Identification and characterization of a novel metallo β-lactamase, SZM-1, in Shenzhen Bay, South China

Metallo beta-Lactamases (MBLs) degrade most clinical beta-lactam antibiotics, especially Carbapenem, posing a huge threat to global health. Studies on environmental MBLs are important for risk assessment of the MBLs transmission among connected habitats, and between environment and human. Here, we described a novel metallo beta-Lactamases, named SZM-1 (Shenzhen metallo-beta-lactamase), from an Arenimonas metagenome-assembled genome recovered from the river sediment in the Shenzhen Bay area, south China. Phylogenetic analysis, primary sequence comparison, structural modeling suggested that the SZM-1 belongs to B1 MBL family, likely harboring a typical di-zinc catalytic center. Furthermore, the gene encoding the MBLs was cloned into Escherichia coli TOP10 for Carba NP test and antimicrobial susceptibility test. The results indicated that the SZM-1 had carbapenemase activity, and conferred the carrier to increased resistance toward carbapenems. Taken together, our results raise alarms about the emergence and spread of the SZM-1, and suggest further surveillance, especially in hospital settings and clinical isolates, to determine whether bla(SZM-1) is a mobilizable antibiotic resistance.

Automated summary

Metallo beta-Lactamases (MBLs) pose a significant threat to global health as they degrade most clinical beta-lactam antibiotics. The discovery of SZM-1, a novel MBL with carbapenemase activity and resistance, raises concerns about its emergence and spread. Further surveillance is needed, especially in hospital settings and clinical isolates, to determine the mobilization of antibiotic resistance associated with bla(SZM-1).