Abstract
New Delhi metallo-β-lactamase, a metallo-β-lactamase carbapenemase type, mediates resistance to most β-lactam antibiotics including penicillins, cephalosporins, and carbapenems. Therefore, it is important to detect blaNDM genes in children’s clinical samples as quickly as possible and analyze their characteristics. Here, a recombinase-aided amplification (RAA) assay, which operates in a single one-step reaction tube at 39°C in 5−15 min, was established to target blaNDM genes in children’s clinical samples. The analytical sensitivity of the RAA assay was 20 copies, and the various bacterial types without blaNDM genes did not amplify. This method was used to detect blaNDM genes in 112 children’s stool samples, 10 of which were tested positive by both RAA and standard PCR. To further investigate the characteristics of carbapenem-resistant bacteria carrying blaNDM in children, 15 carbapenem-resistant bacteria (Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, Citrobacter freundii, Klebsiella oxytoca, Acinetobacter junii, and Proteus mirabilis) were isolated from the 10 samples. Notably, more than one bacterial type was isolated from three samples. Most of these isolates were resistant to cephalosporins, cefoperazone-sulbactam, piperacillin-tazobactam, ticarcillin-clavulanic acid, aztreonam, co-trimoxazole, and carbapenems. blaNDM–1 and blaNDM–5 were the two main types in these samples. These data show that the RAA assay has potential to be a sensitive and rapid blaNDM gene screening test for clinical samples. The common existence of blaNDM and multi-drug resistance genes presents major challenges for pediatric treatment.
Highlights
Since their first use in 1985, broad-spectrum carbapenems have been commonly used in clinical practice (Lyon, 1985), but carbapenemase-producing Enterobacterales bacteria pose an increasingly important threat to global health (Trecarichi and Tumbarello, 2017)
To further analyze the characteristics of carbapenem-resistant strains with blaNDM from children, the minimum inhibitory concentrations (MICs), blaNDM genotypes and clinical diagnosis pertaining to these isolates were investigated
K. pneumoniae 2146, A. baumannii 1, and P. aeruginosa contain blaNDM-1 genes, A. baumannii 2 contains blaKPC-2 gene, whereas the other bacterial types were all sensitive strains
Summary
Since their first use in 1985, broad-spectrum carbapenems have been commonly used in clinical practice (Lyon, 1985), but carbapenemase-producing Enterobacterales bacteria pose an increasingly important threat to global health (Trecarichi and Tumbarello, 2017). Class B enzymes are metallo-β-lactamases (MBL) and include New Delhi metallo-β-lactamases (NDM), imipenemase (IMP), and Verona integron-encoded metallo-β-lactamase (VIM). The first clinical bacterial strain carrying this gene was isolated in 2009 from a Swedish patient who had traveled to India in 2007, where he acquired a K. pneumoniaerelated urinary tract infection. Carbapenem resistance in this isolate was mediated through the production of a novel carbapenemase designated NDM-1 (Yong et al, 2009). NDM-positive bacteria, which include Enterobacteriaceae, Pseudomonas, and Acinetobacter, cause various infections with high mortality rates (Rahman et al, 2018; Yang et al, 2020). To further analyze the characteristics of carbapenem-resistant strains with blaNDM from children, the minimum inhibitory concentrations (MICs), blaNDM genotypes and clinical diagnosis pertaining to these isolates were investigated
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