Here we present a STI ‘cheat sheet’ to commonly encountered STIs – their etiology, workup and treatment. The following recommendations are based on the Canadian PHAC guidelines. We will not cover the important aspect of taking a sexual history, but an excellent resource may be found through PHACs website.

Herpes

  • Caused by HSV-1,2 and the presence increases the risk of HIV transmission 
  • For both sexes is located anywhere in the ‘boxer short area’
    • Appears as grouped vesicles evolving toward superficial circular ulcers on an erythematous base
    • Smooth margin and base
    • Enlarged, non-fluctuant and tender inguinal lymph nodes most common in primary infection
  • Diagnosis: Most often visual, can be confirmed by viral culture on 3 unroofed/wet vesicles
  • Asymptomatic spread does occur, but the risk is highest during outbreaks. Patients should be advised to always use condoms.
  • Treatment:
    • Ideally initiated within 72 hours (because it is the only timeframe studied), but should ideally treat anyone with lesions
    • Treatment will decrease the severity and duration of illness
    • First presentation (treatment for 7-10 days):
      • Acyclovir 400 mg po TID or 200 mg po 5 times daily OR
      • Famciclovir 250 mg po TID OR
      • Valacyclovir 1000 mg po BID
    • Episodic treatment (for 5 days):
      • Acyclovir 800 my po TID
      • Famciclovir 1000 mg po BID
      • Valacyclovir 500 mg po BID for 3 days or 1000 mg po OD for 5 days
  • Complications:
    • Meningoencephilitis
    • Hepatitis, pneumonitis, disseminated infection, Transverse Myelitis

Syphilis

  • Caused by Treponema pallidum 
  • Classically in the 20-29 age group, but increasing in those >65 years old

STI

  • Primary Syphilis
    • Painless chancre: clean based ulceration 1-2 cm in size
    • Develops at any site of inoculation
    • Associated lymphadenopathy
  • Secondary Syphilis
    • Occurs in 25% of patients
    • Occurs over weeks –> months
    • Rash, lymphadenopathy, mucous membrane lesions, systemic symptoms
    • Epitrochlear lymph nodes is a classic presentation
    • Latent phase:
      • <12 months = Early Latent AND is infectious
      • >12 months = Late, non-infectious (except for transmission via pregnancy)
  • Tertiary Syphilis 
    • Untreated risk of progression: 25-40%
    • CV disease, gummatous disease, aortitis, aortic anerysms and neuro syphilis
    • Neurosyphilis:
      • Altered mental status, meningitis, CNS abscess, stroke, cranial nerve, auditory and ophthalmic abnormalities.
  • Diagnosis
    • Syphilis serology (VDRL) is not as accurate in primary syphilis (70-80%), so recommend Darkfield microscopy of ulcer or Treponemal-specific enzyme immunoassay (EIA).
      • A positive non-treponemal test should always be confirmed with a specific treponemal test because of a high false-positive rate
    • All other stages of syphilis can be accurately diagnosed with VDRL (sensitivity approaches 100%)
  • Treatment
    • Primary/Secondary/Early Latent
      • Pen G 2.4 million units IM x one
    • Late latent/Tertiary
      • Pen G 2.4 million units IM x 3 weekly doses
    • Neurosyphilis
      • Pen G 3-4 million units IV q4h x 10-14 days

Chancroid

  • Ulcerating STI caused by Haemophilus ducreyi
  • Most common in the developing world
  • Presents with tender erythematous papule at the inoculation site
    • Irregular borders, inflammed
    • May have associated tender lymphadenopathy that may develop into a ‘bubo’ (a large, painful, fluctuant node which may drain purulent material)
  • Chancroid is a clinical diagnosis, as it is hard to culture
  • Treatment: 
    • Azithromycin 1000 mg po in a single dose OR
    • Ceftriaxone 250 mg IM/IV

Trichomonas

  • Caused by Trichomonas vaginalis
  • Globally, this is the most common non-viral STI
  • Occurs in the urogenital tract, and compared to STI predominantly in older females
  • Presentation ranges from asymptomatic to PID:
    • May develop pruritis, dysparenuria, discharge, and postcoital bleeding
    • Green-yellow, frothy discharge
  • Diagnosis is made via NAAT
  • Treatment:
    • Flagyl 500 mg po BID x 7 days

