Evaluating Bacterial Vaginosis Using the Nugent Scoring System
CHAPTER ONE
OBJECTIVE OF STUDY
Bacterial vaginosis is the most common form of vaginal infection in women of reproductive age. It is a condition with diverse etiology and an important cause of morbidity in women of reproductive age. This study was carried out to determine the accuracy of using the Nugent scoring system as a means of diagnosing Bacterial vaginosis.
CHAPTER TWO
LITERATURE REVIEW
Bacterial vaginosis (BV) is a disorder of the vaginal ecosystem characterized by a change in the vaginal flora from the normally predominant lactobacillus to one dominated by sialidase-enzyme-producing organisms including Gardnerella vaginalis, Mobiluncus spp., Prevotella bivia, Bacteroides spp., Peptostreptococcus spp., Ureaplasma urealyticum, and Mycoplasma hominis (Hills, 1993). Several studies have linked BV to an increased risk of acquisition of sexually transmitted diseases (STDs) and human immunodeficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) (Sewankambo et al., 1997, Taha et al., 1998) as well as a number of gynaecological complications (Faro et al., 1993). BV is a disordering of the chemical and biological balance of the normal flora. Lactobacillus species are the predominant bacteria in normal vaginal flora constituting the greatest percentage of total vaginal flora. Lactobacilli species present in the vaginal flora decreases vaginal pH by producing lactic acid and thus mediate the first line of protection against vaginal infection. In addition, hydrogen peroxide production by some lactobacillus species has been found to suppress the growth of many microbial organisms (Dickson et al., 2006).
BV is the most common cause of abnormal vaginal discharge in adult women. The prevalence of BV ranged between 10-30% in different population all over the world (Morws et al., 2001). Several investigations have been performed to identify one or several bacteria comprising the decisive pathogenic factor in the syndrome, but so far no specific bacteria have been implicated in causing BV. Rather, it seems that all these organisms may play a synergistic role in producing the symptoms of BV. The condition is although common especially in low settings but under diagnosed. This may be due to confusion over its complex polymicrobial nature (Hillier et al., 1992).
BV as a specific entity has been recognized since the 1950s and is characterized by an increased malodorous discharge. It is associated with marked changes in vaginal flora often described as a change in local vaginal ecology and a notable absence of inflammation, a reduction in LB species and an increase in Gardnerella vaginalis. Several anaerobic species including mobiluncus spp, Prevotella species and others such as Mycoplasma hominis have been described. The stimuli for these changes are very poorly understood. BV is common and recent works have heightened the importance of its recognition. The two most widely accepted methods for the diagnosis of bacterial vaginosis, Amsel’s composite criteria (Amsel et al., 1983) and Nugent’s Gram stain evaluation of bacterial morphotypes (Nugent et al., 1991) are not used sufficiently in routine practice (Langsford et al., 2001), mostly in low income countries. Although the diagnosis of BV by Amsel’s criteria is simple, it is relatively insensitive and not easily subjected to quality control, and the apparent complexity of the latter may have limited its routine application by clinical laboratories.
CHAPTER THREE
MATERIALS AND METHODS
MEDIA AND REAGENT USED
MEDIA
- Blood Agar
- Chocolate Agar
- Mac Conkey Agar
- MRS Agar
REAGENTS
- Crystal violet stain
- Lugol’s iodine
- Acetone
- Neutral red
- 10% Potassium hydroxide solution
BLOOD AGAR
FORMULA GRAM/LITRE
Beef extract 3.0
Peptone 5.0
Agar 12.0
Sodium chloride 8.0
Sterile blood 100ml
Distilled water 1 litre
PREPARATION
To 1 liter of distilled water in a conical flask, 28 grams of nutrient agar powder was weighed added and mixed. The mixture was then transferred into a bottle and sterilized by autoclaving at 1210C for 15 minutes. It was then allowed to cool to a temperature of 500C. Sterile human blood was then added to the mixture to give a final concentration of 10% blood agar. The mixture was then aseptically poured into sterile Petri dishes and allowed to set.
CHAPTER FOUR
RESULT
A total of sixty seven (67) samples were collected for this project work and the presence of BV cases was evaluated for.
Table 2: shows a summary of the characteristics of women that were enrolled in the study
Table 3: Shows the distribution of BV cases among different age groups
Table 4: Shows the relationship of Gram positive cocci, Gram negative bacilli and presence of yeast cells with the different groups of Nugent scoring
GPC: The distribution of GPC among the three groups was not statistically significant (P=0.99).
