Indian Journal of Pathology and Microbiology

: 2009  |  Volume : 52  |  Issue : 1  |  Page : 56--58

Bacterial vaginosis with special reference to anaerobes

AH Sumati1, NK Saritha2,  
1 Department of Microbiology, J. N. Medical College, Belgaum, Karnataka, India
2 Department of Microbiology, V. M. Medical College, Solapur, Maharashatra, India

Correspondence Address:
A H Sumati
Department, of Microbiology, J N. Medical College, Belgaum, Karanataka 590 010


Aims: This study was undertaken to assess the prevalence of bacterial vaginosis (BV) and to estimate the prevalence of anaerobic organisms in vaginal discharge of women suffering from bacterial vaginosis. Settings and Design: Patients attending the Obstetrics and Gynecology Department of a Medical College Hospital. A one year cross-sectional study. Methods and Materials: High vaginal swabs taken from 174 female patients complaining of abnormal vaginal discharge. BV was diagnosed by clinical composite criteria and by gram stain. Anaerobes were isolated and identified from the discharge. Statistical Analysis Used: Chi square test, with level of significance set at a value of P<0.05. Results: BV was diagnosed in 68.39% of the cases by using clinical composite criteria and in 58.4% of the cases by gram stain. Anaerobic culture isolation of vaginal swabs revealed that out of 174 cases 143 (82.65%) were culture positive for anaerobes. Bacteroides were significantly raised in BV as compared with non bacterial vaginosis (NBV; <0.05%). Conclusions: Anaerobic bacteria are important pathogens in the causation of bacterial vaginosis along with other aerobic organisms. Bacteroides and peptostreptococci are significantly raised in BV.

How to cite this article:
Sumati A H, Saritha N K. Bacterial vaginosis with special reference to anaerobes.Indian J Pathol Microbiol 2009;52:56-58

How to cite this URL:
Sumati A H, Saritha N K. Bacterial vaginosis with special reference to anaerobes. Indian J Pathol Microbiol [serial online] 2009 [cited 2020 Aug 10 ];52:56-58
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Bacterial vaginosis (BV) is a condition characterized by raised vaginal pH and milky white discharge in which the normal vaginal flora is replaced by mixed flora of aerobic, anaerobic and microaerophilic species. [1] The microbiology of BV is complex and involves various organisms such as G ardnerella vaginalis , mixed anaerobes such as Mobiluncus, Bacteroides, Prevotella , Peptostreptococci, Eubacterius , Mycoplasms hominis and other aerobic organisms. [1]

The clinical composite criteria of BV comprise of an increased homogenous greyish white vaginal discharge, increased vaginal pH> 4.5, a fishy smell on addition of 10% KOH to vaginal fluid (whiff test) and the presence of clue cells. [2] The laboratory methods for the diagnosis of BV include direct Gram stain of vaginal secretions, culture for Gardnerella vaginalis and other organisms associated with BV, biochemical tests for metabolic byproducts of vaginal bacteria (gas liquid chromatography) and Proline amino peptidase tests, etc. [2] The etiology and pathogenesis of BV is still unclear. Very few studies have been conducted in this part of the country. Therefore, the study was undertaken to assess the prevalence of BV and to estimate the prevalence of anaerobic organisms in the vaginal discharge of women suffering from BV.

 Materials and Methods

This study included 174 female patients of a reproductive age group who were attending the Obstetrics and Gynecology Departments of Government Medical College, as outpatients and inpatients complaining of abnormal vaginal discharge, excluding those who were planning to undergo any pelvic surgical operation (procedures) and patients on antibiotic treatment.

A routine gynecologic speculum examination was performed on each patient and a medical history was taken. Vaginal secretions were collected using two vaginal swabs from each patient and transported to the laboratory. One swab in 3 ml of sterile thioglycollate broth for anaerobic culture, another swab was brought in 0.5 ml of saline for non culture methods. While taking the swab color, consistency and odor of vaginal discharge was also noted. The pH of vaginal discharge was measured directly by placing indicator paper for pH range of 4.0-6.0 on the vaginal wall. An Amine test was performed. [3] From one swab, wet mount preparation and smears for Gram staining were prepared, which were examined for the presence of clue cells, Pus cells, yeast and parasites. Gram stain smears were read for morphotyping and scoring patterns according to Nugent criteria. [4] Patients not fulfilling the minimum of three out of four diagnostic criteria [2] were considered normal and served as controls.

