scholarly journals In Vitro Evolution of Cefiderocol Resistance in an NDM-Producing Klebsiella pneumoniae Due to Functional Loss of CirA

2021 ◽  
Author(s):  
Christi L. McElheny ◽  
Erin L. Fowler ◽  
Alina Iovleva ◽  
Ryan K. Shields ◽  
Yohei Doi
Keyword(s):  
Klebsiella Pneumoniae ◽  
Gram Negative Bacteria ◽  
In Vitro Evolution ◽  
Gram Negative ◽  
Functional Loss ◽  
Iron Transporter

Cefiderocol, a newly approved cephalosporin agent with an extensive spectrum of activity against Gram-negative bacteria, binds siderophore and uses its receptors to access the bacterial periplasm. Loss of functional CirA, an iron transporter, has been associated with cefiderocol resistance.

scholarly journals In-vitro activity of levofloxacin against bacterial pathogens collected in China：A ten-year（2009-2018） retrospective study

2020 ◽  
Author(s):  
LU GAN ◽  
Yun Li ◽  
Yuan Lv ◽  
Bo Zheng
Keyword(s):  
Streptococcus Pneumoniae ◽  
Klebsiella Pneumoniae ◽  
Haemophilus Influenzae ◽  
Community Acquired Pneumonia ◽  
Resistance Rate ◽  
Gram Negative Bacteria ◽  
Icu Patients ◽  
Gram Negative ◽  
Resistance Rates

Abstract Background： This study was designed to evaluate the in-vitro activity of levofloxacin against bacterial pathogens collected from Chinese hospitalized patients between 2009 and 2018, and analysis the trends of levofloxacin resistance in China.Methods In this analysis, antimicrobial minimum inhibitory concentrations (MICs) experiments with levofloxacin and controls against a range of Gram-positive and Gram-negative bacteria collected from 2009 to 2018. MICs were determined using the agar dilution method according to the guidelines of Clinical and Laboratory Standards Institute (CLSI)，2019. Antimicrobial susceptibility was determined using CLSI breakpoints. Statistical tests were analysed by Statistical Package for the Social Sciences software (SPSS, Inc., Chicago, IL, USA), calculating the MIC90.Results In the past decade，the antibacterial activities of levofloxacin against Escherichia coli, Enterobacter cloacae, Pseudomonas aeruginosa and Stenotrophomonas maltophilia, which were common gram-negative bacteria, were stable; the resistance rates of these bacteria had no significant changes or decreased slightly. The levofloxacin resistance rates of Staphylococcus aureus and Enterococcus faecalis, which were gram positive bacteria, decreased from 48.4% and 36.9% in 2009-2010 to 22.8% and 25.7% in 2017-2018, respectively, respectively. The levofloxacin resistance rate among Haemophilus influenzae, Streptococcus pneumoniae and Streptococcus pneumoniae, the common pathogens of community acquired pneumonia (CAP), were less than 3%. The levofloxacin resistance rates for Klebsiella pneumoniae and Acinetobacter baumannii increased. No difference in the levofloxacin resistance rates by age group (18-64, 65-74, ≥75 years old age groups) was observed. The resistance rate of strains isolated from ICU patients was usually 10-20% higher than that of non-ICU patients.Conclusion In recent ten years, levofloxacin has continued to be active in-vitro against the strains in its antibacterial spectrum. No significant change of resistance rates was observed and it still has a good antibacterial effect on the main pathogenic bacteria of community-acquired pneumonia, such as Streptococcus pneumoniae, Haemophilus influenzae, Klebsiella pneumoniae and MSSA.

scholarly journals In VitroActivity of Ceftazidime-Avibactam against 338 Molecularly Characterized Gentamicin-Nonsusceptible Gram-Negative Clinical Isolates Obtained from Patients in Canadian Hospitals

2015 ◽  
Vol 59 (6) ◽  
pp. 3623-3626 ◽  
Author(s):  
Andrew J. Denisuik ◽  
James A. Karlowsky ◽  
Tyler Denisuik ◽  
Wright W. Nichols ◽  
Thomas A. Keating ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
16S Rrna ◽  
Klebsiella Pneumoniae ◽  
Gram Negative Bacteria ◽  
Aminoglycoside Resistance ◽  
Single Strain ◽  
Gram Negative ◽  
Content Type ◽  
16S Rrna Methylase

