Outer Membrane Permeability and  -Lactamase Content in Pseudomonas maltophilia Clinical Isolates and Laboratory Mutants

1988 ◽  
Vol 10 (4) ◽  
pp. 765-769 ◽  
Author(s):  
H. Mett ◽  
S. Rosta ◽  
B. Schacher ◽  
R. Frei
Keyword(s):  
Membrane Permeability ◽  
Outer Membrane ◽  
Clinical Isolates ◽  
Pseudomonas Maltophilia ◽  
Outer Membrane Permeability

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 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 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 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.

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