scholarly journals Mechanisms of Tolerance and Resistance to Chlorhexidine in Clinical Strains of Klebsiella pneumoniae Producers of Carbapenemase: Role of New Type II Toxin-Antitoxin System, PemIK

Toxins ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 566
Author(s):  
Ines Bleriot ◽  
Lucia Blasco ◽  
Mercedes Delgado-Valverde ◽  
Ana Gual-de-Torrella ◽  
Anton Ambroa ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Molecular Mechanisms ◽  
Cross Resistance ◽  
Type Ii ◽  
Clinical Strains ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
New Type ◽  
High Level

Although the failure of antibiotic treatment is normally attributed to resistance, tolerance and persistence display a significant role in the lack of response to antibiotics. Due to the fact that several nosocomial pathogens show a high level of tolerance and/or resistance to chlorhexidine, in this study we analyzed the molecular mechanisms associated with chlorhexidine adaptation in two clinical strains of Klebsiella pneumoniae by phenotypic and transcriptomic studies. These two strains belong to ST258-KPC3 (high-risk clone carrying β-lactamase KPC3) and ST846-OXA48 (low-risk clone carrying β-lactamase OXA48). Our results showed that the K. pneumoniae ST258-KPC3CA and ST846-OXA48CA strains exhibited a different behavior under chlorhexidine (CHLX) pressure, adapting to this biocide through resistance and tolerance mechanisms, respectively. Furthermore, the appearance of cross-resistance to colistin was observed in the ST846-OXA48CA strain (tolerant to CHLX), using the broth microdilution method. Interestingly, this ST846-OXA48CA isolate contained a plasmid that encodes a novel type II toxin/antitoxin (TA) system, PemI/PemK. We characterized this PemI/PemK TA system by cloning both genes into the IPTG-inducible pCA24N plasmid, and found their role in persistence and biofilm formation. Accordingly, the ST846-OXA48CA strain showed a persistence biphasic curve in the presence of a chlorhexidine-imipenem combination, and these results were confirmed by the enzymatic assay (WST-1).

scholarly journals Whole Transcriptomic Analysis of Mechanisms of Tolerance and Resistance to Chlorhexidine in Clinical Strains of Klebsiella Pneumoniae Producers of Carbapenemase

2020 ◽  
Author(s):  
Ines Bleriot ◽  
Lucia Blasco ◽  
Mercedes Delgado ◽  
Ana Gual de Torrella ◽  
Anton Ambroa ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Biofilm Formation ◽  
Molecular Mechanisms ◽  
Cross Resistance ◽  
Beta Lactamase ◽  
Tolerance Mechanisms ◽  
Clinical Strains ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
High Level

Although the failure of antibiotic treatment is normally attributed to resistance, tolerance and persistence display a significant role in the lack of response to antibiotics. Due to the fact that several nosocomial pathogens show a high level of tolerance and/or resistance to chlorhexidine, in this study we analyzed the molecular mechanisms associated with chlorhexidine adaptation in two clinical strains of Klebsiella pneumoniae by phenotypic and transcriptomic studies. These two strains belong to ST258-KPC3 (high-risk clone carrying β-lactamase KPC3) and ST846-OXA48 (low-risk clone carrying β-lactamase OXA48). Our results showed that K. pneumoniae ST258-KPC3CA and ST846-OXA48CA strains exhibited a different behavior under CHLX pressure, adapting to this biocide through resistance and tolerance mechanisms, respectively. Furthermore, the appearance of cross-resistance to colistin was observed in the ST846-OXA48CA strain (tolerant to CHLX), using the broth microdilution method. Interestingly, this ST846-OXA48CA isolate contained a plasmid that encodes a novel type II toxin/antitoxin (TA) system, PemK/PemI. We characterized this PemK/PemI TA system by cloning both genes into the IPTG-inducible pCA24N plasmid, and found their role in persistence and biofilm formation. Accordingly, the ST846-OXA48CA strain showed a persistence biphasic curve in the presence of a chlorhexidine-imipenem combination, and these results were confirmed by the enzymatic assay (WST-1).

scholarly journals «PemIK (PemK/PemI) type II TA system from Klebsiella pneumoniae clinical strains inhibits lytic phage»

2021 ◽  
Author(s):  
Ines Bleriot ◽  
Lucia Blasco ◽  
Olga Pacios ◽  
Laura Fernández-García ◽  
Antón Ambroa ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Metabolic Activity ◽  
Reference Strain ◽  
Phage Infection ◽  
Clinical Strain ◽  
Lytic Phage ◽  
Type Ii ◽  
Clinical Strains ◽  
Qrt Pcr

