Overexpression of genes of the dha regulon and its effects on cell growth, glycerol fermentation to 1,3-propanediol and plasmid stability in Klebsiella pneumoniae

2006 ◽  
Vol 41 (10) ◽  
pp. 2160-2169 ◽  
Author(s):  
Ping Zheng ◽  
Kirsten Wereath ◽  
Jibin Sun ◽  
Joop van den Heuvel ◽  
An-Ping Zeng
Keyword(s):  
Cell Growth ◽  
Klebsiella Pneumoniae ◽  
Plasmid Stability ◽  
Glycerol Fermentation ◽  
Dha Regulon

Role of dihydroxyacetone kinases I and II in the dha regulon of Klebsiella pneumoniae

2014 ◽  
Vol 177 ◽  
pp. 13-19 ◽  
Author(s):  
Dong Wei ◽  
Min Wang ◽  
Biao Jiang ◽  
Jiping Shi ◽  
Jian Hao
Keyword(s):  
Klebsiella Pneumoniae ◽  
Dha Regulon

scholarly journals 494. Fitness Cost of mcr-1-Mediated Colistin Resistance in Carbapenemase-Producing Klebsiella pneumoniae

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S241-S241
Author(s):  
Yi-Tsung Lin ◽  
Yi-Hsiang Cheng ◽  
Sheng-Hua Chou ◽  
Ying-Chi Huang ◽  
Liang Chen
Keyword(s):  
Growth Rate ◽  
Klebsiella Pneumoniae ◽  
Whole Genome Sequencing ◽  
Genome Sequencing ◽  
Plasmid Stability ◽  
Fatal Case ◽  
Fitness Cost ◽  
Whole Genome ◽  
Colistin Resistance ◽  
The Impact

Abstract Background The emergence of mobile colistin resistance gene mcr-1, a plasmid-borne polymyxin resistance mechanism, in carbapenem-resistant Klebsiella pneumoniae is an alarming concern. However, previous studies showed that the acquisition of mcr-1 was associated with a significant biological fitness cost in K. pneumoniae. We aimed to study the impact of mcr-1 on the biological fitness in clinical carbapenemase-producing K. pneumoniae strains. Methods Clinical carbapenemase-producing K. pneumoniae strains were collected consecutively at the Taipei Veterans General Hospital between November 2017 and December 2018. The strain positive for mcr-1 was subjected to whole-genome sequencing to delineate its genomic features. Escherichia coli J53 strain was used as the recipient strain in plasmid conjugation assay and the transconjugants were selected with sodium azide and colistin. Plasmid stability was tested by serial passaging in antibiotic-free LB broth for 28 days. The growth rate was compared between the parental mcr-1-bearing strain and the plasmid-cured strain. Results One ST11 strain isolated from a fatal case with bacteremia (KP2509) was found to harbor blaKPC-2, blaOXA-48, and mcr-1. This strain was resistant to colistin (MIC=8 mg/L) and imipenem (MIC≥16 mg/L). Whole-genome sequencing of KP2509 showed that mcr-1, blaKPC-2 and blaOXA-48 were located on an IncHI-FIB type plasmid of 319 Kb, an IncFII type plasmid of 96 Kb, and an IncL type plasmid of 64 Kb, respectively. Conjugation efficiency of mcr-1-bearing plasmid was 2.24 × 10–4, and the colistin MIC of E. coli J53 transconjugant increased from 0.5 to 8 mg/L. The mcr-1-bearing plasmid in KP2509 showed high plasmid stability, and only ~1% were lost after 27-day passages. The resulting plasmid-cured strain (PC-KP2509) was susceptible to colistin (MIC=0.5 mg/L) and had a similar growth rate to that of parental mcr-1-bearing strain KP2509. Conclusion We identified an ST11 K. pneumoniae strain carrying blaKPC-2, blaOXA-48, and mcr-1 genes causing a fatal bacteremia. The large mcr-1-bearing plasmid confers a moderate level of colistin resistance but without significant biological fitness cost in carbapenemase-producing K. pneumoniae, which could result in a serious threat clinically. Disclosures All authors: No reported disclosures.

scholarly journals Fitness cost of mcr-1-mediated polymyxin resistance in Klebsiella pneumoniae

