Metallo-β-lactamase-production in meropenem-susceptible Pseudomonas aeruginosa isolates: risk for silent spread

Memórias do Instituto Oswaldo Cruz

Renata Cristina Picão²  Floristher Elaine Carrara-marroni¹  Ana Cristina Gales²  Emerson José Venâncio¹  Danilo Elias Xavier²  Maria Cristina Bronharo Tognim¹  Jacinta Sanchez Pelayo¹ 

[1] ,Universidade Federal de São Paulo Departamento de Infectologia Laboratório ALERTASão Paulo SP ,Brasil

关键词: Beta-lactam resistance;    Beta-lactamase;    meropenem;    efflux pumps;    Gram-negative non-fermenting;   

DOI  :  10.1590/S0074-02762012000600007

来源: SciELO

【 摘 要 】

The aim of this study was to characterize two metallo-β-lactamases (MBLs)-producing Pseudomonas aeruginosa clinical isolates showing meropenem susceptibility. Antimicrobial susceptibility was assessed by automated testing and Clinical and Laboratory Standards Institute agar dilution method. MBL production was investigated by phenotypic tests. Molecular typing was determined by pulsed field gel electrophoresis (PFGE). MBL-encoding genes, as well as their genetic context, were identified by polymerase chain reaction (PCR) and sequencing. The location of blaIMP-16 was determined by plasmid electrophoresis, Southern blot and hybridization. Transcriptional levels of blaIMP-16, mexB, mexD, mexF, mexY, ampC and oprD were determined by semi-quantitative real time PCR. The P. aeruginosa isolates studied, Pa30 and Pa43, showed imipenem and meropenem susceptibility by automated testing. Agar dilution assays confirmed meropenem susceptibility whereas both isolates showed low level of imipenem resistance. Pa30 and Pa43 were phenotypically detected as MBL producers. PFGE revealed their clonal relatedness. blaIMP-16 was identified in both isolates, carried as a single cassette in a class 1 integron that was embedded in a plasmid of about 60-Kb. Pa30 and Pa43 overexpressed MexAB-OprM, MexCD-OprJ and MexXY-OprM efflux systems and showed basal transcriptional levels of ampC and oprD. MBL-producing P. aeruginosa that are not resistant to meropenem may represent a risk for therapeutic failure and act as silent reservoirs of MBL-encoding genes.

【 授权许可】

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