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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060
EISSN: 1678-8060
Vol. 107, No. 6, 2012, pp. 747-751
Bioline Code: oc12116
Full paper language: English
Document type: Research Article
Document available free of charge

Memórias do Instituto Oswaldo Cruz, Vol. 107, No. 6, 2012, pp. 747-751

 en Metallo-β-lactamase-production in meropenem-susceptible Pseudomonas aeruginosa check for this species in other resources isolates: risk for silent spread
Picão, Renata Cristina; Carrara-Marroni, Floristher Elaine; Gales, Ana Cristina; Venâncio, Emerson José; Xavier, Danilo Elias; Tognim, Maria Cristina Bronharo & Pelayo, Jacinta Sanchez


The aim of this study was to characterize two metallo-β-lactamases (MBLs)-producing Pseudomonas aeruginosa check for this species in other resources clinical isolates showing meropenem susceptibility. Antimicrobial susceptibility was assessed by automated testing and Clinical and Laboratory typing was determined by pulsed field gel electrophoresis (PFGE) and sequencing. The location of blaIMP-16 was determine 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 mipenem and meropenem susceptibility by automated testing. Ager dilution assays confirmed meropenem susceptibility whereas both isolates showed low level of imipenem re-sistance. 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 transriptional levles of ampC and oprD. MBL-producing P.aeruginosa that are not resistant to meropenem amy represent a risk for therapeutic failure and act as silent reservoirs of MBL-encoding genes.

β-lactam resistance - β-lactamase - meropenem - efflux pumps - Gram-negative non-fermenting

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