Gonorrhea

  • Gram negative Diplococcus – Neisseria gonorrhaeae
  • In males may be asymptomatic, or with urethral discharge, dysuria
  • Females are often asymptomatic until they develop signs of ascending infection
  • Various presentations:
    • Gonococcal proctitis: Rectal pain, tenesmus, D.C bleeding
    • Gonococcal pharyngitis: Have a high pre-test based on Hx
    • Gonococcal conjunctivitis: maternal spread (rare, because of drops given at birth), usually develops from rubbing the eye with inoculated hand. Significant purulent secretions with significant associated morbidity
    • Disseminated Gonococcal Infection (DGI)
      • Rash (petechial, pustular, distal extremities)
      • Polyarthralgia
      • tenosynovitis
      • Septic arthritis
      • Rare: myocarditis/hepatitis/meningitis
  • Diagnosis:
    • NAAT – via swabs or first catch urine
      • 1st catch urine sensitivity in females is 94% (swab is 98.3%)
      • 1st catch urine sensitivity in males is 96% (swab is 97.8%)
      • Swabs are not FDA approved for pharynx/rectal diagnosis, but labs have demonstrated appropriate sensitivities
      • Swabs may be done cervical/vaginal/urethral – which is why self-swabbing is acceptable
  • Treatment:
    • Ceftriaxone 250 mg IV/IM
    • Azithromycin 1000 mg po –> For synergy and possible co-infection with chlamydia
    • When seen without diagnostic testing results available, if you have a high pre-test probability, consider emperic treatment

Chlamydia

  • Most prevalent STI in the United States
  • If symptomatic, presents with urethral discharge, dysuria
  • Without treatment will likely progress to upper tract infection: PID, orchitis/epididymitis
  • Diagnosis: via NAAT, similar sensitivity/specificity profile to gonorrhea above
  • Swabs may be done cervical/vaginal/urethral – which is why self-swabbing is acceptable
  • Treatment: 
    • Azithromycin 1000 mg po
    • Ceftriaxone 250 mg IM/IV –>co-infection is common, so most would advocate to treat for both
    • When seen without diagnostic testing results available, if you have a high pre-test probability, consider emperic treatment

PID

  • Ascending infection from the endocervix –> upper reproductive tract
  • Most commonly due to chlamydia/gonorrhea, but can include any potential GU pathogens
  • PID IS A CLINICAL DIAGNOSIS 
    • Minimum criteria:
      • Cervical motion tenderness OR
      • Adnexal tenderness OR
      • Uterine tenderness
    • Additional criteria:
      • Mucopurulent cervical discharge
      • Cervical friability
      • Fever
      • Elevated ESR, CRP
      • WBC on microscopy of vaginal secretions
      • Positive NAAT for chlaymdia/gonorrohea
  • Treatment:
    • Outpatient management:
      • Empirically treat for Chlamydia/Gonorrhea, plus:
        • Doxycycline 100 mg po BID x 14 days OR
        • Azithro 500 mg po once, and then 250 mg po OD to complete a 7 day course
    • Inpatient management:
      • Cefoxitin 2 g IV q6h PLUS Doxycycline 100 mg po/IV q12h OR
      • Clindamycin 900 mg IV q8h PLUS gentamycin (3-5 mg/kg IV)

Orchitis/Epididymitis

  • Ascending infection in the upper reproductive tract
  • Most cases present with testicular pain, swelling, and tenderness
  • Usually infectious, but may be traumatic or autoimmune in nature
  • In younger males (<35) or those with risk factors, is typically Chlamydia/Gonorrhea
  • In older males (>35) or for those without risk factors, is typically E. Coli, coliforms or pseudomonas
    • Important to note the distinction should be primarily made based on history
  • The Diagnosis is clinical. Testing is to identify the pathogen, and to rule out other emergent causes of testicular pain (i.e.: testicular torsion)
    • Send urine culture and NAAT
  • Treatment:
    • <35 or with STI risk factors:
      • Ceftriaxone 250 mg IV/IM AND Doxycycline 100 mg po BID X 10 days
    • >35 or no STI risk factors:
      • Levofloxacin 750 mg po OD x 10 days
    • If no improvement within 72 hours, consider a return to ED/completing U/S to rule out underlying abscess

Bacterial Vaginosis

  • Alteration in vaginal flora by replacing lactobacillus with polymicrobial organisms
  • Malodorous/fishy smell/white discharge
    • Key to note: does not cause vaginitis symptoms (i.e.: dysuria, pruritis, burning or vaginal inflammation) – would suggest an alternative diagnosis
  • Diagnosis:
    • Based on the Amsel critiera:
      • Homogenous, thin, greyish-white discharge that smoothly coats the vaginal walls
      • Vaginal pH > 4.5
      • Presence of clue cells (if microscopy available)
      • Fishy odour/positive whiff test
    • Culture: gold standard
      • Is often ‘indeterminate’ – requires clinical correlation to symptoms during QA/follow up process
  • Treatment:
    • Flagyl 500 mg po BID x 7 days

Vulvovaginal Candidiasis

  • Candida albicans. 75% of females in their life time will develop this
  • Discharge, pruritis, dysparenuria, dysuira (external)
  • Vulvar erythema, satellite lesions, thick curdy white discharge
  • Diagnosis: Made clinically
  • Treatment:
    • Topical azoles versus oral fluconazole
    • Cure rates are similar
    • Topical agents have quicker symptom relief (1-2 days) but less convenience to single oral treatment agent
    • Oral is cheaper, but with slightly higher side effect profile
Shahbaz Syed
Dr. Syed is an staff Emergency physician at the Ottawa Hospital, with an fellowship in Digital Scholarship and special interests in rational resource utilization.