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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

Fluorescence imaging of EMRSA-16-GFP in cells with granulocyte appearance of the yolk sac of zebrafish embryos infected by the circulation valley at 30 hpf; image obtained 26 h post infection (hpi). Scale bar 10 μm.
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Figure 4: Fluorescence imaging of EMRSA-16-GFP in cells with granulocyte appearance of the yolk sac of zebrafish embryos infected by the circulation valley at 30 hpf; image obtained 26 h post infection (hpi). Scale bar 10 μm.

Mentions: We employed EMRSA-16-GFP in order to visualize bacteria within 30 hpf embryos following injection into the circulation. Introduction of the GFP cassette into EMRSA-16 elicited a small but significant increase in embryo survival (data not shown); therefore, for these experiments an inoculum of 1 × 104 CFU was employed. At 26 hpi, fluorescent bacteria were visible in the circulation valley and lining blood vessels. The large majority of bacteria were found within cells resembling phagocytes. Figure 4 shows typical clusters within granulocyte-like cells of the yolk sac; large numbers of bacteria were found in this anatomical site after administration into the circulation. Growth of EMRSA-16-GFP in ECg-containing E3 medium attenuated the bacteria in similar fashion to that found with the non-fluorescent parent strain but no differences were noted in the distribution of ECg-treated and untreated fluorescent bacteria over the 70 h observation period. At 70 hpi, only very few fluorescent bacteria could be detected in survivors.


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)

Fluorescence imaging of EMRSA-16-GFP in cells with granulocyte appearance of the yolk sac of zebrafish embryos infected by the circulation valley at 30 hpf; image obtained 26 h post infection (hpi). Scale bar 10 μm.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 4: Fluorescence imaging of EMRSA-16-GFP in cells with granulocyte appearance of the yolk sac of zebrafish embryos infected by the circulation valley at 30 hpf; image obtained 26 h post infection (hpi). Scale bar 10 μm.
Mentions: We employed EMRSA-16-GFP in order to visualize bacteria within 30 hpf embryos following injection into the circulation. Introduction of the GFP cassette into EMRSA-16 elicited a small but significant increase in embryo survival (data not shown); therefore, for these experiments an inoculum of 1 × 104 CFU was employed. At 26 hpi, fluorescent bacteria were visible in the circulation valley and lining blood vessels. The large majority of bacteria were found within cells resembling phagocytes. Figure 4 shows typical clusters within granulocyte-like cells of the yolk sac; large numbers of bacteria were found in this anatomical site after administration into the circulation. Growth of EMRSA-16-GFP in ECg-containing E3 medium attenuated the bacteria in similar fashion to that found with the non-fluorescent parent strain but no differences were noted in the distribution of ECg-treated and untreated fluorescent bacteria over the 70 h observation period. At 70 hpi, only very few fluorescent bacteria could be detected in survivors.

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