Vaginal smear testing is used to diagnose, monitor, and evaluate the treatment of patients with fungal vaginitis, bacterial vaginitis, vulvovaginitis, and pregnant women with group B streptococci vaginal colonization.
Normal vaginal flora consists of a wide range of microorganisms, such as Lactobacillus species, streptococci, enterococci, and coagulase-negative staphylococci. Anaerobic species such as Bacteroides and anaerobic cocci, Gardnerella vaginalis, fungi, coliforms, Ureaplasma urealyticum, and Mycoplasma species may also be part of normal flora but are often blamed for vaginal infections.
Fungal vaginitis or vaginal candidiasis occurs when various changes in the vaginal environment allow the overgrowth of fungi, often present as part of normal flora. Increased levels of estrogen promote their growth. Fungal overgrowth is often observed in the following situations:
- After antimicrobial treatment
- In patients with diabetes mellitus
- In immunosuppressed patients
- Use of contraceptives
Although Candida albicans is isolated in 80-90% of cases of vaginal candidiasis, the remaining 10-15% of the cases include C. krusei, C. kefyr, C. tropicalis and C. glabrata. Mycotic vaginitis usually presents with itching, dysuria, and whitish discharge, although sometimes there may be only mucosal redness and pain. Infections with species other than Candida albicans can lead to treatment failure and persistent infections.
Vaginitis can be caused by Candida species and trichomonas (Trichomonas vaginalis). In children, infections caused by beta-hemolytic streptococci and Staphylococcus aureus are quite common. Group A streptococci can also cause vaginal discharge in adults. Atrophic vaginitis is a rare condition usually associated with older ages. The majority of women with mild to moderate atrophy are asymptomatic. Decreased levels of endogenous estrogens cause thinning of the vaginal epithelium, helping to reduce lactic acid and increase vaginal pH. This change causes excessive growth of mixed flora and the disappearance of lactobacilli. The vaginal discharge contains polymorphonuclear cells and small round basal epithelial cells.
Vulvovaginitis is mainly seen in girls before puberty but can affect women of all ages. Vulvovaginitis can be related to poor hygiene, soap irritation of the skin, or streptococcal infections. Symptoms include irritation, pain, and discharge. Causes of vulvovaginitis include:
- Group A streptococcus (according to Lancefield)
- Staphylococcus aureus
- Candida albicans
- Haemophilus influenzae
- Neisseria gonorrhoeae
Other unusual microorganisms that can cause vaginitis include Salmonella and Shigella.
Bacterial vaginitis is characterized by an increase in anaerobes and a decrease in Lactobacillus species. Bacterial vaginitis has previously been considered a harmless disorder. However, it is now thought to be associated with various genital infections and various complications such as:
- Endometritis and fever after childbirth
- Premature birth and low birth weight
- Premature rupture of membranes
- Sepsis after vaginal hysterectomy
- Pelvic inflammatory disease
- Urinary tract infections
Bacterial vaginitis can be diagnosed in the laboratory if there are at least three of the following four criteria present:
- Gray-white, thin homogenous vaginal discharge
- The pH of the vaginal discharge is > 4.5
- Positive amine odor test (release of fish odor when the vaginal discharge is mixed with 5-10% potassium hydroxide)
- Presence of Clue cells at microscopic examination
Normal vaginal flora is associated with the presence of only species of Lactobacillus or the presence of a minimal number of G. vaginalis morphotypes. The change in vaginal flora associated with bacterial vaginitis is characterized by a decrease in the number of lactobacilli which are replaced by a mixed flora of aerobic, anaerobic, and microaerophilic species. The microorganisms associated with bacterial vaginitis include:
- Prevotella species
- Gardnerella vaginalis
- Mobiluncus species
- Peptostreptococcus species
- Mycoplasma hominis
Although G. vaginalis is found regularly in a large number of women with bacterial vaginitis, the microorganism can also be isolated from 60% of asymptomatic women. Direct examination of vaginal secretions is more important for the diagnosis of bacterial vaginitis than isolation of G. vaginalis from these samples. Gram staining of vaginal smears (using the Nugent or Hay criteria) is the most sensitive method for the laboratory diagnosis of bacterial vaginitis as it detects both Clue cells and possible bacterial morphotype disorders associated with bacterial vaginitis.
Group B streptococci according to Lancefield
Group B streptococcus according to Lancefield (Streptococcus agalactiae) normally colonizes the vagina in many women. During pregnancy, this microorganism can infect the amniotic fluid, which can lead to neonatal septicemia, pneumonia, and meningitis. Patients at high risk for group B streptococcal infection should be screened for the possibility of being carriers.
Situations considered to be at high risk of streptococcal infection include:
- Fever during childbirth
- Premature childbirth
- Premature rupture of membranes
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.