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 Synthesis and Antimicrobial Resistant Modulatory Activity of 2,4-Dinitrophenylhydrazone Derivatives as Agents against Some ESKAPE Human Pathogens

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Alberta Ade ◽  
Cedric D. K. Amengor ◽  
Abena Brobbey ◽  
Isaac Ayensu ◽  
Benjamin K. Harley ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Klebsiella Pneumoniae ◽  
Inhibitory Concentration ◽  
Fungal Species ◽  
Human Pathogens ◽  
Visible Spectroscopy ◽  
Active Compounds ◽  
Gram Negative ◽  
Uv Visible

A library of six novel phenylhydrazones were synthesized and evaluated for their in vitro antimicrobial and resistance modulating activity against a panel of Gram-positive, Gram-negative, and fungal species. The compounds were produced in good yields of 60–92% w/w and characterized using melting point, UV-visible spectroscopy, infrared, and nuclear magnetic resonance (1H, 13C, and DEPT-Q) techniques. Mass spectroscopy was used to confirm the identity of one of the most active compounds, 5 [SA5]. The phenylhydrazones showed activity against all the six selected microorganisms with minimum inhibitory concentration (MIC) values of the most active compounds, 1 [BP1] and 5 [SA5], at 138 µM (Klebsiella pneumoniae) and 165 µM (Streptococcus pneumoniae), respectively. Compound 1 [BP1] further demonstrated a high resistance modulatory activity at 1.078 µM against Streptococcus pneumoniae and Klebsiella pneumoniae.

scholarly journals Antibiotic Resistant Bacterial Isolates from Captive Green Turtles andIn VitroSensitivity to Bacteriophages

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Alessandro Delli Paoli Carini ◽  
Ellen Ariel ◽  
Jacqueline Picard ◽  
Lisa Elliott
Keyword(s):  
Rapid Evolution ◽  
Chelonia Mydas ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Green Turtles ◽  
Resistant Genes ◽  
Resistance Rates

This study aimed to test multidrug resistant isolates from hospitalised green turtles(Chelonia mydas)and their environment in North Queensland, Australia, forin vitrosusceptibility to bacteriophages. Seventy-one Gram-negative bacteria were isolated from green turtle eye swabs and water samples. Broth microdilution tests were used to determine antibiotic susceptibility. All isolates were resistant to at least two antibiotics, with 24% being resistant to seven of the eight antibiotics. Highest resistance rates were detected to enrofloxacin (77%) and ampicillin (69.2%). More than 50% resistance was also found to amoxicillin/clavulanic acid (62.5%), ceftiofur (53.8%), and erythromycin (53.3%). All the enriched phage filtrate mixtures resulted in the lysis of one or more of the multidrug resistant bacteria, includingVibrio harveyiandV. parahaemolyticus. These results indicate that antibiotic resistance is common in Gram-negative bacteria isolated from hospitalised sea turtles and their marine environment in North Queensland, supporting global concern over the rapid evolution of multidrug resistant genes in the environment. Using virulent bacteriophages as antibiotic alternatives would not only be beneficial to turtle health but also prevent further addition of multidrug resistant genes to coastal waters.

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 Pharmacodynamic Activities of ABT-492, a Novel Quinolone, Compared to Those of Levofloxacin against Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis

2004 ◽  
Vol 48 (1) ◽  
pp. 203-208 ◽  
Author(s):  
Shana M. Gunderson ◽  
Robert A. Hayes ◽  
John P. Quinn ◽  
Larry H. Danziger
Keyword(s):  
Streptococcus Pneumoniae ◽  
Haemophilus Influenzae ◽  
Moraxella Catarrhalis ◽  
Maximal Activity ◽  
Community Acquired Pneumonia ◽  
Maximal Effect ◽  
Bacterial Isolates ◽  
Atypical Pathogens ◽  
Time Kill

