Genitourinary Microbiology Flashcards
Answer F
This patient has urinary frequency and urgency consistent with a urinary tract infection (UTI). Women are more susceptible to UTIs because the female urethra is closer to the rectum and shorter than the male urethra. Sexual intercourse is often a precipitating factor because it introduces enteric bacteria to the periurethral area, leading to ascending infection of the bladder.
UTIs are categorized into either upper (eg, pyelonephritis) or lower (eg, cystitis) infections based on the ascension of bacteria through the urinary tract. Pyelonephritis and cystitis can share concomitant clinical features including dysuria, suprapubic pressure, and hematuria. Urinalysis with microscopy is often performed to confirm the diagnosis of UTI, but both upper and lower UTIs can show hematuria, pyuria (presence of urine white blood cells [WBCs]), and bacteriuria (Choices A and D).
However, the presence of WBC casts on urinalysis differentiates between upper and lower UTIs and can confirm the diagnosis of pyelonephritis. This is because WBC casts are formed only in renal tubules, where WBCs precipitate with Tamm-Horsfall protein secreted by tubular epithelial cells. WBC casts can also be seen with other intrarenal disorders (eg, acute interstitial nephritis), but urinary frequency and urgency are not typically present.
(Choices B and C) Fever and leukocytosis are nonspecific signs indicating systemic inflammation. Although they are usually present with pyelonephritis and absent with lower UTIs (eg, cystitis), they may occur in numerous other conditions (eg, pelvic inflammatory disease). In contrast, urine WBC casts are specific for intrarenal pathology.
(Choice E) In patients with urinary frequency and urgency, sterile pyuria (WBCs but no bacteria) is suggestive of urethritis from an atypical organism such as Chlamydia trachomatis or Ureaplasma species.
Educational objective:
Both upper (eg, pyelonephritis) and lower (eg, cystitis) urinary tract infections (UTIs) can show microscopic hematuria, pyuria, and bacteriuria on urinalysis with microscopy. However, the presence of white blood cell (WBC) casts can confirm the diagnosis of pyelonephritis in patients with UTI symptoms because WBC casts form only in the renal tubules.
Answer C
This patient has recurrent urinary tract infections (UTIs), most recently with a more severe and complicated clinical course (ie, pyelonephritis). The bacteria that cause most UTIs, both lower (ie, cystitis) and upper (ie, pyelonephritis), originate from fecal flora (eg, Escherichia coli, Enterococcus) that ascend the urinary tract. In women, bacterial ascent to the bladder through the relatively short urethra is often facilitated by sexual intercourse.
Antibacterial defenses in the bladder include anterograde urine flow that flushes urethral bacteria downstream and a mucus layer that interferes with bacterial attachment to mucosa. When these mechanisms are disrupted (eg, neurogenic bladder) or overcome by bacterial virulence factors (eg, fimbriae to augment attachment), cystitis occurs. However, the detrusor muscle typically seals the ureterovesical junction (UVJ), prohibiting retrograde urine flow into the ureter and preventing pyelonephritis from developing.
Recurrent acute bacterial cystitis, as seen in this patient, can cause chronic inflammation of the bladder wall that weakens the UVJ over time. This may allow transient retrograde flow of infected urine into the ureter during micturition, contributing to the pathogenesis of pyelonephritis in patients with recurrent cystitis. Once in the ureter, the bacteria can adhere to the uroepithelium and ascend into the kidney.
(Choice A) Urinary frequency may be a symptom of a UTI but is not a risk factor for infection. In fact, frequent urination may protect against UTIs by flushing bacteria downstream.
(Choice B) Hematogenous bacterial spread is a rare cause of pyelonephritis. This mechanism is most common in hospitalized or elderly patients with multiple potential infectious sources or significantly weakened immune defenses. This patient is young and otherwise healthy, making hematogenous spread unlikely.
(Choices D and E) Normal urethral flora (eg, lactobacilli, nonpathogenic staphylococci and streptococci) generally do not cause infection; however, distal urethral colonization by pathogenic gram-negative rods may occur when endogenous urethral flora are suppressed (eg, use of antibiotics). Although this may have a role in the pathogenesis of cystitis, it would not facilitate progession to pyelonephritis.
Educational objective:
Retrograde urine flow through the ureterovesical junction, either due to anatomic abnormalities (eg, short intravesical ureter) or functional disruption (eg, neurogenic bladder, chronic inflammation), contributes to the development of acute pyelonephritis.
