Hemolysin from Escherichia coli induces oxidative stress in blood

Baronetti, José L.; Villegas, Natalia Ángel; Aiassa, Virginia; Paraje, María Gabriela; Albesa, Inés

doi:10.1016/j.toxicon.2013.03.014

Cited by 12 publications

(10 citation statements)

References 36 publications

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“…As a common enteric isolate, we hypothesize that extra-intestinal EAEC may arise via the transfer the pAA plasmid more classical invasive pathogens, thus transferring additional virulence traits. This is supported by the high prevalence of classical ExPEC virulence genes within our EAEC, such as hlyA which is known to induce oxidative stress in blood [25], and which is also associated with polymorphonuclear lysis/necrosis and lung injury in vivo in a rat model of E. coli pneumonia [36]. The low prevalence of the chromosomal aaiC gene in our strains compared to aggR and aatA on the pAA plasmid may be additional support for transfer of the pAA plasmid.…”

Section: Plos Neglected Tropical Diseasesmentioning

confidence: 52%

Escherichia coli ST131 clones harbouring AggR and AAF/V fimbriae causing bacteremia in Mozambican children: Emergence of new variant of fimH27 subclone

et al. 2020

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Multidrug-resistant Escherichia coli ST131 fimH30 responsible for extra-intestinal pathogenic (ExPEC) infections is globally distributed. However, the occurrence of a subclone fimH27 of ST131 harboring both ExPEC and enteroaggregative E. coli (EAEC) related genes and belonging to commonly reported O25:H4 and other serotypes causing bacteremia in African children remain unknown. We characterized 325 E. coli isolates causing bacteremia in Mozambican children between 2001 and 2014 by conventional multiplex polymerase chain reaction and whole genome sequencing. Incidence rate of EAEC bacteremia was calculated among cases from the demographic surveillance study area. Approximately 17.5% (57/325) of isolates were EAEC, yielding an incidence rate of 45.3 episodes/10 5 children-years-at-risk among infants; and 44 of isolates were sequenced. 72.7% (32/44) of sequenced strains contained simultaneously genes associated with ExPEC (iutA, fyuA and traT); 88.6% (39/44) harbored the aggregative adherence fimbriae type V variant (AAF/V). Sequence type ST-131 accounted for 84.1% (37/44), predominantly belonging to serotype O25:H4 (59% of the 37); 95.6% (35/44) harbored fimH27. Approximately 15% (6/41) of the children died, and five of the six yielded ST131 strains (83.3%) mostly (60%; 3/5) due to serotypes other than O25:H4. We report the emergence of a new subclone of ST-131 E. coli strains belonging to O25:H4 and other serotypes harboring both ExPEC and EAEC

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Section: Plos Neglected Tropical Diseasesmentioning

confidence: 52%

Escherichia coli ST131 clones harbouring AggR and AAF/V fimbriae causing bacteremia in Mozambican children: Emergence of new variant of fimH27 subclone

et al. 2020

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“…The ability of SOD to inhibit the reduction of NBT by the O 2 − generated through the illumination of riboflavin in the presence of oxygen and the electron donor methionine was evaluated in the samples [15]. The results were expressed as SOD activity (%)/BBU.…”

Section: Methodsmentioning

confidence: 99%

“…Another form of stress is termed nitrosative stress, where reactive nitrogen intermediates (RNI), such as nitrate (NO 3 − ) and nitrite (NO 2 − ), are used as terminal electron acceptors under anaerobic conditions, whereas nitric oxide (NO) is a short-lived free radical produced enzymatically by nitric oxide synthesis in various types of cells, and it has a great diffusion across membranes [14]. In the antioxidant defense system, some major enzymes involved in the detoxification of ROS are superoxide dismutase (SOD) and catalase (CAT), among others [15]. However, oxidative imbalance is due to an overproduction of ROS or a reduction in the oxidative defenses is insufficient to remove the free radicals, and therefore the antioxidant system plays a very important role in the control of this process.…”

Section: Introductionmentioning

confidence: 99%

Relevance of Biofilms in the Pathogenesis of Shiga-Toxin-ProducingEscherichia coliInfection