2018 ◽  
Vol 73 (6) ◽  
pp. 1604-1610 ◽  
Author(s):  
Sue C Nang ◽  
Faye C Morris ◽  
Michael J McDonald ◽  
Mei-Ling Han ◽  
Jiping Wang ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Lipid A ◽  
Plasmid Stability ◽  
Fitness Cost ◽  
Infection Model ◽  
Competition Assay ◽  
In Vivo Growth ◽  
The Impact

Abstract Objectives The discovery of mobile colistin resistance mcr-1, a plasmid-borne polymyxin resistance gene, highlights the potential for widespread resistance to the last-line polymyxins. In the present study, we investigated the impact of mcr-1 acquisition on polymyxin resistance and biological fitness in Klebsiella pneumoniae. Methods K. pneumoniae B5055 was used as the parental strain for the construction of strains carrying vector only (pBBR1MCS-5) and mcr-1 recombinant plasmids (pmcr-1). Plasmid stability was determined by serial passaging for 10 consecutive days in antibiotic-free LB broth, followed by patching on gentamicin-containing and antibiotic-free LB agar plates. Lipid A was analysed using LC–MS. The biological fitness was examined using an in vitro competition assay analysed with flow cytometry. The in vivo fitness cost of mcr-1 was evaluated in a neutropenic mouse thigh infection model. Results Increased polymyxin resistance was observed following acquisition of mcr-1 in K. pneumoniae B5055. The modification of lipid A with phosphoethanolamine following mcr-1 addition was demonstrated by lipid A profiling. The plasmid stability assay revealed the instability of the plasmid after acquiring mcr-1. Reduced in vitro biological fitness and in vivo growth were observed with the mcr-1-carrying K. pneumoniae strain. Conclusions Although mcr-1 confers a moderate level of polymyxin resistance, it is associated with a significant biological fitness cost in K. pneumoniae. This indicates that mcr-1-mediated resistance in K. pneumoniae could be attenuated by limiting the usage of polymyxins.

PARAMETER IDENTIFICATION AND TERMINAL STEADY-STATE OPTIMIZATION FOR S SYSTEM IN MICROBIAL CONTINUOUS FERMENTATION

2012 ◽  
Vol 05 (02) ◽  
pp. 1250020
Author(s):  
XIAOFANG LI ◽  
RONGNING QU
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Klebsiella Pneumoniae ◽  
Parameter Identification ◽  
State Constraints ◽  
Continuous Fermentation ◽  
Commercial Production ◽  
Maximum Volume ◽  
Glycerol Fermentation ◽  
Identification Model

In this paper, we propose a special S system to describe the process of continuous glycerol fermentation to 1,3-propanediol by Klebsiella pneumoniae. Some properties of solution for S system are discussed. Moreover, in order to identify the values of parameters such that S system can simulate the fermentation as exactly as possible, we develop a parameter identification model, and prove the identifiability of parameters. Numerical results show that the average relative error between computational value and experimental data is 20.0875% lower than 24.4225% in previous work, which demonstrates that S system is better in describing continuous fermentation. Finally, we present a terminal steady-state optimization model with state constraints. Optimization results show that the maximum volume yields of 1,3-propanediol at terminal moment increased from 114.3 to 124.911 mmolL-1h-1. The results provide reference for the commercial production of 1,3-propanediol.

scholarly journals Characterization of a mcr-1 and CRISPR-Cas System Co-harboring Plasmid in a Carbapenemase-Producing High-Risk ST11 Klebsiella pneumoniae Strain

2021 ◽  
Vol 12 ◽  
Author(s):  
Yi-Hsiang Cheng ◽  
Sheng-Hua Chou ◽  
Po-Han Huang ◽  
Tsuey-Ching Yang ◽  
Yu-Fan Juan ◽  
...  
Keyword(s):  
Growth Rate ◽  
Klebsiella Pneumoniae ◽  
Plasmid Stability ◽  
Medical Center ◽  
Conjugative Plasmid ◽  
Type Iv ◽  
Positive Strain ◽  
Stable Plasmid

