scholarly journals Resistance to (β-lactams, and reduced susceptibility to carbapenems, in clinical isolates of Klebsiella pneumoniae due to interplay between CTX-M-15 and altered outer membrane permeability

2006 ◽  
Vol 21 (2) ◽  
pp. 41-44 ◽  
Author(s):  
H Segal ◽  
B Gay Elisha
Keyword(s):  
Klebsiella Pneumoniae ◽  
Membrane Permeability ◽  
Outer Membrane ◽  
Clinical Isolates ◽  
Outer Membrane Permeability

scholarly journals Investigation of the Antibacterial Activity and Efflux Pump Inhibitory Effect of Cycas thouarsii R.Br. Extract against Klebsiella pneumoniae Clinical Isolates

2021 ◽  
Vol 14 (8) ◽  
pp. 756
Author(s):  
Walaa A. Negm ◽  
Mona El-Aasr ◽  
Amal Abo Kamer ◽  
Engy Elekhnawy
Keyword(s):  
Antibacterial Activity ◽  
Klebsiella Pneumoniae ◽  
Membrane Permeability ◽  
Outer Membrane ◽  
Membrane Integrity ◽  
Membrane Depolarization ◽  
Clinical Isolates ◽  
Resistant Bacteria ◽  
Outer Membrane Permeability ◽  
The Impact

The vast spread of multidrug-resistant bacteria has encouraged researchers to explore new antimicrobial compounds. This study aimed to investigate the phytochemistry and antibacterial activity of Cycas thouarsii R.Br. leaves extract against Klebsiella pneumoniae clinical isolates. The minimum inhibitory concentration (MIC) values of C. thouarsii extract ranged from 4 to 32 µg/mL. The impact of the treatment of the isolates with sub-inhibitory concentrations of C. thouarsii extract was investigated on the bacterial growth, membrane integrity, inner and outer membrane permeability, membrane depolarization, and bacterial morphology using a scanning electron microscope (SEM) and on the efflux activity using qRT-PCR. Interestingly, most K. pneumoniae isolates treated with C. thouarsii extract showed growth inhibition—a decrease in membrane integrity. In addition, we observed various morphological changes, a significant increase in inner and outer membrane permeability, a non-significant change in membrane depolarization, and a decrease in efflux activity after treatment. The phytochemical investigation of C. thouarsii extract revealed the isolation of one new biflavonoid, 5,7,7”,4”’-tetra-O-methyl-hinokiflavone (3), and five known compounds, stigmasterol (1), naringenin (2), 2,3-dihydrobilobetin (4), 4’,4’’’-O-dimethyl amentoflavone (5), and hinokiflavone (6), for the first time. Moreover, the pure compounds’ MICs’ ranged from 0.25 to 2 µg/mL. Thus, C. thouarsii could be a potential source for new antimicrobials.

scholarly journals Novel Cassette Assay To Quantify the Outer Membrane Permeability of Five β-Lactams Simultaneously in Carbapenem-Resistant Klebsiella pneumoniae and Enterobacter cloacae

mBio ◽  
2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Tae Hwan Kim ◽  
Xun Tao ◽  
Bartolome Moya ◽  
Yuanyuan Jiao ◽  
Kari B. Basso ◽  
...  
Keyword(s):  
Antimicrobial Resistance ◽  
Klebsiella Pneumoniae ◽  
Membrane Permeability ◽  
Outer Membrane ◽  
Enterobacter Cloacae ◽  
Clinical Isolates ◽  
Gram Negative ◽  
Content Type ◽  
Carbapenem Resistant ◽  
Outer Membrane Permeability

