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).

4

9

22

40

33

30

2

4342

44

39

44

0

5

10

15

20

25

30

35

40

45

50

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

Years

% M

RSA

in I

nfec

tions

Dia

gnos

ed fo

r St

aphy

loco

ccus

aur

eus

HPAEARSS

MRSA Prevalence in UK Between 1990 and 2005

HPA (2007); EARSS (2005).

20.6

32.547.2

60.6 70.4

68.1

72

78.2

11.8

58.2

40.3

49.650.5

0

10

20

30

40

50

60

70

80

90

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

Years

% M

RS

A in

Dea

ths

Dia

gnos

ed f

or

Sta

phyl

ococ

cus

aure

us

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