Chronic contaminated surfaces

Internal biosecurity is frequently identified as the weakest link in swine biosecurity operations. Two components of the internal biosecurity assessment (BioCheck-U, Ghent) that seem to show consistent poor average numbers are: management of compartments with equipment, and cleaning and disinfection protocols (Laanen, M., et al, 2013; Backhans, A., et al; Postman, M., et al, 2015; and Collineau, L., et al, 2017).
calendar icon 13 August 2020
clock icon 7 minute read

These low internal biosecurity scores have been correlated with an increase average number and quantity of antimicrobials used in pigs from birth to slaughter time (Treat Incidence TI-200, Raash, S., et al, 2018). This paper is intended to review some of the potential gaps and opportunities related to the cleaning section within this type of protocol and where to focus.

Farrowing crates and post weaning/nursery surfaces, such as floors, panels, feeders do pose challenges for cleaning not just because of the porosity level, but due to other factors such as the higher fat sow and nursery diets that bring stickier feces, the residual placenta and other potential extra polymeric proteins more difficult to remove, and the higher temperature needed for piglets (sticky-attached surface effect). Also, the more frequent usage (at least 5 times/year) could facilitate the rolling of prior bacteria into the new sows and piglets. Bacteria level has been expected somewhere in between 50 to 20 million/cm2 after dry cleaning has been performed. The challenge for a great cleaning protocol is trying to reduce that number of bacteria from the contaminated surface by at least 200 times to be able to have it ready for the intervention with a disinfectant. If the goal is that after using a disinfectant the bacteria should be lower than 500/cm2 (Waddilove, J., 1999); the surface contamination of bacteria cannot be more than 1,000,000/cm2.

People usually evaluate the cleaning and disinfection (C&D) protocol after the use of the disinfectant, but not after the cleaning protocol. If you would like to achieve the best possible effect of any disinfectant, the surface should have less than 5% organic load, reduced/eliminated biofilm effect and the bacteria level should be less than 100,000/cm2 on average critical surfaces.

The following factors must be included when planning to design and set a cleaning process/protocol: First, thoroughly dry clean to eliminate all visual gross physical dirt on surfaces, starting with ceilings from center to lateral walls, from top down, and from the entrance to the exit or the furthest point working towards the exit (all mechanical movements should be cohesive to reduce recontaminations). Visually inspect the results to ensure a thorough initial cleaning.

After the dry-cleaning inspection, it is time for presoaking and soaking. The objective of presoaking is to facilitate the detachment of organic matter. It has been suggested 6-8 hours’ time is need for presoaking, while other authors suggest presoaking overnight (Hurnik, D., 2005; Correge, I. & Dubroca, S., 2003). Other protocols suggest shorter times (2-4 hours). It seems to depend on the level of chronic contamination of each surface, porosity level and water quality.

The most important aspect of an effective deep presoak is to help to detach organic matter from previous animals and help detergents and hot water to lower the bacteria counts/cm2 and/or the ATP readings. This step should be the use of low-pressure jets (around 500 PSI) because the use of high-pressure jets/washing equipment could potentially increase the risk of suspended particles able to carry bacteria (less than 4 µm). Presoaking has been proved to reduce around 23% of labor time needed for the whole cleaning process and up to 30% reduction of total water usage (Hurnik, D., 2005; Correge, I., 2006). But, by itself, does not reduce the bacteria level as the main final goal to be achieved. Detergent and hot pressurized water are needed, these work in synergy with, or depend on, the presoaking step.

A great quality, well-formulated alkaline detergent is needed here to work on dislodging organic matter, to tolerate hard water conditions (500 – 1000 ppm), and well-balanced quality surfactants with good foaming helps to increase the contact time (20-30 minutes). Using appropriate jets and nozzles helps to improve coverage and consistency to benefit the efficacy of these types of detergents and achieve rationally final cost/benefit per m2. Complete foam coverage is the visual goal with this step.

Now it is time for the high-pressure hot water use. The ideal pressure of the equipment should be between 1,000 to 1,200 PSI. Pressure close to 2,000 PSI could increase the potential risk of suspended particles into the environment (this effect into the environment could be detrimental in order to achieve lower bacteria at the end of the whole process). In terms of hot water parameters, the best possible effect could be achieved with a minimum of 55°C (130°F) up to 60°C (140°F). Water temperatures higher than 65°C could potentially create a negative effect due to a coagulation effect of certain proteins when present on certain material surfaces and porosity level. Because of these previous factors of coverage, pressure, nozzles, flow and temperature, it is important to have routine calibration protocols for the equipment used in the C&D process. Studies have shown that no matter if a protocol uses hot or cold water without a presoaking/soaking step, surfaces were not able to obtain acceptable results in terms of reduced contamination after disinfection (Luyckx, K.Y., et al, 2015).

Now it’s the time to allow the surfaces to dry and to perform an inspection and verification protocol to validate and make sure that the numbers of bacteria/cm2 are around 100,000/cm2 or lower, before applying any disinfectant. Previous studies showed that in winter months a room heating treatment could benefit the persistence of a low bacteria count (Correge, I., 2003)

Prevalence of early enteric problems have been associated with hygiene gaps. It is well documented that Lawsonia, Serpulina/Brachyspira, E. coli and Clostridium could persist long enough despite disinfectant use because the level of those bacteria have not been reduced by existing cleaning protocols (Gadd, J., 2005; Hurnik, D., 2005). When some companies have adopted and performed a disciplined and consistent cleaning protocol, but still experience rolling issues related with enteric predominant problems in postweaning/nursery; instead of trying to use more disinfectant or trying to change or “rotate” the disinfectant, they have implemented what it’s called a “double” washing protocol without changing anything in the disinfection protocol or process. The second washing step should be carried out using an acid detergent, so the pH helps to break more biofilm and work in lowering the bacteria level.

The monitoring/verification of the final C&D on those critical surfaces at the farrowing crates and nursery has been done with ATP readings (luminometer – AccuPoint® Advanced). An ideal target could be to achieve readings usually lower or around 300 RLU, the majority lower than 150 and most of the time closer to “0” RLU. The clinical/subclinical conditions associated with early diarrhea have reduced its prevalence. A baseline development will help in terms of the most appropriate numbers.

There is an immediate need to prevent this type of chronic-contaminated surface; farrowing crates and nursery surfaces (floors, panels, slats, feeders, etc.). The cost benefit has been widely documented in terms of return of investment (Gadd, J., 2005). A cleaning goal should consistently reduce and eliminate this rolling effect. Critical surfaces need a much better cleaning process due to potential bacteria accumulation, therefore the effect of double washing using a good alkaline detergent and then a good acid detergent could help to better attack scale and biofilm effect that could allow bacteria load accumulation on predisposing factors on critical surfaces of farrowing crates and nursery facilities.

The disinfectant and/or the disinfection process will not be able to replace any of the goals that are not achieved with the cleaning process. It is more cost-effective to work in the improvements of the cleaning protocols and process. When talking about farrowing crates, and other similar critical surfaces, a preventive program could be that at least two of the C&D processes per year (of the five C&D protocols per year) could be replaced with this double washing protocol.

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Dr Ricardo Munoz,

Technical Services at Neogen
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