Constitutive stable DNA replication in Escherichia coli cells lacking type 1A topoisomerase activity

•New procedure to detect cSDR at the cellular level.•A dnaT::aph mutation inhibits cSDR.•cSDR in topA topB, topA, but not topB null mutants.•topB is not uniquely required during cSDR.•topA and topB share a function especially required during cSDR.