Document Detail

Attenuated virulence and biofilm formation in Staphylococcus aureus following sublethal exposure to triclosan.
MedLine Citation:
PMID:  22430975     Owner:  NLM     Status:  MEDLINE    
Subeffective exposure of Staphylococcus aureus to the biocide triclosan can reportedly induce a small-colony variant (SCV) phenotype. S. aureus SCVs are characterized by low growth rates, reduced pigmentation, and lowered antimicrobial susceptibility. While they may exhibit enhanced intracellular survival, there are conflicting reports regarding their pathogenicity. The current study reports the characteristics of an SCV-like strain of S. aureus created by repeated passage on sublethal triclosan concentrations. S. aureus ATCC 6538 (the passage 0 [P0] strain) was serially exposed 10 times to concentration gradients of triclosan to generate strain P10. This strain was then further passaged 10 times on triclosan-free medium (designated strain ×10). The MICs and minimum bactericidal concentrations of triclosan for P0, P10, and ×10 were determined, and growth rates in biofilm and planktonic cultures were measured. Hemolysin, DNase, and coagulase activities were measured, and virulence was determined using a Galleria mellonella pathogenicity model. Strain P10 exhibited decreased susceptibility to triclosan and characteristics of an SCV phenotype, including a considerably reduced growth rate and the formation of pinpoint colonies. However, this strain also had delayed coagulase production, had impaired hemolysis (P < 0.01), was defective in biofilm formation and DNase activity, and displayed significantly attenuated virulence. Colony size, hemolysis, coagulase activity, and virulence were only partially restored in strain ×10, whereas the planktonic growth rate was fully restored. However, ×10 was at least as defective in biofilm formation and DNase production as P10. These data suggest that although repeated exposure to triclosan may result in an SCV-like phenotype, this is not necessarily associated with increased virulence and adapted bacteria may exhibit other functional deficiencies.
Joe Latimer; Sarah Forbes; Andrew J McBain
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Publication Detail:
Type:  Journal Article     Date:  2012-03-19
Journal Detail:
Title:  Antimicrobial agents and chemotherapy     Volume:  56     ISSN:  1098-6596     ISO Abbreviation:  Antimicrob. Agents Chemother.     Publication Date:  2012 Jun 
Date Detail:
Created Date:  2012-05-14     Completed Date:  2012-09-13     Revised Date:  2013-06-26    
Medline Journal Info:
Nlm Unique ID:  0315061     Medline TA:  Antimicrob Agents Chemother     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3092-100     Citation Subset:  IM    
School of Pharmacy and Pharmaceutical Sciences, The University of Manchester, Manchester, United Kingdom.
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MeSH Terms
Anti-Bacterial Agents / pharmacology*
Biofilms / drug effects*
Coagulase / metabolism
Deoxyribonucleases / metabolism
Hemolysin Proteins / metabolism
Microbial Sensitivity Tests
Staphylococcus aureus / drug effects*,  metabolism
Triclosan / pharmacology*
Virulence / drug effects
Reg. No./Substance:
0/Anti-Bacterial Agents; 0/Coagulase; 0/Hemolysin Proteins; 3380-34-5/Triclosan; EC 3.1.-/Deoxyribonucleases
Comment In:
Antimicrob Agents Chemother. 2012 Nov;56(11):6068-9; author reply 6072   [PMID:  23074229 ]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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