Knowing that not all disinfectants are suitable for all purposes will require a little knowledge in order to make an apprioprate choice and minimize risk of the biosecurity.

ALDEHYDES
Glutaraldehyde, Formaldehyde (formaline)

Mode of action:
The mode of action both of "gluts" is almost similar, and acts on proteina by denaturation and on nucleic acids by akylation. The reaction is irreversible and pH-dependent, working better at alkaline pH and less at neutral or acid pH.
Exemple:
Glutaraldehyde is favoured by an alkaline pH (e.g. 8.0), but the solution is less stable in such conditions and the disinfectant activity decreases.

Advantages:

  • Very effective against most of bacteria, viruses and fungi, but not against parasites eggs.
  • Least sensitive to the presence of organic matter,
  • Ideal for use in foot mats and foot baths
  • Relatively inexpensive.

Disadvantages:

  • Not effective in low temperature (<5°C or 41°F)
  • Irritant and pungent odor
  • carcinogenic (formaldehydes) and allergic in contact with skin.
QUATERNARY AMMONIUM SALTS ("Quats")
This group of compounds is excellent against bacteria and fungi, but not effective against nonenveloped viruses (such as Gumboro virus and Chicken Anemia Virus by chickens or Aquabirnavirus and Betanodavirus by fish). They are cationic (positively charge) detergents and generally used in foot mats rather than footbaths and are affective against bacteria and fungi at low concentration of 0.5%.
 
Mode of action:
Structure and function disruption resulting in leakage of cell components and cell death.
 
Advantages:
  • Strong antimicrobial action, colorless, odorless, tasteless, and nontoxic.
  • Effective against Gram-positive bacteria, less effective against Gram-negative bacteria. Also destroy fungi, moebas, and enveloped viruses.
  • They are excellent in areas where viral kill is not too important (hatcheries, food preparation enviroment). 
  • Quats are relatively insensitive to low temperature and organic matter.

Disadvantages:

  • Neutralized by soaps and anionic detergents
  • Pseudomonas strains that are resistant and can grow in presents of Quats are a big problem concern in hospitals

GLUTARALDEHYDE + QUATERNARY AMMONIUM SALTS

The combination of "gluts" and "quats" as a disinfectant is quite common. Although improving performnce at lower temperatures, efficacy against non-enveloped viruses is sacrificied (see quaternary ammonium salts). There are required for a foot mat at concentration of 2 - 6% to be effective against all virusses, bacteria and fungi.

CHLOROCRESOLS
Phenols

Use as a foot mat disinfectant and can also helps to prevent coccidiosis in the cleaned poultry barn.

Mode of action:
Cross-linking, coagulating, and clumping leads to leakage of cellular components and finally to death of the microbial cell.

Advantages:

  • Very effective in the presence of organic matter,
  • Effective against bacteria, (especially Gram-positive bacteria) and enveloped viruses,
  • Limited toxicity,
  • Tipically effective as a deodorizer.
Disadvantages:
  • Poor to limited residual activity,
  • Not sporicidal activity

HALOGENS - Oxidizing disinfectants 
Chlorine (bleach, hypochlorite)

Chlorine is the most widely used disinfectant in Canada and USA.

Mode of action:
They are oxidizing agents and therefore denature proteins and caused microorganisms death.

Advantages:

  •  Inexpensive disinfectant,
  • They are active against most of pathogens such as viruses, bacteria, molds, and algae, but not bacterial spores,
Disadvantages:
  • Rhey are rapidly inactivated in the presents of organic matters,
  • Strong oxidizing agents reactive,
  • Disinfection efficiency is temperature depended (at close to 0°C or 32°F disinfection efficiency is very poor),
  • They are corrosive also to stainless steel surfaces,
  • Frequent refreshing is required.
 

Concentration of disinfectant required

to eliminate micro-organisms

Sensitivity  

Disinfectant      

product %

Non-eveloped   

viruses

Enveloped 

viruses

Bacteria    Fungi    

Coccidial   

oocysts

Organic   

matter

Temp   

<5°C

 Glutaraldehyde

 Formalaldehyde

 1  1  1  1  - X  XXX

 Glutaraldehyde

+ QUATS

 0.5 - 1  1 - 3  2 - 4  2 - 6  -  XX  XXX
 QUATS

 NOT 

Effective

 1  1  0.1 - 0.5  -  XX  X
 Chlorocresols  4  2  0.5  2  3 - 4  X  XX

 Oxidizing

Disinfectants

 0.2 - 1  0.5 - 3  1 - 2  0.5 - 5  -  XXX  
                   Source: German Veterinary Industry website (www.dvg.de)
 
What concentration of disinfectant should be used?
 
Always use the concentration recommended by th eapproval body in the country of manufacture (if in the EU), or use the officially approved rate in the country of use.
A few hints:
  • If using a disinfectant that is sensitive to organic, double the normal concentration when using it in disinfection foot mat.
  • Change the disinfectant solution in the foot mat regularly, especialy if it is sensitive to organic matter.
  • If the temperature falls below 4°C (39°F) and the glutaraldehyde  based product is being used, increase the concentration or change to a product group which is insensitive to low temperatures.
When should disinfectant be renewed in a foot mat?  

It is dificult to say - "nobody knows"!
It depends upon:
  • the persons traffic,
  • the amount of organic matter which has ended up in the foot mat,
  • the type of disinfectant used,
  • If outdoor - could be diluted by rain, or affected by sunlight (evaporate or decrease of effectivnes),
  • Water quality - may also affect the efficacy of the disinfect.

Some producers offer a pH indicator to enable users to see if the disinfectant is still useable. At best this will tell the user the pH of the disinfectant solution in the foot mat, and nothing else (not real effectivenes).

There would also have to be tests using different water qualities and pH-values. The only raliable way to maintain effective biosecurity using a foot mat is to ensure that the correct concentration of disinfectant is used in the foot mat and that it is change regurarly.

The table below could be considered as a general quide.

 

General Replenishment

to disinfectant / week

Disinfectant  Light soiling    Heavy soiling  

Glutaraldehyde

Formaldehyde

 1
Gluts + Quats  2
Chlorocresols  1
Oxidizing Disinfectants       2 - 4 3 - 7 
QUATs  2