CTX-M-123, a Novel Hybrid of the CTX-M-1 and CTX-M-9 Group β-Lactamases Recovered from Escherichia coli Isolates in China

Abstract

ABSTRACTThe chimericblaCTX-M-123gene was identified in two ceftazidime-resistantEscherichia coliisolates from animals in different Chinese provinces. Like other CTX-M-1/9 group hybrids (CTX-M-64 and CTX-M-132), the ends (amino acids 1 to 135 and 234 to 291) of CTX-M-123 match CTX-M-15 while the central part (122 to 241) matches CTX-M-14.blaCTX-M-123is carried on related, but not identical, ∼90-kb IncI1 plasmids in the two isolates, and one isolate simultaneously carries the group 1blaCTX-M-55gene on an additional IncI2 plasmid.