Answer C
Dysuria in sexually active male patients is most commonly due to urethritis and less commonly caused by prostatitis, epididymitis, or urinary tract infection (UTI). In this case, the patient’s lack of systemic symptoms, absence of penile discharge, and positive urine dipstick analysis are consistent with UTI.
The most common cause of UTI is fecal florae, including gram-negative rods (eg, Escherichia coli [most common]) and gram-positive cocci (eg, Enterococcus faecalis). Female patients are at highest risk because their urethra is short and close to the anus, but male patients with a history of insertive anal intercourse are also at increased risk.
Urinalysis findings often provide diagnostic insight in identifying the causal bacterium:
Leukocyte esterase: Leukocyte esterase is an enzyme released by lysed white blood cells and is a marker of inflammation. Although nonspecific, its presence is supportive of UTI.
Nitrite: Nitrites are a metabolic by-product of bacteria producing nitrate reductase, an enzyme that reduces normal urinary nitrate (NO3−) to nitrite (NO2−). These bacteria include Escherichia coli and Proteus mirabilis. Enterococcus faecalis and Staphylococcus saprophyticus do not produce nitrate reductase, making their presence inconsistent with this patient’s positive urinary nitrites (Choices B and F).
pH: Alkaline urine (pH >8) in the setting of UTI is suggestive of a bacterium that produces urease (eg, Proteus mirabilis); urease hydrolyzes urea to ammonia (NH3), which is then protonated to ammonium (NH4+), alkalizing the urine. This helps differentiate P mirabilis from other nitrate reductase–producing bacteria. In this case, the patient has a relatively acidic (ie, pH = 5) urine, a finding that makes infection with P mirabilis unlikely (Choice E).
This patient’s dipstick analysis with positive leukocyte esterase, nitrites, and a mildly acidic pH is most consistent with an Escherichia coli UTI.
(Choice A) UTI with Candida albicans is generally seen only in elderly, hospitalized, and immunocompromised patients. In addition, dipstick analysis would be positive for leukocyte esterase but negative for nitrites.
(Choice D) Genital herpes simplex virus infection typically presents with clusters of vesicles (not seen in this patient) that may cause dysuria. Leukocyte esterase may be present in the urine, but nitrites would not.
Educational objective:
The most common cause of urinary tract infection is Escherichia coli, a nitrate reductase–producing bacterium. Dipstick analysis should be significant for leukocyte esterase, nitrites, and a mildly acidic pH.
Answer A
This patient’s dysuria, suprapubic tenderness, and urinalysis abnormalities suggest acute simple cystitis. Women are at much greater risk than men for urinary tract infections (UTIs) because they have a shorter urethra lying in close proximity to the anus and vaginal introitus, which allows enteric flora (eg, Escherichia coli) to spread to the vaginal opening and subsequently ascend through the urethra to the bladder. The major risk factor in otherwise healthy young women is recent sexual intercourse. Although urinating after intercourse flushes bacteria from the lower urinary tract (thereby reducing UTI risk), patients may still develop a UTI.
(Choice B) Hematologic infections generally enter the urinary tract through the glomeruli and cause pyelonephritis. Although pyuria and bacteriuria are usually present, most patients are systemically ill with fever, chills, and/or fatigue. Hematologic dissemination directly to the bladder is uncommon.
(Choice C) Lymphatic spread of infection is common in skin and soft tissue infections (eg, cellulitis) and is often marked by erythematous streaks on the skin. Lymphatic spread to the urinary tract system is uncommon.
(Choice D) Although poor genital hygiene can increase the risk that bacteria spread from the anus to the vaginal introitus, the primary mechanism of acute simple cystitis is the ascending spread of bacteria through the urethra to the bladder.
(Choice E) Sexually transmitted infections, particularly Chlamydia trachomatis, Trichomonas vaginalis, and Neisseria gonorrhea, often cause dysuria in women. However, these infections are frequently associated with vaginal discharge. In addition, suprapubic tenderness is less common.
Educational objective:
Women are at high risk for urinary tract infections due to a shorter urethra that is close to the anus and vaginal introitus, which allows enteric pathogens to colonize the vagina and ascend to the bladder. Acute simple cystitis is generally marked by dysuria, urinary frequency/urgency, suprapubic tenderness, and pyuria/bacteriuria on urinalysis.