Villegas

Baronetti

Albesa

et al. 2013

The Scientific World Journal

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The present study was designed to determine the relationships among biofilm formation, cellular stress and release of Shiga toxin (Stx) by three different clinical Shiga toxin-producing Escherichia coli (STEC) strains. The biofilm formation was determined using crystal violet stain in tryptic soy broth or thioglycollate medium with the addition of sugars (glucose or mannose) or hydrogen peroxide. The reactive oxygen species (ROSs) were detected by the reduction of nitro blue tetrazolium and reactive nitrogen intermediates (RNI) determined by the Griess assay. In addition, the activities of two antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), were studied. For the cytotoxicity studies, Vero cells were cultured with Stx released of STEC biofilms. The addition of sugars in both culture mediums resulted in an increase in biofilm biomass, with a decrease in ROS and RNI production, low levels of SOD and CAT activity, and minimal cytotoxic effects. However, under stressful conditions, an important increase in the antioxidant enzyme activity and high level of Stx production were observed. The disturbance in the prooxidant-antioxidant balance and its effect on the production and release of Stx evaluated under different conditions of biofilm formation may contribute to a better understanding of the relevance of biofilms in the pathogenesis of STEC infection.

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“…Results were expressed as SOD activation percentage compared to control (100%)/BBU (SOD activation/BBU) (Baronetti et al 2013). …”

Section: Superoxide Dismutase Activitymentioning

confidence: 99%

Reduction ofCandida tropicalisbiofilm by photoactivation of aHeterophyllaea pustulataextract

Marioni

Arce

Cabrera

et al. 2016

Pharmaceutical Biology

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Context: Biofilm formation is an important problem, since this growth mode confers resistance to drugs usually used in therapeutics. Objective: In vitro antifungal activity of extracts obtained from Heterophyllaea pustulata Hook f. (Rubiaceae) were studied against Candida tropicalis biofilms, evaluating the effect of irradiation and the oxidative and nitrosative stresses as possible mechanisms of action. Materials and methods: Hexane, benzene, ethyl acetate and ethanol extracts were evaluated at three concentrations (0.2, 0.1 and 0.05 mg/mL) over mature biofilm, under darkness and irradiation. After 48 h of incubation, biofilm quantitation was performed by the O'Toole and Kolter method. Reactive oxygen species (ROS) was measured by nitro-blue tetrazolium (NBT) reaction and reactive nitrogen intermediates (RNI) by the Griess reagent. Superoxide dismutase activation (SOD, NBT assay) and total antioxidant system (FRAP test) were studied. Results: Only the benzene extract at 0.2 mg/mL reduced the biofilms formation. The slight decrease achieved in darkness (17.06 ± 2.80% reduction) was increased by light action (39.31 ± 3.50% reduction), clearly observing a photostimulation. This great reduction was confirmed by confocal microscopy. In darkness, biofilm reduction was mediated by an increase in RNI, whereas under irradiation, the ROS action was most important. Although no SOD activation was observed, a strong stimulation of the total antioxidant system was detected. HPLC analysis established a high content of several anthraquinones in this extract. Discussion and conclusion: Biofilm reduction by benzene extract was mainly mediated by oxidative stress triggered under light action, confirming a photodynamic sensitization, which could be attributed to its high content of photosensitizing anthraquinones. ARTICLE HISTORY

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Hemolysin from Escherichia coli induces oxidative stress in blood

Cited by 12 publications

References 36 publications

Escherichia coli ST131 clones harbouring AggR and AAF/V fimbriae causing bacteremia in Mozambican children: Emergence of new variant of fimH27 subclone

Escherichia coli ST131 clones harbouring AggR and AAF/V fimbriae causing bacteremia in Mozambican children: Emergence of new variant of fimH27 subclone

Relevance of Biofilms in the Pathogenesis of Shiga-Toxin-ProducingEscherichia coliInfection

Reduction ofCandida tropicalisbiofilm by photoactivation of aHeterophyllaea pustulataextract

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