What is the diagnosis and treatment for a patient presenting with vaginal discharge and vulvar sores, potentially indicating a sexually transmitted infection (STI) such as herpes simplex virus (HSV) or bacterial vaginosis?

Diagnosis and Management of Vaginal Discharge with Vulvar Sores

The most critical first step is to distinguish between infectious causes (herpes simplex virus, chancroid, syphilis) and non-infectious causes (aphthous ulcers, inflammatory conditions) through direct visualization and laboratory testing, as clinical diagnosis alone is unreliable and can lead to both false positive and false negative diagnoses. 1

Immediate Diagnostic Approach

Physical Examination Findings to Document

• Examine for vesicular lesions that progress to shallow ulcers or erosions - these are characteristic of HSV and typically heal within 10 days without scarring 1
• Look specifically for the morphology of ulcers: HSV presents with vesicles that burst into shallow erosions, while chancroid (Haemophilus ducreyi) presents as painful genital ulcers 1, 2
• Document the presence and character of vaginal discharge: white cottage cheese-like discharge suggests candidiasis, while thin malodorous discharge suggests bacterial vaginosis or trichomoniasis 1, 3
• Measure vaginal pH immediately - pH ≤4.5 indicates vulvovaginal candidiasis, while pH >4.5 suggests bacterial vaginosis or trichomoniasis 4

Essential Laboratory Testing

• Collect specimens from the base of ulcers using a sterile swab for HSV testing - open vesicles with a sterile needle and collect fluid for viral culture or nucleic acid amplification testing (NAAT), as these are the most sensitive methods 1
• Perform concurrent testing for Treponema pallidum (syphilis serology) since HSV and syphilis can coexist in the same lesion 1
• Obtain vaginal discharge specimens for wet mount microscopy with 10% KOH preparation to visualize yeast, pseudohyphae, or motile trichomonads 1, 4
• All patients with genital ulcers should have serologic testing for syphilis and appropriate cultures for gonorrhea performed at the time of diagnosis 2

Treatment Based on Diagnosis

For Confirmed or Suspected Genital Herpes

• Initiate acyclovir treatment immediately without waiting for laboratory confirmation if clinical presentation is consistent with HSV, as treatment is most effective when started within 72 hours of symptom onset 1, 5
• Acyclovir dosing for genital herpes: standard regimens range from 200 mg orally 5 times daily to 800 mg depending on whether this is primary infection or recurrent episode 5
• Counsel patients that acyclovir is not a cure and that they should avoid sexual contact when lesions or symptoms are present, though transmission can occur during asymptomatic viral shedding 5
• Maintain adequate hydration during treatment to prevent renal complications 5

For Vulvovaginal Candidiasis (if discharge is present with normal pH)

• Treat with topical azoles for 3-7 days for uncomplicated cases: clotrimazole 1% cream 5g intravaginally for 7-14 days, or clotrimazole 100mg vaginal tablet for 7 days 1, 3
• Alternative: oral fluconazole 150mg as a single dose for non-pregnant patients 3
• For complicated or recurrent cases, extend treatment to 7-14 days of topical azole therapy or fluconazole 150mg repeated after 3 days, followed by maintenance therapy for 6 months 3
• Pregnant women should only receive 7-day topical azole therapy, never oral fluconazole 3

For Bacterial Vaginosis or Trichomoniasis (if pH >4.5)

• Metronidazole 500mg orally twice daily for 7 days is the preferred treatment for bacterial vaginosis 4, 6
• For trichomoniasis: metronidazole 2g orally as a single dose 1, 4
• Sexual partners must be treated simultaneously for trichomoniasis to prevent reinfection 3, 4
• Advise patients to avoid alcohol during and for 24 hours after metronidazole treatment 4

For Chancroid (Haemophilus ducreyi)

• Azithromycin is indicated for genital ulcer disease in men due to Haemophilus ducreyi, though efficacy in women has not been established due to limited clinical trial data 2
• Azithromycin at recommended doses should not be relied upon to treat syphilis, which may be masked by treatment for other STIs 2

Critical Pitfalls to Avoid

• Never rely on clinical diagnosis alone - the clinical differentiation of HSV from other causes of genital ulceration (syphilis, chancroid, inflammatory conditions) is unreliable 1
• Do not assume vulvar ulcers are always infectious - non-infectious causes including Behçet syndrome, Crohn disease, and acute vulvar aphthosis (ulcus vulvae acutum) can present identically 1, 7
• Do not treat candidiasis based solely on symptoms - approximately 10-20% of asymptomatic women harbor Candida species, and treatment without confirmation leads to unnecessary therapy 1
• Avoid single-dose metronidazole (2g) for bacterial vaginosis when 7-day regimens are feasible, as cure rates are lower with single-dose therapy 6
• Never initiate herpes treatment more than 72 hours after symptom onset without clear indication, as efficacy data beyond this window are lacking 5

Special Populations

• HIV-infected patients receive identical treatment regimens as HIV-negative patients for all vulvovaginal infections 1, 3
• Pregnant women with symptomatic trichomoniasis should be treated with metronidazole 2g single dose, as multiple studies show no teratogenic effects 1
• For pregnant women with candidiasis, only 7-day topical azole therapy is appropriate 3