Answer E
This patient with intermittent leakage of urine likely has stress urinary incontinence (SUI). In women, the pelvic floor muscles contract to stabilize the urethra against the anterior vaginal wall. This contraction decreases the angle between the bladder neck and the urethra (ie, urethrovesical angle), thereby compressing the urethra, stopping urine flow, and maintaining continence.
Chronically increased intrabdominal pressure (eg, obesity, chronic cough from COPD) can cause weakened pelvic floor muscle support. In addition, prior pregnancies (including cesarean deliveries) typically increase the laxity of pelvic floor muscles and connective tissue. In patients with SUI, the weakened pelvic floor muscles can no longer stabilize the urethra, leading to urethral hypermobility, an increased urethrovesical angle, and resultant urinary incontinence (Choice A). On examination, patients typically have leakage of urine during the Valsalva maneuver. Patients with severe pelvic floor laxity can also develop herniation of the bladder into the vagina (ie, cystocele), which further worsens SUI symptoms.
Treatment can include pelvic floor muscle (ie, Kegel) exercises and pessary placement, which help support and maintain normal pelvic anatomy.
(Choice B) Vesicovaginal fistula is an abnormal connection between the bladder and vagina that most commonly occurs due to bladder injury from surgical or obstetric complications (eg, operative vaginal delivery). Unlike SUI, vesicovaginal fistulas cause continuous urinary dribbling rather than intermittent urinary leakage, and pelvic examination shows leakage of urine from the vagina (not the urethra).
(Choices C and D) The bladder receives both sympathetic and parasympathetic innervation to control continence and micturition. Sympathetic stimulation promotes urine storage and continence by increasing urethral sphincter tone. In contrast, parasympathetic activity stimulates detrusor muscle contraction and micturition. Therefore, increased bladder sphincter sympathetic activity or reduced detrusor parasympathetic activity would promote continence rather than the urinary leakage seen in this patient.
Educational objective:
Stress urinary incontinence (intermittent, involuntary leakage of urine) is caused by weakened pelvic floor muscle support that often occurs due to chronically increased intraabdominal pressure (eg, obesity, chronic cough, prior pregnancies).
Answer E
In women age <35, infertility is the lack of conception after ≥12 months of unprotected intercourse (Choice C). In women, causes of infertility are often classified into disorders of the uterus, fallopian tubes, or ovaries.
In this patient with a history of fever, abdominal pain, and vaginal discharge, the cause of infertility is most likely fallopian tube obstruction from prior pelvic inflammatory disease (PID). PID occurs when a lower genital tract infection (eg, Neisseria gonorrhoeae, Chlamydia trachomatis) compromises the endocervical barrier, allowing polymicrobial vaginal bacteria to ascend and infect the normally sterile upper genital tract (ie, uterus, fallopian tubes). When infection spreads to the fallopian tubes, it creates an inflammatory exudate that promotes tubal wall adhesion and damage; prolonged infection can result in permanent tubal scarring and obstruction that impede the fertilization and/or implantation of future pregnancies (ie, tubal factor infertility, ectopic pregnancy).
To prevent these complications, patients with PID require a broad-spectrum antibiotic regimen with coverage for N gonorrhoeae, C trachomatis, and polymicrobial vaginal flora. Treatment typically consists of a cephalosporin (eg, ceftriaxone), doxycycline, and metronidazole. Ceftriaxone covers gram-negative bacteria (eg, N gonorrhoeae), doxycycline covers gram-positive and atypical organisms (eg, C trachomatis), and metronidazole covers anaerobic bacteria (eg, Gardnerella vaginalis). This patient received incomplete antibiotic treatment (ceftriaxone only), which likely led to a persisting or prolonged infection and increased risk for tubal scarring.
(Choice A) Advanced maternal age (ie, age ≥35) is associated with decreased fertility due to the diminishing quantity and quality of oocytes as women approach menopause (average age: 51).
(Choice B) Chronic ovulatory dysfunction (eg, polycystic ovary syndrome) is a common cause of infertility; however, this diagnosis is unlikely in this patient with regular, monthly (ie, ovulatory) menses.
(Choice D) Long-term oral contraceptive use is not associated with infertility. Shortly after oral contraceptives are discontinued, patients typically resume menses and return to their baseline fertility level.
Educational objective:
Tubal factor infertility, which occurs due to tubal scarring and obstruction, is a complication of pelvic inflammatory disease. The risk for permanent tubal scarring increases with inadequate antibiotic treatment due to persisting or prolonged infection of the upper genital tract.
