Universidade Federal Fluminense, Niterói, Rio de Janeiro, Brazil
8.1 Bacterial Vaginosis
Vaginal discharge, bacterial vaginosis, BV.
BV is a syndrome that occurs due to an imbalance in the vaginal microbiome and is characterized by a reduction in lactobacilli, particularly those that are producers of hydrogen peroxide, resulting in a large increase in anaerobic bacteria.
8.1.3 Incubation Period
There is no determined incubation period.
8.1.4 Etiological Agent
Gardnerella vaginalis, Mobiluncus sp., Mycoplasma hominis, Bacteroides, Prevotella sp., Peptostreptococcus sp. and Atoponium vaginae, among others.
This infection is symptomatic in 50% of cases and can produce a range of symptoms, including a grey, white or yellow-colored discharge, which is liquid and homogenous, and which is often described as having a disagreeable odor (of “rotting fish”) that worsens after unprotected vaginal intercourse and during menstruation. Both semen and blood are alkaline and increase the volatility of the substances produced by anaerobic bacteria, causing this characteristic smell. There is generally no vaginal inflammation, itching, dysuria or dyspareunia.
It has been reported that around 30% of cases of BV can vanish without any specific treatment. On the other hand, around 40% cases are recurring within 3 months of treatment.
Direct examination of a sample taken from the vagina in saline solution: presence of guide cells, key cells, target cells or clue cells (epithelial vaginal cells with multiple superimposed bacteria in the cytoplasm). Where Mobiluncus is present, these pathogens may be identified via their characteristic shape and movement, as well as the formation of comma cells that have bacteria sticking to their surface in the same way as clue cells.
Bacterioscopy of vaginal swabs stained using the Gram technique show an absence of lactobacilli and polymorphonuclear cells with target cells and numerous cocobacilli or Gram-negative bacilli. The Nugent Score is considered to be the golden standard for the diagnosis of BV (Table 8.1).
The Nugent Score
The pH of the vagina is above 4.5 and the amine test is generally positive (due to associations with other anaerobic bacteria).
A positive result for the KOH test (10%) represents the volatility of amines present in vaginal material that cause the strong smell of rotting fish or ammonia.
Colpocytology (“preventative”) may reveal clue cells and an abnormal microbiota, however this procedure should not be routinely carried out for this purpose.
Enzymatic and biomolecular tests have recently been incorporated into clinical practice. These include BVblue® (BV blue® (Gryphus Diagnostics, Birmingham, AL, USA), an exam that evaluates the enzymatic activity of sialidase, an enzyme produced by enzymes such as Gardnerella vaginalis, Bacteroides spp., Prevotella spp. and Mobiluncus spp., which are all associated with BV, and Affirm VPIII® (BD Affirm VPIII™, a molecular system to detect vaginitis caused by Candida, Gardnerella and Trichomonas. Processing just one sample, the test uses complementary DNA sequences that interlink with or hybridize just the nucleic acids from the target organism, generating a reaction that reveals a blue coloring in sphere shapes on the exam cards. Test results: the first card on the left gave a positive reaction for Gardnerella and Candida, the second gave a negative reaction and the third was positive for Candida).
The presence of polymorphonuclear cells in cases of BV diagnosed using Amsel criteria (Table 8.2) or the Nugent Score has still not been clarified, but some studies have demonstrated that this could be related to cases associated with Candida (mixed vaginitis).
Evaluation of Laboratory Methods
Affirm VIII (BD)
Amsel criteria for the diagnosis of BV
pH > 4.5
Positive amine test (10% KOH)
8.1.7 Treatment and Control of Cure
Oral metronidazole 500 g, 12/12 h for 7 days.
Oral metronidazole, secnidazole or tinidazole 2 g, single dose.
Metronidazole gel 0.75%, 5 g, applied to the vagina twice a day for 5 days.
Oral clindamycin 300 mg, 12/12 h for 7 days.
Clindamycin cream 2%, 5 g, applied to the vagina at night for 7 days.
Although treatment regimens involving a single dose are easier to follow, they are associated with a higher incidence of recurrence. Repeating the single dose a week later can increase their efficacy.
