Antimicrobial activity of amniotic fluid against Chlamydia trachomatis, Mycoplasma hominis, and Ureaplasma urealyticum.

Amniotic fluids obtained by amniocentesis at 16 weeks to term were examined for the presence of Chlamydia trachomatis, Mycoplasma hominis, and Ureaplasma urealyticum. Of 140 fluids tested, none harbored chlamydiae, and only one harbored mycoplasma, M. hominis. A number of amniotic fluids were subsequently tested for their ability to inhibit the growth of these microorganisms. Amniotic fluids and chlamydial suspensions in a 2:1 ratio were incubated 30 to 90 minutes before their inoculation in McCoy cells. Procedures were followed for chlamydial isolation. Genital mycoplasmas were incubated with amniotic fluid samples for 24 or 48 hours at 35 degrees C. Growth in amniotic fluid specimens was compared with growth in pseudoamniotic fluid and broth controls. Fourteen amniotic fluid specimens collected from gestations of 16 to 40 weeks, were found to be inhibitory to the formation of inclusions of C. trachomatis in McCoy cells. Ten amniotic fluid specimens (16 to 39 weeks, gestation) demonstrated various degrees of inhibition against M. hominis, and three fluids were inhibitory to the growth of Ureaplasma. The inhibitor was heat and protease resistant and activity was proportional to concentration. The molecular weight of the inhibitor was probably greater than 10,000 daltons, and pH, although perhaps a contributing factor, was not the cause of the inhibition.