Effect of subinhibitory concentrations of antimicrobial agents (quinolones and macrolide) on the production of verotoxin by enterohemorrhagic Escherichia coli O157:H7

1999 ◽  
Vol 45 (9) ◽  
pp. 732-739 ◽  
Author(s):  
M Yoh ◽  
E K Frimpong ◽  
S P Voravuthikunchai ◽  
T Honda
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Agent ◽  
Antimicrobial Agents ◽  
Enterohemorrhagic Escherichia Coli ◽  
Escherichia Coli O157 ◽  
Ministry Of Health ◽  
Wide Range ◽  
Subinhibitory Concentrations

In Japan, antimicrobial agent therapy for patients with diarrhea due to enterovirulent organisms including enterohemorrhagic Escherichia coli (EHEC) is common, and norfloxacin (NFLX), fosfomycin, and kanamycin are recommended for EHEC treatment by the Japanese Ministry of Health and Welfare. The aim of this study was to analyze the effects of antimicrobial agents which have been used or recommended for the treatment of EHEC on the production of verotoxin (VT) in vitro. Subinhibitory concentrations of quinolones, NFLX, sparofloxacin (SPFX), and grepafloxacin (GPFX) markedly stimulated the productions of VT1 and VT2. The macrolide azithromycin (AZM), erythromycin (EM), and clarithromycin (CAM) did not stimulate the production of VT at a wide range of concentrations. These in vitro results indicate that when quinolones are prescribed for a patient infected with EHEC, the concentration of antimicrobial agents used in vivo and the susceptibility of the EHEC strains against quinolones should be taken into consideration.Key words: EHEC, O157:H7, verotoxin, quinolone, macrolide.

scholarly journals In VivoEfficacy of Anuran Trypsin Inhibitory Peptides against Staphylococcal Skin Infection and the Impact of Peptide Cyclization

2015 ◽  
Vol 59 (4) ◽  
pp. 2113-2121 ◽  
Author(s):  
U. Malik ◽  
O. N. Silva ◽  
I. C. M. Fensterseifer ◽  
L. Y. Chan ◽  
R. J. Clark ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Cyclic Peptide ◽  
Sequence Similarity ◽  
Infection Model ◽  
Content Type ◽  
Wide Range ◽  
Inhibitory Activities ◽  
The Impact

ABSTRACTStaphylococcus aureusis a virulent pathogen that is responsible for a wide range of superficial and invasive infections. Its resistance to existing antimicrobial drugs is a global problem, and the development of novel antimicrobial agents is crucial. Antimicrobial peptides from natural resources offer potential as new treatments against staphylococcal infections. In the current study, we have examined the antimicrobial properties of peptides isolated from anuran skin secretions and cyclized synthetic analogues of these peptides. The structures of the peptides were elucidated by nuclear magnetic resonance (NMR) spectroscopy, revealing high structural and sequence similarity with each other and with sunflower trypsin inhibitor 1 (SFTI-1). SFTI-1 is an ultrastable cyclic peptide isolated from sunflower seeds that has subnanomolar trypsin inhibitory activity, and this scaffold offers pharmaceutically relevant characteristics. The five anuran peptides were nonhemolytic and noncytotoxic and had trypsin inhibitory activities similar to that of SFTI-1. They demonstrated weakin vitroinhibitory activities againstS. aureus, but several had strong antibacterial activities againstS. aureusin anin vivomurine wound infection model. pYR, an immunomodulatory peptide fromRana sevosa, was the most potent, with complete bacterial clearance at 3 mg · kg−1. Cyclization of the peptides improved their stability but was associated with a concomitant decrease in antimicrobial activity. In summary, these anuran peptides are promising as novel therapeutic agents for treating infections from a clinically resistant pathogen.

scholarly journals Bactericidal Activities of Meropenem and Ertapenem against Extended-Spectrum-β-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae in a Neutropenic Mouse Thigh Model

2007 ◽  
Vol 51 (4) ◽  
pp. 1481-1486 ◽  
Author(s):  
C. Andrew DeRyke ◽  
Mary Anne Banevicius ◽  
Hong Wei Fan ◽  
David P. Nicolau
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Infection Model ◽  
Bacterial Reduction ◽  
Efficacy Analysis ◽  
Percent Time ◽  
Extended Spectrum ◽  
Wide Range