A 26-year-old woman comes to the office for a wellness visit. The patient has noticed some vaginal discharge for the past few weeks. She has been sexually active with her male partner for 6 months. The patient has been taking oral contraceptive pills since she became sexually active at age 16. Bimanual examination reveals a small, mobile uterus and no cervical motion tenderness. On speculum examination, the cervix has an area of erythema surrounding the external os and scant clear discharge. A pap test is performed and cytological findings are shown in the image below.
The observed cytology findings most likely represent which of the following?
A. Clue cells
B. Endocervical cells
C. Endometrial cells
D. Koilocytes
E. Parabasal cells
Answer D
This patient’s Pap test shows koilocytes, which are abnormal squamous cells with characteristic cytologic features caused by human papillomavirus (HPV) infection.
HPV is a sexually transmitted DNA virus with predilection for squamous epithelium (eg, cervix, anus). Active viral replication in infected cells causes cytoplasmic clearing around the nucleus with dense cytoplasm at the periphery, resulting in a perinuclear halo. Koilocytes also have enlarged, dark nuclei with irregular nuclear contours (ie, raisinoid appearance) and may be binucleated.
In cervical Pap tests, koilocytes are a hallmark feature of low-grade squamous intraepithelial lesion (LSIL), a precursor lesion of squamous cell carcinoma typically detected on routine screening (ie, asymptomatic patients). LSIL is usually caused by HPV strains (eg, 16, 18) with high oncogenic risk. Oncogenesis from high-risk HPV is attributed to viral proteins E6 and E7, which inhibit p53 and Rb, leading to unregulated cell proliferation.
In most cases of LSIL, the infection is cleared within months by the patient’s immune response, and the cytologic abnormalities regress (ie, they are unlikely to progress to a high-grade lesion).
(Choice A) Clue cells are squamous cells covered with adherent bacteria that obscure the normal epithelial cell margins. They can be seen in the setting of bacterial vaginosis, which involves a change in vaginal flora from lactobacilli to anaerobic, gram-variable rods (eg, Gardnerella vaginalis) and typically presents with grayish-white, fishy-smelling vaginal discharge.
(Choice B) Glandular endocervical cells are columnar cells with vacuolated cytoplasm that often form a honeycomb or picket-fence pattern. Their presence in a Pap test indicates adequate sampling of the cervical squamocolumnar junction.
(Choice C) Endometrial cells have small, dark nuclei with little cytoplasm and are often present in clusters. They may be present in a Pap test during menses and are not clinically significant in young women with no risk factors for endometrial cancer (eg, obesity, chronic anovulation). However, in postmenopausal women, endometrial cells are concerning for possible endometrial cancer.
(Choice E) Parabasal cells are immature squamous cells with round nuclei, basophilic cytoplasm, and a higher nucleus-to-cytoplasm ratio. They can predominate in Pap tests from atrophic cervical epithelium caused by low estrogen levels (eg, postmenopausal, postpartum).
Educational objective:
A koilocyte is an atypical squamous cell characterized by perinuclear cytoplasmic clearing (ie, halo) and a large, dark nucleus with irregular contours (ie, raisinoid appearance). These cytologic features are a viral cytopathic effect of human papillomavirus (HPV) infection.
A 20-year-old woman comes to the office due to increasing vaginal discharge and vulvar pruritus. The patient has had vaginal discharge for the past 4 days. She is sexually active with multiple partners and uses oral contraceptive pills. Vital signs are normal. Pelvic examination is performed, and wet mount microscopy of a vaginal swab is shown in the exhibit. Which of the following is the most appropriate pharmacotherapy for this patient?
A. Acyclovir
B. Ceftriaxone
C. Clindamycin
D. Doxycycline
E. Fluconazole
F. Metronidazole
Answer E
This patient with vulvar pruritus and vaginal discharge has candidal vulvovaginitis, an infection typically caused by overgrowth of Candida albicans. C albicans is a yeast and component of normal vaginal flora; however, alterations in the balance of normal vaginal flora can allow for excessive Candida proliferation and symptomatic infection. These imbalances can occur due to increased estrogen levels, such as with estrogen-containing contraceptive use or pregnancy. Additional predisposing factors include recent antibiotic use, immunosuppression (eg, systemic corticosteroids), sexual activity, and diabetes mellitus (particularly if poorly controlled).
