We appreciate Dr Rubinoff's comments and would agree with the thrust of his argument—that is, single-dose therapy can and should be given to reliable women with acute, uncomplicated UTI without having to resort to the antibody-coated bacteria (ACB) assay. Our using the ACB assay for research purposes does not constitute a requirement that it be used in everyday clinical practice. To put the ACB test and single-dose therapy in perspective, we would make the following comments:
Single-dose therapy is effective in 85% to 95% of women with ACB-negative infection, with most of these failures occurring in women with first infections for which the ACB test is unreliable.
Single-dose therapy is effective in 40% to 50% of patients with ACB-positive infection (R. H. Rubin, MD, unpublished data, October to December, 1980), confirming Dr Rubinoff's observation. Thus, the ACB-positive population is nonhomogeneous, and the response to single-dose