Increased risk of premature birth, chorioamnionitis, premature rupture of membranes, puerperal infection, infection (cellulitis) after abortion and intraepithelial neoplasia (this may be a co-factor for HPV). It is also an important risk factor for HIV.
8.1.9 Differential Diagnosis
Trichomoniasis, candidiasis, idiopathic vaginitis, aerobic vaginitis.
The symptoms of trichomoniasis can be confused with those of BV, meaning that laboratory diagnosis is indispensable in these cases.
The rate of recurrence within 3 months is generally 30%.
It is not considered to be one of the classic STDs, and for this reason the sexual partner is not usually treated, except if they have symptoms and are carrying the agents associated with BV.
Metronidazole may cause side effects, such as a metallic taste in the mouth, nausea and abdominal pain. Patients should be advised not to drink alcohol during their treatment due to the Antabuse effect.
BV represents an important biological risk for other genital infections. Routine screening in pregnant women and patients infected with HIV is highly recommended, as the diagnosis method is very effective.
Infection caused by a fungus of the Candida genus in the female (mainly the vulva and vagina) and male genitourinary tract. Its presence in the oral cavity is related to immunodeficiency. Although some partners also present infection with Candida in the penis, it is not considered to be one of the classic STDs.
8.2.3 Incubation Period
Since Candida can be a normal part of the vaginal microbiome, imbalances in the vaginal ecology can lead to the growth of fungi and the onset of signs and symptoms. There is no defined incubation period for candidiasis.
8.2.4 Etiological Agent
Candida albicans is responsible for over 80% of cases of candidiasis. Other cases are caused by infection by other non-albicans Candida species. Candida is a commensal opportunistic fungus that lives in the mucous membrane of the digestive system and the vagina. It is a type of yeast that doesn’t contain chlorophyll, is Gram-positive, develops better in more acidic environments (<4.0) and exists in two forms: vegetative growth (pseudohyphae/pseudomycelia) and reproducing (blastospore or blastoconidium).
Uncomplicated candidiasis: light or moderate sporadic candidiasis caused by C. albicans and found in immunocompetent patients.
Complicated candidiasis: recurring serious infections (3–4 attacks/year) caused by non- albicans Candida species or affecting patients with immunosuppression or uncontrolled diabetes.
Women: vaginal discharge with the appearance of curdled milk, as well as itching, hyperemia and vulval edema (more intense in pregnant women). Complaints also include a stinging sensation during intercourse and painful and frequent urination.
Men: balanoposthitis with light to severe erythema, edema and accumulation of a white secretion in the balanopreputial groove. Itching is also common.
Direct examination (10% KOH) of vaginal swabs can reveal fungal pseudohyphae/pseudomycelia or blastospores. Bacterioscopy using the Gram technique may also be used.
Vaginal pH < 4.0.
Cultures using a medium such as Sabouraud agar.
Bacterioscopy using the Gram technique or colpocytology using the Papanicolaou technique can reveal both pseudohyphae/pseudomycelia and blastospores.
Since 10–15% of women affected are completely asymptomatic, Candida in the vagina does not necessarily mean there is a disease and that treatment is required. Clinical examinations should always be taken into account.
Evaluation of Laboratorial Methods
Direct examination (10% KOH)
8.2.7 Treatment and Control of Cure
Tioconazole, clotrimazole, isoconazole, miconazole, terconazole, nystatin cream, vaginal creams or pessaries, vaginal application at night in a single dose or over 10 days.
Oral fluconazole 150 mg, single dose.
Oral itraconazole 100 mg, two pills repeated after 12 h.
Oral ketoconazole 200 mg, 12/12 h for 5 days.
Oral fluconazole 150 mg, three doses in intervals of 3 days.
Boric acid 600 mg, in the form of a vaginal gel or pessary, applied to the vagina at night for 2 weeks (indicated for cases of non-albicans Candida).
Dissemination of the disease leads to endocarditis, meningitis and septicemia, which is often fatal. Dissemination is hematogenous. Candidiasis is the most commonly seen infection in patients with diabetes or immunosuppression, appearing at an early stage as soon as cellular immunity is compromised. As well as recurring vulvovaginal candidiasis, infections can be lead to oropharyngitis or in more advanced stages of immunosuppression can spread and cause esophagitis, lung abscesses and lesions to the digestive tract as far as the anus.