The second swab was processed by inoculating samples onto freshly prepared blood agar with hemin and vitamin K supplement. Metronidazole 5 g discs and Gentamicin 10 g were placed on primary and secondary streaking, respectively for observing primary sensitivity and presumptive identification of anaerobes. Plates were incubated anaerobically in a gas pack anaerobic jar (Dynamicro) for 48-72 hours. Pure growth of anaerobes was obtained after repeated subculture and organisms were identified up to the genus level on the basis of standard methods. [5],[6]


Of the 174 vaginal samples collected, 60.11% (104) were from patients between the ages of 26 and 40 years old followed by 40.22% between the ages of 18 and 25 years old. BV was diagnosed in 68.39% (119) of the patients using clinical composite criteria as suggested by Amsel; 31% of the patients had only one or two out of the four clinical criteria.

A sample of vaginal fluid was used to prepare an air dried smear that was stained and scored according to the Nugent system. The scoring resulted in 101 samples diagnosed as BV with a Nugent score of 7 to 10, 44 samples diagnosed as intermediate with a Nugent score of 4 to 6. and 29 samples diagnosed as normal with a Nugent score of 0 to 3. [Table 1].

Out of 174 cases, 146 were culture positive for anaerobes. The Gram negative anaerobes 108(74%) out-numbered the Gram positive ones. The distribution of various isolated anaerobes is shown in [Table 2]. This table shows that out of the total anaerobic isolates, 75.3% were from BV and only 25% were from NBV suggesting anaerobes were significantly increased in BV. Bacteroides isolation was significantly higher in BV as compared with NBV ( P = P =>0.05) [Table 2].


Bacterial vaginosis is an important genital syndrome because it affects a large number of women of reproductive age. The presence of BV puts patients at increased risk of upper genital tract infections with severe consequences to fertility and the outcome of pregnancy. [7]

Bacterial vaginosis usually affects women in the reproductive age group but it may also be seen in menopausal women and women who have had a hysterectomy. [7] We observed that 52% of cases in our study were of women between the ages of 26 and 40 years old.

In our study, 68.4% (119) of patients were diagnosed as BV using Amsels criteria. Out of 174 samples, 101 (58.4%) samples were diagnosed as BV and 44 were diagnosed as intermediate (25.28%) using Nugent's gram stain scoring system. The intermediate stage is considered a transitional phase and the patients may go on to frank BV. [8]

Gram staining of vaginal secretions is more reliable with sensitivity of 89-93% and specificity of 70-83%. [4] Gram staining of vaginal smears are least expensive, requires the least time to perform, are more widely available than other laboratory methods and is the most interpretative of the laboratory methods. [4] Gram staining of vaginal smears are more useful than the culture for the diagnosis of BV. Anaerobes were isolated in 75.3% of the cases of BV and in 25% of the cases of non bacterial vaginosis. Anaerobes were significantly raised in BV as compared with NBV. Peptostreptococci, Bacteroides, Fusobacterias, Porphyromonas and Veillonella are associated with BV.

Blackwell, et al., [9] Spiegel, [10] and Easrnon, et al . [11] suggested that organisms like Peptostreptococci, Bacteroides fusobacterias, Porphyromonas , Veillonella, peptococci and Mobiluncus organisms may be associated with BV.

In the study by Rosenstein, et al. [8] Anaerobic streptococci were isolated in 74% of patients with BV, while b acteroides and other gram negative rods were isolated in 60% of the patients. Levison, et al. [12] isolated Peptostreptococci in 5 of the patients, Peptococci in 5 of the patients and Bacteroides in 6 of 12 patients with non specific vaginitis. In the study by Krohn, et al. [13] The Bacteroides species were isolated in 62% of the cases and peptostreptococci in 59% of pregnant women having BV with three of the four clinical signs being positive.

The difference in the type of rate of isolations of anaerobes reflects the difference in the population under study and the different methods of investigations. Therefore, it can be concluded that anaerobic bacteria are important pathogens in the causation of BV along with other aerobic organisms. Most of these anaerobes can be isolated by using simple media and culture techniques.


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