ABSTRACT ABT-492 is a novel quinolone with potent activity against gram-positive, gram-negative, and atypical pathogens, making this compound an ideal candidate for the treatment of community-acquired pneumonia. We therefore compared the in vitro pharmacodynamic activity of ABT-492 to that of levofloxacin, an antibiotic commonly used for the treatment of pneumonia, through MIC determination and time-kill kinetic analysis. ABT-492 demonstrated potent activity against penicillin-sensitive, penicillin-resistant, and levofloxacin-resistant Streptococcus pneumoniae strains (MICs ranging from 0.0078 to 0.125 μg/ml); β-lactamase-positive and β-lactamase-negative Haemophilus influenzae strains (MICs ranging from 0.000313 to 0.00125 μg/ml); and β-lactamase-positive and β-lactamase-negative Moraxella catarrhalis strains (MICs ranging from 0.001 to 0.0025 μg/ml), with MICs being much lower than those of levofloxacin. Both ABT-492 and levofloxacin demonstrated concentration-dependent bactericidal activities in time-kill kinetics studies at four and eight times the MIC with 10 of 12 bacterial isolates exposed to ABT-492 and with 12 of 12 bacterial isolates exposed to levofloxacin. Sigmoidal maximal-effect models support concentration-dependent bactericidal activity. The model predicts that 50% of maximal activity can be achieved with concentrations ranging from one to two times the MIC for both ABT-492 and levofloxacin and that near-maximal activity (90% effective concentration) can be achieved at concentrations ranging from two to five times the MIC for ABT-492 and one to six times the MIC for levofloxacin.

scholarly journals In VitroActivity of Delafloxacin Tested against Isolates of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis

2016 ◽  
Vol 60 (10) ◽  
pp. 6381-6385 ◽  
Author(s):  
Robert K. Flamm ◽  
Paul R. Rhomberg ◽  
Michael D. Huband ◽  
David J. Farrell
Keyword(s):  
United States ◽  
Streptococcus Pneumoniae ◽  
Haemophilus Influenzae ◽  
Moraxella Catarrhalis ◽  
The United States ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Content Type

ABSTRACTDelafloxacin, an investigational anionic fluoroquinolone, is active against a broad range of Gram-positive and Gram-negative bacteria. In this study, 200Streptococcus pneumoniae(plus 30 levofloxacin-resistant isolates), 200Haemophilus influenzae, and 100Moraxella catarrhalisisolates selected primarily from the United States (2014) were tested against delafloxacin and comparator agents. Delafloxacin was the most potent agent tested. MIC50and MIC90values against allS. pneumoniaeisolates were 0.008 and 0.015 μg/ml. Delafloxacin susceptibility was not affected by β-lactamase status againstH. influenzaeandM. catarrhalis.

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 Postantibiotic Effect of Tigecycline against 14 Gram-Positive Organisms

2008 ◽  
Vol 53 (2) ◽  
pp. 782-784 ◽  
Author(s):  
G. A. Pankuch ◽  
P. C. Appelbaum
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Haemophilus Influenzae ◽  
Acinetobacter Baumannii ◽  
Enterobacter Cloacae ◽  
Postantibiotic Effect ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Negative Organisms

ABSTRACT The in vitro postantibiotic effects (PAEs), postantibiotic sub-MIC effects (PA-SMEs), and sub-MIC effects of tigecycline were determined for 14 gram-positive and gram-negative organisms. The pneumococcal, staphylococcal, and enterococcal PAEs were 1.9 to 5.1, 2.9 to 5.7, and 3.9 to 6.1 h, respectively, and those for Haemophilus influenzae, Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, and Acinetobacter baumannii were 1.1 to 5.0, 1.9 to 2.1, 1.7 to 1.8, 1.0 to 1.7, and 0.7 to 3 h, respectively. The PA-SMEs (four times the MIC) ranged from 6.7 to >11 h for gram-positive organisms and from 2.3 to >11.3 h for gram-negative organisms.

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