Comparison of amniotic fluid matrix metalloproteinase-8 and cathelicidin in the diagnosis of intra-amniotic infection

OBJECTIVE: To evaluate the association of amniotic fluid (AF) matrix metalloproteinase-8 (MMP-8) and cathelicidin concentrations with microbial invasion of the amniotic cavity (MIAC) in pregnancies with preterm prelabor rupture of the membranes or intact membranes. STUDY DESIGN: Amniocentesis was performed in 54 singleton pregnancies between 22(+0) and 34(+2) gestational weeks with suspected intra-amniotic infection. AF-MMP-8 was analysed by immunoassay and AF-cathelicidin by commercial ELISA. Standard biochemical methods, molecular microbiology and culture techniques were used. RESULTS: MIAC was present in 18 (33%) women. The cutoff value for the diagnosis of MIAC was 41.5 ng ml(-1) for AF-MMP-8, and 11.6 ng ml(-1) for AF-cathelicidin. With these cutoff values AF-MMP-8 had a sensitivity of 100%, specificity of 69%, positive predictive value of 62% and negative predictive value of 100% for MIAC. The corresponding values for AF-cathelicidin were 89, 81, 70 and 94%. CONCLUSION: The performance of AF-cathelicidin in the prediction of MIAC is comparable to AF-MMP-8.