Abstract Since their discovery, toxin-antitoxin systems have captivated many scientists. Recent studies demonstrated that a key role of TA systems is phage inhibition. Therefore, the aim of this study was to investigate the role of the PemIK (PemK/PemI) type II TA system in phage inhibition by its intrinsic expression in clinical strains of Klebsiella pneumoniae carrying OXA-48 carbapenemase and by induced its expression in an IPTG-inducible plasmid in a reference strain of K. pneumoniae ATCC®10031™. qRT-PCR revealed that pemK toxin in clinical strain ST16-OXA48 was induced when phage did not infect the strain, whereas when phage infection was successful pemK toxin was not induced. In addition, induced expression of the whole system did not inhibit phage infection, whereas overexpression of the pemK toxin prevented infection during the first hours. To investigate the molecular mechanism involved in the PemK toxin-mediated inhibition of phage infection, an assay measuring metabolic activity was performed, which revealed that production of toxin PemK led to the dormancy of the bacteria. Thus, we demonstrate that the PemK/PemI TA system plays a role in phage infection, and that the action of the free toxin causes the cells to go into a dormant state resulting in inhibition of phage infections.

The role of the bla KPC gene in antimicrobial resistance of Klebsiella pneumoniae

2019 ◽  
Author(s):  
Atossa Ghasemnejad ◽  
Monir Doudi ◽  
Nour Amirmozafari
Keyword(s):  
Klebsiella Pneumoniae ◽  
Antimicrobial Susceptibility ◽  
Diffusion Method ◽  
Disc Diffusion ◽  
Broth Microdilution ◽  
Disc Diffusion Method ◽  
Biochemical Tests ◽  
Microdilution Method ◽  
Broth Microdilution Method

Background and Objectives: Klebsiella pneumoniae isolates that produce K. pneumoniae carbapenemase (KPC) have be- come a grave concern for the treatment of infections. KPC-producing strains are not only able to hydrolyze carbapenems but are also resistant to a variety of β-lactam and non-β-lactam antibiotics. The present study evaluated the prevalence of bla in K. pneumoniae infections and determined the antimicrobial susceptibility of the isolates. Materials and Methods: The K. pneumoniae isolates were identified by biochemical tests and confirmed by genotyping. The modified Hodge test (MHT) was performed to detect carbapenemases, and antimicrobial susceptibility was determined for all isolates by the disc diffusion method. Also, for MHT-positive isolates, supposed to carbapenemases isolates, broth microdilution method was used to measure the minimum inhibitory concentrations (MICs) of meropenem and colistin. Results: The bla KPC genotypic evaluation revealed that only 5 of 96 isolates carried bla genes. Antimicrobial pattern showed that isolates carrying bla were resistant to cefepime, ticarcillin/tazobactam, and aztreonam discs. Also, results of broth microdilution method showed that KPC-producing K. pneumoniae was resistant to meropenem and colistin, according to the CLSI and EUCAST. Conclusion: In this study nearly half the isolates showed carbapenemase activity as shown by MHT results, but only few of them were carrying bla . Thus bla gene is not the main cause of resistance spread to carbapenems in Isfahan, Iran.

scholarly journals Mortality of Pandrug-Resistant Klebsiella pneumoniae Bloodstream Infections in Critically Ill Patients: A Retrospective Cohort of 115 Episodes

Antibiotics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 76
Author(s):  
Matthaios Papadimitriou-Olivgeris ◽  
Christina Bartzavali ◽  
Alexandra Georgakopoulou ◽  
Fevronia Kolonitsiou ◽  
Chrisavgi Papamichail ◽  
...  
Keyword(s):  
Septic Shock ◽  
Klebsiella Pneumoniae ◽  
Critically Ill ◽  
Critically Ill Patients ◽  
Primary Outcome ◽  
Bloodstream Infections ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Carbapenemase Gene ◽  
Comorbidity Index

