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

Abstract

Metallo β-Lactamases (MBLs) degrade most clinical β-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 β-Lactamases, named SZM-1 (Shenzhen metallo-β-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 blaSZM–1 is a mobilizable antibiotic resistance.

Plasmid-Mediated Genes Were Responsible for the Resistance and Spread of Metallo Beta-Lactamase (MBL)-Producing Pseudomonas Aeruginosa Isolates in Poultry Milieus

“…Several studies have shown that there is an increase in the evolution and spread of MBL-producing bacteria in the non-hospital environment as reported in our study [5,7,20]. Furthermore, the results from our study corroborates to previous studies which have reported the prevalence of MBL-producing bacteria in livestock and poultry [7,11]. In this study, we detected the blaIMP-1 MBL genes in 3 P. aeruginosa isolates (6.3%) while the blaIMP-2 MBL genes were detected in 2 isolates of P. aeruginosa (4.2%) from poultry milieus.…”

“…Molecular analysis: PCR analysis for the detection of specific MBL genes (blaIMP-1, blaIMP-2, blaVIM-1, blaVIM-2) in the P. aeruginosa isolates that showed reduced susceptibility to any of the tested carbapenems (imipenem and meropenem) was performed in accordance to a previously used protocol [11,14,15]. DNA was extracted from the P. aeruginosa isolates using GENESpin DNA isolation kit (Eurofins, Hamburg) according to the manufacturer's guidelines.…”

“…Previous reports suggest that MBLs can efficiently hydrolyze all beta-lactam drugs except aztreonam (a monobactam) in vitro [9,10]. The prevalence of bacteria producing MBLs is gradually growing globally [11]. And bacterial strains such as Pseudomonas aeruginosa harbouring plasmids (extra-chromosomal DNA that allows transmission of genetic materials including resistance genes between bacteria species) that mediate MBL production could worsen the antibiotic crisis by allowing MBL genes to be easily transmitted between bacteria genera and species in a particular environment (e.g., poultry milieus).…”