1671 Antimicrobial Efficacy of Ozone on Enterococcus faecalis
H.H. CHANG, C. FULTON, and E. LYNCH, Queen's University of Belfast, United Kingdom


Aim: To investigate the bactericidal efficacy of Ozone on different concentrations of Enteroccocus faecalis

Methods:  Enterococcus faecalis was cultured overnight on blood agar plates.  A suspension of the micro-organisms was made up to an approximate concentration 108 using McFarland Standards in phosphate buffered saline (PBS).  Serial dilutions to 107, 106, 105 were made.  From these 50 μl of each concentrate was pipetted into each well of a microtitre plate.  Each well of concentrate was treated in turn with Ozone (HealOzone Unit, CurOzone, USA and KAVO, Germany) at different exposure times of 10s, 20s, 30s and 60s.  Samples were taken from the wells, spiral plated, incubated and enumeration of the colony forming units(cfu) performed.

Exp Time ►


60 seconds

30 seconds

20 seconds

10 seconds

In PBS-no treatment


2 x 103cfu

4.0 x 105cfu

2.0 x 107cfu

5.5 x 107cfu

6.0 x 108cfu


0 cfu

0 cfu

3.4 x 105cfu

4.4 x 105 cfu

5.6 x 107cfu


0 cfu

0 cfu

0 cfu

0 cfu

6.5 x 106 cfu


0 cfu

0 cfu

0 cfu

0 cfu

5.2 x 105cfu

Exp Time=time exposed to Ozone                                  PBS = phosphate buffered saline

Conc.= approximate concentration of the bacterial suspension



Ozone kills all Enterococcous faecalis when its concentration in suspension is 106 and lower, even at exposure times of only 10 seconds.

Seq #174 - Oral Microbiology & Immunology I
11:00 AM-12:15 PM, Friday, 27 June 2003 Svenska Massan Exhibition Hall B

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