With C albicans overgrowth, patients develop vulvovaginal inflammation that can result in erythema; pruritus; and a thick, white, clumpy vaginal discharge. Diagnosis is made via wet mount microscopy, which typically shows pseudohyphae with budding yeast and true hyphae. Treatment of vulvovaginal candidiasis is with azole antifungal medications (eg, fluconazole), which decrease ergosterol synthesis and disrupt fungal cellular membrane formation.
(Choice A) Acyclovir is used to treat herpes simplex virus infection, which can occasionally cause multinucleated giant cells to be visualized on cervical cytology, but not wet mount microscopy. Herpes simplex virus is a rare cause of cervicitis, and patients typically have concomitant, painful vulvovaginal vesicles.
(Choices B and D) Ceftriaxone is used to treat Neisseria gonorrhoeae infection, and doxycycline is used to treat Chlamydia trachomatis infection. These bacteria typically cause acute cervicitis with mucopurulent cervical discharge and a friable cervix, rather than vulvovaginitis. Neither pathogen is easily visualized on wet mount microscopy because C trachomatis has an unusual peptidoglycan cell wall and N gonorrhoeae is intracellular.
(Choices C and F) Clindamycin and metronidazole are used to treat Gardnerella vaginalis, an anaerobic bacterium that causes bacterial vaginosis (BV). BV can be identified by clue cells, which are vaginal epithelial cells covered in bacteria. Metronidazole also treats Trichomonas vaginalis, a protozoan infection characterized by frothy, yellow-green vaginal discharge and motile, flagellated trichomonads on wet mount microscopy.
Educational objective:
Vulvovaginal candidiasis typically presents with thick, white, clumpy vaginal discharge; vulvovaginal erythema and pruritus; and pseudohyphae on wet mount microscopy. Treatment is with an antifungal medication (eg, fluconazole).
Answer D
This patient with tender, vesicular genital lesions and systemic symptoms (eg, fever, fatigue) likely has a primary genital herpes infection. Patients typically develop a characteristic genital rash consisting of small, grouped vesicles that progress into ulcers with crusting; the lesions may be pruritic and associated with painful inguinal lymphadenopathy.
Genital herpes is caused by herpes simplex virus (HSV) type 1 or 2; patients exposed to one serotype can acquire the other. HSV can lie dormant in the sacral dorsal root ganglia and then reactivate; as a result, patients develop recurrent genital lesions. Recurrence is more common with HSV-2, and tends to be localized (no systemic symptoms) or asymptomatic (thereby increasing the risk for inadvertent transmission). Barrier contraception use decreases transmission.
(Choice A) Fluctuant lymphadenitis (pus-filled inguinal buboes) can occur 1-2 weeks after Haemophilus ducreyi infection (ie, chancroid). Chancroid presents with multiple, painful genital ulcers and painful lymphadenopathy, but the lesions are typically deep with a gray exudate. Systemic symptoms are uncommon.
(Choice B) Untreated syphilis (Treponema pallidum infection) can infect the dorsal roots of the spinal column and lead to tertiary neurosyphilis, which may be characterized by tabes dorsales (locomotor ataxia) and general paresis. Unlike primary genital herpes, primary syphilis typically presents with a painless genital ulcer with a clean base (chancre).
(Choice C) Varicella-zoster virus also invades the dorsal root sensory ganglia, and reactivation causes herpes zoster (shingles). One complication is postherpetic neuralgia (persistent pain after resolution of herpes zoster lesions). Patients typically have a painful vesicular rash in a dermatomal distribution and no systemic involvement.
(Choice E) Human papillomavirus (HPV) infection increases the risk of cervical and vulvar carcinoma. Certain strains (HPV 6 and 11) can cause anogenital warts (condylomata acuminata), which are pink or skin-colored papules or verrucous lesions, not ulcers. In addition, primary HPV infections do not cause fever or painful lymphadenopathy.
Educational objective:
Primary genital herpes (herpes simplex virus type 1 or 2 infection) presents as multiple, grouped vesicles on the genitals that progress to ulcers. Primary infections can cause systemic symptoms (eg, fever, malaise) and painful inguinal lymphadenopathy. Because HSV can invade and lie latent in the sacral dorsal root ganglia, patients are at risk for viral reactivation and recurrent genital lesions.