Background: The increased frequency of bacteraemias caused by pandrug-resistant Klebsiella pneumoniae (PDR-Kp) has significant implications. The aim of the present study was to identify predictors associated with mortality of PDR-Kp bacteraemias. Methods: Patients with monomicrobial bacteraemia due to PDR-Kp were included. K. pneumoniae was considered PDR if it showed resistance to all available groups of antibiotics. Primary outcome was 30-day mortality. Minimum inhibitory concentrations (MICs) of meropenem, tigecycline, fosfomycin, and ceftazidime/avibactam were determined by Etest, whereas for colistin, the broth microdilution method was applied. blaKPC, blaVIM, blaNDM, and blaOXA genes were detected by PCR. Results: Among 115 PDR-Kp bacteraemias, the majority of infections were primary bacteraemias (53; 46.1%), followed by catheter-related (35; 30.4%). All isolates were resistant to tested antimicrobials. blaKPC was the most prevalent carbapenemase gene (98 isolates; 85.2%). Thirty-day mortality was 39.1%; among 51 patients with septic shock, 30-day mortality was 54.9%. Multivariate analysis identified the development of septic shock, Charlson comorbidity index, and bacteraemia other than primary or catheter-related as independent predictors of mortality, while a combination of at least three antimicrobials was identified as an independent predictor of survival. Conclusions: Mortality of PDR-Kp bloodstream infections was high. Administration of at least three antimicrobials might be beneficial for infections in critically ill patients caused by such pathogens.

scholarly journals Activity of Ceftazidime-Avibactam against Fluoroquinolone-Resistant Enterobacteriaceae and Pseudomonas aeruginosa

2015 ◽  
Vol 59 (6) ◽  
pp. 3059-3065 ◽  
Author(s):  
C. Pitart ◽  
F. Marco ◽  
T. A. Keating ◽  
W. W. Nichols ◽  
J. Vila
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Resistant Mutant ◽  
Fluoroquinolone Resistance ◽  
Cross Resistance ◽  
Content Type ◽  
E Coli ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
The Impact

ABSTRACTCeftazidime-avibactam and comparator antibiotics were tested by the broth microdilution method against 200Enterobacteriaceaeand 25Pseudomonas aeruginosastrains resistant to fluoroquinolones (including strains with the extended-spectrum β-lactamase [ESBL] phenotype and ceftazidime-resistant strains) collected from our institution. The MICs and mechanisms of resistance to fluoroquinolone were also studied. Ninety-nine percent of fluoroquinolone-resistantEnterobacteriaceaestrains were inhibited at a ceftazidime-avibactam MIC of ≤4 mg/liter (using the susceptible CLSI breakpoint for ceftazidime alone as a reference). Ceftazidime-avibactam was very active against ESBLEscherichia coli(MIC90of 0.25 mg/liter), ESBLKlebsiella pneumoniae(MIC90of 0.5 mg/liter), ceftazidime-resistant AmpC-producing species (MIC90of 1 mg/liter), non-ESBLE. coli(MIC90of ≤0.125 mg/liter), non-ESBLK. pneumoniae(MIC90of 0.25 mg/liter), and ceftazidime-nonresistant AmpC-producing species (MIC90of ≤0.5 mg/liter). Ninety-six percent of fluoroquinolone-resistantP. aeruginosastrains were inhibited at a ceftazidime-avibactam MIC of ≤8 mg/liter (using the susceptible CLSI breakpoint for ceftazidime alone as a reference), with a MIC90of 8 mg/liter. Additionally, fluoroquinolone-resistant mutants from each species tested were obtainedin vitrofrom two strains, one susceptible to ceftazidime and the other a β-lactamase producer with a high MIC against ceftazidime but susceptible to ceftazidime-avibactam. Thereby, the impact of fluoroquinolone resistance on the activity of ceftazidime-avibactam could be assessed. The MIC90values of ceftazidime-avibactam for the fluoroquinolone-resistant mutant strains ofEnterobacteriaceaeandP. aeruginosawere ≤4 mg/liter and ≤8 mg/liter, respectively. We conclude that the presence of fluoroquinolone resistance does not affectEnterobacteriaceaeandP. aeruginosasusceptibility to ceftazidime-avibactam; that is, there is no cross-resistance.

Clinical Study of the Treatment of Klebsiella pneumoniae with Comprehensive Nursing Intervention Combined with New Nano Silver

2020 ◽  
Vol 20 (10) ◽  
pp. 6063-6069
Author(s):  
Shenghua Cao ◽  
Xiaoqian Wu ◽  
Jianling Zhao ◽  
Xinhong Jia
Keyword(s):  
Klebsiella Pneumoniae ◽  
Nursing Intervention ◽  
Bactericidal Effect ◽  
Inhibitory Effect ◽  
Control Group ◽  
Nano Silver ◽  
Clinical Nurses ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Management Modes

