16: Sexually Transmitted Infections

Question 1

What are the common etiologies of urethritis?

Answer 1

• Gonorrhea
• Chlamydia
• Mycoplasma genitalium

Question 2

For chlamydia trachomatis:

1. Pathogen
2. Pathogenesis
3. Epidemiology
4. Clinical presentation
5. Diagnosis
6. Treatment

Answer 2

1. Obligate intracellular parasite (use host ATP) similar to GNs but lack rigid peptidoglycan layer; serovars A-C (endemic trachoma), D-K (genital tract infx), L2-4 (lymphogranuloma venereum [LGV])
2. Life cycle: reticulate bodies (replication inside host) –> inclusion bodies (infection) –> elementary bodies (lysis)
3. Most common STD in US, highest prevalence <25yrs
4. Incubation 7-21 days; most asymptomatic; male: urethritis, epididymitis, prostatis, proctitis; female: cervicitis (80% asymp); Reiter’s syndrome: autoimmune disease of arthritis, urethritis, uveitis, conjunctivitis,skin lesions; newborn inclusion conjunctivitis; Lymphogranuloma venereum (LGV): painless genital ulcer –> tender inguinal lymph nodes + systemic illness –> draining sinus tracts, strictures, lymphatic obstruction
5. NAAT; cell culture less sensitive; serology for LGV; no GS b/c intracellular
6. Azithromycin or doxycycline (azithro better if considering M. genitalium); co-tx for GC if rates >5% in pop. (3GC); doxycycline or erythromycin for LGV

Question 3

For herpes simplex:

1. Pathogen
2. Pathogenesis
3. Clinical presentation
4. Diagnosis
5. Treatment

Answer 3

1. Icosahedral DS DNA virus
2. HSV-1: orolabial lesions and keratitis, can cause genital lesions which tend not to be recurrent; HSV-2 is primary cause of recurrent genital lesions
3. Primary infx: male: painful balanitis, urethritis; women: painful vulvovaginitis, cervicitis, urethritis; systemic sx (fever, HA, malaise), 21 days to resolution; recurrence (70%) is shorter/fewer, unilateral, prodrome
4. Viral culture (early in course), direct immunofluoresence, detect DNA (in situ hybridization or PCR), serology
5. Acylclovir, famciclovir or valacyclovir to decrease duration/severity

Question 4

For calymmatobacterium granulomatis:

1. Pathogen
2. Epidemiology
3. Clinical presentation
4. Diagnosis
5. Treatment

Answer 4

1. Klebsiella granulomatis
2. Papua New Guinea, India, Southern Africa, Caribbean, South America
3. Painless subcutaneous nodule without regional lymphadenopathy
4. Dark-staining Donovan bodies in a smear of the lesion or tissue prep
5. Doxycyline for 21 days or til improved

Calymmatobacterium are calm (painless, no lymphadenopathy).

Question 5

For chancroids:

1. Pathogen
2. Epidemiology
3. Clinical presentation
4. Diagnosis
5. Treatment

Answer 5

1. Haemophilus ducreyi: GNC
2. Common in Africa, most cases male, major risk for HIV acquisition
3. Painful ulcer with ragged undermined edges and a gray/yellow exudate, usually a solitary lesion; buboes (expansive, tender lymph nodes), tissue destruction
4. Culture or visualization on aspiration
5. Macrolide, cephalosporin, quinolone

Question 6

For neisseria gonorrhoeae:

1. Pathogen
2. Pathogenesis
3. Epidemiology
4. Clinical presentation
5. Diagnosis
6. Treatment

Answer 6

1. GND, kidney-bean shaped; aerobic, non-motile, nonspore-forming; ferments glucose only (N. men ferments maltose as well)
2. Pilin: attachment, phase variation; OPA: adhesion; porin: invasion; RMP: block complement; IgA protease: inhibit immune response
3. 2nd most common STD in US; peak age 15-24yo; recurrence common
4. Incubation 2-5 days; men (95%): urethra w/ purulent discharge, dysuria; women (50%): endocervix w/ incr. vaginal discharge/bleeding, incr. urinary freq, dysuria, abdominal pain; co-infection (30%) w/ chlamydia; disseminated in pts. w/ C5-8 deficiency
5. Gold standard: NAAT; GS for men w/ GC urethritis; culture
6. 3GC (ceftriaxone), azithromycin (macrolide) for uncomplicated GC in limited circumstances; azithro or doxycycline (tetracycline) as presumptive tx

Question 7

What is PID?

Answer 7

Pelvic inflammatory disease

• In females, when GC/CT infx ascends to involve ovaries/fallopian tubes
• Sx: lower abdominal pain, systemic illness
• Sequelae: infertility, ectopic pregnancy, chronic pelvic pain

Question 8

What is lymphogranuloma venereum?

Answer 8

• L serovars (L2, 3, 4) of chlamydia trachomatis
• Primary (3-30 days): painless genital lesion (papule/ulcer)
• Secondary (days-weeks):** **tender inguinal/femoral lymphadenopathy, fever, headache, myalgias, proctocolitis
• Late (months-years): draining sinus tracts, urethral/rectal strictures, lymphatic obst, chronic hard inguinal masses
• Tx: doxycycline or erythromycin for 21 days