Effects of recent sexual activity and use of a diaphragm on the vaginal microflora.

We prospectively studied 40 women over a median period of 28 weeks to ascertain the effects on vaginal microflora of sexual intercourse alone compared with sexual intercourse associated with use of a diaphragm with a spermicide (diaphragm/spermicide). Compared with no sexual intercourse, sexual intercourse with use of a diaphragm/spermicide in the preceding 3 days was strongly associated with increases in rates of vaginal colonization with uropathogenic flora, including Escherichia coli (P < .0001), other gram-negative uropathogens (P = .0045), group D streptococci (P = .014), and group B streptococci (P = .0015). Except for E. coli colonization, no such increases in rates of vaginal colonization were seen at visits preceded by sexual intercourse without use of a diaphragm/spermicide. Compared with no sexual intercourse, sexual intercourse with use of a diaphragm/spermicide in the preceding 3 days also was associated with a marked increase in rates of candidal colonization (P < .0001) and with a decrease in rates of lactobacillus colonization (P < .0001). We conclude that bacterial and fungal microflora in the vagina are strongly influenced by recent use of a diaphragm/spermicide and minimally affected by sexual intercourse alone.