In vivo modification of porin activity conferring antibiotic resistance toEnterobacter aerogenes

Cephalosporins are widely used in chemotherapy of bacterial infections and resistance mechanisms seriously impair their antibacterial activity. Severa l resistant strains of Enterobacter aerogenes, a frequently isolated nosoco mial pathogen, were analyzed. One isolate exhibited a strong modification o f the porin antigenic pattern, especially with an immunological probe direc ted against an epitope located inside the pore lumen. A strong decrease of cefepime uptake was evidenced for this isolate, similarly to ones observed for porin-deficient strains: these kinetics show a serious alteration of th e channel properties which may support cephalosporin resistance. This is th e first E. aerogenes isolate using such adaptive response which defines an original enterobacterial answer to cephalosporin. (C) 1999 Academic Press.