ABSTRACTThe mechanism of aminoglycoside resistance among 338 gentamicin-nonsusceptible Gram-negative bacteria (207Enterobacteriaceaeand 131Pseudomonas aeruginosa) was assessed, and thein vitroactivity of ceftazidime-avibactam against these isolates was determined. Aminoglycoside-modifying enzymes were detected in 91.8% ofEnterobacteriaceaeand 13.7% ofP. aeruginosaisolates. A single strain ofKlebsiella pneumoniaeharbored a 16S rRNA methylase (ArmA). The ceftazidime-avibactam MIC90values were 0.5 μg/ml (MIC, ≤8 μg/ml for 100% of isolates) and 16 μg/ml (MIC, ≤8 μg/ml for 87.8% of isolates) against gentamicin-nonsusceptibleEnterobacteriaceaeandP. aeruginosaisolates, respectively.

scholarly journals In vitro evolution of colistin resistance in the Klebsiella pneumoniae complex follows multiple evolutionary trajectories with variable effects on fitness and virulence characteristics

2020 ◽  
Author(s):  
Axel B. Janssen ◽  
Dennis J. Doorduijn ◽  
Grant Mills ◽  
Malbert R.C. Rogers ◽  
Marc J.M. Bonten ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Lipid A ◽  
Multidrug Resistant ◽  
Sensu Stricto ◽  
Cross Resistance ◽  
Gram Negative Bacteria ◽  
Colistin Resistance ◽  
Gram Negative ◽  
Evolutionary Trajectories

AbstractThe increasing prevalence of multidrug-resistant Gram-negative opportunistic pathogens, including Klebsiella pneumoniae, has led to a resurgence in the use of colistin as a last-resort drug. Colistin is a cationic lipopeptide antibiotic that selectively acts on Gram-negative bacteria through electrostatic interactions with anionic phosphate groups of the lipid A moiety of lipopolysaccharides (LPS). Colistin resistance in K. pneumoniae is mediated through loss of these phosphate groups, or modification with cationic groups (e.g. 4-amino-4-deoxy-L-arabinose (L-Ara4N), or phosphoethanolamine), but also hydroxylation of acyl-groups of lipid A. Here, we study the in vitro evolutionary trajectories towards colistin resistance in clinical K. pneumoniae complex strains (three K. pneumoniae sensu stricto strains and one K. variicola subsp. variicola strain) and their impact on fitness and virulence characteristics.Through population sequencing during the in vitro evolution experiment, we found that resistance develops through a combination of single nucleotide polymorphisms (SNPs), insertion and deletions (indels), and the integration of insertion sequence (IS) elements, affecting genes associated with LPS biosynthesis and modification, and capsule structures. The development of colistin resistance decreased the maximum growth rate of one K. pneumoniae sensu stricto strain, but not in the other three K. pneumoniae sensu lato strains. Colistin-resistant strains had lipid A modified through hydroxylation, palmitoylation, and L-Ara4N addition. Colistin-resistant K. pneumoniae sensu stricto strains exhibited cross-resistance to LL-37, in contrast to the K. variicola subsp. variicola strain that did not change in susceptibility to LL-37. Virulence, as determined in a Caenorhabditis elegans survival assay, was higher in two colistin-resistant strains.Our study suggests that nosocomial K. pneumoniae complex strains can rapidly develop colistin resistance de novo through diverse evolutionary trajectories upon exposure to colistin. This effectively shortens the lifespan of this last-resort antibiotic for the treatment of infections with multidrug-resistant Klebsiella.Author summaryBacteria that frequently cause infections in hospitalised patients are becoming increasingly resistant to antibiotics. Colistin is a positively charged antibiotic that is used for the treatment of infections with multidrug-resistant Gram-negative bacteria. Colistin acts by specifically interacting with the negatively charged LPS molecule in the outer membrane of Gram-negative bacteria. Colistin resistance is mostly mediated through modification of LPS to reduce its negative charge. Here, we use a laboratory evolution experiment to show that strains belonging to the Klebsiella pneumoniae complex, a common cause of multidrug-resistant hospital-acquired infections, can rapidly accumulate mutations that reduce the negative charge of LPS without an appreciable loss of fitness. Colistin resistance can lead to cross-resistance to an antimicrobial peptide of the human innate immune system, but can increase susceptibility to serum, and virulence in a nematode model. These findings show that extensively resistant K. pneumoniae complex strains may rapidly develop resistance to the last-resort antibiotic colistin via different evolutionary trajectories, while retaining their ability to cause infections.

