Enterobacter hormaechei subsp. steigerwaltii strain SC10435 was isolated in 1963 from human blood culture in Toronto, Canada. This strain is resistant to penicillins, cephalosporins, aztreonam, and pipercillin-tazobactam and it is sensitive to carbapenems. The depositor states that this strain produces a Class C, AmpC-type beta-lactamase (P99 cephalosporinase).