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

Author

  • Dr. Shahbaz Syed is a FRCPC Emergency Physician at the University of Ottawa, he is also the assistant director of Digital Scholarship and Knowledge Dissemination, and Co-Editor in Chief of the EMOttawa Blog.