Bacterial Vaginosis Case File

Bacterial Vaginosis Case File

Eugene C. Toy, MD, Patti Jayne Ross, MD, Benton Baker III, MD, John C. Jennings, MD

CASE 38

An 18-year-old nulliparous woman complains of a vaginal discharge with a fishy odor over the past 2 weeks. She states that the odor is especially prominent after intercourse. Her last menstrual period was 3 weeks ago. She denies being treated for vaginitis or sexually transmitted diseases. She is in good health and takes no medications other than an oral contraceptive agent. On examination, her blood pressure (BP) is 110/70 mm Hg, heart rate (HR) is 80 beats per minute, and temperature is afebrile. The thyroid is normal to palpation. The heart and lung examinations are normal. Her breasts are Tanner stage V as is the pubic and axillary hair. The external genitalia are normal; the speculum examination reveals a homogeneous, white vaginal discharge and a fishy odor. No erythema or lesions of the vagina are noted.

» What is the most likely diagnosis?

» What is the best treatment for this condition?

ANSWER TO CASE 38:

Bacterial Vaginosis                                           

Summary: An 18-year-old nulliparous woman complains of a fishy vaginal discharge, which is worse after intercourse. The speculum examination reveals a homogeneous, white vaginal discharge and a fishy odor. No erythema or lesions of the vagina are noted.

• Most likely diagnosis: Bacterial vaginosis (BV).
• Best treatment for this condition: Metronidazole orally or vaginally; clindamycin is an alternative.

ANALYSIS

Objectives

1. Know the three common infectious causes of vaginitis or vaginosis, which are BV, Trichomoniasis, and Candida vulvovaginitis.
2. Know the diagnostic criteria for bacterial vaginosis.
3. Know the treatments for the corresponding causes of vaginitis and vaginosis.

Considerations

This 18-year-old woman complains of a vaginal discharge that has a fishy odor, which is the most common symptom of bacterial vaginosis. The discharge associated with BV has a typical white, homogenous vaginal coating, described as “spilled milk over the tissue.” The pH is not given in this scenario, but it is likely alkaline. Although a whiff test was not performed with potassium hydroxide (KOH) in this patient, the worsening of the discharge after intercourse is presumably due to the alkaline semen. The vaginal epithelium is not erythematous or inflamed, which also fits with bacterial vaginosis. Of the three most common causes of infectious vaginal discharge (Candida, Trichomonas, and BV), bacterial vaginosis is the only etiology that is not inflammatory (hence the suffix “-osis” and not “-itis.”) BV is a result of a predominance of anaerobic bacteria rather than a true infection. Therefore, antibiotic therapy targeting anaerobes, such as metronidazole or clindamycin, is appropriate.

APPROACH TO:

Vaginal Infections                                              

DEFINITIONS

BACTERIAL VAGINOSIS: Condition of excessive anaerobic bacteria in the vagina, leading to a discharge that is alkaline.

CANDIDA VULVOVAGINITIS: Vaginal and/ or vulvar infection caused by Candida species, usually with heterogeneous discharge and inflammation.

TRICHOMONAS VAGINITIS: Infection of the vagina caused by the protozoa Trichomonas vaginalis, usually associated with a frothy green discharge and intense inflammatory response.

CLINICAL APPROACH

The three most common types of vaginal infections are bacterial vaginosis, trichomonal vaginitis, and candidal vulvovaginitis (Table 38– 1).

Bacterial vaginosis is not a true infection, but rather an overgrowth of anaerobic bacteria, which replaces the normal lactobacilli of the vagina. Although it may be sexually transmitted, this is not always the case. The most common symptom is a fishy or “musty” odor, often exacerbated by menses or intercourse. Since both of these situations introduce an alkaline substance, the vaginal pH is elevated above normal. The addition of 10% potassium hydroxide solution leads to the release of amines, causing a fishy odor (whiff test). There is no inflammatory reaction; hence, the patient will not complain of swelling or irritation, and typically, the microscopic examination does not usually reveal leukocytes. Microscopy of the discharge in normal saline (wet mount) typically shows clue cells (Figure 38– 1), which are coccoid bacteria adherent to the external surfaces of epithelial cells. Three out of four Amsel’s criteria are indicative of BV: (1) homogenous, gray–white discharge, (2) vaginal pH > 4.5, (3) positive whiff test, and (4) clue cells on wet mount. The Gram stain is considered the gold standard for diagnosing BV but is rarely performed clinically.

Bacterial vaginosis is associated with genital tract infections such as endometritis, pelvic inflammatory disease, and pregnancy complications such as preterm delivery and preterm premature rupture of membranes. Treatment includes oral or vaginal metronidazole. Patients should be instructed to avoid alcohol while taking metronidazole to avoid a disulfiram reaction. Clindamycin is another effective treatment.

