Journal of Microbiology

Research Support, Non-U.S. Gov'ts

Virulence Determinants in Vancomycin-Resistant Enterococcus faecium vanA Isolated from Different Sources at University Hospital of Londrina, Paraná, Brazil: Flávia Imanishi Ruzon , Suelen Balero de Paula , Renata Lumi Kanoshiki , Jussevania Pereira-Santos , Gilselena Kerbauy , Renata Katsuko Takayama Kobayashi , Lucy Megumi Yamauchi , Márcia Regina Eches Perugini , Sueli Fumie Yamada-Ogatta; J. Microbiol. 2010;48(6):814-821. Published online January 9, 2011; DOI: https://doi.org/10.1007/s12275-010-0099-5

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Abstract: Enterococcus faecium, especially those showing multidrug resistance, has emerged as a significant cause of healthcare-associated infections worldwide. However, relatively little is known about the virulence and pathogenesis of this species. The aim of this study was to determine the occurrence of four putative virulence determinants of E. faecium and to correlate them with phenotypic traits. Using forty E. faecium vanA-type isolates from hospitalized patients and their environmental vicinity, we determined the following: the antimicrobial susceptibility profile, occurrence of the genes cylA, efaA, esp, and gelE, hemolytic and gelatinase activities, capacity to form biofilm and in vitro adhesion to epithelial cells. All isolates were shown to be resistant to vancomycin and teicoplanin, as well as to two or more other antimicrobials. All isolates harbored at least one putative virulence marker, and the prevalence was as follows: esp, 87.5%; efaA, 82.5%; gelE, 70%; and cylA, 65%. The presence of 4 genes was observed in 32.5% isolates. The presence of the efaA was associated with the presence of esp, regardless of the source of the isolates. A positive association with the presence of cylA and hemolytic activity in the sheep blood agar assay was observed. No association was found for gelE and gelatinase production in the agar plate assay, for efaA and LLC-MK2 cell adhesion, and for esp and biofilm formation on polystyrene surface. These results show the presence of putative virulence genes in multiple antimicrobial resistant E. faecium isolates from different sources in a hospital setting.

Enterococcus faecium Isolated from Honey Synthesized Bacteriocin-Like Substances Active against Different Listeria monocytogenes Strains: Carolina Ibarguren , Raúl R. Raya , María C. Apella , M. Carina Audisio; J. Microbiol. 2010;48(1):44-52. Published online March 11, 2010; DOI: https://doi.org/10.1007/s12275-009-0177-8

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Abstract: Four Enterococcus faecium strains, isolated from honeycombs (C1 and M2d strains) and feral combs (Mori1 and M1b strains) secreted antimicrobial substances active against fourteen different Listeria spp. strains. The antimicrobial compound(s) present in the cell free supernatant were highly thermostable (121°C for 15 min) and inactivated by proteolytic enzymes, but not by α-amylase and lipase, thus suggesting a peptidic nature. Since the structural bacteriocin gene determinants of enterocins A and B were PCR amplified from the four E. faecium isolates, only the bacteriocin produced by strain C1 was further characterized: it showed a broad band of approximately 4.0-7.0 kDa in SDS-PAGE and was bactericidal (4 log decrease) against L. monocytogenes 99/287. L. monocytogenes 99/287R, a clone spontaneously resistant to the enterocin produced by E. avium DSMZ17511 (ex PA1), was not inhibited by the enterocin-like compounds produced by strain C1. However, it was inhibited in mixed culture fermentations by E. faecium C1 and a bacteriostatic effect was observed. The bacteriocin-producer Enterococcus strains were not haemolytic; gelatinase negative and sensitive to vancomycin and other clinically relevant antibiotics.

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