scholarly journals Potency of Meropenem-Vaborbactam in Lung Surfactant

2017 ◽  
Vol 62 (1) ◽  
Author(s):  
Debora Rubio-Aparicio ◽  
Jeff Loutit ◽  
Michael Dudley ◽  
Olga Lomovskaya
Keyword(s):  
Antibacterial Activity ◽  
Klebsiella Pneumoniae ◽  
Pulmonary Surfactant ◽  
Lung Surfactant ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Content Type ◽  
Fixed Concentration

ABSTRACT This study investigated whether pulmonary surfactant has an effect on the in vitro antibacterial activity of either meropenem alone or meropenem in combination with vaborbactam at a fixed concentration of 8 μg/ml against several Klebsiella pneumoniae carbapenemase (KPC)-producing strains of Gram-negative bacteria. Results showed that the potency of meropenem alone and that of meropenem-vaborbactam were not affected when tested with pulmonary surfactant.

Synthesis, In Vitro and In Silico Studies of Indolequinone Derivatives against Clinically Relevant Bacterial Pathogens

2020 ◽  
Vol 20 (3) ◽  
pp. 192-208 ◽  
Author(s):  
Talita Odriane Custodio Leite ◽  
Juliana Silva Novais ◽  
Beatriz Lima Cosenza de Carvalho ◽  
Vitor Francisco Ferreira ◽  
Leonardo Alves Miceli ◽  
...  
Keyword(s):  
In Silico ◽  
Bacterial Infections ◽  
Antimicrobial Agents ◽  
Mass Spectrometry Analysis ◽  
World Health ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Dione Derivative ◽  
In Silico Studies

Background: According to the World Health Organization, antimicrobial resistance is one of the most important public health threats of the 21st century. Therefore, there is an urgent need for the development of antimicrobial agents with new mechanism of action, especially those capable of evading known resistance mechanisms. Objective: We described the synthesis, in vitro antimicrobial evaluation, and in silico analysis of a series of 1H-indole-4,7-dione derivatives. Methods: The new series of 1H-indole-4,7-diones was prepared with good yield by using a copper(II)- mediated reaction between bromoquinone and β-enamino ketones bearing alkyl or phenyl groups attached to the nitrogen atom. The antimicrobial potential of indole derivatives was assessed. Molecular docking studies were also performed using AutoDock 4.2 for Windows. Characterization of all compounds was confirmed by one- and two-dimensional NMR techniques 1H and 13C NMR spectra [1H, 13C – APT, 1H x 1H – COSY, HSQC and HMBC], IR and mass spectrometry analysis. Results: Several indolequinone compounds showed effective antimicrobial profile against Grampositive (MIC = 16 µg.mL-1) and Gram-negative bacteria (MIC = 8 µg.mL-1) similar to antimicrobials current on the market. The 3-acetyl-1-(2,5-dimethylphenyl)-1H-indole-4,7-dione derivative exhibited an important effect against different biofilm stages formed by a serious hospital life-threatening resistant strain of Methicillin-Resistant Staphylococcus aureus (MRSA). A hemocompatibility profile analysis based on in vitro hemolysis assays revealed the low toxicity effects of this new series. Indeed, in silico studies showed a good pharmacokinetics and toxicological profiles for all indolequinone derivatives, reinforcing their feasibility to display a promising oral bioavailability. An elucidation of the promising indolequinone derivatives binding mode was achieved, showing interactions with important sites to biological activity of S. aureus DNA gyrase. These results highlighted 3-acetyl-1-(2-hydroxyethyl)-1Hindole- 4,7-dione derivative as broad-spectrum antimicrobial prototype to be further explored for treating bacterial infections. Conclusion: The highly substituted indolequinones were obtained in moderate to good yields. The pharmacological study indicated that these compounds should be exploited in the search for a leading substance in a project aimed at obtaining new antimicrobials effective against Gram-negative bacteria.

