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Common Methods in Microbial Control

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Ch<strong>in</strong>g-Tsan Huang (黃慶璨)<br />

Office: Agronomy Hall, Room 111<br />

Tel: (02) 33664454<br />

E-mail: cthuang@ntu.edu.tw<br />

<strong>Common</strong> <strong>Methods</strong> <strong>in</strong> <strong>Microbial</strong> <strong>Control</strong><br />

Prescott Microbiology 2008.<br />

1<br />

2<br />

Chemotherapy<br />

Heavy metal<br />

Chemical agents<br />

Antibiotics<br />

Peptides<br />

Resistance!<br />

Photodynamic action<br />

http://www.biu.ac.il/PH/biophysics/PDT.jpg<br />

3<br />

4


Nature reviews cancer, 2003 (3) 380-7<br />

Characteristics<br />

PS<br />

Selective adsorption or b<strong>in</strong>d<strong>in</strong>g by cancer cells<br />

Different rates of metabolism between normal and<br />

cancer cells<br />

Excitation by an appropriate wavelength<br />

Porphyr<strong>in</strong>s<br />

Cyan<strong>in</strong>e dyes<br />

qu<strong>in</strong>ones<br />

5<br />

6<br />

J Dent Res. 86(11):<br />

1126, 2007.<br />

Ref : Malik et al. 1990<br />

7<br />

8


-Am<strong>in</strong>olaevul<strong>in</strong>ic acid<br />

(ALA): Endogenous<br />

ALA<br />

PpIX<br />

Small range of wavelength<br />

White light<br />

Halogen lamp<br />

LED (Light Emitt<strong>in</strong>g Diode)<br />

Merocyan<strong>in</strong>e 540<br />

(MC 540): Exogenous<br />

Laser (Light Amplification by Stimulated<br />

Emission of Radiation )<br />

9<br />

10<br />

Interact with cells only<br />

No adsorption or neutralization by EPS<br />

MW is generally small<br />

Less transport limitation<br />

B<strong>in</strong>d<strong>in</strong>g to cells<br />

Not related to physiology<br />

Already exist <strong>in</strong> cells<br />

Less chance to <strong>in</strong>duce resistant stra<strong>in</strong>s<br />

11<br />

12


http://www.erc.montana.edu/MultiCellStrat/06-Meet<strong>in</strong>g_Antimic-Challenge/SuscpHypotheses.htm<br />

J Dent Res. 86(11):<br />

1126, 2007.<br />

13<br />

14<br />

Periodontol 2000.<br />

2009;51:109-40.<br />

PACT with TBO-Gold Nanorods<br />

Chem. Commun., 2009, 4853 - 4855<br />

15<br />

16


8<br />

<br />

S. aureus<br />

Relation between<br />

antimicrobial activity<br />

and excitation level of<br />

MC 540<br />

: 1-fold<br />

: 2-fold<br />

: 5-fold<br />

: 10-fold<br />

Incubation time (m<strong>in</strong>)<br />

: 5 µg/ml<br />

:10 µg/ml<br />

: 15 µg/ml<br />

: 20 µg/ml<br />

17<br />

18<br />

S. aureus<br />

MC540-mediated PDT on<br />

antimicrobial activity and<br />

excitation level of MC540<br />

: 0 µg/ml<br />

: 5 µg/ml<br />

: 10 µg/ml<br />

: 15 µg/ml<br />

: 20 µg/ml<br />

Light dose (J/cm 2 )<br />

A threshold value of photosensitizer<br />

excited is required to reach complete<br />

kill.<br />

19<br />

20


S. aureus<br />

Irradiation on<br />

antimicrobial activity<br />

and excitation level<br />

of MC 540<br />

: 0 µg/ml<br />

: 5 µg/ml<br />

: 10 µg/ml<br />

: 15 µg/ml<br />

: 20 µg/ml<br />

21<br />

22<br />

0 J/cm 2 30 J/cm 2 60 J/cm 2<br />

20 m<br />

150 J/cm 2 300 J/cm 2 600 J/cm 2<br />

Pump LED<br />

Material<br />

23<br />

24


Step 1<br />

Step 2<br />

Initiative conc.: 10 8 cells/mL<br />

Interaction conc.: 10 7 cells/mL<br />

Step 3<br />

Step 4<br />

MSSA MRSA<br />

25<br />

26<br />

P. aerug<strong>in</strong>osa<br />

Relation between antimicrobial activity and<br />

excitation level of -ALA<br />

With irradiation Without irradiation<br />

360 J cm -2<br />

120 J cm -2<br />

240 J cm -2<br />

P. aerug<strong>in</strong>osa<br />

Irradiation on excitation level of -ALA<br />

120 J cm -2<br />

<strong>Control</strong><br />

27<br />

28


Regrowth (recovery)<br />

A rapid resumption of biofilms after antimicrobial<br />

treatment was term<strong>in</strong>ated.<br />

The rema<strong>in</strong><strong>in</strong>g biofilms conta<strong>in</strong> enough viable<br />

organisms.<br />

The residual biofilm enhances transport and sorption<br />

of microbial cells and other compounds to the surface.<br />

Some oxidiz<strong>in</strong>g antimicrobial agents preferentially<br />

removes EPS and not biofilm cells.<br />

EPS is rapidly created by surviv<strong>in</strong>g organisms.<br />

P. aerug<strong>in</strong>osa<br />

Regrowth after -ALA-mediated PDT<br />

1st 2nd<br />

<strong>Control</strong><br />

29<br />

30<br />

Microorganisms<br />

Photosensitizers<br />

Exogenous PS<br />

MC540, MB, HpD<br />

Endogenous PS<br />

-ALA<br />

Natural PS<br />

C-Phycocyan<strong>in</strong><br />

Bacteria<br />

Gram + Gram -<br />

S. aureus P. aerug<strong>in</strong>osa<br />

S. epidermidis E. coli<br />

S. aureus<br />

S. epidermidis<br />

S. aureus<br />

S. epidermidis<br />

P. aerug<strong>in</strong>osa<br />

E. coli<br />

P. aerug<strong>in</strong>osa<br />

E. coli<br />

Gram-positive cell wall Gram-negative cell wall<br />

31<br />

32

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