We set out to study the prevalence of the mcr-1 gene in carbapenemase-producing Klebsiella pneumoniae (CPKP) strains, and to determine whether its presence is associated with a fitness cost. A total of 234 clinical CPKP isolates were collected from a tertiary medical center in Taiwan from January 2018 to January 2019. The mcr-1 and carbapenemase genes were detected by polymerase chain reaction (PCR) followed by Sanger sequencing. The mcr-1-positive carbapenemase-producing strain was characterized by whole genome sequencing, a plasmid stability test and a conjugation assay. In vitro growth rate and an in vivo virulence test were compared between the parental mcr-1-positive strain and its mcr-1 plasmid-cured strain. We identified only one mcr-1 positive strain (KP2509), co-harboring blaKPC–2 and blaOXA–48, among 234 (1/234, 0.43%) CPKP strains. KP2509 and its Escherichia coli mcr-1 transconjugant showed moderate colistin resistance (MIC = 8 mg/L). The mcr-1 is located on a large conjugative plasmid (317 kb), pKP2509-MCR, with three replicons, IncHI, IncFIB, and IncN. Interestingly, a complete Type IV-A3 CRISPR-Cas system was identified in pKP2509-MCR. Plasmid pKP2509-MCR was highly stable in KP2509 after 270 generation of passage, and the pKP2509-MCR cured strain PC-KP2509 showed similar growth rate and in vivo virulence in comparison to KP2509. The prevalence of mcr-1 in CPKP strains remains low in our center. Notably, we identified a large plasmid with multiple replicons containing both the mcr-1 and the Type IV-3A CRISPR-Cas genes. The further spread of this highly stable plasmid raises concern that it may promote the increase of mcr-1 prevalence in CPKP.

scholarly journals Acquisition of a Stable and Transferable blaNDM-5-Positive Plasmid With Low Fitness Cost Leading to Ceftazidime/Avibactam Resistance in KPC-2-Producing Klebsiella pneumoniae During Treatment

2021 ◽  
Vol 11 ◽  
Author(s):  
Jiangqing Huang ◽  
Shengcen Zhang ◽  
Zhichang Zhao ◽  
Min Chen ◽  
Yingping Cao ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Plasmid Stability ◽  
Bioinformatic Analysis ◽  
Fitness Cost ◽  
Resistance Pattern ◽  
Carbapenem Resistant ◽  
Significant Difference ◽  
Union Hospital ◽  
Growth Assay ◽  
Medical University

The emergence and prevalence of carbapenem-resistant Enterobacteriaceae (CRE) have drawn worldwide attention. Ceftazidime/avibactam (CAZ/AVI) gives us a valuable alternative strategy to treat CRE infections. Unfortunately, CAZ/AVI resistance could occur during CAZ/AVI treatment. The CAZ/AVI-resistant Carbapenem-resistant Klebsiella pneumoniae (CR-KP) (KP137060) and earlier CAZ/AVI-susceptible isolate (KP135194) from the same hospitalized patient were collected at Fujian Medical University Union Hospital between October and November 2019. In this study, CAZ/AVI MICs of CAZ/AVI-susceptible and -resistant isolates (KP135194 and KP137060) were 4 mg/L and 128 mg/L, respectively; and the two isolates had the same antibiotic resistance pattern to other carbapenems. Two strains were then submitted for whole-genome sequencing and bioinformatic analysis. ompK36 was not detected in two isolates. No mutation was observed in blaKPC-2, ompK35 and ompK37 in this study and there was no significant difference of the expression in blaKPC-2, ompK35 and ompK37 between the two isolates (p>0.05). Two isolates were sequence type 11 and harbored blaKPC-2, blaSHV-182 and blaTEM-1B. Compared with KP135194, KP137060 harbored an additional blaNDM-5 positive plasmid. blaNDM-5 gene could be successfully transferred into E. coli J53 at a conjugation frequency of 1.14×10-4. Plasmid stability testing showed that blaKPC-2- and blaNDM-5-harboring plasmids were still stably maintained in the hosts. Growth assay and growth competition experiments showed there was no significant difference in fitness cost between two CR-KP isolates. Our study described the acquisition of a blaNDM-5-harboring plasmid leading to resistance to ceftazidime/avibactam in KPC-2-producing Klebsiella pneumoniae during treatment. This phenomenon deserves further exploration.

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