[1] SmithKline Beecham Pharmaceut, Epidemiol, Collegeville, PA 19486 USA
[2] Vanderbilt Univ, Sch Med, Nashville, TN USA
[3] SmithKline Beecham Pharmaceut, Antiinfect, Harlow, Essex, England
[4] SmithKline Beecham Pharmaceut, Antiinfect, Collegeville, PA 19486 USA