Chlamydia trahomatis in cell culture. I. Comparison of efficiencies of infection in several chemically defined media, at various pH and temperature values, and after exposure to diethylaminoethyl-dextran

Three chemically defined cell culture media, Eagle minimum essential medium (MEM) with Earle basal salt solution, Eagle MEM with Hanks basal salt solution, and a modified Eagle MEM, were tested and found capable of supporting the development of Chlamydia trachomatis in 60 Co-treated McCoy cells. The enhancement of trachoma infection by diethylaminoethyl-dextran (DEAE-D) was greater at pH values closer to neutrality than at any other pH values measured at the start of the experiments. Centrifugation of the trachoma inoculum onto cell monolayers at 33 C increased the number of inclusions when compared to centrifugation at 20 C. When the inoculum was centrifuged onto cell monolayers and subsequent incubation was at temperatures ranging from 34 to 39 C, the greatest number of inclusions was observed after incubation from 35 through 37 C. Enhancement of the trachoma infection by DEAE-D was tested at temperatures ranging from 35 to 37 C. These cultures had three- to fivefold increases in inclusions when compared to previously reported experiments in which DEAE-D-treated cultures were incubated at 34 C.