year of infection, late latent after
- Tertiaryyears later: gummas, aortitis, neurosyphilis (tabes dorsalis, general paresis, Argyll Robertson pupils)
Serology. Nontreponemal tests (RPR, VDRL) are quantitative: titers track disease activity and fall with successful treatment, so they are used to monitor response. Treponemal tests (FTA-ABS, TP-PA) confirm infection but stay positive for life and cannot gauge cure. Dark-field microscopy visualizes spirochetes from a chancre before serology turns positive. False-positive nontreponemal results occur with pregnancy, lupus and antiphospholipid antibodies, injection drug use and some viral infections.
Treatment. Penicillin G treats every stage. Early syphilis (primary, secondary, early latent) gets one IM dose of benzathine penicillin; late latent or unknown-duration disease gets three weekly doses; neurosyphilis, including ocular and otic syphilis, needs IV aqueous penicillin for 10–14 days. Nonpregnant penicillin-allergic patients can take doxycycline (not for neurosyphilis, which calls for penicillin desensitization), but penicillin-allergic pregnant patients must be desensitized, because only penicillin reliably prevents congenital syphilis.
Jarisch-Herxheimer reaction: fever and myalgias within hours of the first dose, from cytokines released as spirochetes lyse. It is not an allergy; give antipyretics and continue treatment.
Genital ulcers, herpes and HPV
| Disease | Ulcer | Nodes | Treatment |
|---|---|---|---|
| Primary syphilis | Single, painless, indurated, clean base | Painless, rubbery | Benzathine penicillin G |
| Herpes (HSV) | Painful grouped vesicles that ulcerate and recur | Tender, mainly in the first episode | Acyclovir or valacyclovir |
| Chancroid (Haemophilus ducreyi) | Painful, ragged, purulent base | Painful, may suppurate | Azithromycin or ceftriaxone |
| Lymphogranuloma venereum | Small, painless, transient | Painful inguinal buboes | Doxycycline for 3 weeks |
Herpes. Genital herpes (HSV-2 more than HSV-1) causes painful grouped vesicles on an erythematous base that ulcerate and recur, often after a tingling prodrome; the first episode is the most severe. A Tzanck smear shows multinucleated giant cells but is insensitive; PCR of the lesion confirms. Acyclovir or valacyclovir, episodic or suppressive, shortens outbreaks and reduces transmission but does not cure the latent ganglionic infection. In pregnancy, suppression is offered from 36 weeks, and lesions or prodrome at labor call for cesarean delivery.
HPV. Human papillomavirus types 6 and 11 cause anogenital warts (condylomata acuminata), treated with cryotherapy, imiquimod, podofilox or excision. Types 16 and 18 drive cervical, anal and oropharyngeal cancer: E6 degrades p53 and E7 inactivates Rb, removing two tumor suppressors. Prevention rests on the 9-valent vaccine (routinely at 11–12 years, catch-up through 26) and Pap/HPV co-testing.
Condylomata lata of secondary syphilis are flat and moist; condylomata acuminata of HPV are warty and cauliflower-like.
Vaginitis and trichomoniasis
| Feature | Bacterial vaginosis | Candida | Trichomonas |
|---|---|---|---|
| Cause | Gardnerella-associated anaerobic overgrowth | Candida albicans | Motile flagellated protozoan |
| Discharge | Thin, gray, fishy | Thick white curd; itch | Frothy, yellow-green, malodorous; vulvar itching |
| pH | >4.5 | Normal | >4.5 |
| Findings | Clue cells; positive whiff test | Pseudohyphae on KOH prep | Motile trophozoites on wet mount; strawberry cervix |
| Treatment | Metronidazole | Fluconazole (topical azole in pregnancy) | Metronidazole for patient and partner |
Key contrasts. Trichomoniasis is sexually transmitted, so the partner is always treated; BV partners are not routinely treated. NAAT is the most sensitive test for trichomonas when the wet mount is negative. Warn patients taking metronidazole about a disulfiram-like reaction with alcohol.
Pelvic inflammatory disease
Diagnosis. PID is ascending gonococcal or chlamydial infection, often with anaerobes, causing lower abdominal pain with cervical motion tenderness and adnexal tenderness. These findings alone justify empiric treatment; keep a low threshold, because every delay scars the tubes. Always check a pregnancy test to exclude ectopic pregnancy, send NAATs, and obtain pelvic ultrasound if an abscess is suspected.
- Cervicitisgonorrhea or chlamydia
- Endometritis, salpingitiscervical motion tenderness
- Tubo-ovarian abscessadnexal mass, sepsis risk
- Fitz-Hugh-Curtisperihepatitis, RUQ pain
Treatment. Ceftriaxone plus doxycycline plus metronidazole covers gonorrhea, chlamydia and anaerobes. Hospitalize for tubo-ovarian abscess, pregnancy, severe illness, failure of or inability to take oral therapy, or when a surgical emergency such as appendicitis cannot be excluded. Treat partners.
Complications. Tubo-ovarian abscess, infertility, ectopic pregnancy, chronic pelvic pain and Fitz-Hugh-Curtis perihepatitis (RUQ pain with violin-string adhesions) all follow PID, and each episode raises the risk of tubal scarring. An abscess that is large, ruptured or not improving on IV antibiotics needs drainage.
Screening and prevention
- Chlamydia and gonorrhea: sexually active women younger than 25 annually, and older women at increased risk.
- HIV: all adults 15–65 at least once, and all pregnant patients.
- Syphilis: all pregnant patients and high-risk individuals, such as men who have sex with men and people with HIV.
Prevention. Treat partners, counsel on condoms, vaccinate against HPV and hepatitis B, and offer HIV preexposure prophylaxis to people at high risk. Any STI diagnosis should prompt testing for the others, including HIV and syphilis.