scholarly journals Coumarin Exhibits Broad-Spectrum Antibiofilm and Antiquorum Sensing Activity against Gram-Negative Bacteria: In Vitro and In Silico Investigation

ACS Omega ◽  
2021 ◽  
Author(s):  
Faizan Abul Qais ◽  
Mohammad Shavez Khan ◽  
Iqbal Ahmad ◽  
Fohad Mabood Husain ◽  
Rais Ahmad Khan ◽  
...  
Keyword(s):  
Broad Spectrum ◽  
In Silico ◽  
Gram Negative Bacteria ◽  
Gram Negative

scholarly journals In Vitro and In Vivo Antibacterial Activities of DW-224a, a New Fluoronaphthyridone

2006 ◽  
Vol 50 (6) ◽  
pp. 2261-2264 ◽  
Author(s):  
Hee-Soo Park ◽  
Hyun-Joo Kim ◽  
Min-Jung Seol ◽  
Dong-Rack Choi ◽  
Eung-Chil Choi ◽  
...  
Keyword(s):  
Antibacterial Activities ◽  
The Other ◽  
Vitro Activity ◽  
Gram Negative Bacteria ◽  
In Vitro Activity ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

ABSTRACT DW-224a showed the most potent in vitro activity among the quinolone compounds tested against clinical isolates of gram-positive bacteria. Against gram-negative bacteria, DW-224a was slightly less active than the other fluoroquinolones. The in vivo activities of DW-224a against gram-positive bacteria were more potent than those of other quinolones.

scholarly journals Interaction of Antimicrobial Peptide Temporin L with Lipopolysaccharide In Vitro and in Experimental Rat Models of Septic Shock Caused by Gram-Negative Bacteria

2006 ◽  
Vol 50 (7) ◽  
pp. 2478-2486 ◽  
Author(s):  
Andrea Giacometti ◽  
Oscar Cirioni ◽  
Roberto Ghiselli ◽  
Federico Mocchegiani ◽  
Fiorenza Orlando ◽  
...  
Keyword(s):  
Septic Shock ◽  
Antimicrobial Peptide ◽  
Gram Negative Bacteria ◽  
Amphibian Skin ◽  
Necrosis Factor Alpha ◽  
Gram Negative ◽  
Rat Models ◽  
E Coli ◽  
Tnf Α

ABSTRACT Sepsis remains a major cause of morbidity and mortality in hospitalized patients, despite intense efforts to improve survival. The primary lead for septic shock results from activation of host effector cells by endotoxin, the lipopolysaccharide (LPS) associated with cell membranes of gram-negative bacteria. For these reasons, the quest for compounds with antiendotoxin properties is actively pursued. We investigated the efficacy of the amphibian skin antimicrobial peptide temporin L in binding Escherichia coli LPS in vitro and counteracting its effects in vivo. Temporin L strongly bound to purified E. coli LPS and lipid A in vitro, as proven by fluorescent displacement assay, and readily penetrated into E. coli LPS monolayers. Furthermore, the killing activity of temporin L against E. coli was progressively inhibited by increasing concentrations of LPS added to the medium, further confirming the peptide's affinity for endotoxin. Antimicrobial assays showed that temporin L interacted synergistically with the clinically used β-lactam antibiotics piperacillin and imipenem. Therefore, we characterized the activity of temporin L when combined with imipenem and piperacillin in the prevention of lethality in two rat models of septic shock, measuring bacterial growth in blood and intra-abdominal fluid, endotoxin and tumor necrosis factor alpha (TNF-α) concentrations in plasma, and lethality. With respect to controls and single-drug treatments, the simultaneous administration of temporin L and β-lactams produced the highest antimicrobial activities and the strongest reduction in plasma endotoxin and TNF-α levels, resulting in the highest survival rates.

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