TY - JOUR
T1 - Characterization of Triclosan-Resistant Mutants Reveals Multiple Antimicrobial Resistance Mechanisms in Rhodospirillum rubrum S1H
AU - Pycke, Benny
AU - Crabbé, Aurélie
AU - Verstraete, Willy
AU - Leys, Natalie
N1 - Score = 10
PY - 2010/5/1
Y1 - 2010/5/1
N2 - Antimicrobial resistance mechanisms were identified in 11 spontaneous high- and low-level triclosan resistance (Tcsr) mutants of Rhodospirillum rubrum S1H by genotyping complemented with transcriptional analyses, antibiotic resistance screening, and membrane permeability analyses. High-end Tcsr (MIC = 8 mg/liter) was the result of a FabI1(G98V) mutation. This point mutation led to an even higher level of Tcsr (MIC > 16 mg/liter) in combination with constitutive upregulation of mexB and mexF efflux pump homologs. Hence, a mechanistic synergy of constitutive efflux pump expression and a FabI1 point mutation could prevent TCSinduced cell permeabilization, which was shown to occur between 4 and 8 mg/liter TCS in the R. rubrum S1H parent strain. Low-level Tcsr mutants constitutively upregulated the emrAB, mexAB, and/or mexF homolog. The
mutants that overexpressed emrAB also derepressed the micropollutant-upregulated factors mufA1 and mufM.
In some cases, low-level Tcsr decreased innate resistance to ampicillin and tetracycline, while in others, a triclosan-induced antibiotic cross-resistance was shown for chloramphenicol and carbenicillin. This study showed that the TCS resistance degree is dependent of the initial exposure concentration in Rhodospirillum rubrum S1H and that similar resistance degrees can be the result of different defense mechanisms, which all have distinct antibiotic cross-resistance profiles.
AB - Antimicrobial resistance mechanisms were identified in 11 spontaneous high- and low-level triclosan resistance (Tcsr) mutants of Rhodospirillum rubrum S1H by genotyping complemented with transcriptional analyses, antibiotic resistance screening, and membrane permeability analyses. High-end Tcsr (MIC = 8 mg/liter) was the result of a FabI1(G98V) mutation. This point mutation led to an even higher level of Tcsr (MIC > 16 mg/liter) in combination with constitutive upregulation of mexB and mexF efflux pump homologs. Hence, a mechanistic synergy of constitutive efflux pump expression and a FabI1 point mutation could prevent TCSinduced cell permeabilization, which was shown to occur between 4 and 8 mg/liter TCS in the R. rubrum S1H parent strain. Low-level Tcsr mutants constitutively upregulated the emrAB, mexAB, and/or mexF homolog. The
mutants that overexpressed emrAB also derepressed the micropollutant-upregulated factors mufA1 and mufM.
In some cases, low-level Tcsr decreased innate resistance to ampicillin and tetracycline, while in others, a triclosan-induced antibiotic cross-resistance was shown for chloramphenicol and carbenicillin. This study showed that the TCS resistance degree is dependent of the initial exposure concentration in Rhodospirillum rubrum S1H and that similar resistance degrees can be the result of different defense mechanisms, which all have distinct antibiotic cross-resistance profiles.
KW - Characterization of Triclosan-Resistant Mutants Reveals Multiple Antimicrobial Resistance Mechanisms in Rhodospirillum rubrum S1H
UR - http://ecm.sckcen.be/OTCS/llisapi.dll/open/ezp_110626
UR - http://knowledgecentre.sckcen.be/so2/bibref/7607
U2 - 10.1128/AEM.02757-09
DO - 10.1128/AEM.02757-09
M3 - Article
SN - 0099-2240
VL - 76
SP - 3116
EP - 3123
JO - Applied and Environmental Microbiology
JF - Applied and Environmental Microbiology
IS - 10
ER -