To investigate the inhibitory effect of new nano silver (nAg-NPs) on Klebsiella pneumoniae producing extended spectrum β-lactamases (EBLs). Clinical interventions are mainly directed to inpatients, or patients with obvious discomfort, symptoms, and signs needing outpatient examination, referral, and clear diagnosis. We randomly selected 88 patients from the rehabilitation department of our hospital from November 2017 to June 2019, and divided them into observation and control groups by drawing lots. Taking ESBL K. pneumoniae as the research object, the bactericidal effect of nAg-NPs was determined using the coating method; the minimal inhibitory concentration (MIC) was measured using the broth microdilution method, and the mechanism of action of nAg-NPs on ESBL K. pneumoniae was evaluated by electron microscopy. After the implementation of different nursing management modes, the incidence of risk events in the observation group was significantly lower than that in the control group, and nursing satisfaction was significantly higher than that in the control group. nAg-NPs (≥0.5 g/mL) had 100% bactericidal effect on ESBL K. pneumoniae, 0.05 g/mL nAg-NPs had obvious bactericidal effect on ESBL K. pneumoniae, 5 g/mL nAg-NPs had obvious bactericidal effect on ESBL K. pneumoniae for 5, 15, 30 and 60 min. Additionally, nAg-NPs showed 3.12 g/mL of MIC. Furthermore, nAg-NPs had a significant effect on the morphology of K. pneumoniae. nAg-NPs shows obvious inhibitory effect on ESBL K. pneumoniae. These results will provide an experimental basis for the further study and clinical application of nAg-NPs with the help of clinical nurses.

scholarly journals In vitro activity of the trinem sanfetrinem (GV104326) against gram-positive organisms.

1996 ◽  
Vol 40 (9) ◽  
pp. 2142-2146 ◽  
Author(s):  
K V Singh ◽  
T M Coque ◽  
B E Murray
Keyword(s):  
Staphylococcus Aureus ◽  
Vitro Activity ◽  
In Vitro Activity ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Gentamicin Resistance ◽  
High Level

The in vitro activity of the trinem sanfetrinem (formerly GV104326) (GV) was compared with that of vancomycin, ampicillin, and/or nafcillin against 287 gram-positive bacteria, including methicillin-resistant Staphylococcus aureus and multiresistant enterococci, by the agar and microbroth dilution methods. GV demonstrated 2 to 16 times more activity than ampicillin and nafcillin against the majority of these organisms. The MIC range of GV was 16 to 64 micrograms/ml for 19 Enterococcus faecium strains that were highly resistant to ampicillin (ampicillin MIC range, 64 to 512 micrograms/ml) and vancomycin resistant and 0.25 to 32 micrograms/ml for resistant Rhodococcus spp. Similar activities (+/-1 dilution) were observed by either the agar or the broth microdilution method. GV demonstrated bactericidal activity against a beta-lactamase-producing Enterococcus faecalis strain and against two methicillin-susceptible Staphylococcus aureus strains in 10(5)-CFU/ml inocula. Synergy between GV and gentamicin was observed against an E. faecalis strain that lacked high-level gentamicin resistance. The activity of GV suggests this compound warrants further study.

scholarly journals Role of β-Lactamases and Porins in Resistance to Ertapenem and Other β-Lactams in Klebsiella pneumoniae

2004 ◽  
Vol 48 (8) ◽  
pp. 3203-3206 ◽  
Author(s):  
George A. Jacoby ◽  
Debra M. Mills ◽  
Nancy Chow
Keyword(s):  
Klebsiella Pneumoniae ◽  
Outer Membrane ◽  
Type Strain ◽  
Wild Type Strain ◽  
Outer Membrane Proteins ◽  
Wild Type ◽  
Resistant Mutants ◽  
High Level ◽  
Level Resistance

ABSTRACT High-level resistance to ertapenem was produced by β-lactamases of groups 1, 2f, and 3 in a strain of Klebsiella pneumoniae deficient in Omp35 and Omp36. From a wild-type strain producing ACT-1 β-lactamase, ertapenem-resistant mutants for which the ertapenem MICs were up to 128 μg/ml and expression of outer membrane proteins was diminished could be selected.

scholarly journals Antibiotic Resistance among Clinical Ureaplasma Isolates Recovered from Neonates in England and Wales between 2007 and 2013

2015 ◽  
Vol 60 (1) ◽  
pp. 52-56 ◽  
Author(s):  
Michael L. Beeton ◽  
Victoria J. Chalker ◽  
Lucy C. Jones ◽  
Nicola C. Maxwell ◽  
O. Brad Spiller
Keyword(s):  
Antibiotic Resistance ◽  
Molecular Mechanisms ◽  
Treatment Options ◽  
Tetracycline Resistance ◽  
Health Clinic ◽  
Broth Microdilution ◽  
England And Wales ◽  
Content Type ◽  
Microdilution Method ◽  
Broth Microdilution Method