ABSTRACT Poor penetration through the outer membrane (OM) of Gram-negative bacteria is a major barrier of antibiotic development. While β-lactam antibiotics are commonly used against Klebsiella pneumoniae and Enterobacter cloacae, there are limited data on OM permeability especially in K. pneumoniae. Here, we developed a novel cassette assay, which can simultaneously quantify the OM permeability to five β-lactams in carbapenem-resistant K. pneumoniae and E. cloacae. Both clinical isolates harbored a blaKPC-2 and several other β-lactamases. The OM permeability of each antibiotic was studied separately (“discrete assay”) and simultaneously (“cassette assay”) by determining the degradation of extracellular β-lactam concentrations via multiplex liquid chromatography-tandem mass spectrometry analyses. Our K. pneumoniae isolate was polymyxin resistant, whereas the E. cloacae was polymyxin susceptible. Imipenem penetrated the OM at least 7-fold faster than meropenem for both isolates. Imipenem penetrated E. cloacae at least 258-fold faster and K. pneumoniae 150-fold faster compared to aztreonam, cefepime, and ceftazidime. For our β-lactams, OM permeability was substantially higher in the E. cloacae compared to the K. pneumoniae isolate (except for aztreonam). This correlated with a higher OmpC porin production in E. cloacae, as determined by proteomics. The cassette and discrete assays showed comparable results, suggesting limited or no competition during influx through OM porins. This cassette assay allowed us, for the first time, to efficiently quantify the OM permeability of multiple β-lactams in carbapenem-resistant K. pneumoniae and E. cloacae. Characterizing the OM permeability presents a critical contribution to combating the antimicrobial resistance crisis and enables us to rationally optimize the use of β-lactam antibiotics. IMPORTANCE Antimicrobial resistance is causing a global human health crisis and is affecting all antibiotic classes. While β-lactams have been commonly used against susceptible isolates of Klebsiella pneumoniae and Enterobacter cloacae, carbapenem-resistant isolates are spreading worldwide and pose substantial clinical challenges. Rapid penetration of β-lactams leads to high drug concentrations at their periplasmic target sites, allowing β-lactams to more completely inactivate their target receptors. Despite this, there are limited tangible data on the permeability of β-lactams through the outer membranes of many Gram-negative pathogens. This study presents a novel, cassette assay, which can simultaneously characterize the permeability of five β-lactams in multidrug-resistant clinical isolates. We show that carbapenems, and especially imipenem, penetrate the outer membrane of K. pneumoniae and E. cloacae substantially faster than noncarbapenem β-lactams. The ability to efficiently characterize the outer membrane permeability is critical to optimize the use of β-lactams and combat carbapenem-resistant isolates.

scholarly journals Sporadic Emergence of Klebsiella pneumoniae Strains Resistant to Cefepime and Cefpirome in Greek Hospitals

1998 ◽  
Vol 36 (1) ◽  
pp. 266-268 ◽  
Author(s):  
L. S. Tzouvelekis ◽  
E. Tzelepi ◽  
E. Prinarakis ◽  
M. Gazouli ◽  
A. Katrahoura ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Membrane Permeability ◽  
Outer Membrane ◽  
Outer Membrane Permeability ◽  
Greek Hospitals ◽  
Hydrolysis Of

The sporadic emergence of Klebsiella pneumoniae strains resistant to cefepime and cefpirome was observed in Greek hospitals during 1996. Examination of six epidemiologically distinct strains and clones selected in vitro provided indications that resistance is due to the cooperation of decreased outer membrane permeability and hydrolysis of the cephalosporins by SHV-5 β-lactamase, which was produced in large amounts.

scholarly journals Role of the Outer Membrane and Porins in Susceptibility of β-Lactamase-Producing Enterobacteriaceae to Ceftazidime-Avibactam

2015 ◽  
Vol 60 (3) ◽  
pp. 1349-1359 ◽  
Author(s):  
Jean-Marie Pagès ◽  
Sabine Peslier ◽  
Thomas A. Keating ◽  
Jean-Philippe Lavigne ◽  
Wright W. Nichols
Keyword(s):  
Membrane Permeability ◽  
Outer Membrane ◽  
Efflux Pump ◽  
Enterobacter Aerogenes ◽  
Antibacterial Activities ◽  
Clinical Isolates ◽  
Membrane Pore ◽  
Content Type ◽  
Porin Proteins ◽  
Outer Membrane Permeability

This study examined the activity of the novel antimicrobial combination ceftazidime-avibactam againstEnterobacteriaceaeexhibiting different outer membrane permeability profiles, specifically with or without porins and with or without expression of the main efflux pump (AcrAB-TolC). The addition of the outer membrane permeabilizer polymyxin B nonapeptide increased the antibacterial activities of avibactam alone, ceftazidime alone, and ceftazidime-avibactam against the characterized clinical isolates ofEscherichia coli,Enterobacter aerogenes, andKlebsiella pneumoniae. This enhancement of activities was mainly due to increased passive penetration of compounds since inhibition of efflux by the addition of phenylalanine-arginine β-naphthylamide affected the MICs minimally. OmpF (OmpK35) or OmpC (OmpK36) pores were not the major route by which avibactam crossed the outer membranes ofE. coliandK. pneumoniae. In contrast, Omp35 and Omp36 allowed diffusion of avibactam across the outer membrane ofE. aerogenes, although other diffusion channels for avibactam were also present in that species. It was clear that outer membrane permeability and outer membrane pore-forming proteins play a key role in the activity of ceftazidime-avibactam. Nevertheless, the MICs of ceftazidime-avibactam (with 4 mg/liter avibactam) against the ceftazidime-resistant clinical isolates of the three species ofEnterobacteriaceaestudied were ≤8 mg/liter, regardless of outer membrane permeability changes resulting from an absence of defined porin proteins or upregulation of efflux.

