Eradication of Intra-Amniotic Ureaplasmas with Clarithromycin: Evidence by Analysis of Gastric Fluid of Preterm Newborns

To examine the effect of antenatal administration of clarithromycin on the eradication of intra-amniotic infection with ureaplasmas. This was based on the results of culture for ureaplasmas of neonatal gastric fluid obtained within 24 hours of birth. We also compared the effect of clarithromycin with other antibiotics. The study population consisted of 64 singleton pregnant women with preterm prelabor rupture of membranes (gestational age: 18-33 weeks) and a positive amniotic fluid culture for ureaplasmas. The study population was divided into two groups according to the antenatal use of clarithromycin within one day of amniocentesis (clarithromycin group [n=29] and non-clarithromycin groups [n=35], respectively). Amniotic fluid was obtained by amniocentesis and neonatal gastric fluid was by nasogastric intubation within 24 hours of birth and cultured for ureaplasmas. 1) Ureaplasmas were isolated in 38% (11/29) of gastric fluid obtained from preterm newborns born to mothers with intra-amniotic infection with these microorganisms in the clarithromycin group; 2) however, ureaplasmas were isolated in 66% (23/35) of those born to mothers with infection with these microorganisms in the non-clarithromycin group (38% vs 66%, p< 0.05); 3) The use of clarithromycin and low amniotic fluid WBC count (< 19 cells/mm3) was significantly associated with the absence of ureaplasmas in gastric fluid after the adjustment of gestational age at amniocentesis (use of clarithromycin: odds ratio 0.27, [95% CI 0.09–0.81], P< 0.05; AF WBC count < 19 cell/mm3, odds ratio 0.12, [95% CI 0.02–0.71], P< 0.05). Ureaplasmas were not isolated in two-thirds of gastric fluid of preterm newborns born to mothers with intra-amniotic infection with ureaplasmas and who received clarithromycin. The use of clarithromycin and low amniotic fluid WBC count were associated with the 73% reduction in the rate of positive culture for ureaplasmas in the gastric fluid of these newborns.