Answer B
This patient likely has a vaginal yeast infection due to overgrowth of Candida albicans. C albicans is a normal component of vaginal flora and exists in balance with the predominant bacteria of the vaginal microbiome, gram-positive Lactobacillus spp. Alterations in the balance of vaginal microbiome allow for excessive Candida proliferation and symptomatic vulvovaginal candidiasis. Common triggers include:
Antibiotic use
High estrogen levels (eg, pregnancy, oral contraceptive pills)
Systemic corticosteroid therapy
Diabetes mellitus, particularly if uncontrolled
Immunosuppression (eg, HIV)
Antibiotic use, as in this patient recently treated for a urinary tract infection, results in decreased number of lactobacilli and is the most common predisposing cause of Candida vaginitis. Patients can develop vulvar, vaginal, and perianal inflammation that results in erythema; pruritus; and a thick, white, clumpy vaginal discharge. Diagnosis is made via wet mount microscopy, which typically shows budding yeast and pseudohyphae.
(Choice A) Decreased glycogen concentration in the vaginal epithelium is typical in postmenopausal and lactating women. This occurs due to low estrogen levels and can result in atrophic vaginitis (eg, vaginal dryness, pruritis). This patient’s regular monthly menstrual cycles indicate adequate estrogen levels.
(Choice C) Enterobial larva and egg deposition occurs with pinworm infection (Enterobius vermicularis). Although this common helminth infection causes perianal and vulvar pruritis that worsens at night, there is no association with thick, white vaginal discharge.
(Choice D) Elevated (alkaline) vaginal pH (>4.5) is associated with bacterial vaginosis and Trichomonas vaginitis, which cannot thrive under acidic conditions. In contrast, C albicans readily adapts to its surrounding pH level; therefore, vaginal pH associated with Candida vaginitis is typically normal (3.8-4.5).
(Choice E) Human papillomavirus can incorporate its DNA into anogenital, cervical, and vaginal epithelial cells. As a result, patients can develop anogenital warts, dysplasia, and malignancy. However, patients do not typically have an associated thick, white vaginal discharge.
Educational objective:
Antibiotic use alters the balance of normal vaginal flora (eg, decreases the number of gram-positive lactobacilli) and facilitates Candida overgrowth. Patients can develop vulvovaginal candidiasis, which presents with vulvar/vaginal/perianal pruritis; erythema; and a thick, white vaginal discharge.
Answer E
This patient with lower abdominal pain, bloody vaginal discharge, hemodynamic instability (eg, tachycardia, orthostatic hypotension), and a positive pregnancy test most likely has a ruptured ectopic pregnancy. Ectopic pregnancies occur due to extrauterine pregnancy implantation, typically in the ampulla of the fallopian tube.
The most common risk factor for ectopic pregnancy is tubal scarring, which impedes normal migration of the fertilized embryo through the fallopian tube and into the uterus. Tubal scarring usually occurs due to prior upper genital tract infection (ie, pelvic inflammatory disease [PID]) associated with either Neisseria gonorrhoeae or Chlamydia trachomatis. Both pathogens cause cervicitis, which compromises the cervix barrier and allows vaginal bacteria to ascend into the normally sterile upper genital tract, resulting in tubal inflammation and scarring.
(Choice A) Escherichia coli, an enteric bacteria, can ascend the urethra to cause a urinary tract infection. Although E coli may be found in the vagina, it does not commonly cause PID in premenopausal women.
(Choices B and G) Gardnerella vaginalis (bacterial vaginosis) and Trichomonas vaginalis (trichomoniasis) can cause vaginal discharge due to lower genital tract inflammation (ie, vaginitis). Neither is associated with increased risk of ectopic pregnancy.
(Choices C and D) Herpes simplex virus (HSV) and human papillomavirus (HPV) typically cause lower genital tract disease. HSV causes multiple small, vesicular genital ulcers and HPV causes genital warts or cervical/vaginal/perianal neoplasia. Neither causes upper genital tract infection or inflammation; therefore, neither is associated with ectopic pregnancy.
(Choice F) Treponema pallidum infection (ie, syphilis) usually begins in the lower genital tract as a single, painless genital chancre (ie, the transmission site). However, it does not cause PID.
Educational objective:
A ruptured ectopic pregnancy can cause abdominal pain, vaginal bleeding, and hemodynamic instability. A common risk factor is tubal scarring from a prior upper genital tract infection (ie, pelvic inflammatory disease) due to Neisseria gonorrhoeae or Chlamydia trachomatis.
