An ethnopharmacological approach to MRSA

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An electronic version (PDF file) of Dr. Quave’s doctoral dissertation “An ethnopharmacological approach to multidrug-resistant Staphylococcus aureus: Evaluation of medicinal plants used in the traditional healing of skin disease” is available for sale here. Upon completion of your order, the link for the downloadable file will appear in the confirmation…

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An electronic version (PDF file) of Dr. Quave’s doctoral dissertation “An ethnopharmacological approach to multidrug-resistant Staphylococcus aureus: Evaluation of medicinal plants used in the traditional healing of skin disease” is available for sale here. Upon completion of your order, the link for the downloadable file will appear in the confirmation table. The link will also immediately be sent to your email address.

185 pages; © Cassandra L. Quave, 2008

Abstract

One-third of botanical remedies from southern Italy are used to treat skin and soft tissue infections (SSTIs). Methicillin-resistant Staphylococcus aureus (MRSA), a common cause of SSTIs, is responsible for increased morbidity and mortality from infections. Therapeutic options are limited by antibiotic resistance. Many plants possess potent antimicrobial compounds for these disorders. Validation of traditional medical practices is important for the people who rely on medicinal plants. Moreover, identification of novel antibiotics and anti-pathogenic agents for MRSA is important to global healthcare.

I took an ethnopharmacological approach to understand how Italian medicinal plants used for the treatment of SSTIs affect MRSA growth and virulence. My hypothesis was that plants used in folk remedies for SSTI would exhibit lower cytotoxicity and greater inhibition of bacterial growth, biofilm formation and toxin production in MRSA than plants used for remedies unrelated to the skin or for plants with no ethnomedical application. The field portion of my research was conducted in the Vulture-Alto Bradano area of southern Italy. I collected 104 plant species and created 168 crude extracts. In the lab, I screened samples for activity against MRSA in a battery of bioassays. Growth inhibition was analyzed using broth microtiter assays for determination of the minimum inhibitory concentration. Interference with quorum-sensing (QS) processes, which mediate pathogenicity, was quantified through RP-HPLC of δ-toxin production. Interference with biofilm formation and adherence was assessed using staining methods. The mammalian cytotoxicity of natural products was analyzed using MTT cell proliferation assay techniques.

Although bacteriostatic activity was limited, extracts from six plants used in Italian folk medicine (Arundo donax, Ballota nigra, Juglans regia, Leopoldia comosa, Marrubium vulgare, and Rubus ulmifolius) significantly inhibited biofilm formation and adherence. Moreover, plants used to treat SSTI demonstrated significantly greater anti-biofilm activity when compared to plants with no ethnomedical application. QSI activity was evident in 90% of the extracts tested and extracts from four plants (Ballota nigra, Castanea sativa, Rosmarinus officinalis, and Sambucus ebulus) exhibited a significant dose-dependent response. Some of the plant remedies for SSTI identified in this study can be validated due to anti-MRSA activity.

Table of Contents

I. INTRODUCTION

  • The target pathogen: Staphylococcus aureus
  • A historical perspective on the emergence of drug-resistance in S. aureus
  • Anti-pathogenic properties of natural products: interference with quorum-sensing processes
  • An ethnopharmacological approach
  • The study site: Vulture-Alto Bradano area of southern Italy
  • Summary
  • References

II. DERMATOLOGICAL REMEDIES IN THE TRADITIONAL PHARMACOPOEIA OF VULTURE-ALTO BRADANO, INLAND SOUTHERN ITALY

  • Abstract
  • Background
  • Methods
  • Results and Discussion
  • The folk medical construct
  • Botanical remedies
  • Malva sylvestris (Malvaceae) – malva
  • Marrubium vulgare (Lamiaceae) – maruggē
  • Matricaria recutita (Asteraceae) – camomilla
  • Zootherapy and remedies of mineral or industrial origin
  • Aged pig fat
  • Garden slug
  • Human breast milk
  • Ethnoveterinary remedies
  • Copper sulphate
  • Hypericum perforatum (Hypericaceae) – iperico
  • Traditional knowledge: current trends and future projections
  • Conclusion
  • Acknowledgements
  • References

III. EFFECTS OF EXTRACTS FROM ITALIAN MEDICINAL PLANTS ON PLANKTONIC GROWTH, BIOFILM FORMATION AND ADHERENCE IN METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS

  • Abstract
  • Introduction
  • Materials and Methods
  • Field research
  • Extraction of natural products
  • Bacteria and culture conditions
  • Growth inhibition
  • Biofilm formation and adherence
  • Mammalian cytotoxicity
  • Statistical analyses
  • Results
  • Effects on planktonic growth of MRSA
  • Mammalian cytotoxicity
  • Biofilm inhibition
  • Discussion
  • Cytotoxicity and creation of a therapeutic index
  • Bacteriostatic activity for MRSA: Erodium malacoides
  • Effects on MRSA biofilm formation and adherence
  • Arundo donax (Poaceae) – canna
  • Ballota nigra (Lamiaceae) – erba cane
  • Juglans regia (Juglandaceae) – noce
  • Leopoldia comosa (Hyacinthaceae) – cipuljdin
  • Marrubium vulgare (Lamiaceae) – maruggē
  • Rubus ulmifolius (Rosaceae) – more
  • Conclusion
  • Acknowledgements
  • References

IV. QUORUM SENSING INHIBITORS FOR METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS FROM ITALIAN MEDICINAL PLANTS

  • Abstract
  • Introduction
  • Materials and Methods
  • Plant material and extraction
  • Bacteria and culture conditions
  • Determination of minimum inhibitory concentrations (MICs)
  • Quantification of δ-toxin production
  • Statistical analysis
  • Results
  • Discussion
  • Acknowledgements
  • References

V. SUMMARY

VITA

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