INVOLVEMENT OF A 43-KILODALTON OUTER-MEMBRANE PROTEIN IN BETA-LACTAM RESISTANCE OF SHIGELLA-DYSENTERIAE

A beta-lactam-sensitive strain (C152) of Shigella dysenteriae showed t wo major outer membrane proteins (OMPs) with M(r)s of 33,000 and 38,00 0, while the clinical isolate M2 lacked the 43,000-M-r OMP, which acte d as a channel for beta-lactam antibiotics. Permeability of beta-lacta ms across the outer membrane (OM) of M2 was lower than that across the OM of C152. Mutants deficient in the 43-kDa OMP could be selected in vitro from strain C152 in the presence of cefoxitin. All beta-lactam-r esistant strains were sensitive to imipenem.