Answer A
This patient’s clinical presentation is most consistent with bacterial vaginosis (BV). BV is caused by an imbalance of the vaginal bacterial flora (eg, decreased lactobacilli colonization) and is associated with sexual activity, cigarette smoking, and vaginal douching. The decreased lactobacilli colonization causes a subsequent increase in vaginal pH and overgrowth of anaerobic bacteria (eg, Gardnerella vaginalis), which generate malodorous amines. The amines cause the characteristic grayish-white, fishy-smelling discharge with no associated vaginal inflammation.
Wet mount microscopy of the discharge shows clue cells (squamous epithelial cells with adherent bacteria). Application of potassium hydroxide to the discharge produces an amine odor (ie, positive whiff test). Treatment is with metronidazole or clindamycin.
(Choice B) A wet mount with epithelial cells and rare leukocytes is consistent with normal vaginal discharge (ie, physiologic leukorrhea). Physiologic leukorrhea is not malodorous.
(Choice C) Gram stain showing gram-negative intracellular diplococci is consistent with Neisseria gonorrhoeae cervicitis, which is characterized by cervical erythema, friability, and purulent cervical discharge.
(Choice D) A wet mount of trichomoniasis would show leukocytes and pear-shaped organisms (flagellated trophozoites). Trichomonas vaginitis typically presents with vulvovaginal erythema and frothy, yellow-green vaginal discharge; patients with Trichomonas cervicitis classically have a cervix with punctate hemorrhage (ie, strawberry cervix).
(Choice E) Pseudohyphae with leukocytes are seen in Candida vaginitis, which would present with thick, white vaginal discharge and associated vaginal inflammation (eg, vaginal erythema, pruritus).
Educational objective:
Bacterial vaginosis is caused by a disruption of the vaginal bacterial flora and is characterized by a thin, gray-white, malodorous vaginal discharge. Clue cells (squamous epithelial cells with adherent bacteria) are seen on wet mount microscopy.
Answer F
Acute cervicitis classically presents with purulent cervical discharge and a friable cervix that bleeds easily with contact (ie, postcoital bleeding). Microscopy showing inflammation (eg, neutrophils) without a visible pathogen is classic for cervicitis due to Chlamydia trachomatis or Neisseria gonorrhoeae, which are often identified by nucleic acid amplification testing.
Left untreated, cervicitis can compromise the endocervical barrier, allowing polymicrobial vaginal flora to ascend into the normally sterile uterus and fallopian tubes. In contrast to cervicitis, infection involving the upper genital tract (ie, pelvic inflammatory disease [PID]) can cause fever, abdominal pain, and cervical motion/uterine/adnexal tenderness due to increased bacterial load and spread.
When the infection extends to the fallopian tube, it creates an inflammatory exudate (ie, salpingitis) that causes the tubal walls to adhere. With prolonged infection, the exudate may be replaced by scar tissue, causing permanent tubal scarring and obstruction that impedes the fertilization and/or implantation of future pregnancies. Therefore, common complications of PID include tubal factor infertility and ectopic pregnancy.
(Choice A) Primary ovarian insufficiency is the accelerated depletion of oocytes and loss of both ovarian follicular development and estrogen production in women age <40. Risk factors include genetic disorders (eg, Turner syndrome) and chemoradiation.
(Choice B) Cervical cancer can occur in patients with chronic human papillomavirus infection (eg, types 16 and 18).
(Choice C) Patients with cervical insufficiency cannot maintain a closed cervix as pregnancy progresses (ie, as the load on the cervix increases); therefore, second-trimester pregnancy loss occurs. Risk factors include prior cervix surgery or inherited collagen disorders (eg, Ehler-Danlos syndrome).
(Choice D) Increased unopposed estrogen stimulation can lead to endometrial hyperplasia. Obesity is a risk factor due to increased androgen-to-estrogen conversion.
(Choice E) Recurrent urinary tract infections typically occur when enteric bacteria colonizing the periurethral area ascend the urethra. Certain sexual behaviors (eg, frequent intercourse, spermicide use) promote periurethral colonization.
Educational objective:
Neisseria gonorrhoeae and Chlamydia trachomatis can cause acute cervicitis (eg, purulent cervical discharge, friable cervix). Untreated, cervicitis can progress to pelvic inflammatory disease and long-term complications such as tubal factor infertility and ectopic pregnancy.
