Metallo-β-Lactamases: the Quiet before the Storm?

Abstract

SUMMARY The ascendancy of metallo-β-lactamases within the clinical sector, while not ubiquitous, has nonetheless been dramatic; some reports indicate that nearly 30% of imipenem-resistant Pseudomonas aeruginosa strains possess a metallo-β-lactamase. Acquisition of a metallo-β-lactamase gene will invariably mediate broad-spectrum β-lactam resistance in P. aeruginosa, but the level of in vitro resistance in Acinetobacter spp. and Enterobacteriaceae is less dependable. Their clinical significance is further embellished by their ability to hydrolyze all β-lactams and by the fact that there is currently no clinical inhibitor, nor is there likely to be for the foreseeable future. The genes encoding metallo-β-lactamases are often procured by class 1 (sometimes class 3) integrons, which, in turn, are embedded in transposons, resulting in a highly transmissible genetic apparatus. Moreover, other gene cassettes within the integrons often confer resistance to aminoglycosides, precluding their use as an alternative treatment. Thus far, the metallo-β-lactamases encoded on transferable genes include IMP, VIM, SPM, and GIM and have been reported from 28 countries. Their rapid dissemination is worrisome and necessitates the implementation of not just surveillance studies but also metallo-β-lactamase inhibitor studies securing the longevity of important anti-infectives.

Determinação da resistência antimicrobiana associada em isolados clínicos de Staphylococcus aureus e Pseudomonas aeruginosa em um hospital público de Goiânia, Estado de Goiás

“…Em função dos aminoglicosídeos e quinolonas, drogas comumente utilizadas como adjuvantes na terapêutica combinada com um -lactâmico 6 apresentarem percentuais de resistência associada com outros antibióticos bastante elevados, supõe-se que o potencial terapêutico dessa associação seja reduzido. Portanto, a resistência aos carbapenens, à ceftazidima e à cefepime (armas principais contra Pseudomonas aeruginosa), principalmente quando associada aos outros antimicrobianos, como aminoglicosídeos e quinolonas, representam um maior desafio para o tratamento 29 . Isso reflete no aumento da mortalidade e da permanência hospitalar e na necessidade maior de procedimentos diagnósticos e/ou terapêuticos 1 .…”

Characterization of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae isolates from the community in Morocco

“…Nevertheless, all CTX-Mproducing strains were susceptible to imipenem. However, the emergence of different types of carbapenemases could compromise the usefulness of this class of antibiotic (Walsh et al, 2005;Walther-Rasmussen & Høiby, 2006).…”

Prevalence of Metallo-beta-Lactamase producing Pseudomonas aeruginosa in wound infections in Duhok city, Iraq

“…10,14,15,21 This coresistance might be due to MBLs encoding is largely association with mobile genetic elements that often carry other resistance genes, resulting in multidrug resistance (MDR). 22 The later observation insight great importance and implies that these antibiotics are no longer be effectively used as empirical therapy for these so-called "superbugs" MBL producing P. aeruginosa infections and reflects a threat limiting the treatment options in our hospitals. The lowest activity of these antibiotics can be attributed in part to earlier and recurrent exposure of the isolates to these drugs which may have enhanced resistant development.…”