CTX-M-1 β-lactamase expression in Escherichia coli is dependent on cefotaxime concentration, growth phase and gene location

Thea S.B. Kjeldsen, Martin Overgaard, S.S. Nielsen, Valeria Bortolaia, Lotte Jelsbak, Morten Sommer, Luca Guardabassi, John Elmerdahl Olsen

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

OBJECTIVES:
Knowledge about the regulatory mechanisms of CTX-M β-lactamase-encoding genes in Escherichia coli is limited. The objectives of this study were to determine the growth response of CTX-M-1-producing E. coli exposed to cefotaxime and to investigate how blaCTX-M-1 expression at mRNA and protein levels is influenced by cefotaxime concentration, growth phase and gene location (chromosome versus plasmid).
METHODS:
Two isogenic E. coli strains, MG1655/CTX-M-1 and MG1655/IncI1/CTX-M-1, containing blaCTX-M-1 on the chromosome and on a wild-type IncI1 plasmid, respectively, were constructed and the MIC of cefotaxime was determined. Growth of the two strains was studied in the presence of increasing concentrations of cefotaxime ranging from 0 to 512 mg/L. The levels of mRNA and protein in different growth phases and at different cefotaxime concentrations were studied by qPCR and selected-reaction-monitoring MS, respectively.
RESULTS:
The MICs of cefotaxime were 168 and 252 mg/L for MG1655/CTX-M-1 and MG1655/IncI1/CTX-M-1, respectively. Both strains displayed a prolonged lag phase when exposed to cefotaxime. The mRNA of blaCTX-M-1 and CTX-M-1 protein levels increased in the presence of high cefotaxime concentrations and varied with growth phase. Higher mRNA expression levels were detected for MG1655/CTX-M-1 compared with MG1655/IncI1/CTX-M-1, but a higher protein level was found for MG1655/IncI1/CTX-M-1 compared with MG1655/CTX-M-1, the latter corresponding well with the higher MIC for this strain.
CONCLUSIONS:
blaCTX-M-1 mRNA expression and CTX-M-1 protein levels were dependent on cefotaxime concentration, growth phase and gene location. These results provide insight into the expression of cephalosporin resistance in CTX-M-1-producing E. coli, improving our understanding of the relationship between antimicrobial therapy and the expression of resistance mechanisms.
OriginalsprogEngelsk
TidsskriftJournal of Antimicrobial Chemotherapy
ISSN0305-7453
DOI
StatusUdgivet - 2015
Udgivet eksterntJa

Citer dette

S.B. Kjeldsen, Thea ; Overgaard, Martin ; Nielsen, S.S. ; Bortolaia, Valeria ; Jelsbak, Lotte ; Sommer, Morten ; Guardabassi, Luca ; Olsen, John Elmerdahl. / CTX-M-1 β-lactamase expression in Escherichia coli is dependent on cefotaxime concentration, growth phase and gene location. I: Journal of Antimicrobial Chemotherapy. 2015.
@article{bdc18bdb71a74d6bb44219b2483a1e4d,
title = "CTX-M-1 β-lactamase expression in Escherichia coli is dependent on cefotaxime concentration, growth phase and gene location",
abstract = "OBJECTIVES:Knowledge about the regulatory mechanisms of CTX-M β-lactamase-encoding genes in Escherichia coli is limited. The objectives of this study were to determine the growth response of CTX-M-1-producing E. coli exposed to cefotaxime and to investigate how blaCTX-M-1 expression at mRNA and protein levels is influenced by cefotaxime concentration, growth phase and gene location (chromosome versus plasmid).METHODS:Two isogenic E. coli strains, MG1655/CTX-M-1 and MG1655/IncI1/CTX-M-1, containing blaCTX-M-1 on the chromosome and on a wild-type IncI1 plasmid, respectively, were constructed and the MIC of cefotaxime was determined. Growth of the two strains was studied in the presence of increasing concentrations of cefotaxime ranging from 0 to 512 mg/L. The levels of mRNA and protein in different growth phases and at different cefotaxime concentrations were studied by qPCR and selected-reaction-monitoring MS, respectively.RESULTS:The MICs of cefotaxime were 168 and 252 mg/L for MG1655/CTX-M-1 and MG1655/IncI1/CTX-M-1, respectively. Both strains displayed a prolonged lag phase when exposed to cefotaxime. The mRNA of blaCTX-M-1 and CTX-M-1 protein levels increased in the presence of high cefotaxime concentrations and varied with growth phase. Higher mRNA expression levels were detected for MG1655/CTX-M-1 compared with MG1655/IncI1/CTX-M-1, but a higher protein level was found for MG1655/IncI1/CTX-M-1 compared with MG1655/CTX-M-1, the latter corresponding well with the higher MIC for this strain.CONCLUSIONS:blaCTX-M-1 mRNA expression and CTX-M-1 protein levels were dependent on cefotaxime concentration, growth phase and gene location. These results provide insight into the expression of cephalosporin resistance in CTX-M-1-producing E. coli, improving our understanding of the relationship between antimicrobial therapy and the expression of resistance mechanisms.",
author = "{S.B. Kjeldsen}, Thea and Martin Overgaard and S.S. Nielsen and Valeria Bortolaia and Lotte Jelsbak and Morten Sommer and Luca Guardabassi and Olsen, {John Elmerdahl}",
year = "2015",
doi = "10.1093/jac/dku332",
language = "English",
journal = "Journal of Antimicrobial Chemotherapy",
issn = "0305-7453",
publisher = "Oxford University Press",

}

CTX-M-1 β-lactamase expression in Escherichia coli is dependent on cefotaxime concentration, growth phase and gene location. / S.B. Kjeldsen, Thea; Overgaard, Martin; Nielsen, S.S.; Bortolaia, Valeria; Jelsbak, Lotte; Sommer, Morten; Guardabassi, Luca; Olsen, John Elmerdahl.