ABSTRACT The purpose of this study was to examine the in vivo efficacies of meropenem and ertapenem against extended-spectrum-β-lactamase (ESBL)-producing isolates with a wide range of MICs. Human-simulated dosing regimens in mice were designed to approximate the free drug percent time above the MIC (fT>MIC) observed for humans following meropenem at 1 g every 8 h and ertapenem at 1 g every 24 h. An in vivo neutropenic mouse thigh infection model was used to examine the bactericidal effects against 31 clinical ESBL Escherichia coli and Klebsiella pneumoniae isolates and 2 non-ESBL isolates included for comparison at a standard 105 inoculum. Three isolates were examined at a high 107 inoculum as well. Meropenem displayed greater in vitro potency, with a median MIC (range) (μg/ml) of 0.125 (0.03 to 32), than did ertapenem, with 0.5 (0.012 to 128). Seven of the 31 ESBL isolates were removed from the efficacy analysis due to their inability to establish infection in the mouse model. When MICs were ≤1.5 μg/ml for ertapenem (≤0.5 μg/ml for meropenem), similar reductions in CFU (≈ 2-log kill) were observed for both ertapenem (fT>MIC ≥ 23%) and meropenem (fT>MIC ≥ 75%). Ertapenem showed bacterial regrowth for seven of eight isolates, with MICs of ≥2 μg/ml (fT>MIC ≤ 20%), while meropenem displayed antibacterial potency that varied from a static effect to a 1-log bacterial reduction in these isolates (fT>MIC = 30 to 65%). At a 107 inoculum, both agents eradicated bacteria due to adequate exposures (fT>MIC = 20 to 45%). Due to low MICs, no difference in bacterial kill was noted for the majority of ESBL isolates tested. However, for isolates with raised ertapenem MICs of ≥2 μg/ml, meropenem displayed sustained efficacy due to its greater in vitro potency and higher resultant fT>MIC.

scholarly journals Nα-lauroyl-l-arginine ethyl ester monohydrochloride, an antimicrobial agent and its use: a review

2020 ◽  
Vol 9 (10) ◽  
pp. e6059108996
Author(s):  
Joyce Fagundes Gomes Motta ◽  
Regiane Ribeiro-Santos ◽  
Maria Clara Guimarães ◽  
Lívia de Aquino Garcia Moura ◽  
Letícia Vitorazi ◽  
...  
Keyword(s):  
Antimicrobial Agent ◽  
Ethyl Ester ◽  
Food Industry ◽  
Antimicrobial Agents ◽  
Food Preservation ◽  
Spoilage Microorganisms ◽  
Strong Antimicrobial Activity ◽  
Insight Into

Growing demand for safe foods coupled with the intent to reduce food waste, seeing as much of it is lost through contamination by spoilage microorganisms, leads to research on antimicrobial agents such as LAE (Nα-lauroyl-L-arginine ethyl ester monohydrochloride). This compound has great antimicrobial potential against a range of microorganisms and, therefore, its use may be of extreme importance for the food industry in the search for antimicrobial agents with a broad spectrum of action. Thus, the objective of this article is to review the research involving LAE, when studied in vitro, in vivo and in the incorporation in different packaging in order to be released in a controlled manner for food products. In conclusion, despite the fact that it has a strong antimicrobial activity, it is still little known and is not accepted in all countries, including Brazil. With greater insight into this antimicrobial agent, more countries could use it, supporting worldwide in food preservation.

scholarly journals Analysis of Paradoxical Efficacy of Carbapenems against Carbapenemase-Producing Escherichia coli in a Murine Model of Lethal Peritonitis

2020 ◽  
Vol 64 (8) ◽  
Author(s):  
Ariane Roujansky ◽  
Victoire de Lastours ◽  
François Guérin ◽  
Françoise Chau ◽  
Geoffrey Cheminet ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Clinical Benefit ◽  
Content Type ◽  
Potential Clinical Benefit ◽  
Mueller Hinton ◽  
Zinc Depletion ◽  
Bacterial Fitness ◽  
Subinhibitory Concentrations

ABSTRACT The clinical benefit of carbapenems against carbapenemase-producing Enterobacteriaceae (CPE) remains in question. MICs of imipenem (IMP) and ertapenem (ERT) against isogenic derivatives of the wild-type strain Escherichia coli CFT073 producing KPC-3, OXA-48, or NDM-1 were 0.25, 2, 16, and 64 mg/liter for IMP and 0.008, 0.5, 8, and 64 mg/liter for ERT, respectively. Swiss ICR-strain mice with peritonitis were treated for 24 h with IMP or ERT. Despite a limited duration of time during which free antibiotic concentrations were above the MIC (down to 0% for the NDM-1-producing strain), IMP and ERT significantly reduced bacterial counts in spleen and peritoneal fluid at 24 h (P < 0.005) and prevented mortality. Several possible explanations were investigated. Addition of 4% albumin or 50% normal human serum did not modify IMP activity. Bacterial fitness of resistant strains was not altered and virulence did not decrease with resistance. In the presence of subinhibitory concentrations of ERT, growth rates of OXA-48, KPC-3, and NDM-1 strains were significantly decreased and filamentation of the NDM-1 strain was observed. The expression of blaNDM-1 was not decreased in vivo compared to in vitro. No zinc depletion was observed in infected mice compared with Mueller-Hinton broth. In conclusion, a paradoxical in vivo efficacy of IMP and ERT against highly resistant carbapenemase-producing E. coli was confirmed. Alternative mechanisms of antibacterial effects of subinhibitory concentrations of carbapenems may be involved to explain in vivo activity. These results are in agreement with a potential clinical benefit of carbapenems to treat CPE infections, despite high carbapenem MICs.

