Original research
Nugent score related to vaginal culture in pregnant women1,

https://doi.org/10.1016/S0029-7844(01)01402-8Get rights and content

Abstract

Objective:

To relate Gram-stained smears, using the Nugent criteria, to quantitative and qualitative vaginal cultures in pregnant women.

Methods:

Two independent evaluators using the Nugent criteria, a standardized method of Gram-stain interpretation designed to detect bacterial vaginosis, scored 104 vaginal smears from pregnant women. The quantitative and qualitative vaginal cultures were assessed at the same time and the results expressed as log10 colony-forming units per gram of vaginal secretion. The Nugent scores were compared with the microbiologic findings.

Results:

The prevalence of normal, intermediate, or bacterial vaginosis vaginal flora as determined by Gram stain was 68%, 21%, and 11%, respectively. A comparison of the mean bacterial counts with the Nugent score showed a weak negative correlation for Lactobacillus species and a positive correlation for gram-variable and gram-negative rods. Additional analysis revealed a strong positive correlation between the mean bacterial counts analyses of Peptostreptococcus, a genus not included in the Nugent scoring system, and the Nugent score. In addition, the Prevotella counts correlated strongly with both the Nugent score and the Peptostreptococcus counts. The quantitative counts for Lactobacillus did not vary significantly among the three defined groups of vaginal microflora; however, significant increases in the concentrations of Gardnerella vaginalis and Prevotella were found as the Nugent score increased.

Conclusion:

A strong correlation was found among the gram-variable and gram-negative genera comprised by the Nugent score. Peptostreptococcus also correlated strongly with the Nugent score and with the Prevotella counts, suggesting that this genus may play a role in determining vaginal health.

Section snippets

Materials and methods

This study was conducted as part of a larger project collecting quantitative data on the microbiologic population in pregnant women in two high-risk cohorts for preterm delivery (prior preterm birth and bleeding during the current pregnancy) and a low-risk cohort (no prior preterm birth or bleeding) to formulate a model to determine the bacteriologic factors promoting preterm labor. Eligible women were identified by the study nurse and approached during routine antenatal care visits at the

Results

Of the 104 smears examined using the Nugent criteria, 71 (68%) were graded as normal, 22 (21%) as intermediate, and 11 (11%) as BV. The mean counts for the individual components comprising the Nugent score were determined. The mean count for Lactobacillus was 9.08 ± 0.50 log10 cfu/g, 8.81 ± 0.80 log10 cfu/g, 8.55 ± 0.84 log10 cfu/g, 8.75 ± 0.58 log10 cfu/g, and 8.30 ± 0.80 log10 cfu/g for a Nugent score of 0, 1, 2, 3, and 4, respectively. The gram-variable and gram-negative score comprised G

Discussion

The vaginal microflora associated with BV during pregnancy has been evaluated by a number of investigators.12, 13, 14, 15, 16 The methods used in these studies to assess the bacterial load have included vaginal swabs diluted in transport media or vaginal wash samples plated directly onto various media. None of these methods provide a denominator for comparing the bacterial counts. In vaginal wash samples, an inherent variability exists because vaginal fluids are randomly diluted depending on

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    This study was supported by grant RO1 HD35667 from the National Institutes of Health.

    1

    The Microbiology and Prematurity Study Group consists of the following: Robin Ross, PhD, Mei-Ling Lee, PhD, Andrea M. DuBois, BS, Wendy Osterling, BS, and David G. Aiello, BS, Channing Laboratory, Brigham and Women’s Hospital, Boston, MA; and Ruth Tuomala, MD, Ellice Lieberman, MD, Amy Cohen, BA, Dorothy Pender, RN, and Linda Steele, MT(ASCP), Department of Obstetrics and Gynecology, Brigham and Women’s Hospital, Boston, MA.

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