Isolation of genital mycoplasmas from the blood of neonates and women with pelvic infection using conventional SPS-free blood culture media

Standard blood culture media used in our laboratory were tested for their ability to support the growth of Mycoplasma hominis and Ureaplasma urealyticum. Small inocula (approximately 10 colony forming units per ml) of both organisms grew in diphasic tryptone soya medium but not in any of several media containing sodium polyanetholesulphonate (SPS) including a modified Schaedler broth (RWH anaerobic medium) and two BACTEC media (6B and 7D). Both organisms were inhibited even by very low concentrations of SPS but grew well in the Royal Women's Hospital (RWH) anaerobic medium when SPS was omitted. During a 22-month period, routine "blind" plating of the aerobic blood cultures on to mycoplasma agar resulted in isolation of M. hominis or U. urealyticum from 12 women with postpartum or postoperative pelvic infection, and from 3 neonates. Genital mycoplasmas represented 35% of significant isolates from adult blood cultures.