Transferable hyperproduction of TEM-1 beta-lactamase in Shigella flexneri due to a point mutation in the pribnow box.

ABSTRACT

TEM-1 hyperproduction in two ampicillin-sulbactam-resistant Shigella flexneri strains was studied. In both strains the blaTEM gene was encoded as a single copy on a large conjugatively transferable plasmid. A single G-->T transversion at position 1 of the -10 consensus sequence was identified to be the mechanism of TEM-1 hyperproduction.