[BabyBoomer]

 
News Report:

Thousands of bottles of a medicinal mouthwash have been recalled from 11 countries, including New Zealand, after harmful bacteria were detected.

Colgate-Palmolive UK says it is recalling its medicinal mouthwash Periogard, which is sold under different brand names in other countries.

It is being taken off the shelves of pharmacies, shops, dental surgeries and hospitals in 11 countries across Europe and Australasia.

Britain's Medicines and Healthcare Products Regulatory Agency (MHRA) said the recall comes after tests found the bacteria Burkholderia in some samples of the product.

[Nizzle]

The active ingredient in Periogard is Chlorhexidine. This targets Gram+ and in a lesser extent Gram- bacteria.
Burkholderia is a Gram- bacteria and the strain found in that particular mouthwash may have built up some resistance against Chlorhexidine...

[Bored chemist]

The fact that it's an alcohol free mouthwash may also be important.

[Phil1907]

Chlorhexidine is a poor antimicrobial and Burkholderia spp. (esp. cepacia) and many Gram negative bacteria are generally resistant. 
Though alcohol containing mouthwash are much more resistant to contamination, substantial cepacia contamination of 70% alcohol antiseptic has been reported.  The bugs weren't growing but were present in clinically significant numbers (associated with septicemia) - presumed to be present in biofilm material.

[Bored chemist]

 "substantial cepacia contamination of 70% alcohol antiseptic has been reported.  "
Now that's a serious alcohol tolerance.

[Phil1907]

It was!!!!  A hospital trying to work in Beirut's turmoil and abyssmal water quality.

[johan_M]

The bugs weren't growing but were present in clinically significant numbers (associated with septicemia) - presumed to be present in biofilm material.

What is Biofilm material?

[Phil1907]

Bacteria are more frequently encounter in nature as communities of cells living in a matrix - think gel - gel of polysaccharide, and other mineral and biological materials.  The matrix with cells is the "biofilm".  Here's a link to a good description - http://www.cs.montana.edu/ross/personal/intro-biofilms-s4.htm and a recent article describing the resistance of bacteria in biofilm to disinfecants.

Biofouling 2011 Oct;27(9):1017-32.  Resistance of bacterial biofilms to disinfectants: a review.

[johan_M]

Bacteria are more frequently encounter in nature as communities of cells living in a matrix - think gel - gel of polysaccharide, and other mineral and biological materials.  The matrix with cells is the "biofilm".  Here's a link to a good description - http://www.cs.montana.edu/ross/personal/intro-biofilms-s4.htm and a recent article describing the resistance of bacteria in biofilm to disinfecants.

Biofouling 2011 Oct;27(9):1017-32.  Resistance of bacterial biofilms to disinfectants: a review.

Interesting link indeed.My company once had a problem with stainless steel valves that we could never replicate. We always assumed it was a type of rust. Now i'm thinking it could have been a biofilm, as you have referred to. The problem was very intermittent and did not reoccur,but we never thought of checking for a biological cause.

[johan_M]

What chemical in the mouthwash does the bacteria colony use as nutrition, or is the biofilm inert and waiting for a better enironment?

 What inorganic chemicals(if any) can bacteria metabolize?

[pheromone66]

bacteria can evolve and create resistance to whatever is killing them.

[Nizzle]

What inorganic chemicals(if any) can bacteria metabolize?

Chemotrophic bacteria metabolizing Iron, Manganese, Hydrogen Sulfide, elemental Sulphur, molecular Hydrogen or Ammonia are already discovered.

But they are not the bacteria that you typically find in a mouth wash

[Phil1907]

Good point Nizzle.  Bacteria responsible for many recalls of mouthwash are primarly water-born heterotrophs such as Burkholderia cepacia.  Not aware of data for contamination in use.

[johan_M]

Do they survive in the mouthwash or do they encapsulate themselves?
What do they metabolize?