Metallo-β-lactamase-producing Pseudomonas aeruginosa in two hospitals from southern Brazil

Abstract

This study determined the prevalence of metallo-β β β β β-lactamase (MBL)-producing Pseudomonas aeruginosa in two hospitals located in the Southern part of Brazil and compare the performance of two different phenotypic tests. Thirty-one non-repetitive Pseudomonas aeruginosa isolates from various clinical samples from patients admitted to two hospitals located in Rio Grande do Sul, Brazil (twenty-three from a hospital in Porto Alegre City and eight isolates from a hospital in Vale dos Sinos Region). All strains suggestive of possessing MBLs by phenotypic methods were included in this study. Phenotypic detection of MBLs was carried out simultaneously by using both the MBL Etest® and disk approximation test using 2-mercaptopropionic acid close to a ceftazidime disk. Strains positive were further confirmed using molecular techniques for bla VIM , bla IMP and bla SPM-1 . The prevalence of MBLs from samples of inpatients from the hospital located in Porto Alegre was 30.4% and that of inpatients from Vale dos Sinos hospital was only 3.1%. Only MBL type SPM-1 was detected in these samples by molecular analysis and all were detected by the Etest® MBL strips. The prevalence of P. aeruginosa that produce MBLs can be markedly different in distinct geographical areas, even among different hospitals in the same area. In our study, the EDTA-based method was the only method able to detect all strains harboring the SPM-1 enzyme.

Characterization of a Carbapenem-Hydrolyzing Enzyme, PoxB, in Pseudomonas aeruginosa PAO1

“…Resistance to the ␤-lactam antibiotics is frequently observed in the clinical setting and is commonly due to the expression of enzymes that can hydrolyze these compounds, namely, ␤-lactamases (13,(49)(50)(51)(52). P. aeruginosa clinical isolates often harbor acquired ␤-lactamases, particularly those of the oxacillinase type (class D) and the metallo-␤-lactamase IMP and VIM types (class B) (23,25,(53)(54)(55)(56)(57)(58). Chromosomally, P. aeruginosa carries a cephalosporinase, AmpC, that provides intrinsic resistance and that can be expressed at high levels in the presence of ␤-lactams (24, 59, 60) and a carbapenemase, PIB-1, that is reported to be ubiquitous but expressed at low levels in strain PAO1 (26).…”

blaIMP and blaVIM mediated carbapenem resistance in Pseudomonas and Acinetobacter species in India

“…In recent years there has been an increase in carbapenem resistance among Gramnegative bacteria in the Indian subcontinent [12,13,14]. Resistance mechanisms include lack of drug penetration (i.e., porin mutations and efflux pumps) and/or carbapenem hydrolysingbetalactamase enzymes [2,15,16]. Over the past few years MBL producing isolates have emerged worldwide and are associated with outbreaks in health-care settings.…”

“…False positive results have been reported in P. aeruginosa as EDTA acts on the membrane of the bacterial cell and increases the cell permeability. Presence of OXA carbapenamases in A. baumannii may also lead to false positive results [7,16]. Hence the results of the MBL phenotypic tests must be interpreted cautiously.…”

High genetic diversity among Pseudomonas aeruginosa and Acinetobacter spp. isolated in a public hospital in Brazil

“…However, despite a resistance rate of just over 25% detected for carbapenems, none of the P. aeruginosa isolates tested were positive for MBL, demonstrating the probable participation of other resistance mechanisms. The isolation rates of MBL-producing P. aeruginosa have widely varied among Brazilian hospitals, with incidences ranging from 3.1% (Wirth et al, 2009) to 35% (Gonçalves et al, 2009. According to Rossi (2011), São Paulo metallo-β-lactamase (SPM) is the most prevalent MBL in Brazilian isolates.…”