Emergence of Carbapenem-Hydrolyzing Enzymes in
            <b>
              <i>Acinetobacter baumannii</i>
              Clinical Isolates
            </b>

Silva, Gabriela; Leitão, Rui; Peixe, Luı́sa

doi:10.1128/jcm.37.6.2109-2110.1999

Cited by 35 publications

(16 citation statements)

References 9 publications

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“…The calculated molecular mass and pI value of the mature protein was 25 090 Da and 9.26, respectively. This theoretical pI value is in accordance with the alkaline pI determined experimentally [29].…”

Section: Sequence Of the Integron-borne Bla Imp Determinant And £Ankisupporting

confidence: 91%

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Molecular characterization of blaIMP-5, a new integron-borne metallo-β-lactamase gene from an Acinetobacter baumannii nosocomial isolate in Portugal

Silva¹

2002

FEMS Microbiology Letters

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Acinetobacter baumannii 65FFC, an imipenem-resistant clinical strain, isolated from the urine of a patient at the Coimbra University Hospital, Portugal, in 1998, produced a metallo-beta-lactamase with a calculated pI 9.3. The isolate was highly resistant to penicillins, broad-spectrum cephalosporins, including ceftazidime, ceftriaxone, cefepime, cefpirome, and to aztreonam, but it remained susceptible to ampicillin/sulbactam, aminoglycosides and quinolones. Nucleotide sequence revealed a new allelic variant of other bla(IMP) genes, named bla(IMP-5). IMP-5 beta-lactamase showed a greater homology with IMP-1, IMP-3 and IMP-4 (identified in Southeast Asia), than with IMP-2, found in Italy (93%, 92%, 91% and 87% of amino acid identity, respectively). bla(IMP-5) was the only gene cassette inserted into a class 1 integron, named In76. This is the first IMP-enzyme reported in Portugal and the second in Europe, indicating a wider dissemination in the environment of bla(IMP) alleles.

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Section: Sequence Of the Integron-borne Bla Imp Determinant And £Ankisupporting

confidence: 91%

“…isolates from a Portuguese teaching hospital. It was con-¢rmed for two isolates that the imipenem resistance was associated with the production of an imipenem hydrolyzing metallo-L-lactamase [29]. This ¢nding prompted us to characterize the imipenem resistance determinant carried by A. baumannii 65FFC isolate.…”

Section: Introductionmentioning

confidence: 99%

Molecular characterization of blaIMP-5, a new integron-borne metallo-β-lactamase gene from an Acinetobacter baumannii nosocomial isolate in Portugal

Silva¹

2002

FEMS Microbiology Letters

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“…Carbapenems have become the preferred treatment for serious Acinetobacter infections in many centres, and have retained better activity than other antimicrobial agents; however, the number of reports of carbapenem resistance is growing steadily and is a cause for concern. In the last few years, carbapenem‐resistant Acinetobacter isolates have been reported worldwide [47,48]. In northern Europe, carbapenem‐resistant strains of A. baumannii have been mostly sporadic, but in some southern European countries, including parts of Spain, they are endemic [49,50].…”

Section: β‐Lactamsmentioning

confidence: 99%

Antimicrobial resistance of Acinetobacter spp. in Europe

Looveren

Goossens

2004

Clinical Microbiology and Infection

284

207

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Bacteria of the genus Acinetobacter are ubiquitous in nature. These organisms were invariably susceptible to many antibiotics in the 1970s. Since that time, acinetobacters have emerged as multiresistant opportunistic nosocomial pathogens. The taxonomy of the genus Acinetobacter underwent extensive revision in the mid-1980s, and at least 32 named and unnamed species have now been described. Of these, Acinetobacter baumannii and the closely related unnamed genomic species 3 and 13 sensu Tjernberg and Ursing (13TU) are the most relevant clinically. Multiresistant strains of these species causing bacteraemia, pneumonia, meningitis, urinary tract infections and surgical wound infections have been isolated from hospitalised patients worldwide. This review provides an overview of the antimicrobial susceptibilities of Acinetobacter spp. in Europe, as well as the main mechanisms of antimicrobial resistance, and summarises the remaining treatment options for multiresistant Acinetobacter infections.

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“…The IMP‐4 enzyme possesses a broad‐spectrum of activity that includes penicillins, cephalosporins, and carbapenems (Chu et al 2001). Finally, Acinetobacter baumannii clinical isolates producing a metallo‐enzyme with characteristics similar to IMP‐1 have been reported in Portugal (Da Silva et al 1999).…”

mentioning

confidence: 95%

Identification of residues critical for metallo‐β‐lactamase function by codon randomization and selection

Materon

Palzkill

2001

Protein Science

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IMP-1 ␤-lactamase is a zinc metallo-enzyme encoded by the transferable bla IMP-1 gene, which confers resistance to virtually all ␤-lactam antibiotics including carbapenems. To understand how IMP-1 recognizes and hydrolyzes ␤-lactam antibiotics it is important to determine which amino acid residues are critical for catalysis and which residues control substrate specificity. We randomized 27 individual codons in the bla IMP-1 gene to create libraries that contain all possible amino acid substitutions at residue positions in and near the active site of IMP-1. Mutants from the random libraries were selected for the ability to confer ampicillin resistance to Escherichia coli. Of the positions randomized, >50% do not tolerate amino acid substitutions, suggesting they are essential for IMP-1 function. The remaining positions tolerate amino acid substitutions and may influence the substrate specificity of the enzyme. Interestingly, kinetic studies for one of the functional mutants, Asn233Ala, indicate that an alanine substitution at this position significantly increases catalytic efficiency as compared with the wild-type enzyme.

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Emergence of Carbapenem-Hydrolyzing Enzymes in Acinetobacter baumannii Clinical Isolates

Cited by 35 publications

References 9 publications

Molecular characterization of blaIMP-5, a new integron-borne metallo-β-lactamase gene from an Acinetobacter baumannii nosocomial isolate in Portugal

Molecular characterization of blaIMP-5, a new integron-borne metallo-β-lactamase gene from an Acinetobacter baumannii nosocomial isolate in Portugal

Antimicrobial resistance of Acinetobacter spp. in Europe

Identification of residues critical for metallo‐β‐lactamase function by codon randomization and selection

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