ABSTRACTUreaplasmaspp. are associated with numerous clinical sequelae with treatment options being limited due to patient and pathogen factors. This report examines the prevalence and mechanisms of antibiotic resistance among clinical strains isolated from 95 neonates, 32 women attending a sexual health clinic, and 3 patients under investigation for immunological disorders, between 2007 and 2013 in England and Wales. MICs were determined by using broth microdilution assays, and a subset of isolates were compared using the broth microdilution method and the Mycoplasma IST2 assay. The underlying molecular mechanisms for resistance were determined for all resistant isolates. Three isolates carried thetet(M) tetracycline resistance gene (2.3%; confidence interval [CI], 0.49 to 6.86%); two isolates were ciprofloxacin resistant (1.5%; CI, 0.07 to 5.79%) but sensitive to levofloxacin and moxifloxacin, while no resistance was seen to any macrolides tested. The MIC values for chloramphenicol were universally low (2 μg/ml), while inherently high-level MIC values for gentamicin were seen (44 to 66 μg/ml). The Mycoplasma IST2 assay identified a number of false positives for ciprofloxacin resistance, as the method does not conform to international testing guidelines. While antibiotic resistance amongUreaplasmaisolates remains low, continued surveillance is essential to monitor trends and threats from importation of resistant clones.

scholarly journals Antimicrobial resistance of Enterococcus faecium and Enterococcus faecalis, isolated from blood culture of patients with hematological malignancies during different study periods

2021 ◽  
Vol 16 (1) ◽  
pp. 54-63
Author(s):  
A. V. Fedorova ◽  
G. A. Klyasova ◽  
I. N. Frolova ◽  
S. A. Khrulnova ◽  
A. V. Vetokhina ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Blood Culture ◽  
Enterococcus Faecalis ◽  
Enterococcus Faecium ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
High Susceptibility ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
High Level

Objective: to determine antimicrobial resistance of Enterococcus faecium and Enterococcus faecalis isolated from blood culture of hematological patients during different study periods.Materials and methods. Antimicrobial susceptibility of Enterococcus spp., collected as part of the multicenter study was tested by the broth microdilution method (USA Clinical and Laboratory Standards Institute (CLSI), 2018), to daptomycin by Etest (bioMeriéux, France). High-level gentamicin resistance (HLGR) and high-level streptomycin resistance (HLSR) was performed by the agar dilution method (CLSI (Oxoid, UK), 2018).Results. The susceptibility of 366 E. faecium (157 in 2002-2009 and 209 in 2010-2017) and 86 E. faecalis (44 in 20022009 and 42 in 2010-2017) was studied. In the second study period (2010-2017) the rise of vancomycin-resistant E. faecium (VREF) increased from 8.3 % to 23.4 % (p = 0.0001), and two linezolid-resistant (LREF) were identified. All VREF and LREF remained susceptible to daptomycin and tigecycline. The rate of susceptible to tetracycline E. faecium remained the same (73.9 and 74.6 %), and an increase in susceptibility to chloramphenicol (74.5 and 82.3 %) was observed. Susceptibility of E. faecium to tetracycline was detected with almost the same rate and in a part of isolates, the increase of susceptibility to chloramphenicol was registered during the analyzed periods. The rise of E. faecium susceptible to HLGR and HLSR has increased significantly in 2010-2017 compared to 2002-2009. Erythromycin, levofloxacin, ampicillin and penicillin had the least activity against E. faecium (less than 5 %).All E. faecalis were susceptible to tigecycline, linezolid, and teicoplanin. Only one of E. faecalis had intermediate resistance to vancomycin. High susceptibility to ampicillin in E. faecalis remained unchanged (97.7 and 97.6 %, respectively). In the second period of the study the rise of susceptible E. faecalis decreased significantly to penicillin (from 97.7 % to 76.2 %), to levofloxacin (from 59.1 % to 31 %), to HLSR (from 52.3 % до 31 %), and to HLGR (from 47.7 % to 26.2 %), remained unchanged to chloramphenicol (52.3 % and 50 %) and was minimal to erythromycin and tetracycline.Conclusion. The study demonstrated higher rates of antibiotic resistance among E. faecium, which consisted of an increase in VREF and the appearance of linezolid-resistant strains. High susceptibility to ampicillin remained in E. faecalis, but there was an increase in resistance to penicillin and aminoglycosides.

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