# Log Reduction

Des O'Connor des at micro-search.com
Tue Jan 29 13:13:53 EST 2002

```The simple approach is to determine survivors over time  in the particular
system you are studying. Usually therefore there would be several instances
of measurement  but you can of course just do two; ie T=o and  T= X where x
is the duration of the antimicrobial process.

It follows that T=0 log (cfu/survivors) - T=x  log(cfu/survivors) =
Log(cfu/killed).

Example start of process  surface A contains 1.0e6 cfu/cm2

End of process surface A contains                 1.0e2  cfu/cm2

Log kill = 4 log cycles

You would account for any decline in the population not due to the
antimicrobial factor by  running a control over the same time period.

Hope this helps if not email me

best Des

""Rottjakob, Dave"" <dave.rottjakob at apptecls.com> wrote in message
news:F03BBB5AFC5A9040A6D4379486806FA4466F00 at esstp.stpaul...

What is the best way to calculate log reduction?

Dave Rottjakob

dave.rottjakob at apptecls.com

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