STI Flashcards
Which of the following is the most common cause of nongonococcal urethritis (NGU) in heterosexual men?
A) Mycoplasma genitalium
B) Trichomonas vaginalis
C) Chlamydia trachomatis
D) Ureaplasma urealyticum
Answer: C) Chlamydia trachomatis
Rationale: C. trachomatis accounts for approximately 30–40% of NGU cases, especially in heterosexual men.
Which diagnostic tests are currently recommended for the initial diagnosis of urethritis in men?
A) N. gonorrhoeae and C. trachomatis testing
B) M. genitalium testing
C) T. vaginalis testing
D) Adenovirus testing
Answer: A) N. gonorrhoeae and C. trachomatis testing
Rationale: Although M. genitalium is a known cause of NGU, routine testing for it is not yet included in the standard initial diagnostic workup.
Which antibiotic is NOT recommended due to declining efficacy for Mycoplasma genitalium?
A) Azithromycin
B) Doxycycline
C) Moxifloxacin
D) Ceftriaxone
Answer: A) Azithromycin
Rationale: Azithromycin’s efficacy in treating M. genitalium is rapidly declining, making alternative treatments necessary.
Which of the following is the most common cause of acute epididymitis in sexually active men under 35 years old?
A) Escherichia coli
B) Chlamydia trachomatis
C) Trichomonas vaginalis
D) Mycoplasma genitalium
Answer: B) Chlamydia trachomatis
Rationale: C. trachomatis is the leading cause of epididymitis in young, sexually active men, followed by N. gonorrhoeae.
Which treatment is recommended for epididymitis caused by sexually transmitted infections?
A) Metronidazole
B) Azithromycin alone
C) Ceftriaxone followed by doxycycline
D) Ciprofloxacin
Answer: C) Ceftriaxone followed by doxycycline
Rationale: This combination covers both N. gonorrhoeae (ceftriaxone) and C. trachomatis (doxycycline).
Which of the following clinical findings is characteristic of vaginal trichomoniasis?
A) Cottage cheese-like discharge
B) Strawberry cervix
C) Fishy odor with KOH test
D) Increased vaginal discharge without irritation
Answer: B) Strawberry cervix
Rationale: Trichomoniasis can cause petechial lesions on the cervix, known as “strawberry cervix,” which are best visualized by colposcopy.
What is the recommended standard treatment for vaginal trichomoniasis?
A) Fluconazole
B) Doxycycline
C) A single 2-g oral dose of metronidazole
D) Intravaginal imidazole therapy
Answer: C) A single 2-g oral dose of metronidazole
Rationale: Metronidazole is the first-line treatment, and treating partners is also necessary to prevent reinfection.
Which of the following is NOT included in the Amsel criteria for bacterial vaginosis diagnosis?
A) White, homogeneous vaginal discharge
B) Vaginal pH >4.5
C) Presence of motile trichomonads on microscopy
D) Fishy odor after adding KOH
Answer: C) Presence of motile trichomonads on microscopy
Rationale: The presence of motile trichomonads is a diagnostic feature of trichomoniasis, not bacterial vaginosis.
Which antibiotic is a first-line treatment for bacterial vaginosis?
A) Fluconazole
B) Metronidazole
C) Doxycycline
D) Ceftriaxone
Answer: B) Metronidazole
Rationale: Metronidazole (oral or gel) is the preferred treatment for bacterial vaginosis.
Which of the following symptoms is more suggestive of vulvovaginal candidiasis than bacterial vaginosis?
A) Fishy vaginal odor
B) Gray-white homogeneous discharge
C) Thick, cottage cheese-like vaginal discharge
D) Vaginal pH >4.5
Answer: C) Thick, cottage cheese-like vaginal discharge
Rationale: Vulvovaginal candidiasis typically presents with thick, white, curd-like discharge, pruritus, and irritation.
Which of the following is the most common pathogen in vulvovaginal candidiasis?
A) Candida glabrata
B) Candida albicans
C) Gardnerella vaginalis
D) Trichomonas vaginalis
Answer: B) Candida albicans
Rationale: C. albicans is responsible for the vast majority of symptomatic vulvovaginal candidiasis cases.
Which sexually transmitted infection is the most common cause of genital ulceration worldwide?
A) Syphilis
B) Chancroid
C) Genital herpes
D) Lymphogranuloma venereum
Answer: C) Genital herpes
Rationale: HSV (especially HSV-2) is the leading cause of genital ulcers globally.
A patient presents with a painless, indurated genital ulcer and firm, nontender inguinal adenopathy. What is the most likely diagnosis?
A) Chancroid
B) Syphilis
C) Genital herpes
D) LGV
Answer: B) Syphilis
Rationale: The painless, indurated ulcer (chancre) and firm, nontender lymphadenopathy are classic findings in primary syphilis.
What is the most common cause of infectious proctitis in men who have sex with men (MSM)?
A) Adenovirus
B) Shigella
C) Neisseria gonorrhoeae and Chlamydia trachomatis
D) Escherichia coli
Answer: C) Neisseria gonorrhoeae and Chlamydia trachomatis
Rationale: These are the primary sexually transmitted causes of proctitis, particularly in MSM.
Which of the following is a distinguishing feature of proctitis compared to proctocolitis?
A) Presence of true diarrhea
B) Involvement of the rectal mucosa only
C) Absence of anorectal pain
D) Caused by ingestion of foodborne pathogens
Answer: B) Involvement of the rectal mucosa only
Rationale: Proctitis is inflammation confined to the rectal mucosa, while proctocolitis extends to the colon.
