Beta-Lactamase Database (BLDB) is a comprehensive, manually curated public resource providing up-to-date structural and functional information focused on this superfamily of enzymes with a great impact on antibiotic resistance. All the enzymes reported and characterised in the literature are presented according to the class (A, B, C and D), family and subfamily to which they belong. All three-dimensional structures of β-lactamases present in the Protein Data Bank are also shown. The characterisation of representative mutants and hydrolytic profiles (kinetics) completes the picture and altogether these four elements constitute the essential foundation for a better understanding of the structure-function relationship within this enzymes family. BLDB can be queried using different protein- and nucleotide-based BLAST searches, which represents a key feature of particular importance in the context of the surveillance of the evolution of the antibiotic resistance. BLDB is available online at http://bldb.eu without any registration and supports all modern browsers.

A multidrug-resistant Acinetobacter baumannii isolate recovered from a patient hospitalized in Switzerland after a transfer from Serbia produced the NDM-1 carbapenemase. The bla _NDM-1 gene was part of a chromosomally located Tn 125 composite transposon bracketed by two copies of the same insertion sequence, IS Aba125 . This transposon was also associated with the acquisition and expression of the bla _NDM-2 gene in an A. baumannii isolate in Germany. Tn 125 appears to be the main vehicle for dissemination of bla _NDM genes in that species.

To analyse the mechanisms responsible for carbapenem resistance in one Acinetobacter baumannii isolate recovered from a patient transferred to Germany from an Egyptian hospital. PCR and sequencing were used to search for β-lactamase and 16S RNA methylase genes. Multilocus sequence typing was used to determine the sequence type (ST) of the isolate. Sequencing of the PCR product obtained using primers for bla_NDM-1 revealed a variant of NDM-1 that had a C to G substitution at position 82 resulting in an amino acid substitution of proline to alanine at position 28. This variant was designated NDM-2. Genes encoding extended-spectrum β-lactamases or 16S RNA methylase were not detected. The strain lacked detectable plasmids and bla_NDM-2 was not transferred by conjugation. MLST showed that the isolate belonged to a new ST, ST103. This work further underlines the spread of NDM carbapenemases in A. baumannii, and the spread of the corresponding gene in the Middle East. It also describes the first variant of NDM-1.

The dissemination of antimicrobial resistance is a major threat to global health. Here, we show that a group of temperate bacterial viruses (phages), termed phage-plasmids, commonly encode different and multiple types of resistance genes of high clinical importance, often in integrons.

The resistome of the multidrug-resistant Escherichia coli strain 271 carrying the plasmid-mediated bla _NDM-1 carbapenemase gene was analyzed by high-throughput genome sequencing. The p271A plasmid carrying the bla _NDM-1 gene was 35.9 kb in size and possessed an IncN-type backbone that harbored a novel replicase gene. Acquisition of the bla _NDM-1 gene on plasmid p271A had been likely the result of a cointegration event involving the transposase of Tn 5403 . The expression of bla _NDM-1 was associated with the insertion sequence IS Aba125 likely originating from Acinetobacter baumannii. E. coli 271 accumulated multiple resistance determinants, including five β-lactamase genes (comprising the extended-spectrum β-lactamase CTX-M-15), two 16S RNA methylase ArmA- and RmtB-encoding genes, and the qepA gene encoding an efflux pump involved in resistance to fluoroquinolones. These resistance genes were located on three additional plasmids, of 160 kb (IncA/C), 130 kb (IncF), and 110 kb (IncI1). In addition, several chromosomally encoded resistance determinants were identified, such as topoisomerase mutations, porin modifications and truncations, and the intrinsic ampC gene of E. coli that was weakly expressed. The multidrug resistance pattern observed for E. coli 271 was therefore the result of combined chromosome- and plasmid-encoded mechanisms.