Can 70% v/v Isopropyl alcohol is effective against all forms of bacteria and fungus?

70% v/v Isopropyl alcohol is very effective sanitizer. However can 70% Isopropyl alcohol is effective against all forms of bacteria and fungus? Let's understand this concept.

Mode of action of 70% v/v Isopropyl alcohol 

70% v/v Isopropyl alcohol penetrate into the cells of microorganism and cause denaturation of protein present in the cell wall of microorganisms.

70% v/v Isopropyl alcohol is very effective against all forms of vegetative cells of bacteria and fungus. During disinfectant validation studies, it has been found  that 70% v/v Isopropyl alcohol is very effective and can kill microorganisms in few seconds. If 70% v/v Isopropyl alcohol is so much effective against the microorganisms then why there is need of filtration of 70% v/v Isopropyl alcohol through 0.2 micron filter?

The answer is the limitation of 70% v/v Isopropyl alcohol. Though, 70% v/v Isopropyl alcohol is very effective against the bacterial and fungal vegetative cells but it is not effective against bacterial and fungal spore cells. Spore cells are the dormant stage of the bacteria or fungus to pass the unfavorable conditions. Bacillus subtilis is the example of spore forming bacteria.  A thick protective layer is made by bacterial or fungal cells out side their cell wall and it become difficult to kill the bacterial or fungal spore cells. Even it become hard to kill bacterial and fungal spore by disinfectants also. High level disinfectants are also available in the market and they can kill the bacterial and fungal spore cells. That's why it is recommended to filter the 70% v/v Isopropyl alcohol through 0.2 micron filter to protect 70% v/v Isopropyl alcohol from bacterial and fungal spores contamination.

Conclusion:

70% v/v Isopropyl alcohol is effective against bacterial and fungal vegetative cells but not effective against bacterial and fungal spore cells. So. filter 70% v/v Isopropyl alcohol through 0.2 micron filter before use.

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