scholarly journals Omp35, a New Enterobacter aerogenes Porin Involved in Selective Susceptibility to Cephalosporins

2004 ◽  
Vol 48 (6) ◽  
pp. 2153-2158 ◽  
Author(s):  
Charléric Bornet ◽  
Nathalie Saint ◽  
Lilia Fetnaci ◽  
Myrielle Dupont ◽  
Anne Davin-Régli ◽  
...  
Keyword(s):  
Membrane Permeability ◽  
Outer Membrane ◽  
Antibiotic Susceptibility ◽  
Enterobacter Aerogenes ◽  
Artificial Membranes ◽  
Specific Location ◽  
Outer Membrane Permeability ◽  
Constriction Region ◽  
High Conductance

ABSTRACT In Enterobacter aerogenes, β-lactam resistance often involves a decrease in outer membrane permeability induced by modifications of porin synthesis. In ATCC 15038 strain, we observed a different pattern of porin production associated with a variable antibiotic susceptibility. We purified Omp35, which is expressed under conditions of low osmolality and analyzed its pore-forming properties in artificial membranes. This porin was found to be an OmpF-like protein with high conductance values. It showed a noticeably higher conductance compared to Omp36 and a specific location of WNYT residues in the L3 loop. The importance of the constriction region in the porin function suggests that this organization is involved in the level of susceptibility to negative large cephalosporins such as ceftriaxone by bacteria producing the Omp35 porin subfamily.

scholarly journals 610. Meropenem-vaborbactam (MV) In Vitro Activity Against Carbapenem-Resistant Klebsiella pneumoniae (CRKP) Isolates with Outer Membrane Porin Gene Mutations

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S285-S285 ◽  
Author(s):  
Mohamad Yasmin ◽  
Steven Marshall ◽  
Michael Jacobs ◽  
Daniel D Rhoads ◽  
Laura J Rojas ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Outer Membrane ◽  
Gene Mutations ◽  
Underlying Mechanism ◽  
Clinical Isolates ◽  
Historical Cohort ◽  
Carbapenem Resistant ◽  
Outer Membrane Porin ◽  
Tract Infections

Abstract Background Vaborbactam is a cyclic boronic acid β-lactamase inhibitor (BLI) developed to potently inhibit Ambler class A&C enzymes, including KPC carbapenemases. Metallo-β-lactamases (MBL) and some Class D oxacillinases (OXA) are not inactivated by vaborbactam. Meropenem-vaborbactam (MV) was recently approved for the treatment of carbapenem-resistant Enterobacteriaceae complicated urinary tract infections. Recent studies have identified outer membrane porin (Ompk35 and -36) mutations in Klebsiella pneumoniae (KP) as a mechanism of decreased susceptibility to MV. We evaluated the activity of MV against a historical cohort of KP clinical isolates with these porin gene mutations. Methods WGS of carbapenem-resistant KP clinical isolates was performed and those harboring mutations in Ompk35 or Ompk36 were selected for testing. Strain KP ATCC BAA-1705 was used as a positive control. Meropenem and MV minimum inhibitory concentrations (MIC) were determined by broth microdilution (BMD) in custom 96-well plates (ThermoFisher Scientific) with a constant 8 µg/mL vaborbactam concentration. The MIC of ceftazidime–avibactam (CZA) was determined by standard BMD reference methods and interpreted according to CLSI criteria. Results A total of 105 KP isolates with either partial or complete mutations in outer membrane porin genes were included in the analysis. All isolates were resistant to Meropenem. The median MV MIC was 0.03 µg/mL (range, 0.015 to >16 µg/mL). Eleven isolates (10.4%) were resistant to MV. Sixteen additional isolates (16.1%) demonstrated higher than expected MV MICs ranging from 1 to 4 µg/mL. Only 1/11 resistant isolates harbored a gene for MBL production. Gene mutations in blaKPC were not detected. See Table 1 for characteristics of resistant isolates. Conclusion Resistance and decreased susceptibility to MV is demonstrated in a historical cohort of KP clinical isolates dating back to 2013. WGS reliably identifies porin variants secondary to gene mutations in Ompk35 and Ompk36 as the underlying mechanism of decreased susceptibility. CZA appears to retain activity against these isolates. Caution should be exercised regarding the empiric use of MV against increasingly resistant KP as a result of non-β-lactamase-mediated mechanisms. Disclosures All authors: No reported disclosures.

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