Distribution and genetic composition of carbapenem-resistance determinants in clinical Acinetobacter isolates – focus on carbapenem-hydrolysing β-lactamases
Distribution and genetic composition of carbapenem-resistance determinants in clinical Acinetobacter isolates – focus on carbapenem-hydrolysing β-lactamases
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DissertationDate of Exam
07.11.2014Date of Publication
11.02.2015Advisor
Seifert, HaraldCo-Referee
Sahl, Hans-GeorgMetadata
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Abstract
Acinetobacter baumannii is of global concern in health-care facilities as it can easily thrive in the hospital environment and infections can be difficult to treat. Widespread multi-drug (MDR) resistance and a potential for epidemic spread contribute to the worldwide success of this hospital-acquired pathogen. Currently the drugs of choice to treat infections with MDR A. baumannii are carbapenems, but resistance is rising. Commonly carbapenem resistance in A. baumannii is based on enzymatic inactivation of the agent, for example by metallo-ß-lactamases like NDM-1 and by carbapenem-hydrolysing oxacillinases (OXA), including the intrinsic OXA-51 subclass and the acquired subclasses OXA-23, OXA-40, OXA-58 and OXA-143. Even though OXA weakly hydrolyse carbapenems they are often associated with insertion sequences (IS) which can provide strong promoters and lead to OXA overexpression.
The aim of this work was to investigate carbapenem-resistance mechanisms in A. baumannii and non-baumannii Acinetobacter spp. For the first time the genetic context of a chromosomally encoded NDM-1 in A. baumannii was analysed. The gene was located on a transposon flanked by ISAba125 that had inserted into a chromosomal transporter gene. Furthermore eighteen novel OXA genes, one OXA subclass (OXA-235-like) and one insertion sequence (ISAcra1) were identified. It was shown that detection of the intrinsic blaOXA-51-like by multiplex PCR is not reliable as the sole method for A. baumannii species identification. OXA-51-like sequencing and rep-PCR-based DiversiLab revealed correlation of blaOXA-51-like variants with A. baumannii international clonal lineages IC1 to IC8. In outbreak-related A. baumannii isolates a conversion of the intrinsic OXA from OXA-66 to OXA-82 was found to be associated with carbapenem resistance and presence of ISAba1. Investigation of closely related OXA-66, OXA-82 (L167V), OXA-109 (P130Q) and OXA-201 (L167V and P130Q) on an isogenic background indicated that carbapenem resistance based on ISAba1-mediated overexpression of the intrinsic OXA is dependent on the OXA-51 variant.
For the first time carbapenem resistance based on IS-mediated overexpression of an intrinsic OXA was observed in A. radioresistens and A. bereziniae. Furthermore OXA-23 was initially detected in Acinetobacter genomic species 14TU/13BJ and OXA-143, as well as co-expressed OXA-23 and OXA-58 were identified in A. pittii isolates. Emergence of OXA-143-like in A. baumannii and A. pittii outside of Brazil and South Korea was observed. Investigation of carbapenem susceptibility under different physiological conditions in A. baumannii revealed a strain-dependent effect of NaCl and sodium-salicylate, while pH 5.8 reduced carbapenem susceptibility of all OXA-58-like-expressing transformants from a resistant (=32 mg/L) to a non-susceptible level (8 mg/L).
Taken together this work illustrates the diversity and variability of carbapenem-hydrolysing ß-lactamases in Acinetobacter spp. and leads to the hypothesis that carbapenem resistance will further disseminate in the Acinetobacter genus in the foreseeable future.
The aim of this work was to investigate carbapenem-resistance mechanisms in A. baumannii and non-baumannii Acinetobacter spp. For the first time the genetic context of a chromosomally encoded NDM-1 in A. baumannii was analysed. The gene was located on a transposon flanked by ISAba125 that had inserted into a chromosomal transporter gene. Furthermore eighteen novel OXA genes, one OXA subclass (OXA-235-like) and one insertion sequence (ISAcra1) were identified. It was shown that detection of the intrinsic blaOXA-51-like by multiplex PCR is not reliable as the sole method for A. baumannii species identification. OXA-51-like sequencing and rep-PCR-based DiversiLab revealed correlation of blaOXA-51-like variants with A. baumannii international clonal lineages IC1 to IC8. In outbreak-related A. baumannii isolates a conversion of the intrinsic OXA from OXA-66 to OXA-82 was found to be associated with carbapenem resistance and presence of ISAba1. Investigation of closely related OXA-66, OXA-82 (L167V), OXA-109 (P130Q) and OXA-201 (L167V and P130Q) on an isogenic background indicated that carbapenem resistance based on ISAba1-mediated overexpression of the intrinsic OXA is dependent on the OXA-51 variant.
