herbal extracts with anti-mrsa and quorum sensor neutralization activities hussein el haj ahmad...

Herbal Extracts with Anti-MRSA and Quorum Sensor

Neutralization Activities

HUSSEIN El Haj Ahmad

SUNIL Maharjan

RATISH S. Pillai

MRSA causes infections:

• In hospitals including:– Catheter-associated bacteraemia– Surgical site infections– Ventillator-associated pneumonia (VAP)

• In community– patients who lack traditional MRSA risk

factors

Alp and Voss (2006); HPA (2007); CDC (2007).

High Global MRSA Prevalence

Canada 2.3%

USA 55%

UK 44%

Australia 26%

China 39%

Japan 74%

Hong Kong 80%

Singapore 63%

South Africa 49%Nigeria 21%

Latin America 29%

Germany 25%France 27%Spain 27%Romania 61%Cyprus 56%

Netherlands 1%

Alpesh and Batts (2006); EARSS (2005); PHAC (1997); Collignon et al (2005).

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33

30

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10

15

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30

35

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1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Years

% M

RSA

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HPAEARSS

MRSA Prevalence in UK Between 1990 and 2005

HPA (2007); EARSS (2005).

20.6

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60.6 70.4

68.1

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78.2

11.8

58.2

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49.650.5

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20

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60

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1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Years

% M

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A in

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NS

MRSA Deaths in UK

National Statistics online (February 2007).

This increase may be related to improved levels of reporting on death certificates.

MRSA Resistance

• MSRA is resistant to several classes of antibiotics.

• Emerging problem: formation of tolerant biofilm – causing chronic and recurrent nosocomial device-related

infections

• Increased demand for new anti-infectives and novel strategies to control MRSA infections

Alpesh and Batts (2006); Rice (2006); Costerton et al., (1999); Donlan and Costerton (2002); Lewis (2001).

– Downregulation of microbial virulence factors– Inhibition of biofilm formation

• Those agents are known as QSI.

• Crude extract and toluene extract of garlic showed– QSI activity against Pseudomonas aeruginosa– Synergism with some conventional antibiotics at sublethal

concentration

• Until now garlic extract and allicin activities against MRSA biofilms are not studied.

Antipathogenic Agents

Watnick and Kotler (1999); Davies et al. (1998); Rasmussen (2005).

MRSA Market

• MRSA market of five antibiotics had increased from 570 million USD in 2002 to 1.5 billion USD in 2006.

• To have a share in this growing market, some pharmaceutical companies are developing newer anti-MRSA agents in their pipelines. – Arpida (iclaprim)– GlaxoSmithKline (pleuromitilin)– Astra-Zeneca (AZD1279)

• Why not to have a share in this market?

Aim

This research aims to study whether:

Allicin alone, allicin mixed with toluene, toluene-, ethanol-, and chloroform- extracts of garlic can prevent or not MRSA biofilm formation.

Materials and Methods

• Clinical isolates– Clinical MRSA isolates, MRSA control strain,

Pseudomonas aeruginosa positive control strain.

• Chemicals– Aqueous extract of allicin, allicin + toluene,

toleuene extract of garlic, ethanol-extract of garlic, and chloroform-extract of garlic.

• MIC and MBC– MIC & MBC of planktonic bacteria and those in

biofilms will be determined according to BSAC guidelines.

Materials and Methods

• Biofilm formation– Plasma method– MBECTM-HTP Assay in Calgary Biofilm Device

• Measurement of microbial count, viability and killing in MRSA biofilms– Microbial viable count will be determined on real-

time basis by plate count and luminometry.

Summary• Global increase in MRSA prevalence

• MRSA grows in biofilms thus increasing its resistance

• Any agent interfering with QS will inhibit biofilm formation and decrease microbial pathogenicity.

• If allicin inhibits MRSA biofilm formation:– it may act as QSI– proven antimicrobial activity, promising natural

agent against serious MRSA infections.

THANK U