Figure 38–1. Vaginal epithelial “clue cells.” Clue cells (A) with a granular appearance in contrast to normal cells (B). (Reproduced with permission from Kasper DL, et al. Harrison’s Principles of Internal Medicine. 16th ed. New York, NY: McGraw-Hill; 2005:767.)

Trichomonas vaginalis is a single-cell anaerobic flagellated protozoan that induces an intense inflammatory reaction. It is a common sexually transmitted disease. Trichomonas vaginalis can survive for up to 6 hours on a wet surface. Aside from causing infection of the vagina, this organism can also inhabit the urethra or Skene’s glands. The most common symptom associated with trichomoniasis is a profuse “frothy” yellow– green to gray vaginal discharge or vaginal irritation. Intense inflammation of the vagina or cervix may be noted, with the classic punctate lesions of the cervix (strawberry cervix). A fishy odor is also common with this disorder, which is somewhat exacerbated with KOH. Microscopy in saline will often display mobile, flagellated organisms. If the wet mount is cold or there are excess leukocytes present, the movement of the trichomonads may be inhibited. Nucleic acid amplification testing is more sensitive than wet mount microscopy. Optimal treatment consists of a fairly high dose of metronidazole (2 g orally) as a one-time dose, with the partner treated as well. Resistant cases may require the same dose every day for 7 days. A newer antiprotozoal agent, Tinidazole, has a similar dosing, side-effect profile, and contraindication for concurrent alcohol; due to its expense, its main role is for metronidazole-resistant cases. Treatment usually does not include vaginal metronidazole because of low therapeutic levels in the urethra or Skene’s glands where trichomonads may reside.

Candidal vaginitis is usually caused by the fungus, Candida albicans, although other species may be causative. The lactobacilli in the vagina inhibit fungal growth; thus, antibiotic therapy may decrease the lactobacilli concentration, leading to Candida overgrowth. Diabetes mellitus, which suppresses immune function, may also predispose patients to these infections. Candidiasis is usually not a sexually transmitted disease. The patient usually presents with intense vulvar or vaginal burning, irritation, and swelling. Dyspareunia (pain with intercourse) may also be a prominent complaint. The discharge usually appears curdy or like cottage cheese, in contrast to the homogenous discharge of bacterial vaginosis. Also, unlike the alkaline pH of BV and Trichomonas infection, the vaginal pH in candidiasis is typically normal (< 4.5). The microscopic diagnosis is confirmed by identification of the hyphae or pseudohyphae after the discharge is mixed with potassium hydroxide. The KOH solution lyses the leukocytes and erythrocytes, making identification of the candidal organisms easier. Treatment includes oral fluconazole (Diflucan) or topical imidazoles, such as terconazole (Terazol), miconazole (Monistat), and clotrimazole (Lotrimin).

CASE CORRELATION See also Case 36 (Gonococcal Cervicitis) to understand the diagnostic approach of abnormal vaginal discharge and trying to discern a cervical versus a vaginal etiology.

COMPREHENSION QUESTIONS

38.1 An 18-year-old G0P0 adolescent female is being seen at the physician’s office for vaginal discharge. A presumptive diagnosis of bacterial vaginosis is made. Which of the following is a finding consistent with BV?

A. pH less than 4.5

B. Frothy vaginal discharge

C. Predominance of anaerobes

D. Flagellated organisms

38.2 A 26-year-old woman completed a course of oral antibiotics for cystitis 1 week ago. She complains of a 1-day history of itching, burning, and a yellowish vaginal discharge. Which of the following is the best therapy?

A. Metronidazole

B. Erythromycin

C. Fluconazole

D. Hydrocortisone

E. Clindamycin

38.3 Which of the following organisms may be isolated from a wet surface 6 hours after inoculation?

A. Candida albicans

B. Trichomonas vaginalis

C. Gardnerella species

D. Peptostreptococci

38.4 A 27-year-old woman complains of a fishy odor and a vaginal discharge. The speculum examination reveals an erythematous vagina and punctuations of the cervix. Which of the following is the most likely treatment for this patient?

A. Oral fluconazole

B. Metronidazole gel applied vaginally

C. Metronidazole taken orally in a single dose

D. Intramuscular ceftriaxone and oral doxycycline

38.5 A 29-year-old woman has been treated for bacterial vaginosis and after 3 days of metronidazole, she notes abdominal discomfort, bloating, and diarrhea. Which of the following is most likely explanation?

