VIM-1 Metallo-β-lactamase in<i>Acinetobacter baumannii</i>

Tsakris, Athanassios; Ikonomidis, Alexandros; Pournaras, Spyros; Tzouvelekis, L. S.; Sofianou, Danai; Legakis, Nicholas J.; Maniatis, Antonios N.

doi:10.3201/eid1206.051097

Cited by 86 publications

(76 citation statements)

References 15 publications

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“…Of the five MBL groups described to date (589), only three have been identified in A. baumannii, including IMP (89,104,113,179,246,265,298,316,402,471,506,530,544,618), VIM (316,335,551,606,615), and SIM (320) types. Several geographic regions, such as Spain, Singapore, Greece, and Australia, have shown the presence of both OXA-and MBLtype enzymes in the same strains (70,298,423,551). Unlike the OXA-type enzymes, MBLs are most commonly found within integrons, which are specialized genetic structures that facilitate the acquisition and expression (via a common promoter) of resistance determinants.…”

Section: ␤-Lactamsmentioning

confidence: 99%

Acinetobacter baumannii : Emergence of a Successful Pathogen

2008

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SUMMARY Acinetobacter baumannii has emerged as a highly troublesome pathogen for many institutions globally. As a consequence of its immense ability to acquire or upregulate antibiotic drug resistance determinants, it has justifiably been propelled to the forefront of scientific attention. Apart from its predilection for the seriously ill within intensive care units, A. baumannii has more recently caused a range of infectious syndromes in military personnel injured in the Iraq and Afghanistan conflicts. This review details the significant advances that have been made in our understanding of this remarkable organism over the last 10 years, including current taxonomy and species identification, issues with susceptibility testing, mechanisms of antibiotic resistance, global epidemiology, clinical impact of infection, host-pathogen interactions, and infection control and therapeutic considerations.

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Section: ␤-Lactamsmentioning

confidence: 99%

Acinetobacter baumannii : Emergence of a Successful Pathogen

2008

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“…However, despite the worldwide occurrence of epidemic carbapenem-resistant strains, MBL-producing A. baumannii isolates have been found to be disseminated only in specific geographic areas (8,10). In Greek hospitals high rates of carbapenem-resistant A. baumannii clinical isolates are also detected, but MBL producers have been recognized in only a few instances (12). Therefore, the detection of these enzymes is of major importance in the control of A. baumannii hospital infections.…”

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confidence: 99%

Hidden VIM-1 Metallo-β-Lactamase Phenotypes among Acinetobacter baumannii Clinical Isolates

et al. 2008

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A total of 87 Acinetobacter baumannii nonrepetitive consecutive clinical isolates were tested for the presence of metallo-␤-lactamases (MBLs). Results of phenotypic assays (MBL Etest, imipenem/imipenem-EDTA combined-disk test, and imipenem/EDTA double-disk synergy test) were negative in all cases, but molecular testing revealed the presence of two bla VIM-1 -carrying isolates. One isolate had bla VIM-1 preceded by a weak P1 promoter, and both had inactivated P2 promoters and reduced bla VIM-1 expression, partially justifying the results revealing hidden MBL phenotypes.Carbapenem-resistant Acinetobacter baumannii strains are increasingly recovered from hospitalized patients worldwide and in some cases are associated with high morbidity and mortality rates (5). Mechanisms of resistance in such strains have been associated with decreased permeability, efflux pump overexpression, and, more lately, production of carbapenemases (10). Metallo-␤-lactamases (MBLs), mainly of types IMP and VIM, are increasingly associated with the reduced susceptibility to carbapenems seen in several gram-negative species (15). However, despite the worldwide occurrence of epidemic carbapenem-resistant strains, MBL-producing A. baumannii isolates have been found to be disseminated only in specific geographic areas (8, 10). In Greek hospitals high rates of carbapenem-resistant A. baumannii clinical isolates are also detected, but MBL producers have been recognized in only a few instances (12). Therefore, the detection of these enzymes is of major importance in the control of A. baumannii hospital infections.Several schemes have been proposed for the phenotypic detection of MBL-producing gram-negative species, including A. baumannii. These tests take advantage of the zinc dependence of MBLs by using chelating agents, such as EDTA, to inhibit enzyme activity (8). However, the phenotypic appearance of MBL-carrying organisms seems to depend on the nature of the bacterial host, since carbapenem-susceptible Enterobacteriaceae organisms may carry MBL genes not readily detectable by conventional assays (15). A recent study introduced a more sensitive procedure for MBL detection in a broad range of host organisms, including carbapenem-susceptible isolates (3). This prompted us to test a series of Greek A. baumannii clinical isolates which appeared to be MBL negative in routine clinical testing.The study included 87 A. baumannii clinical isolates consecutively recovered from separate patients during October 2006 to March 2007 at the University Hospital of Larissa, Larissa, Greece. Species identification was performed by use of an API 20NE system (bioMerieux, Marcy l'Etoile, France) and PCR amplification of the intrinsic bla OXA-51 allele (13). Imipenem and meropenem MICs were tested by the agar dilution method according to CLSI recommendations and interpretive criteria (1), while status of susceptibility to other ␤-lactams, as well as to aminoglycosides, quinolones, and colistin, was investigated by disk diffusion testing. Pseudomonas aeruginosa A...

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“…VIM-2-producing Acinetobacter spp. have been isolated in the Far East (Lee, et al, 2003) and in Germany (Toleman, 2004), while the VIM-1 determinant has been reported only in Greece (Tsakris 2006). One study recently identified VIM-4, which is nothing but a point mutant of VIM-1 and that has been previously identified only in Enterobacteriaceae (Luzzaro et al, 2008) and Pseudomonas spp.…”

Section: B-classmentioning

confidence: 99%

“…Concurrently, it was also observed in Greece that blaVIM-1 which is widespread in P. aeruginosa had apparently crossed the species barrier to reach Acinetobacter spp. Such examples might be yet another example of resistance genes crossing genus barrier (Tsakris et al, 2006).…”

Section: B-classmentioning

confidence: 99%