# Calculations of bacterial count - (Jul/14/2008 )

Can anyone please help me regarding the calculations of log of bacterial count.

e.g if no of colonies drop from 8.1x10^{7} to 5.6x10^{5} how to calculate the percentage reduction ???

-divyagarga-

Micro usually has folks estimating log reduction rather than percentage reduction (except perhaps for commercials for disinfectant/sanitizer products). Otherwise just do the math [(81 million-560,000)/81 million]100

-jorge1907-

QUOTE (jorge1907 @ Jul 14 2008, 01:56 AM)

Micro usually has folks estimating log reduction rather than percentage reduction (except perhaps for commercials for disinfectant/sanitizer products). Otherwise just do the math [(81 million-560,000)/81 million]100

Thank u jorge.

Actually i also want to understand the logic behind log reduction. Is there any informative article ?

-divyagarga-

QUOTE (divyagarga @ Jul 15 2008, 04:32 AM)

QUOTE (jorge1907 @ Jul 14 2008, 01:56 AM)

Micro usually has folks estimating log reduction rather than percentage reduction (except perhaps for commercials for disinfectant/sanitizer products). Otherwise just do the math [(81 million-560,000)/81 million]100

Thank u jorge.

Actually i also want to understand the logic behind log reduction. Is there any informative article ?

http://www.cfsan.fda.gov/~dms/a2z-l.html

and http://www.cmlsupport.org.uk/?q=node/670

http://www.thebody.com/Forums/AIDS/Labs/Ar...ts/Q145384.html

http://www.kaiscience.com/a_107-What_is_Log_Reduction

could these links help you?

I also have the following papers here :

Estimating the Antimicrobial Log Reduction: Part 1. Quantitative Assays

(http://www.mediafire.com/?necgy2sty1l)

and Estimating the Antimicrobial Log Reduction: Part 2. Presence/Absence

(ttp://www.mediafire.com/?b1wbbwb144h)

so if you think you will need a good reference or a paper about it, then you might wanna download those files.

(I must admit, those papers arent that easy, but they explain everything in detail)

-pito-