Contribution of microscopic smear examination to the diagnosis of early maternofetal infection. Experience acquired at the Lille Teachings Hospital.

A prospective study was conducted in 3056 live-born infants delivered at th e Jeanne-de-Flandre maternity hospital of the Lille Teaching Hospital betwe en January and August 1997. Clinical, laboratory test, and microbiological test findings were compared. A cohort of 1003 infants who remained in the m aternity ward but were considered at increased risk of maternofetal infecti on (MFI) based on history and/or obstetrical criteria and/or neonatal crite ria underwent routine collection of specimens including gastric fluid, auri cular and anal swabs, amniotic fluid, and placental fragments. Microscopic examination of gastric fluid smears, the first result available to the clin ician, was found to have 27.5% sensitivity (983 samples). Positive predicti ve value (PPV) was only 17.8% because of a high rate of colonization (16.8% ), defined as absence of clinical symptoms and three peripheral specimens p ositive for the same organism. However, negative predictive value (NPV) was as high as 99.8% as a result of high sensitivity (97.8%) in the infected n eonates. The gastric fluid smear was positive in 30% and 35% of neonates bo rn to mothers with hyperpyrexia during early and late labor, respectively, and in 42% of neonates born to mothers with a history of group B streptococ cus carriage during the pregnancy. Forty-two per cent of neonates with a hi story of fetal tachycardia had a positive gastric fluid smear. Diagnostic c riteria for infection were three peripheral specimens positive for the same organism, C-reactive protein elevation, and/or one or more clinical signs suggestive of infection, and/or a positive central specimen (blood, CSF). T he infection rate in infants who remained in the maternity ward was 1.6%. T he most common causative organisms were group B streptococci. These finding s illustrate the useful contribution of gastric fluid smears to the early d iagnosis of MFI and confirm the predominant role of group B streptococci.