Effect of Tannins on the In Vitro Growth of Escherichia coli O157:H7 and In Vivo Growth of Generic Escherichia coli Excreted from Steers

2007 ◽  
Vol 70 (3) ◽  
pp. 543-550 ◽  
Author(s):  
BYENG R. MIN ◽  
WILLIAM E. PINCHAK ◽  
ROBIN C. ANDERSON ◽  
TODD R. CALLAWAY
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Bacterial Growth ◽  
Escherichia Coli O157 ◽  
Tannin Extract ◽  
Bacterial Growth Rate ◽  
Linear Effect ◽  
E Coli

The effect of commercially available chestnut and mimosa tannins in vitro (experiment 1) or in vivo (experiment 2) on the growth or recovery of Escherichia coli O157:H7 or generic fecal E. coli was evaluated. In experiment 1, the mean growth rate of E. coli O157:H7, determined via the measurement of optical density at 600 nm during anaerobic culture in tryptic soy broth at 37°C, was reduced (P &lt; 0.05) with as little as 400 μg of either tannin extract per ml of culture fluid. The addition of 200, 400, 600, 800, and 1,200 μg of tannins per ml significantly (P &lt; 0.01) reduced the specific bacterial growth rate when compared with the nontannin control. The specific growth rate decreased with increasing dose levels up to 800 μg of tannins per ml. Bacterial growth inhibition effects in chestnut tannins were less pronounced than in mimosa tannins. Chestnut tannin extract addition ranged from 0 to 1,200 μg/ml, and a linear effect (P &lt; 0.05) was observed in cultures incubated for 6 h against the recovery of viable cells, determined via the plating of each strain onto MacConkey agar, of E. coli O157:H7 strains 933 and 86-24, but not against strain 6058. Similar tests with mimosa tannin extract showed a linear effect (P &lt; 0.05) against the recovery of E. coli O157:H7 strain 933 only. The bactericidal effect observed in cultures incubated for 24 h with the tannin preparations was similar, although it was less than that observed from cultures incubated for 6 h. When chestnut tannins (15 g of tannins per day) were infused intraruminally to steers fed a Bermuda grass hay diet in experiment 2, fecal E. coli shedding was lower on days 3 (P &lt; 0.03), 12 (P = 0.08), and 15 (P &lt; 0.001) when compared with animals that were fed a similar diet without tannin supplementation. It was concluded that dietary levels and sources of tannins potentially reduce the shedding of E. coli from the gastrointestinal tract.

scholarly journals A Toxic Environment: a Growing Understanding of How Microbial Communities Affect Escherichia coli O157:H7 Shiga Toxin Expression

2020 ◽  
Vol 86 (24) ◽  
Author(s):  
Erin M. Nawrocki ◽  
Hillary M. Mosso ◽  
Edward G. Dudley
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Microbial Interactions ◽  
Severe Illness ◽  
Content Type ◽  
E Coli ◽  
Wide Range ◽  
Lambdoid Prophage

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) strains, including E. coli O157:H7, cause severe illness in humans due to the production of Shiga toxin (Stx) and other virulence factors. Because Stx is coregulated with lambdoid prophage induction, its expression is especially susceptible to environmental cues. Infections with Stx-producing E. coli can be difficult to model due to the wide range of disease outcomes: some infections are relatively mild, while others have serious complications. Probiotic organisms, members of the gut microbiome, and organic acids can depress Stx production, in many cases by inhibiting the growth of EHEC strains. On the other hand, the factors currently known to amplify Stx act via their effect on the stx-converting phage. Here, we characterize two interactive mechanisms that increase Stx production by O157:H7 strains: first, direct interactions with phage-susceptible E. coli, and second, indirect amplification by secreted factors. Infection of susceptible strains by the stx-converting phage can expand the Stx-producing population in a human or animal host, and phage infection has been shown to modulate virulence in vitro and in vivo. Acellular factors, particularly colicins and microcins, can kill O157:H7 cells but may also trigger Stx expression in the process. Colicins, microcins, and other bacteriocins have diverse cellular targets, and many such molecules remain uncharacterized. The identification of additional Stx-amplifying microbial interactions will improve our understanding of E. coli O157:H7 infections and help elucidate the intricate regulation of pathogenicity in EHEC strains.

