Multidrug-resistant Acinetobacter baumannii Harboring OXA-24 carbapenemase, Spain.
Ontology highlight
ABSTRACT:
SUBMITTER: Acosta J
PROVIDER: S-EPMC3358182 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:During 2005 we detected a multicity outbreak of infections or colonization due to high-level imipenem-resistant Acinetobacter baumannii (MIC, 64 microg/ml). One hundred isolates from diverse sources were obtained from seven acute-care hospitals and two extended-care facilities; 97% of the isolates belonged to one clone. Susceptibility testing of the first 42 isolates (January to April 2005) revealed broad resistance profiles. Half of the isolates were susceptible to ceftazidime, with many isolates susceptible only to colistin. The level of AmpC beta-lactamase expression was stronger in isolates resistant to ceftazidime. PCR and subsequent nucleotide sequencing analysis identified bla(OXA-40). The presence of an OXA-40 beta-lactamase in these isolates correlated with the carbapenem resistance. By Southern blot analysis, a bla(OXA-40)-specific probe revealed that the gene was both plasmid and chromosomally located. This is the first time in the United States that such carbapenem resistance in A. baumannii has been attributable to a carbapenemase.
| S-EPMC1563549 | biostudies-literature
Project description:The emergence of class D β-lactamases with carbapenemase activity presents an enormous challenge to health practitioners, particularly with regard to the treatment of infections caused by Gram-negative pathogens such as Acinetobacter baumannii. Unfortunately, class D β-lactamases with carbapenemase activity are resistant to β-lactamase inhibitors. To better understand the details of the how these enzymes bind and hydrolyze carbapenems, we have determined the structures of two deacylation-deficient variants (K84D and V130D) of the class D carbapenemase OXA-24 with doripenem bound as a covalent acyl-enzyme intermediate. Doripenem adopts essentially the same configuration in both OXA-24 variant structures, but varies significantly when compared to the non-carbapenemase class D member OXA-1/doripenem complex. The alcohol of the 6α hydroxyethyl moiety is directed away from the general base carboxy-K84, with implications for activation of the deacylating water. The tunnel formed by the Y112/M223 bridge in the apo form of OXA-24 is largely unchanged by the binding of doripenem. The presence of this bridge, however, causes the distal pyrrolidine/sulfonamide group to bind in a drastically different conformation compared to doripenem bound to OXA-1. The resulting difference in the position of the side-chain bridge sulfur of doripenem is consistent with the hypothesis that the tautomeric state of the pyrroline ring contributes to the different carbapenem hydrolysis rates of OXA-1 and OXA-24. These findings represent a snapshot of a key step in the catalytic mechanism of an important class D enzyme, and might be useful for the design of novel inhibitors.
| S-EPMC3057435 | biostudies-literature
Project description:Purpose:A novel variant of OXA-23, named OXA-423, was identified in an Acinetobacter baumannii clinical isolate. The aim of this study was to analyse the resistance phenotype of OXA-423. Methods:The A. baumannii strain WY-0713 was isolated from an intensive care unit patient. PCR was used to detect the bla OXA-23-like genes. Amplifying, cloning and sequencing were performed for the complete bla OXA-23-like. The novel bla OXA-423 and its ancestor bla OXA-23 were cloned into the expression vector pET-28b(+), and transformed into E. coli Rosetta (DE3) for antibiotic susceptibility testing. SDS-PAGE, modified Hodge test and CarbaNP test were used for detecting the expression of OXA-423 and OXA-23. Results:PCR screening of A. baumannii WY-0713 was positive for bla OXA-23-like genes. Sequencing of the PCR product identi?ed a novel bla OXA-23-like, named bla OXA-423 which encoding OXA-423. OXA-423 differed from OXA-23 by a crucial amino acid substitution (Val128Ala). The V128A substitution was located at the conserved active-site motifs SAV of OXA-23. Antibiotic susceptibility testing performed using isogenic E. coli showed that the MICs of E. coli Rosetta (pET-OXA-423) for penicillins and carbapenems were lower (reduced MICs 4-fold to 16-fold) than that of E. coli Rosetta (pET-OXA-23). The MICs of cefotaxime, ceftazidime and aztreonam for both transformants remained the same as the acceptor strain. Moreover, OXA-423 was slightly inhibited by sulbactam, clavulanic acid and tazobactam. SDS-PAGE analysis showed that OXA-423 and OXA-23 were conspicuously expressed. Modified Hodge test and CarbaNP test were positive demonstrated both of them were functional. Conclusion:OXA-423, the first report of an amino acid substitution located at conserved active-site motifs of OXA-23, conferred lower MIC values of penicillins and carbapenems as compared with OXA-23, while without affecting the resistance pro?les of expanded-spectrum cephalosporins and aztreonam.
| S-EPMC7666985 | biostudies-literature
Project description:Two epidemiologically unrelated carbapenem-resistant Acinetobacter baumannii isolates were investigated as representatives of the first Italian isolates producing the OXA-24 carbapenemase. Both isolates were of European clonal lineage II and carried an identical OXA-24-encoding plasmid, named pABVA01. Comparative analysis revealed that in pABVA01, bla(OXA-24) was part of a DNA module flanked by conserved inverted repeats homologous to XerC/XerD binding sites, which in other Acinetobacter plasmids flank different DNA modules, suggesting mobilization by a novel site-specific recombination mechanism.