For the first time carbapenem resistance based on IS-mediated overexpression of an intrinsic OXA was observed in A. radioresistens and A. bereziniae. Furthermore OXA-23 was initially detected in Acinetobacter genomic species 14TU/13BJ and OXA-143, as well as co-expressed OXA-23 and OXA-58 were identified in A. pittii isolates. Emergence of OXA-143-like in A. baumannii and A. pittii outside of Brazil and South Korea was observed. Investigation of carbapenem susceptibility under different physiological conditions in A. baumannii revealed a strain-dependent effect of NaCl and sodium-salicylate, while pH 5.8 reduced carbapenem susceptibility of all OXA-58-like-expressing transformants from a resistant (=32 mg/L) to a non-susceptible level (8 mg/L).
Taken together this work illustrates the diversity and variability of carbapenem-hydrolysing ß-lactamases in Acinetobacter spp. and leads to the hypothesis that carbapenem resistance will further disseminate in the Acinetobacter genus in the foreseeable future.
Subjects
Oxacillinase, Carbapenem, Resistenz, Insertionssequenz, Acinetobacter, resistance, insertion sequence
Classification (DDC)
540 Chemie 570 Biowissenschaften, BiologieZander, Esther: Distribution and genetic composition of carbapenem-resistance determinants in clinical Acinetobacter isolates – focus on carbapenem-hydrolysing β-lactamases. - Bonn, 2015. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5n-38917
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5n-38917
@phdthesis{handle:20.500.11811/6403,
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5n-38917,
author = {{Esther Zander}},
title = {Distribution and genetic composition of carbapenem-resistance determinants in clinical Acinetobacter isolates – focus on carbapenem-hydrolysing β-lactamases},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2015,
month = feb,
note = {Acinetobacter baumannii is of global concern in health-care facilities as it can easily thrive in the hospital environment and infections can be difficult to treat. Widespread multi-drug (MDR) resistance and a potential for epidemic spread contribute to the worldwide success of this hospital-acquired pathogen. Currently the drugs of choice to treat infections with MDR A. baumannii are carbapenems, but resistance is rising. Commonly carbapenem resistance in A. baumannii is based on enzymatic inactivation of the agent, for example by metallo-ß-lactamases like NDM-1 and by carbapenem-hydrolysing oxacillinases (OXA), including the intrinsic OXA-51 subclass and the acquired subclasses OXA-23, OXA-40, OXA-58 and OXA-143. Even though OXA weakly hydrolyse carbapenems they are often associated with insertion sequences (IS) which can provide strong promoters and lead to OXA overexpression.
The aim of this work was to investigate carbapenem-resistance mechanisms in A. baumannii and non-baumannii Acinetobacter spp. For the first time the genetic context of a chromosomally encoded NDM-1 in A. baumannii was analysed. The gene was located on a transposon flanked by ISAba125 that had inserted into a chromosomal transporter gene. Furthermore eighteen novel OXA genes, one OXA subclass (OXA-235-like) and one insertion sequence (ISAcra1) were identified. It was shown that detection of the intrinsic blaOXA-51-like by multiplex PCR is not reliable as the sole method for A. baumannii species identification. OXA-51-like sequencing and rep-PCR-based DiversiLab revealed correlation of blaOXA-51-like variants with A. baumannii international clonal lineages IC1 to IC8. In outbreak-related A. baumannii isolates a conversion of the intrinsic OXA from OXA-66 to OXA-82 was found to be associated with carbapenem resistance and presence of ISAba1. Investigation of closely related OXA-66, OXA-82 (L167V), OXA-109 (P130Q) and OXA-201 (L167V and P130Q) on an isogenic background indicated that carbapenem resistance based on ISAba1-mediated overexpression of the intrinsic OXA is dependent on the OXA-51 variant.
