Researchers from Northwestern University refuted the claim of extra protection against bacteria by antimicrobial paints. 

Recent findings by the researchers were published in the journal Indoor Air that reported that Bacillus timonesis is the sole survivor of bacteria that were applied with antimicrobial, synthetic latext paints. Researchers tested the pain on commonly found bacteria found inside homes. The soil is the conventional habitat of most bacilli, but most are found in indoor places. 

"If you attack bacteria with antimicrobial chemicals, then they will mount a defense," said Northwestern's Erica Hartmann, who led the study. "Bacillus is typically innocuous, but by attacking it, you might prompt it to develop more antibiotic resistance."

The natural environment of bacteria involves something warm and moist. If they are exposed to dry and cold environments, such as indoor surfaces, they die. Thus, Hartmann formulated the question on why indoor environments need to use antimicrobial paints as this will cause to the bacteria to be resistant. 

Bacillus forms spores. These spore-forming bacteria becomes dormant for their protection. Even the harshest condition cannot destroy bacteria when they lie dormant. They reactivate when there are improved conditions. 

"When it's in spore form, you can hit it with everything you've got, and it's still going to survive," said Hartmann, assistant professor of civil and environmental engineering in Northwestern's McCormick School of Engineering. "We should be judicious in our use of antimicrobial products to make sure that we're not exposing the more harmless bacteria to something that could make them harmful."

One concern for antimicrobial products is that manufacturers do not test these with common bacteria but only with more pathogenic bacteria, such as E. coil or Staphylococcus. 

"E. coli is like the 'lab rat' of the microbial world," Hartmann said. "It is way less abundant in the environment than people think. We wanted to see how the authentic indoor bacteria would respond to antimicrobial surfaces because they don't behave the same way as E. coli."