Efficacy of Plant-Derived Antimicrobials in Controlling Enterohemorrhagic Escherichia coli Virulence In Vitro

2016 ◽  
Vol 79 (11) ◽  
pp. 1965-1970 ◽  
Author(s):  
SANGEETHA ANANDA BASKARAN ◽  
ANUP KOLLANOOR-JOHNY ◽  
MEERA SURENDRAN NAIR ◽  
KUMAR VENKITANARAYANAN
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Antimicrobial Agents ◽  
Intestinal Epithelial Cells ◽  
Enterohemorrhagic Escherichia Coli ◽  
Host Cells ◽  
Intestinal Epithelial ◽  
Virulence Gene Expression ◽  
Human Intestinal Epithelial Cells

ABSTRACTEscherichia coli O157:H7 is a major foodborne pathogen that can cause serious human illness characterized by hemorrhagic diarrhea and kidney failure. The pathology of enterohemorrhagic E. coli O157:H7 (EHEC) infection is primarily mediated by verotoxins, which bind to the globotriaosylceramide receptor on host cells. Antibiotics are contraindicated for treating EHEC infection because they lead to increased verotoxin release, thereby increasing the risk of renal failure and death in patients. Thus, alternative strategies are needed for controlling EHEC infections in humans. This study investigated the effect of subinhibitory concentrations of five plant-derived antimicrobial agents (PDAs) that are generally considered as safe, i.e., trans-cinnamaldehyde, eugenol, carvacrol, thymol, and β-resorcylic acid, on EHEC motility, adhesion to human intestinal epithelial cells, verotoxin production, and virulence gene expression. All tested PDAs reduced EHEC motility and attachment to human intestinal epithelial cells (P &lt; 0.05) and decreased verotoxin synthesis by EHEC. The reverse transcription real-time PCR data revealed that PDAs decreased the expression of critical virulence genes in EHEC (P &lt; 0.05). The results collectively suggest that these PDAs could be used to reduce EHEC virulence, but follow-up studies in animal models are necessary to validate these findings.

scholarly journals Shiga Toxin Gene Loss and Transfer In Vitro and In Vivo during Enterohemorrhagic Escherichia coli O26 Infection in Humans

2007 ◽  
Vol 73 (10) ◽  
pp. 3144-3150 ◽  
Author(s):  
Martina Bielaszewska ◽  
Rita Prager ◽  
Robin Köck ◽  
Alexander Mellmann ◽  
Wenlan Zhang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Gene Loss ◽  
Pulsed Field Gel Electrophoresis ◽  
Enterohemorrhagic Escherichia Coli ◽  
Toxin Gene ◽  
Shiga Toxins ◽  
E Coli

ABSTRACT Escherichia coli serogroup O26 consists of enterohemorrhagic E. coli (EHEC) and atypical enteropathogenic E. coli (aEPEC). The former produces Shiga toxins (Stx), major determinants of EHEC pathogenicity, encoded by bacteriophages; the latter is Stx negative. We have isolated EHEC O26 from patient stools early in illness and aEPEC O26 from stools later in illness, and vice versa. Intrapatient EHEC and aEPEC isolates had quite similar pulsed-field gel electrophoresis (PFGE) patterns, suggesting that they might have arisen by conversion between the EHEC and aEPEC pathotypes during infection. To test this hypothesis, we asked whether EHEC O26 can lose stx genes and whether aEPEC O26 can be lysogenized with Stx-encoding phages from EHEC O26 in vitro. The stx 2 loss associated with the loss of Stx2-encoding phages occurred in 10% to 14% of colonies tested. Conversely, Stx2- and, to a lesser extent, Stx1-encoding bacteriophages from EHEC O26 lysogenized aEPEC O26 isolates, converting them to EHEC strains. In the lysogens and EHEC O26 donors, Stx2-converting bacteriophages integrated in yecE or wrbA. The loss and gain of Stx-converting bacteriophages diversifies PFGE patterns; this parallels findings of similar but not identical PFGE patterns in the intrapatient EHEC and aEPEC O26 isolates. EHEC O26 and aEPEC O26 thus exist as a dynamic system whose members undergo ephemeral interconversions via loss and gain of Stx-encoding phages to yield different pathotypes. The suggested occurrence of this process in the human intestine has diagnostic, clinical, epidemiological, and evolutionary implications.

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