Postantibiotic Effect, and Postantibiotic Effect of Subinhibitory Concentrations, of Sparfloxacin on Gram-Negative Bacteria

Chemotherapy ◽  
1994 ◽  
Vol 40 (1) ◽  
pp. 30-36 ◽  
Author(s):  
Inga Odenholt-Tornqvist ◽  
Stellan Bengtsson
Keyword(s):  
Gram Negative Bacteria ◽  
Postantibiotic Effect ◽  
Gram Negative ◽  
Subinhibitory Concentrations

Postantibiotic effect of aminoglycosides on Gram-negative bacteria evaluated by a new method

1988 ◽  
Vol 22 (1) ◽  
pp. 23-33 ◽  
Author(s):  
Barbro Isaksson ◽  
Lennart Nilsson ◽  
Rolf Maller ◽  
Lars Sör´n
Keyword(s):  
New Method ◽  
Gram Negative Bacteria ◽  
Postantibiotic Effect ◽  
Gram Negative

scholarly journals Antimicrobial Peptides: Virulence and Resistance Modulation in Gram-Negative Bacteria

2020 ◽  
Vol 8 (2) ◽  
pp. 280 ◽  
Author(s):  
Marylise Duperthuy
Keyword(s):  
Antimicrobial Peptides ◽  
Bacterial Resistance ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Low Concentrations ◽  
Resistance Modulation ◽  
Subinhibitory Concentrations ◽  
The Impact

Growing resistance to antibiotics is one of the biggest threats to human health. One of the possibilities to overcome this resistance is to use and develop alternative molecules such as antimicrobial peptides (AMPs). However, an increasing number of studies have shown that bacterial resistance to AMPs does exist. Since AMPs are immunity molecules, it is important to ensure that their potential therapeutic use is not harmful in the long term. Recently, several studies have focused on the adaptation of Gram-negative bacteria to subinhibitory concentrations of AMPs. Such concentrations are commonly found in vivo and in the environment. It is therefore necessary to understand how bacteria detect and respond to low concentrations of AMPs. This review focuses on recent findings regarding the impact of subinhibitory concentrations of AMPs on the modulation of virulence and resistance in Gram-negative bacteria.

scholarly journals Quinolones Sensitize Gram-Negative Bacteria to Antimicrobial Peptides

2006 ◽  
Vol 50 (7) ◽  
pp. 2361-2367 ◽  
Author(s):  
Miguel A. Campos ◽  
Pau Morey ◽  
José A. Bengoechea
Keyword(s):  
Antimicrobial Peptides ◽  
Antibacterial Agents ◽  
Divalent Cations ◽  
Polymyxin B ◽  
Gram Negative Bacteria ◽  
Front Line ◽  
Gram Negative ◽  
Outer Membranes ◽  
Resistant Strains ◽  
Subinhibitory Concentrations

ABSTRACT The treatment of infections caused by bacteria resistant to the vast majority of antibiotics is a challenge worldwide. Antimicrobial peptides (APs) make up the front line of defense in those areas exposed to microorganisms, and there is intensive research to explore their use as new antibacterial agents. On the other hand, it is known that subinhibitory concentrations of antibiotics affect the expression of numerous bacterial traits. In this work we evaluated whether treatment of bacteria with subinhibitory concentrations of quinolones may alter the sensitivity to APs. A 1-h treatment of Klebsiella pneumoniae with 0.25× the MIC of ciprofloxacin rendered bacteria more sensitive to polymyxins B and E, human neutrophil defensin 1, and β-defensin 1. Levofloxacin and nalidixic acid at 0.25× the MICs also increased the sensitivity of K. pneumoniae to polymyxin B, whereas gentamicin and ceftazidime at 0.25× the MICs did not have such an effect. Ciprofloxacin also increased the sensitivities of K. pneumoniae ciprofloxacin-resistant strains to polymyxin B. Two other pathogens, Pseudomonas aeruginosa and Haemophilus influenzae, also became more sensitive to polymyxins B and E after treatment with 0.25× the MIC of ciprofloxacin. Incubation with ciprofloxacin did not alter the expression of the K. pneumoniae loci involved in resistance to APs. A 1-N-phenyl-naphthylamine assay showed that ciprofloxacin and levofloxacin increased the permeabilities of the K. pneumoniae and P. aeruginosa outer membranes, while divalent cations antagonized this action. Finally, we demonstrated that ciprofloxacin and levofloxacin increased the binding of APs to the outer membrane by using dansylated polymyxin B.

scholarly journals In Vitro Pharmacodynamic Studies of L-749,345 in Comparison with Imipenem and Ceftriaxone against Gram-Positive and Gram-Negative Bacteria

1998 ◽  
Vol 42 (9) ◽  
pp. 2365-2370 ◽  
Author(s):  
Inga Odenholt ◽  
Elisabeth Löwdin ◽  
Otto Cars
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Comparative Studies ◽  
Gram Negative Bacteria ◽  
Postantibiotic Effect ◽  
Gram Positive ◽  
Gram Negative ◽  
Methicillin Resistant ◽  
Gram Negative Organisms

ABSTRACT L-749,345 is a new parenteral carbapenem with a very long half-life similar to that of ceftriaxone. The aim of the present study was to investigate different pharmacodynamic parameters of L-749,345 in comparison with those of ceftriaxone and imipenem. The following studies were performed: (i) comparative studies of the MICs of L-749,345, imipenem, and ceftriaxone for 70 strains of gram-positive and gram-negative bacteria; (ii) comparative studies of the rate of killing of gram-positive and gram-negative bacteria by L-749,345, imipenem, and ceftriaxone; (iii) studies of the postantibiotic effects of L-749,345, imipenem, and ceftriaxone; and (iv) studies of the postantibiotic sub-MIC effects of L-749,345, imipenem, and ceftriaxone. Significantly lower MICs of L-749,345 compared with those of ceftriaxone were found for all gram-negative organisms except Haemophilus influenzae. The MICs of L-749,345 were similar to those of imipenem for all organisms except Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus, for which the MICs of L-749,345 were higher. A concentration-dependent killing of methicillin-resistant S. aureus but not methicillin-susceptible strains was noted for both L-749,345 and imipenem. All three of the investigated drugs exhibited a postantibiotic effect against the gram-positive strains but exhibited no postantibiotic effect against the gram-negative strains.

scholarly journals The postantibiotic effect of imipenem: relationship with drug concentration, duration of exposure, and MIC.

1997 ◽  
Vol 41 (8) ◽  
pp. 1735-1737 ◽  
Author(s):  
W J Munckhof ◽  
D Olden ◽  
J D Turnidge
Keyword(s):  
Escherichia Coli ◽  
Drug Concentration ◽  
Drug Exposure ◽  
Gram Negative Bacteria ◽  
Postantibiotic Effect ◽  
Gram Positive ◽  
Time Curve ◽  
Gram Negative ◽  
Concentration Time ◽  
Drug Concentrations

The postantibiotic effect (PAE) of imipenem against Escherichia coli was measured at a wide variety of drug concentrations and times of exposure. We observed that the area under the concentration-time curve of drug exposure (AUC), the product of time of exposure and concentration of drug, is a much better predictor of the duration of the PAE than either parameter alone. We also measured the PAE of imipenem against strains of gram-positive and gram-negative bacteria for which MICs varied widely. The E50, the AUC required to produce 50% of the maximum PAE, is correlated with the MIC and is independent of species. This may explain why the duration of the PAE differs for bacteria of the same species for which MICs are different.

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