| S-EPMC2715606 | biostudies-literature
Project description:Class D β-lactamases capable of hydrolyzing last-resort carbapenem antibiotics represent a major challenge for treatment of bacterial infections. Wide dissemination of these enzymes in Acinetobacter baumannii elevated this pathogen to the category of most deadly and difficult to treat. We present here the structure of the OXA-58 β-lactamase, a major class D carbapenemase of A. baumannii, determined to 1.30-Å resolution. Unlike two other Acinetobacter carbapenemases, OXA23 and OXA-24, the OXA-58 enzyme lacks the characteristic hydrophobic bridge over the active site, despite conservation of the residues which participate in its formation. The active-site residues in OXA-58 are spatially conserved in comparison to those in other class D β-lactamases. Lys86, which activates water molecules during the acylation and deacylation steps, is fully carboxylated in the OXA-58 structure. In the absence of a substrate, a water molecule is observed in the active site of the enzyme and is positioned in the pocket that is usually occupied by the 6α-hydroxyethyl moiety of carbapenems. A water molecule in this location would efficiently deacylate good substrates, such as the penicillins, but in the case of carbapenems, it would be expelled by the 6α-hydroxyethyl moiety of the antibiotics and a water from the surrounding medium would find its way to the vicinity of the carboxylated Lys86 to perform deacylation. Subtle differences in the position of this water in the acyl-enzyme complexes of class D β-lactamases could ultimately be responsible for differences in the catalytic efficiencies of these enzymes against last-resort carbapenem antibiotics.
| S-EPMC4023756 | biostudies-literature
Project description:Resistance of Acinetobacter baumannii clinical isolates to carbapenems is on the rise worldwide mainly in association with the production of OXA-23. Until recently, however, OXA-23 was absent in Spain. In this work, we report the molecular characterization of a hospital outbreak of OXA-23-producing A. baumannii in Barcelona caused by a multidrug-resistant (MDR) clone belonging to international clone IC-II/sequence type ST85 between October 2010 and May 2011. blaOXA-23 was carried in a plasmid of 90 kb and located within the composite transposon Tn2006.
| S-EPMC3811394 | biostudies-literature
Project description:Acinetobacter baumannii RYC 52763/97, a clinical isolate involved in a prolonged nosocomial outbreak at our hospital, was resistant to all beta-lactams tested, including imipenem and meropenem, which had MICs of 128 and 256 microg/ml, respectively. This strain synthesized three beta-lactamases: a plasmid-mediated TEM-1 beta-lactamase (pI 5.4), an AmpC-type chromosomal cephalosporinase (pI 9.4), and a novel, presumptively chromosomally mediated OXA-related enzyme (pI 9.0) named OXA-24. After cloning and sequencing, the deduced amino acid sequence of the OXA-24 beta-lactamase showed 40% homology with the OXA-10 (PSE-2) and OXA-7 beta-lactamases, 39% homology with the OXA-11 and OXA-5 enzymes, and 33% homology with the LCR-1 beta-lactamase. The amino acid sequence of the OXA-24 beta-lactamase contained the STFK motif found in serine beta-lactamases, but the typical class D triad KTG was replaced by KSG and the motif YGN was replaced by FGN. The OXA-24 beta-lactamase hydrolyzed benzylpenicillin and cephaloridine but lacked activity against oxacillin, cloxacillin, and methicillin. The enzymatic activity was inhibited by chloride ions and by tazobactam (50% inhibitory concentration [IC(50)], 0.5 microM), sulbactam (IC(50), 40 microM), and clavulanic acid (IC(50), 50 microM). Carbapenem MICs for an Escherichia coli transformant (pBMB-1) expressing the cloned OXA-24 enzyme had a fourfold increase. Relative V(max)/K(m) values of 13 and 6 were obtained with imipenem and meropenem, respectively, and a positive microbiological assay result with imipenem was obtained with a purified enzymatic extract of this transformant strain. Therefore, we consider this new beta-lactamase to be involved in the carbapenem resistance of A. baumannii RYC 52763/97.
| S-EPMC89912 | biostudies-literature
Project description:Eighty-two carbapenem-resistant isolates of Acinetobacter baumannii from a single hospital in Bilbao were typed into two major clusters and several subclusters. Disk synergy tests and PCR indicated the production of a zinc-independent OXA-class carbapenemase. Sequencing identified this enzyme, OXA-40, as a variant of the OXA-24-OXA-25-OXA-26 cluster.
| S-EPMC154648 | biostudies-literature
Project description: Not available
| S-EPMC3647512 | biostudies-literature
Project description:During 2005, 66 carbapenem-resistant isolates of Acinetobacter baumannii were collected from seven tertiary-care hospitals participating in a nationwide surveillance network in Colombia. The isolates were multidrug resistant and produced the carbapenemases OXA-23 and OXA-51. Forty-five belonged to four clones while 21 were unique pulsotypes. One clone was present in two hospitals within one city, while another had spread between two hospitals in different cities. Blood, secretions, and abdominal fluids were the most frequent sites of isolation. This is the first description of widespread dissemination of OXA-23 in South America.
| S-EPMC1891364 | biostudies-literature