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Volume 47, Number 5, October 2014

Antimicrobial activity of a UV-stable bacteriocin-like inhibitory substance (BLIS) produced by Enterococcus faecium strain DSH20 against vancomycin-resistant Enterococcus (VRE) strains 


Dariush Shokri, Saeideh Zaghian, Fatemeh Khodabakhsh, Hossein Fazeli, Sina Mobasherizadeh, Behrooz Ataei


Received: March 10, 2013    Revised: May 2, 2013    Accepted: May 7, 2013   

 

Background and purpose: 

The narrow spectrum of action of most bacteriocins is an important limitation for their application as antimicrobial agents. The current study describes a novel bacteriocin-like inhibitory substance (BLIS) that display extended spectrum antimicrobial activity against vancomycin-resistant Enterococcus (VRE) strains. 



 

Methods:

Acquired resistance profiles of Enterococcus isolates determined based on the European Centre for Disease Prevention and Control (ECDC) and the Centers for Disease Control and Prevention (CDC) definition as multidrug-resistant (MDR), extensively drug-resistant (XDR) and pandrug resistant (PDR). BLIS activity of Enterococcus isolates was investigated against Enterococcus faecalis (E. faecalis) ATCC 29212 as the indicator strain and clinical isolates including VRE, methicillin resistant Staphylococcus aureus (MRSA) and Gram-negative bacteria containing Pseudomonas aeruginosa (P. aeruginosa), Klebsiella, Acinetobacter, and Escherichia coli (E. coli). 



 

Results:

Among 273 Enterococcus isolates, 27 and 2 VRE isolates, respectively, were XDR and PDR and eight isolates had BLIS activity against the indicator strain. One of these isolates, identified as E. faecium strain DSH20 based on its phenotypical and biochemical properties, as well as its 16S rRNA gene sequence, had potent BLIS production against all 29 VRE strains, but had no activity against MRSA, P. aeruginosa, Klebsiella, Acinetobacter, and E. coli strains. It was heat stable up to 121°C for 15 minutes (autoclave condition), active within the pH range of 3–9 and had UV stability, but its activity disappeared by treatment with proteinase K, pepsin, and trypsin, demonstrating its proteinaceous nature. It was designated as an approximately 35 kDa peptide using the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) method. 



 

Conclusion:

This peptide is a potential agent for use as an alternative antibacterial agent for the treatment of drug-resistant strains of VRE infection. 



 

Key words:

BLIS, Enterococcus faecium, Pandrug resistant (PDR), Vancomycin-resistant Enterococcus (VRE)