Identification of Cultivable Bacteria in Amniotic Fluid Using Cervicovaginal Fluid Protein Microarray in Preterm Premature Rupture of Membranes

We aimed to identify cervicovaginal fluid (CVF) protein biomarkers of microbial invasion of the amniotic cavity (MIAC) in women with preterm premature rupture of membranes (PPROM), using an antibody microarray. This retrospective cohort study included 99 consecutive women with singleton pregnancies and PPROM (23–33 weeks) who underwent amniocentesis and who gave CVF samples. CVF proteomes from the MIAC (n = 20) versus non-MIAC groups (n = 20) were comparatively profiled by an antibody microarray using a nested case-control study design. The seven candidate biomarkers of interest were validated in the total cohort (n = 99) by enzyme-linked immunosorbent assays (ELISA). For comparison with candidate markers, amniotic fluid (AF) white blood cell (WBC) count was also measured. The primary outcome measure was MIAC (defined as positive AF culture). Thirty of the proteins studied exhibited significant intergroup differences. Measurements of the total cohort with ELISA confirmed a significant increase in the levels of CVF IL-8, lipocalin-2, MIP-1α, MMP-9, and TIMP-1 in women with MIAC, independent of gestational age at sampling. A combined, non-invasive model was developed by using a stepwise regression procedure, which included CVF IL-8 and CVF MMP-9 (area under the curve [AUC] = 0.763), and this AUC was comparable with the AUC of AF WBC. Using protein–antibody microarray technology, we found several novel, independent, non-invasive biomarkers to identify MIAC in women with PPROM: IL-8, lipocalin-2, MIP-1α, MMP-9, and TIMP-1. Furthermore, the combined non-invasive model (IL-8 and MMP-9) was a useful independent predictor for MIAC with good discriminatory power, similar to AF WBC count.