For the first time carbapenem resistance based on IS-mediated overexpression of an intrinsic OXA was observed in A. radioresistens and A. bereziniae. Furthermore OXA-23 was initially detected in Acinetobacter genomic species 14TU/13BJ and OXA-143, as well as co-expressed OXA-23 and OXA-58 were identified in A. pittii isolates. Emergence of OXA-143-like in A. baumannii and A. pittii outside of Brazil and South Korea was observed. Investigation of carbapenem susceptibility under different physiological conditions in A. baumannii revealed a strain-dependent effect of NaCl and sodium-salicylate, while pH 5.8 reduced carbapenem susceptibility of all OXA-58-like-expressing transformants from a resistant (=32 mg/L) to a non-susceptible level (8 mg/L).
Taken together this work illustrates the diversity and variability of carbapenem-hydrolysing ß-lactamases in Acinetobacter spp. and leads to the hypothesis that carbapenem resistance will further disseminate in the Acinetobacter genus in the foreseeable future. },
url = {https://hdl.handle.net/20.500.11811/6403}
}
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5n-38917,
author = {{Esther Zander}},
title = {Distribution and genetic composition of carbapenem-resistance determinants in clinical Acinetobacter isolates – focus on carbapenem-hydrolysing β-lactamases},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2015,
month = feb,
note = {Acinetobacter baumannii is of global concern in health-care facilities as it can easily thrive in the hospital environment and infections can be difficult to treat. Widespread multi-drug (MDR) resistance and a potential for epidemic spread contribute to the worldwide success of this hospital-acquired pathogen. Currently the drugs of choice to treat infections with MDR A. baumannii are carbapenems, but resistance is rising. Commonly carbapenem resistance in A. baumannii is based on enzymatic inactivation of the agent, for example by metallo-ß-lactamases like NDM-1 and by carbapenem-hydrolysing oxacillinases (OXA), including the intrinsic OXA-51 subclass and the acquired subclasses OXA-23, OXA-40, OXA-58 and OXA-143. Even though OXA weakly hydrolyse carbapenems they are often associated with insertion sequences (IS) which can provide strong promoters and lead to OXA overexpression.
The aim of this work was to investigate carbapenem-resistance mechanisms in A. baumannii and non-baumannii Acinetobacter spp. For the first time the genetic context of a chromosomally encoded NDM-1 in A. baumannii was analysed. The gene was located on a transposon flanked by ISAba125 that had inserted into a chromosomal transporter gene. Furthermore eighteen novel OXA genes, one OXA subclass (OXA-235-like) and one insertion sequence (ISAcra1) were identified. It was shown that detection of the intrinsic blaOXA-51-like by multiplex PCR is not reliable as the sole method for A. baumannii species identification. OXA-51-like sequencing and rep-PCR-based DiversiLab revealed correlation of blaOXA-51-like variants with A. baumannii international clonal lineages IC1 to IC8. In outbreak-related A. baumannii isolates a conversion of the intrinsic OXA from OXA-66 to OXA-82 was found to be associated with carbapenem resistance and presence of ISAba1. Investigation of closely related OXA-66, OXA-82 (L167V), OXA-109 (P130Q) and OXA-201 (L167V and P130Q) on an isogenic background indicated that carbapenem resistance based on ISAba1-mediated overexpression of the intrinsic OXA is dependent on the OXA-51 variant.
For the first time carbapenem resistance based on IS-mediated overexpression of an intrinsic OXA was observed in A. radioresistens and A. bereziniae. Furthermore OXA-23 was initially detected in Acinetobacter genomic species 14TU/13BJ and OXA-143, as well as co-expressed OXA-23 and OXA-58 were identified in A. pittii isolates. Emergence of OXA-143-like in A. baumannii and A. pittii outside of Brazil and South Korea was observed. Investigation of carbapenem susceptibility under different physiological conditions in A. baumannii revealed a strain-dependent effect of NaCl and sodium-salicylate, while pH 5.8 reduced carbapenem susceptibility of all OXA-58-like-expressing transformants from a resistant (=32 mg/L) to a non-susceptible level (8 mg/L).
Taken together this work illustrates the diversity and variability of carbapenem-hydrolysing ß-lactamases in Acinetobacter spp. and leads to the hypothesis that carbapenem resistance will further disseminate in the Acinetobacter genus in the foreseeable future. },
url = {https://hdl.handle.net/20.500.11811/6403}
}
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