Tips for proper selection of cleaning, disinfection products
By Neal Benjamin, DVM
Carthage Veterinary Service
Proper cleaning and disinfection are requisites to achieving effective disease prevention and world-class swine production. Unfortunately, I’ve found some swine operations occasionally cut corners in this area when faced with staffing shortages or when herd health has been good.
There are a myriad of commercial disinfectants and detergents available, and each has advantages and disadvantages. It can be challenging to decide which product is the best choice for a particular application.
In this article, I’ll focus on general guidelines about how to make the best use of chemical disinfectants and review different classes of these products. I’ve provided generic product names as examples, not as a recommendation of one over another.
Before choosing a disinfectant, it’s important to remember that while some disinfectants work better in the presence of small amounts of manure, serum or other organic material, no disinfectant currently on the market will achieve thorough disinfection in the presence of moderate amounts of manure. That’s why it’s critically important to ensure the area you’re disinfecting has been thoroughly washed and that no visible manure or other organic material is remaining.
Prior to cleaning, it’s usually helpful to soak the barn with a detergent/descaler/degreaser. Most commercial products in this category contain a mixture of ingredients that help reduce surface tension and promote the dissolving and penetrating ability of water. Detergents help water dissolve and penetrate dried manure, bacterial biofilms and the fatty components of manure and scours from previous batches of piglets, rendering them more susceptible to removal. Simply put, detergents make the wash job easier and more effective.
Consider that some products are compatible and some aren’t. For example, quaternary ammonium compounds work well with products that have a high pH (alkaline) but may be inactivated by products with a low pH (acidic), such as some degreasers. To avoid a compatibility problem, all surfaces should be rinsed to remove detergent before a disinfectant is applied, though in practice, thorough power washing will often remove the degreaser without additional rinsing.
After application of a disinfectant, allow enough contact time to achieve proper disinfection. This may be 10 minutes or more and is specified on the product label.
Rotation of disinfectants has been recommended to help prevent pathogens from developing resistance.1 I’ve found little evidence in the literature that meaningful resistance to disinfectants arises when the products are used at label rates, but I don’t see any downside to rotating. If a producer begins to see changes, such as an increase in scours for example, it’s probably a good idea to change disinfectants.
Porous, wooden or uneven surfaces can be difficult to thoroughly disinfect and can enable some pathogens to escape disinfection.
Fumigation with formaldehyde or similar compounds can be an effective option for disinfecting barns with large amounts of wood or similarly difficult surfaces, but safety and ease of application in barns that are not all-in/all-out make the use of such compounds impractical for many farms. Remodeling to eliminate porous material is an option, but when this isn’t realistic, it’s important to remove as much manure as possible to reduce the pathogen load before disinfection and consider using a product containing a disinfectant with better activity in the presence of organic materials (such as potassium peroxymonosulfate).
On farms using rubber mats to provide heat zones for piglets in farrowing crates, it should be kept in mind that as mats age, threads inside the vulcanized rubber can become exposed and frayed. These threads trap pathogens, allowing them to evade thorough disinfection and inactivation. The solution is disposal of mats that become worn.
Bleach, iodine, chlorhexadine
Halogen disinfectants include sodium hypochlorite — household bleach — and iodine. In the hog industry, iodine is often used as an antiseptic applied to piglets after processing and is occasionally used for disinfecting processing instruments.
Both bleach and iodine are inactivated by organic material and degrade relatively quickly over time. Therefore, while bleach is an excellent general disinfectant, it’s not a good choice when organic material is present — as can be found in foot baths.
For foot baths, I typically recommend using an oxidizing agent (more on those below). If bleach is used, I usually advise using a highly concentrated powdered product and remixing twice daily. Iodine used to disinfect surgical instruments for processing piglets should be changed frequently.
Bleach has often been used in porcine epidemic diarrhea virus outbreaks in the US since 2013, but other common commercial disinfectants may be equally effective.2 Bleach is generally effective against non-enveloped viruses, such as rotavirus.
Another chemical that’s good for instrument disinfection is chlorhexidine, a biguanide used in a few different products. Chlorhexidine, however, has a limited spectrum of activity against viruses, so it’s not appropriate for general disinfection.
Potassium peroxymonosulfate, also found in several available products, is an oxidizing agent with a broad spectrum of activity. It retains some activity in the presence of small, though not large, amounts of organic material.
Such disinfectants are generally considered to be effective in footbaths and, according to label claims, retain activity for up to 7 days after preparation, depending on the product. Potassium peroxymonosulfate is another good choice for activity against non-enveloped viruses such as rotavirus.
Hydrogen peroxide, another oxidizing agent found in various products, has a good spectrum of activity against many bacteria and viruses.
Products with phenols, used according to the label concentrations, can be very effective against bacteria and enveloped viruses.
Phenols as well as hydrogen peroxide, however, are less effective against rotaviruses and other non-enveloped viruses.
Quaternary ammonium compounds
Quaternary ammonium compounds are effective against Gram-positive bacteria such as Clostridium and enveloped viruses such as porcine reproductive and respiratory syndrome, influenza or parainfluenza, but may not be effective against Gram-negative bacteria such as Echerichia coli, Salmonella or the non-enveloped viruses.
To overcome some of these deficiencies, some products combine a quaternary ammonium compound with an aldehyde compound, which has good action against non-enveloped viruses and Gram-negative bacteria.
For more complete information about the spectrum of activity, contact time and concentration for a given product, as well as directions for use, be sure to review the product label. Disinfectants are regulated by the Environmental Protection Agency and claims cannot be made about their efficacy against a given pathogen without submitting evidence to the government.
It’s impossible to list all the possible disinfectants and their advantages and disadvantages here, but you can find a more thorough review on Iowa State University’s Center for Food Security and Public Health website (http://www.cfsph.iastate.edu).
Another excellent resource for choosing the best disinfectants is your veterinarian, who will take into account the disease challenges on a given farm.
1. Sutton SV. Disinfectant Rotation in a Cleaning/Disinfection Program for Clean Rooms and Controlled Environments. Disinfection and Decontamination: Principles, Applications and Related Issues. 2007;165.
2. Bowman AS, Nolting JM, Nelson SW, Bliss N, Stull JW, Wang Q, et al. Effects of disinfection on the molecular detection of porcine epidemic diarrhea virus. Vet Microbiol. 2015;179:213-8.
Posted on August 30, 2018