Sensitivity and specificity of subgingival bacteria in predicting preterm birth- a pilot cohort study

Preterm birth (PTB) increases the risk of adverse outcomes for new born infants. Subgingival bacteria are implicated in causing PTB. The aim of the present study was to assess the accuracy of some subgingival gram positive and gram negative bacteria detected by routine lab procedures in predicting PTB.

Pregnant Saudi women (n= 170) visiting King Fahad hospital, Dammam, Saudi Arabia, were included in a pilot cohort study. Plaque was collected in the 2^nd trimester and screened for subgingival anaerobes using Vitek2. Pregnancy outcome (preterm/full term birth) was assessed at delivery. Sensitivity, specificity and positive and negative likelihood ratios were calculated for the identified bacteria to predict PTB.

Data about time of delivery was available for 94 subjects and 22 (23.4%) had PTB. Three gram negative and 4 gram positive subgingival bacteria had sensitivity ≥ 95% with two of each having negative likelihood ratios ≤0.10. Three gram positive bacteria had specificity > 95% with only one having positive likelihood ratio >2.

Subgingival bacteria identified using readily available lab techniques in the plaque of pregnant Saudi women in their 2^nd trimester have useful potential to rule out PTB.