Literature reviews  >  Articles for review > Bradshaw et al. Evaluation of a point-of-care test... 

Rapid and reliable point-of-care tests are needed to improve the diagnosis and management of bacterial vaginosis.

Evaluation of a point-of-care test, BVBlue, and clinical and laboratory criteria for diagnosis of bacterial vaginosis.
Bradshaw CS, Morton AN, Garland SM, Horvath LB, Kuzevska I, Fairley CK.
Journal of Clinical Microbiology 2005;43:1304-1308.
 
Summary:

Question

What is the performance of the BVBlue test for the diagnosis of bacterial vaginosis (BV) compared to a diagnosis using the Nugent gram stain score or the Amsel clinical criteria?

Design

This article describes the evaluation of the performance of the BVBlue test, a point-of-care test, compared to those of the Nugent and Amsel methods for the diagnosis of BV in women attending a sexual health service with symptoms of abnormal vaginal discharge and/or odor.

Participants

Two hundred eighty-eight women presenting to Melbourne Sexual Health Centre, Melbourne, Victoria, Australia with symptoms of abnormal vaginal discharge or odor were tested.Women were excluded if they were pregnant, HIV infected, postmenopausal, not fluent in English, menstruating, or had used a lubricant or vaginal medication in the previous 3 days.The mean age was 29 years. Thirty-eight percent had a history of BV and 13% engaged in sex work in the past 12 months.

Description of Tests and Diagnostic Standard

A swab of vaginal secretions was collected from the lateral wall by a clinician during a speculum examination for pH determination (Spezialindikator strips, Merck & Co.), wet preparation, Gram stain, and amine test.A second swab was collected and placed in the BVBlue vial (Gryphus Diagnostics, L. L. C.), which contained the chromogenic substrate of bacterial sialidase.The BVBlue test is a chromogenic point-of-care test based on detection of increased vaginal fluid sialidase activity.Two drops of developer solution was added after a 10 minute incubation at room temperature.A blue-green color indicated a positive result; a yellow color indicated a negative result.The vaginal Gram stained smear, the wet preparation, and the amine test were performed on site by two laboratory staff.Women were diagnosed with BV if they had a Nugent Gram stain score of >7 or if they were positive for at least three of four Amsel criteria.

Main Outcome Measures

The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the BVBlue test were calculated for the diagnosis of BV as determined using the Nugent Gram stain score and the Amsel clinical criteria.

Main Results

BV was diagnosed in 108 (38%), 118 (41%), and 120 (42%) of the 288 women by the Nugent score, Amsel criteria, and BVBlue test, respectively.One of the 288 BVBlue tests was inconclusive.Thirty-six (12.5%) of the 288 specimens had a Nugent score of 4 to 6 and of these, 54% and 50% were BV positive by the Amsel criteria and the BVBlue test, respectively.The performances of the BVBlue test compared to the Nugent score and to the Amsel criteria when some specimens were excluded and when different Nugent scores were used to define BV positivity are shown in Table 1.The performances of several clinical and laboratory findings for the diagnosis of BV as determined by the Nugent score when results with scores of 4 to 6 were excluded from the analyses are shown in Table 2.Making a diagnosis of BV if either the BVBlue test result or the amine test result was positive was the best performing approach.

Table 1.Performance of BVBlue test for diagnosis of BV when determined by Amsel criteria or Nugent gram stain score

Table 2.Performances of clinical and laboratory findings for the diagnosis of BV as determined by the Nugent score when results with scores of 4 to 6 are excluded

Authors' Conclusions

The BVBlue test performed well compared with conventional diagnostic methods for the assessment of women with symptoms suggestive of BV at the bedside and performed significantly better than other simple tests, such as vaginal pH determination and the amine test, which do not require microscopy.The BVBlue test is able to provide a more objective and more rapid diagnosis of BV at the bedside compared to conventional diagnostic methods.

Source of funding:Test kits provided by Gryphus Diagnostics

For correspondence:C. S. Bradshaw, Melbourne Sexual Health Center, 580 Swanston St., Carlton, 3053, Victoria, Australia.E-mail address: cbradshaw@mshc.org.au

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