Sexually-transmitted infection

Background

• Most common reportable infectious diseases
• Typically treated syndromically
• Often have sequelae such as infertility, cancer, chronic pain, and psychiatric illness

Microbiology

Bacteria

Organism	Disease	First-line treatment	Treatment if allergic	Treatment if pregnant
Chlamydia trachomatis	chlamydia	azithromycin 1 g po once		azithromycin 1 g po once, or amoxicillin 500 mg po tid for 7 days
Chlamydia trachomatis serovars L1, L2, L3	lymphogranuloma venereum	doxycycline 100 mg PO for 3 weeks		erythromycin 500 mg PO qid for 3 weeks
Haemophilus ducreyi	chancroid	azithromycin 1 g po once	ceftriaxone 250 mg IM once	usual treatment
Klebsiella granulomatis	granuloma inguinale (donovanosis)	doxycycline 100 mg po bid for 3 weeks		erythromycin
Mycoplasma genitalium	non-gonococcal urethritis/cervicitis	azithromycin 500 mg PO on day one, followed by 250 mg PO on days two to five	moxifloxacin 400 mg PO daily for 7 days
Neisseria gonorrhoeae	gonorrhea	ceftriaxone 250 mg IM once + azithromycin 1 g PO once	gentamicin 240 mg IM once + azithromycin 2 g PO once	usual treatment
Treponema pallidum pallidum	primary, secondary, and EL syphilis	penicillin 2.4 MU IM once	doxycycline 100 mg PO bid for 14 days	usual treatment
	LL and tertiary syphilis	penicillin 2.4 MU IM weekly for 3 weeks	desensitization or doxycycline 100 mg PO bid for 28 days	usual treatment
	neurosyphilis	penicillin 4 MU IV q4h for 10-14 days	desensitization	usual treatment

Viruses

• HIV
• Hepatitis B
• Hepatitis C
• Herpes simplex virus
• Others: molluscum contagiosum, cytomegalovirus, hepatitis A

Protozoa

Organism	Disease	First-line treatment	Treatment if allergic	Treatment if pregnant
Trichomonas vaginalis	trichomoniasis	metronidazole 2 g PO once		usual treatment

Ectoparasites

• Scabies
• Public lice