I: Journal of Antimicrobial Chemotherapy, 2015.

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

TY - JOUR

T1 - CTX-M-1 β-lactamase expression in Escherichia coli is dependent on cefotaxime concentration, growth phase and gene location

AU - S.B. Kjeldsen, Thea

AU - Overgaard, Martin

AU - Nielsen, S.S.

AU - Bortolaia, Valeria

AU - Jelsbak, Lotte

AU - Sommer, Morten

AU - Guardabassi, Luca

AU - Olsen, John Elmerdahl

PY - 2015

Y1 - 2015

N2 - OBJECTIVES:Knowledge about the regulatory mechanisms of CTX-M β-lactamase-encoding genes in Escherichia coli is limited. The objectives of this study were to determine the growth response of CTX-M-1-producing E. coli exposed to cefotaxime and to investigate how blaCTX-M-1 expression at mRNA and protein levels is influenced by cefotaxime concentration, growth phase and gene location (chromosome versus plasmid).METHODS:Two isogenic E. coli strains, MG1655/CTX-M-1 and MG1655/IncI1/CTX-M-1, containing blaCTX-M-1 on the chromosome and on a wild-type IncI1 plasmid, respectively, were constructed and the MIC of cefotaxime was determined. Growth of the two strains was studied in the presence of increasing concentrations of cefotaxime ranging from 0 to 512 mg/L. The levels of mRNA and protein in different growth phases and at different cefotaxime concentrations were studied by qPCR and selected-reaction-monitoring MS, respectively.RESULTS:The MICs of cefotaxime were 168 and 252 mg/L for MG1655/CTX-M-1 and MG1655/IncI1/CTX-M-1, respectively. Both strains displayed a prolonged lag phase when exposed to cefotaxime. The mRNA of blaCTX-M-1 and CTX-M-1 protein levels increased in the presence of high cefotaxime concentrations and varied with growth phase. Higher mRNA expression levels were detected for MG1655/CTX-M-1 compared with MG1655/IncI1/CTX-M-1, but a higher protein level was found for MG1655/IncI1/CTX-M-1 compared with MG1655/CTX-M-1, the latter corresponding well with the higher MIC for this strain.CONCLUSIONS:blaCTX-M-1 mRNA expression and CTX-M-1 protein levels were dependent on cefotaxime concentration, growth phase and gene location. These results provide insight into the expression of cephalosporin resistance in CTX-M-1-producing E. coli, improving our understanding of the relationship between antimicrobial therapy and the expression of resistance mechanisms.

AB - OBJECTIVES:Knowledge about the regulatory mechanisms of CTX-M β-lactamase-encoding genes in Escherichia coli is limited. The objectives of this study were to determine the growth response of CTX-M-1-producing E. coli exposed to cefotaxime and to investigate how blaCTX-M-1 expression at mRNA and protein levels is influenced by cefotaxime concentration, growth phase and gene location (chromosome versus plasmid).METHODS:Two isogenic E. coli strains, MG1655/CTX-M-1 and MG1655/IncI1/CTX-M-1, containing blaCTX-M-1 on the chromosome and on a wild-type IncI1 plasmid, respectively, were constructed and the MIC of cefotaxime was determined. Growth of the two strains was studied in the presence of increasing concentrations of cefotaxime ranging from 0 to 512 mg/L. The levels of mRNA and protein in different growth phases and at different cefotaxime concentrations were studied by qPCR and selected-reaction-monitoring MS, respectively.RESULTS:The MICs of cefotaxime were 168 and 252 mg/L for MG1655/CTX-M-1 and MG1655/IncI1/CTX-M-1, respectively. Both strains displayed a prolonged lag phase when exposed to cefotaxime. The mRNA of blaCTX-M-1 and CTX-M-1 protein levels increased in the presence of high cefotaxime concentrations and varied with growth phase. Higher mRNA expression levels were detected for MG1655/CTX-M-1 compared with MG1655/IncI1/CTX-M-1, but a higher protein level was found for MG1655/IncI1/CTX-M-1 compared with MG1655/CTX-M-1, the latter corresponding well with the higher MIC for this strain.CONCLUSIONS:blaCTX-M-1 mRNA expression and CTX-M-1 protein levels were dependent on cefotaxime concentration, growth phase and gene location. These results provide insight into the expression of cephalosporin resistance in CTX-M-1-producing E. coli, improving our understanding of the relationship between antimicrobial therapy and the expression of resistance mechanisms.

U2 - 10.1093/jac/dku332

DO - 10.1093/jac/dku332

M3 - Journal article

JO - Journal of Antimicrobial Chemotherapy

JF - Journal of Antimicrobial Chemotherapy

SN - 0305-7453

ER -