Adhesion assay in gonococcal troubleshooting:

I'm using ME-180 cervical cancer cell lines (Epithelial cells) in 24 wells cell culture plate (100% confluent) for further adhesion and invasion experiments in Neisseria gonorrhoea FA1090 strain. However, I looked at microscope cells after disruption with saponin, and after 15 mins the 1% saponin in PBS did not seem to be disrupting these epithelial cells (at least not in the 15-minute incubation period); there was little evidence of any cellular disruption, and even after vigorous pipetting, the cells were dislodged from the well bottom, but still largely intact and in clumps, meaning that any viable counts would effectively be counts of cell clumps, not attached gonococci. Although, most article papers use similar concentrations and incubation time.

Any suggestions or a specific protocol for this kind of cell?