A 32-year-old woman, gravida 1 para 1, comes to the office for vaginal discharge. The patient has no chronic medical conditions and takes no daily medications. Her last menstrual period was 3 weeks ago. The patient has recently become sexually active with a new partner and uses an intrauterine device for contraception. Cytology of the discharge is shown in the image below:
Which of the following best describes the predominant organism causing this patient’s condition?
A. Anaerobic gram-variable rod
B. Diploid fungus
C. Gram-negative diplococcus
D. Intracellular gram-negative bacterium
E. Motile protozoan
F. Naked DNA virus
Answer A
Bacterial vaginosis (BV) is most commonly caused by an overgrowth of the facultative anaerobic, gram-variable rod Gardnerella vaginalis and loss of normal lactobacilli flora. A classic symptom is a thin, malodorous, grayish-white vaginal discharge. The odor becomes more prominent with the addition of potassium hydroxide (whiff test) to a sample due to the anaerobes that release amines. Wet mount microscopy of the discharge and cytologic smears characteristically show clue cells, which are vaginal squamous epithelial cells covered with multiple, small, adherent G vaginalis organisms. Treatment is with metronidazole or clindamycin.
(Choice B) Candida albicans vaginitis is associated with intense vaginal pruritus; white, curd-like discharge; and labial erythema. Pseudohyphae of this diploid fungus are seen on potassium hydroxide preparations of the vaginal discharge.
(Choices C and D) Neisseria gonorrhoeae and Chlamydia trachomatis are transmitted sexually, commonly together. These organisms can cause cervicitis, which typically presents with a mucopurulent cervical discharge. Microscopy of N gonorrhoeae shows gram-negative intracellular diplococci, and C trachomatis microscopy is typically normal or shows leukocytes.
(Choice E) Trichomonas vaginalis is a flagellated protozoan that causes trichomoniasis, which is associated with a yellow-green, frothy discharge. Motile, flagellated trophozoites are seen on wet mount microscopy.
(Choice F) Human papillomavirus is a naked DNA virus that can cause condylomata acuminata and cervical cancer. Condylomata are commonly caused by strains 6 and 11, and oncogenic strains include types 16 and 18. Human papillomavirus infections do not typically cause vaginal discharge.
Educational objective:
Bacterial vaginosis is associated with a grayish-white, malodorous vaginal discharge due to an overgrowth of Gardnerella vaginalis, a facultative anaerobic, gram-variable rod. Clue cells (squamous epithelial cells covered with bacterial organisms) are seen on wet mount microscopy or cytology.
Answer F
The most likely cause of this patient’s abnormal vaginal discharge is Trichomonas vaginalis, a sexually transmitted infection that often presents with a malodorous, thin, frothy, yellow-green vaginal discharge. The trichomonads infect the squamous epithelium of the vagina, resulting in vulvovaginal inflammation and subsequent vulvar pruritus, dyspareunia, vulvovaginal erythema, and discharge.
Wet mount saline microscopy of trichomoniasis typically shows characteristic motile, flagellated protozoans. Nucleic acid amplification testing can also be performed and is the gold standard. Treatment of the patient and the patient’s sexual partners is with metronidazole.
(Choice A) Cervical cytology (ie, Pap test) is a screening test for cervical cancer. Most patients with high-grade cervical lesions or cervical cancer are asymptomatic; patients with symptoms typically present with postcoital bleeding or a mucopurulent cervical discharge with an associated cervical lesion.
(Choice B) Neisseria gonorrhoeae is a common sexually transmitted infection that may present with mucopurulent (not frothy) vaginal discharge originating from an inflamed cervix. A Gram stain may show gram-negative diplococci in polymorphonuclear leukocytes. Gram staining is not performed for T vaginalis because the process often changes the organism’s shape, making it difficult to identify.
(Choice C and E) pH and whiff tests can be used to diagnose bacterial vaginosis, which typically presents with thin, off-white, malodorous discharge with no associated vaginitis. In bacterial vaginosis, the addition of potassium hydroxide (KOH) to the vaginal discharge releases amines, causing a characteristic odor (eg, positive whiff test). Vaginal pH is elevated in both bacterial vaginosis and trichomonas infection; therefore, pH testing is not specific for diagnosis.
(Choice D) Urine culture is used to diagnose urinary tract infections, which can present with dysuria; however, patients do not have associated vaginal discharge.
Educational objective:
Trichomonas vaginalis is a sexually transmitted motile protozoan which can be seen on wet mount microscopy of vaginal discharge. It presents with yellow-green, frothy vaginal discharge and vulvovaginal erythema.