GNB: There was a significant difference in the distribution of GNB among the three groups (p=0.0018)
Yeast cells: There was no statistical significance in the distribution of yeast cells among the three groups.
Table 5: Shows the comparism of BV with each of the Amsel criteria.
The relationship of clue cell, whiff test and pH>4.5 shows a statistically significant difference in distribution (P=0.0001, P=0.0051 and P=0.0077 respectively). The distribution of discharge does not show to be statistically significant (P=0.0978).
CHAPTER FIVE
DISCUSSION AND CONCLUSION
In this study, an attempt was made at evaluating BV cases using the Nugent criteria. A total of 67 women consented to participate in the study from July to September 2012. The age range was 16-45 with a mean age of 24.9 years. The prevalence of BV was found to be 13.4% in agreement with previous study where a study carried out on Nigerian women showed the prevalence of BV to be 14.2% (Anukam et al., 2006). The highest prevalence was found in the age group of 16-20 with a percentage of 33.3 and the lowest prevalence in the age group of 36-45 with a percentage of 11.1 (Table 3). Table 4 show the association of BV with other organism, It shows the distribution of Gram positive cocci, Gram negative bacilli and presence of yeast cells as detected by microscopy. About 50% of individuals with Gram negative bacilli were found to have BV, this shows that there is a high association between BV and gram negative bacilli (P=0.0018). The occurrence of Gram negative bacilli has been found to be associated with BV (Gardner and Duke, 1955). Another study carried out by Spiegel (Spiegel et al., 1983) described appearances of gardnerella morphological types along with other small gram-negative rods and gram-positive cocci, in contrast to this study where the presence of GPC was found to be of no association with BV. The presence of GPC in BV samples was found to be statistically insignificant (P=0.99). Yeast as detected by microscopy was more common in women with normal and intermediate flora and was absent in women with BV (P=0.2276). Table 5 shows the distribution of other criteria over the categories of patients with and without BV. Individuals with vaginal discharge accounted for 25.4% of the sample size out of which 44.4% had BV. Clue cells were also found to be in highest percentage (77.8%) in BV cases. This shows to be highly statistically significant (P=0.001) and there is a high association of Clue cells with bacterial vaginosis (Cramer’s V=0.6796) A positive whiff test and pH>4.5 also shows to be highly statistically significant (P=0.0051 and p=0.0077 respectively) but there was a moderate association of whiff test and pH.4.5 (Cramer’s V=0.3968, Cramer’s V=0.3811 respectively). These criteria are a direct reflection of the symptoms to look out for when diagnosing BV. These criteria may be a reflection of diet as well as lifestyle as in the case of douching or having new or multiple sex partners which are factors that predisposes an individual to BV (Schwebke et al., 1999).
CONCLUSION
This study seems to suggest that a gram stained smear of vaginal discharge may be utilized when it comes to diagnosing BV. The laboratory can influence the effective treatment of most patients with BV by providing a rapid direct microscopy result.
In conclusion, the method of microscopy used in this study for the diagnosis of BV would be suitable for a medical microbiology setting in developing countries including Nigeria and could be used to complement or confirm the clinician’s evaluation of patients with abnormal vaginal discharge.
REFERENCES
- Amsel R, Totten PA, Spiegel CA, Chen KC, Eschenbach D and Holmes KK (1983). “Nonspecific Vaginitis. Diagnosti Ccriteria and Microbial and Epidemiologic Associations”. Am. J. Med. 74: 14–22.
- Andrea BS and Chaplin KC (2011). Comparism of Aptima Trichomonas vaginalis Transcription-Mediated Amplification Assay and Affirm VPIII for Detection of Trichomonas vaginalis in Symptomatic Women; Performance Parameters and Epidemiologic Implication. J. Clin. Microbiol. 49: 866-869.
- Anukam KC, Osazuwa EO, Ahonkhai I and Reid G (2006). Vaginal Microbiota of Women Attending a Reproductive Health care Service in Benin City Nigeria. Sex. Trans. Dis. 33: 59-62.
- Azargoon A and Darvishzaden S (2006). Association of Bacterial Vaginosis, Trichomonas vaginalis and Vaginal Acidity with Outcome of Pregnancy. Arch. Iran. Med. 9: 213-17.
- Bradshaw CS, Morton AN, Hocking J et al. (2006). “High Recurrence Rates of Bacterial Vaginosis over the Course of 12 months after Oral Metronidazole Therapy and Factors Associated with Recurrence”. J. Infect. Dis. 193: 1478–86.
