Distinct Mechanisms of Dissemination of NDM-1 Metallo-β-Lactamase in Acinetobacter Species in Argentina.

A 4-year surveillance of carbapenem-resistant Acinetobacter spp. isolates in Argentina identified 40 strains carrying blaNDM-1 Genome sequencing revealed that most were Acinetobacter baumannii, whereas seven represented other Acinetobacter spp. The A. baumannii genomes were closely related, suggesting recent spread. blaNDM-1 was located in the chromosome of A. baumannii strains and on a plasmid in non-A. baumannii strains. A resistance gene island carrying blaPER-7 and other resistance determinants was found on a plasmid in some A. baumannii strains.

Adams MD ，Pasteran F ，Traglia GM ，Martinez J ，Huang F ，Liu C ，Fernandez JS ，Lopez C ，Gonzalez LJ ，Albornoz E ，Corso A ，Vila AJ ，Bonomo RA ，Ramirez MS ... -  《-》

Molecular characterization of blaNDM-1 in an Acinetobacter baumannii strain isolated in Germany in 2007.

Pfeifer Y ，Wilharm G ，Zander E ，Wichelhaus TA ，Göttig S ，Hunfeld KP ，Seifert H ，Witte W ，Higgins PG ... -  《-》

Carbapenem-resistant Acinetobacter baumannii producing OXA-23 in Thailand.

Niumsup PR ，Boonkerd N ，Tansawai U ，Tiloklurs M ... -  《JAPANESE JOURNAL OF INFECTIOUS DISEASES》

Characterization of plasmids carrying the blaOXA-24/40 carbapenemase gene and the genes encoding the AbkA/AbkB proteins of a toxin/antitoxin system.

Carbapenem-resistant Acinetobacter baumannii (CRAb) is a major source of nosocomial infections in Spain associated with the production of OXA-58-like or OXA-24/40-like β-lactamase enzymes. We analysed the plasmids carrying the bla(OXA-24/40)-like gene in CRAb isolates obtained a decade apart. The presence of β-lactamases was screened for by PCR (metallo-β-lactamases, carbapenem-hydrolysing class D β-lactamases, GES and KPC) in 101 CRAb isolates obtained in two multicentre studies (GEIH/REIPI-Ab-2000 and GEIH/REIPI-Ab-2010; n = 493 Acinetobacter spp). We analysed the distribution and characterization of the plasmids carrying the bla(OXA-24/40)-like gene and sequenced two plasmids, AbATCC223p (2000) and AbATCC329p (2010) from A. baumannii ATCC 17978 transformants. Acquisition of the bla(OXA-24/40)-like gene was the main mechanism underlying resistance to carbapenems (48.7% in 2000 compared with 51.6% in 2010). This gene was mainly isolated in ST2 A. baumannii strains in both studies, although some novel STs (ST79 and ST80) appeared in 2010. The gene was located in plasmids (8-12 kbp) associated with the repAci2 or repAci2/repGR12 types. The sequences of AbATCC223p (8840 bp) and AbATCC329p (8842 bp) plasmids were similar, particularly regarding the presence of the genes encoding the AbkA/AbkB proteins associated with the toxin/antitoxin system. Moreover, the abkA/abkB gene sequences (>96% identity) were also located in plasmids harbouring the bla(OXA-58)-like gene. The action of OXA-24/40 and OXA-58 β-lactamase-like enzymes represents the main mechanism underlying resistance to carbapenems in Spain in the last decade. AbkA/AbkB proteins in the toxin/antitoxin system may be involved in the successful dissemination of plasmids carrying the bla(OXA-24/40)-like gene, and probably also the bla(OXA-58)-like gene, thus contributing to the plasmid stability.

Mosqueda N ，Gato E ，Roca I ，López M ，de Alegría CR ，Fernández Cuenca F ，Martínez-Martínez L ，Pachón J ，Cisneros JM ，Rodríguez-Baño J ，Pascual A ，Vila J ，Bou G ，Tomás M ，GEIH-GEMARA (SEIMC) and REIPI ... -  《-》

Phenotypic and genotypic characterization of carbapenem-resistant Acinetobacter baumannii isolates from Egypt.

Antibiotic use is largely under-regulated in Egypt leading to the emergence of resistant isolates. Carbapenems are last resort agents to treat Acinetobacter baumannii infections resistant to other classes of antibiotics. However, carbapenem-resistant isolates are emerging at an alarming rate. This study aimed at phenotypically and molecularly characterizing seventy four carbapenem-unsusceptible A. baumannii isolates from Egypt to detect the different enzymes responsible for carbapenem resistance. Carbapenemase production was assessed by a number of phenotypic methods: modified Hodge test (MHT), carbapenem inactivation method (CIM), combined disc test (CDT), CarbAcineto NP test and boronic acid disc test. Polymerase chain reaction (PCR) was used to screen the isolates for the presence of some genes responsible for resistance to carbapenems, as well as some insertion sequences. PCR amplification of class D carbapenemases revealed the prevalence of blaOXA-51 and blaOXA-23 in 100% of the isolates and of blaOXA-58 in only one isolate (1.4%). blaVIM and blaNDM-1 belonging to class B metallo-β-lactamases were present in 100 and 12.1% of the isolates, respectively. The prevalence of ISAba1, ISAba2 and ISAba3 was 100, 2.7 and 4.1%, respectively. None of the tested isolates carried blaOXA-40 , blaIMP , blaSIM , blaSPM , blaGIM or the class A blaKPC . Taking PCR as the gold standard method for the detection of different carbapenemases, the sensitivities of the MHT, CIM, CDT, CarbAcineto NP test and boronic acid disc/imipenem or meropenem test for this particular collection of isolates were 78.4, 68.9, 79.7, 95.9, and 56.8% or 70.3%, respectively. The widespread detection of carbapenem-resistant A. baumannii (CR-AB) has become a real threat to the efficacy of treatment regimens. Among the studied cohort of CR-AB clinical isolates, blaOXA-51 , blaOXA-23 and blaVIM were the most prevalent, followed by blaNDM-1 and blaOXA-58 . The genotypic detection of carbapenemases among CR-AB clinical isolates using PCR was most conclusive, followed closely by the phenotypic testing using CarbAcineto NP test.

Abouelfetouh A ，Torky AS ，Aboulmagd E 《Antimicrobial Resistance and Infection Control》