A. Alcohol use

B. Clostridium difficile colitis

C. Medication side effect

D. Undiagnosed salpingitis

ANSWERS

38.1 C. There is a predominance of anaerobes in bacterial vaginosis. The vaginal pH in BV is usually > 4.5, and the discharge is homogenous. The most common symptom is a fishy or “musty” odor when introduced to an alkaline substance (ie, 10% KOH, semen, or menses). Clue cells are found on microscopy. BV is associated with genital tract infection, such as endometritis, pelvic inflammatory disease, and pregnancy complications, such as preterm delivery and PPROM. Frothy discharge, normal to acidic pH, and flagellated organisms are more typical of trichomoniasis.

38.2 C. After antibiotic therapy, candidal organisms often proliferate and may induce an overt infection. The mechanism is likely that the lactobacilli are eliminated by the antibiotic, allowing overgrowth of yeast. Treatment of candidal vulvovaginitis is oral fluconazole or imidazole cream. Metronidazole is used to treat BV and T. vaginalis. Patients should be instructed to avoid alcohol while taking metronidazole to avoid a disulfiram reaction. Erythromycin may be used in the treatment of syphilis in nonpregnant women allergic to penicillin. Clindamycin is typically used in conjunction with gentamicin in the treatment of infections requiring broad-spectrum antibiotics, necessitating anaerobic coverage (ie, postpartum endomyometritis). Hydrocortisone is most commonly indicated for severe allergic reactions.

38.3 B. Trichomonas vaginalis is a hardy organism and may be isolated from a wet surface up to 6 hours after inoculation. The organism’s difficulty to eradicate is the reason that therapy requires high tissue levels, metronidazole 2 g orally all at once, to be able to obtain sufficiently high tissue levels to be effective. Not uncommonly, a single course is not effective, and a 2- or 3-day course of metronidazole of high dose orally is needed.

38.4 C. The patient takes 2 g of metronidazole as a single dose to attain sufficient tissue levels to eradicate the trichomonads. Metronidazole gel is not as effective. Erythematous vagina and punctuations of the cervix (strawberry cervix) are classic findings of the inflammatory effects induced by trichomoniasis. Classic findings in candidal vaginitis include the curdy or cottage cheese appearance of the vaginal discharge with hyphae or pseudohyphae found on microscopy after discharge is mixed with KOH; this would be treated by fluconazole. HPV is associated with findings of cervical dysplasia. Ceftriaxone and doxycycline is the treatment for PID. Metronidazole gel would treat BV.

38.5 C. The most common side effects from metronidazole are gastrointestinal including nausea, abdominal discomfort, bloating or diarrhea. A disulfiram (Antabuse) effect that can be seen with metronidazole includes facial flushing, headache, hypotension, tachycardia, dizziness, and nausea and vomiting.

    CLINICAL PEARLS    

» The three most common types of vaginal infections are trichomoniasis, candidal vaginitis, and bacterial vaginosis. » Both BV and trichomoniasis is associated with alkaline pH and positive whiff test. » Candidal vulvovaginitis is a common infection in women who are pregnant, taking broad-spectrum antibiotics, diabetic, or immunocompromised. » Bacterial vaginosis is associated with preterm delivery, postpartum endometritis, and pelvic inflammatory disease. » Trichomonal vaginitis is associated with an intense inflammatory process and may induce punctuations of the cervix known as “strawberry cervix.”

REFERENCES

American College of Obstetricians and Gynecologists. Vaginitis. ACOG Practice Bulletin 72. Washington, DC; 2006. (Reaffirmed 2015.) 

Amsel R, Totten PA, Spiegel CA, et al. Nonspecific vaginitis. Diagnostic criteria and microbial and epidemiologic associations. Am J Med. 1983;74:14-22. 

Centers for Disease Control and Prevention (CDC). Sexually-Transmitted Diseases Treatment Guidelines; 2015. http:/ / www.cdc.gov/ std/ tg2015/ vaginal-discharge.htm; Accessed 30.06.15. 

Eckert LO, Lentz GM. Infections of the lower and upper genital tracts. In: Lentz GM, Lobo RA, Gershenson DM, Katz VL, eds. Comprehensive Gynecology. 6th ed. Philadelphia, PA: Mosby; 2012: 531-539. 

McGregor JA, Lench JB. Vulvovaginitis, sexually transmitted infections, and pelvic inflammatory disease. In: Hacker NF, Gambone JC, Hobel CJ, eds. Essentials of Obstetrics and Gynecology. 5th ed. Philadelphia, PA: Saunders; 2010:265-275. 

Mohammadezadeh F, Dolatian M, Jorjani M, Alavi Majd H. Diagnostic value of Amsel’s clinical criteria for diagnosis of bacterial vaginosis. Global J Health Sci. 2014;7(3):8-14.

HomeObstetrics and Gynecology Case FileBacterial Vaginosis Case File