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Epicatechin gallate, a naturally occurring polyphenol, alters the course of infection with β-lactam-resistant Staphylococcus aureus in the zebrafish embryo.

Stevens CS, Rosado H, Harvey RJ, Taylor PW - Front Microbiol (2015)

Bottom Line: No significant increases in survival were noted when infected embryos were maintained in medium containing 12.5-100 μg/mL ECg with or without 4 or 16 μg/mL oxacillin.However, when EMRSA-16 was grown in medium containing 12.5 μg/mL ECg and the bacteria used to infect embryos by either the circulation valley or yolk sac, there were significant increases in embryo survival in both the presence and absence of oxacillin.We conclude that exposure to ECg prior to infection reduces the lethality of EMRSA-16, renders cells more susceptible to elimination by immune processes and compromises their capacity to establish an inflammatory response in comparison to non-exposed bacteria.

View Article: PubMed Central - PubMed

Affiliation: UCL School of Pharmacy, University College London London, UK.

ABSTRACT
(-)-epicatechin gallate (ECg) substantially modifies the properties of Staphylococcus aureus and reversibly abrogates β-lactam resistance in methicillin/oxacillin resistant (MRSA) isolates. We have determined the capacity of ECg to alter the course of infection in zebrafish embryos challenged with epidemic clinical isolate EMRSA-16. At 30 h post fertilization (hpf), embryos were infected by injection of 1-5 × 10(3) colony forming units (CFU) of EMRSA-16 into the circulation valley or yolk sac. Infection by yolk sac injection was lethal with a challenge dose above 3 × 10(3) CFU, with no survivors at 70 hpf. In contrast, survival at 70 hpf after injection into the circulation was 83 and 44% following challenge with 3 × 10(3) and 1-5 × 10(3) CFU, respectively. No significant increases in survival were noted when infected embryos were maintained in medium containing 12.5-100 μg/mL ECg with or without 4 or 16 μg/mL oxacillin. However, when EMRSA-16 was grown in medium containing 12.5 μg/mL ECg and the bacteria used to infect embryos by either the circulation valley or yolk sac, there were significant increases in embryo survival in both the presence and absence of oxacillin. ECg-modified and unmodified, GFP-transformed EMRSA-16 bacteria were visualized within phagocytic cells in the circulation and yolk sac; pre-treatment with ECg also significantly increased induction of the respiratory burst and suppressed increases in IL-1β expression typical of infection with untreated EMRSA-16. We conclude that exposure to ECg prior to infection reduces the lethality of EMRSA-16, renders cells more susceptible to elimination by immune processes and compromises their capacity to establish an inflammatory response in comparison to non-exposed bacteria.

No MeSH data available.


Related in: MedlinePlus

Uptake of epicatechin gallate (ECg) and oxacillin by uninfected 30 hpf zebrafish embryos incubated at 28.5°C in E3 medium. (A) Uptake of ECg: , control, E3 medium containing 37.5 μg/mL ECg and 12 μg/mL oxacillin, no embryos; , untreated embryos in E3 medium containing 37.5 μg/mL ECg and 12 μg/mL oxacillin; , sham treated (PBS) embryos in E3 medium containing 37.5 μg/mL ECg and 12 μg/mL oxacillin. (n = 150 per group) (B), uptake of oxacillin: symbols as for (A); n = 150 per group. Each concentration determined by HPLC on five occasions; mean ± SD.
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Figure 2: Uptake of epicatechin gallate (ECg) and oxacillin by uninfected 30 hpf zebrafish embryos incubated at 28.5°C in E3 medium. (A) Uptake of ECg: , control, E3 medium containing 37.5 μg/mL ECg and 12 μg/mL oxacillin, no embryos; , untreated embryos in E3 medium containing 37.5 μg/mL ECg and 12 μg/mL oxacillin; , sham treated (PBS) embryos in E3 medium containing 37.5 μg/mL ECg and 12 μg/mL oxacillin. (n = 150 per group) (B), uptake of oxacillin: symbols as for (A); n = 150 per group. Each concentration determined by HPLC on five occasions; mean ± SD.

Mentions: To determine if lack of efficacy of ECg was due to a failure of uptake of the polyphenol by the fish, uninfected embryos (untreated and PBS sham-injected) were incubated in E3 medium containing 37.5 μg/mL ECg and 12 μg/mL oxacillin, the samples removed and the concentrations of ECg and oxacillin in the medium quantified by HPLC. No components of E3 medium masked peaks attributable to the test substances (data not shown). Each group of 150 embryos was incubated in a single petri dish. Representative data is shown in Figure 2. There were large, significant reductions in the concentrations of both ECg and oxacillin in the presence of pooled embryos. A significant decrease in ECg concentration was found after 17 h incubation with untreated embryos and a smaller but significant effect at this time point was evident with sham-injecteded embryos (Figure 2A). At 70 h, less than 5% of the initial concentration of ECg was detected in E3 medium. There were significant reductions in the oxacillin concentration in solution after 17–26 h incubation and the concentrations continued to decline over the 70 h incubation period. Up to 50 hpi, the oxacillin concentration declined more rapidly with untreated embryos in comparison to sham-injected fish (Figure 2B).


