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PLoS One. 2014 Jan 23;9(1):e86669. doi: 10.1371/journal.pone.0086669. eCollection 2014.

Evaluation of epidemiological cut-off values indicates that biocide resistant subpopulations are uncommon in natural isolates of clinically-relevant microorganisms.

Author information

1
Quotient Bioresearch, Fordham, United Kingdom.
2
Dipartimento de Biotecnologie, Università di Siena, Siena, Italy.
3
Servicio de Microbiología and CIBER en Epidemiología y Salud Pública and Instituto Ramón y Cajal de Investigación Sanitaria, Madrid, Spain.
4
Gazi University School of Medicine, Department of Medical Microbiology, Ankara, Turkey.
5
Centro Nacional de Biotecnologia-CSIC, Madrid, Spain.

Abstract

To date there are no clear criteria to determine whether a microbe is susceptible to biocides or not. As a starting point for distinguishing between wild-type and resistant organisms, we set out to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) distributions for four common biocides; triclosan, benzalkonium chloride, chlorhexidine and sodium hypochlorite for 3319 clinical isolates, with a particular focus on Staphylococcus aureus (N = 1635) and Salmonella spp. (N = 901) but also including Escherichia coli (N = 368), Candida albicans (N = 200), Klebsiella pneumoniae (N = 60), Enterobacter spp. (N = 54), Enterococcus faecium (N = 53), and Enterococcus faecalis (N = 56). From these data epidemiological cut-off values (ECOFFs) are proposed. As would be expected, MBCs were higher than MICs for all biocides. In most cases both values followed a normal distribution. Bimodal distributions, indicating the existence of biocide resistant subpopulations were observed for Enterobacter chlorhexidine susceptibility (both MICs and MBCs) and the susceptibility to triclosan of Enterobacter (MBC), E. coli (MBC and MIC) and S. aureus (MBC and MIC). There is a concern on the potential selection of antibiotic resistance by biocides. Our results indicate however that resistance to biocides and, hence any potential association with antibiotic resistance, is uncommon in natural populations of clinically relevant microorganisms.

PMID:
24466194
PMCID:
PMC3900580
DOI:
10.1371/journal.pone.0086669
[Indexed for MEDLINE]
Free PMC Article

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