For patients with recurring vulvovaginal candidiasis, serological screening for HIV must be offered.
8.2.9 Differential Diagnosis
Most women will experience at least one attack of candidiasis in their lives.
The various treatment regimens available (local and/or oral) have similar efficacies that rarely exceed 90%.
In recurring (over 3 episodes/year) or serious cases, screening for HIV and diabetes should be offered.
Pregnant women should be given just vaginal medication for 12–14 days.
Not all vulvovaginal itching is caused by candidiasis.
Trichomonas vaginitis, vaginal discharge.
Infection caused by the protozoan parasite Trichomonas vaginalis in the female and male genitourinary tract. Together with candidiasis and BV, this is one of the main types of vaginal infection. It is classified as a classic curable STD, alongside syphilis, gonorrhea and chlamydia.
It is estimated that there are over 276.4 million new cases of this infection in the world every year. In Brazil, this figure is estimated at over 4.3 million per year. Trichomoniasis is generally more prevalent in populations with lower socio-economic development, and is even found in countries with a high human development index.
8.3.3 Incubation Period
T. vaginalis is a pathogen exclusive to humans. Therefore, there are hardly any detailed studies on its incubation. It is assumed that symptoms will appear within 1–2 weeks of after inoculation of T. vaginalis in the vagina. However, this depends on the quantity of inoculums, the virulence of the parasite and local immunity.
8.3.4 Etiological Agent
Trichomonas vaginalis: an oval protozoan parasite with high motility as a result of its four flagella. It is a little larger than a leukocyte and smaller than a vaginal epithelial cell.
It is easily killed by drying or prolonged exposure to sunlight. However, vaginal samples mixed with saline solution can keep the parasite active for over 5 h. Rare cases of non-sexual transmission by fomites have been reported, including in children.
Women are the main victims of this infection, although many (50%) are oligosymptomatic or asymptomatic. The main symptoms are a bullous yellow-green discharge with an unpleasant odor, a stinging sensation during intercourse and diffuse colpitis, also known as “tiger” (multifocal) colpitis. Many women with trichomoniasis present vulval itching. Most infected men are asymptomatic.
Direct examination of vaginal swabs in saline solution reveals the protozoa actively moving between epithelial cells and leukocytes. The parasite can also be visualized via bacterioscopy using the Gram technique or colpocytology with staining.
Cultures in Diamond’s medium provide excellent results, but recently this has been substituted with more up-to-date techniques, such as OSOM Trichomonas Rapid Test and Affirm VIII®, which are available on the market and offer good sensitivity and specificity.
Vaginal pH is >4.5 and the amine test generally produces positive results (as a result of association with other anaerobic bacteria).
Similarly to BV, in cases of trichomoniasis there is an extensive microbiota of anaerobic bacteria. Therefore, the amine test (10% KOH) on vaginal samples is often positive.
Evaluation of Laboratory Methods
Direct (saline) examination
8.3.7 Treatment and Control of Cure
Oral metronidazole 2 g, 250 mg, 8/8 h for 7 days.
Oral secnidazole 2 g, single dose.
Oral tinidazole, 2 g, single dose.
Control of cure can be carried out with the same exams used for diagnosis 1–2 weeks after treatment. Even if sexual partners are not experiencing any symptoms they should be called in for guidance, clinical examination, treatment and tests for other STDs, including HIV and hepatitis B.
Resistance to single doses of metronidazole has already been reported. In these rare cases, oral metronidazole 500 mg, 8/8 h, with vaginal metronidazole for 10 days is recommended.
Recurrences happen more as a result of lack of treatment of partners and/or non-completion of treatment in women.
Although regimens involving a single dose are easier to follow, they have a higher incidence of recurrence. Repeating the single dose a week later can increase their efficacy, but this increases the rate of side effects.
There is evidence that Trichomonas infection is associated with a higher risk of contracting HIV, a higher risk of complications during pregnancy and post-surgical infections.
Men: Prostatitis and epididymitis, with oligospermia being an aggravating factor, sometimes leading to infertility.
Women: Trichomonas vaginalis may be one of the microorganism vectors in pelvic inflammatory disease (PID).