Epicatechin gallate, a naturally occurring polyphenol, alters the course of infection with β-lactam-resistant Staphylococcus aureus in the zebrafish embryo.

Stevens CS, Rosado H, Harvey RJ, Taylor PW - Front Microbiol (2015)

Uptake of epicatechin gallate (ECg) and oxacillin by uninfected 30 hpf zebrafish embryos incubated at 28.5°C in E3 medium. (A) Uptake of ECg: , control, E3 medium containing 37.5 μg/mL ECg and 12 μg/mL oxacillin, no embryos; , untreated embryos in E3 medium containing 37.5 μg/mL ECg and 12 μg/mL oxacillin; , sham treated (PBS) embryos in E3 medium containing 37.5 μg/mL ECg and 12 μg/mL oxacillin. (n = 150 per group) (B), uptake of oxacillin: symbols as for (A); n = 150 per group. Each concentration determined by HPLC on five occasions; mean ± SD.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585009&req=5

Figure 2: Uptake of epicatechin gallate (ECg) and oxacillin by uninfected 30 hpf zebrafish embryos incubated at 28.5°C in E3 medium. (A) Uptake of ECg: , control, E3 medium containing 37.5 μg/mL ECg and 12 μg/mL oxacillin, no embryos; , untreated embryos in E3 medium containing 37.5 μg/mL ECg and 12 μg/mL oxacillin; , sham treated (PBS) embryos in E3 medium containing 37.5 μg/mL ECg and 12 μg/mL oxacillin. (n = 150 per group) (B), uptake of oxacillin: symbols as for (A); n = 150 per group. Each concentration determined by HPLC on five occasions; mean ± SD.
Mentions: To determine if lack of efficacy of ECg was due to a failure of uptake of the polyphenol by the fish, uninfected embryos (untreated and PBS sham-injected) were incubated in E3 medium containing 37.5 μg/mL ECg and 12 μg/mL oxacillin, the samples removed and the concentrations of ECg and oxacillin in the medium quantified by HPLC. No components of E3 medium masked peaks attributable to the test substances (data not shown). Each group of 150 embryos was incubated in a single petri dish. Representative data is shown in Figure 2. There were large, significant reductions in the concentrations of both ECg and oxacillin in the presence of pooled embryos. A significant decrease in ECg concentration was found after 17 h incubation with untreated embryos and a smaller but significant effect at this time point was evident with sham-injecteded embryos (Figure 2A). At 70 h, less than 5% of the initial concentration of ECg was detected in E3 medium. There were significant reductions in the oxacillin concentration in solution after 17–26 h incubation and the concentrations continued to decline over the 70 h incubation period. Up to 50 hpi, the oxacillin concentration declined more rapidly with untreated embryos in comparison to sham-injected fish (Figure 2B).

Bottom Line: No significant increases in survival were noted when infected embryos were maintained in medium containing 12.5-100 μg/mL ECg with or without 4 or 16 μg/mL oxacillin.However, when EMRSA-16 was grown in medium containing 12.5 μg/mL ECg and the bacteria used to infect embryos by either the circulation valley or yolk sac, there were significant increases in embryo survival in both the presence and absence of oxacillin.We conclude that exposure to ECg prior to infection reduces the lethality of EMRSA-16, renders cells more susceptible to elimination by immune processes and compromises their capacity to establish an inflammatory response in comparison to non-exposed bacteria.

View Article: PubMed Central - PubMed

Affiliation: UCL School of Pharmacy, University College London London, UK.

ABSTRACT
(-)-epicatechin gallate (ECg) substantially modifies the properties of Staphylococcus aureus and reversibly abrogates β-lactam resistance in methicillin/oxacillin resistant (MRSA) isolates. We have determined the capacity of ECg to alter the course of infection in zebrafish embryos challenged with epidemic clinical isolate EMRSA-16. At 30 h post fertilization (hpf), embryos were infected by injection of 1-5 × 10(3) colony forming units (CFU) of EMRSA-16 into the circulation valley or yolk sac. Infection by yolk sac injection was lethal with a challenge dose above 3 × 10(3) CFU, with no survivors at 70 hpf. In contrast, survival at 70 hpf after injection into the circulation was 83 and 44% following challenge with 3 × 10(3) and 1-5 × 10(3) CFU, respectively. No significant increases in survival were noted when infected embryos were maintained in medium containing 12.5-100 μg/mL ECg with or without 4 or 16 μg/mL oxacillin. However, when EMRSA-16 was grown in medium containing 12.5 μg/mL ECg and the bacteria used to infect embryos by either the circulation valley or yolk sac, there were significant increases in embryo survival in both the presence and absence of oxacillin. ECg-modified and unmodified, GFP-transformed EMRSA-16 bacteria were visualized within phagocytic cells in the circulation and yolk sac; pre-treatment with ECg also significantly increased induction of the respiratory burst and suppressed increases in IL-1β expression typical of infection with untreated EMRSA-16. We conclude that exposure to ECg prior to infection reduces the lethality of EMRSA-16, renders cells more susceptible to elimination by immune processes and compromises their capacity to establish an inflammatory response in comparison to non-exposed bacteria.

No MeSH data available.


Related in: MedlinePlus