BIBLIOTHèQUE

Light intensity was detected inside cages in a DCC (Dynamic Containment Cages) system in a room with artificial lighting. Detections were done in three positions at animal level inside each cage: front, middle, and back at animal level in cages with bedding. The test shows that with a lighting of over 200 lux incident on the DCC rack, with cages made of Polysulfone (H-TEMP) and Polyetherimide (U-TEMP) cover and top, light intensity inside cages was never above 48 lux. Mean values of light intensity in the centre and in the back of the cages are respectively 14.2 and 10.5 lux.

Air flow velocity inside a DCC cage was measured in different to detected the air flow distribution. Measurements were done at different heights from the cage floor using 80, 100 and 120 ACH (Air change per hour). Tests showed a symmetric airflow distribution inside the cage and a maximum air velocity value of 0.25 m/s at animal level. Air flow distribution was therefore homogeneous at high level in cage. The combination of these two factors allow and guarantee a good air recirculation inside cages.

Excessive light intensity in animal rooms and consequently inside modern transparent cages for rodents can be a matter of concern due to deleterious effects especially on albino animals.

Polysulphone (PSU) is today  the most widely used plastic for the production of caging enclosures; its yellowish colour is particularly appreciated in terms of barrier activity to the outside light.

A new completely clear polysulphone material has recently been developed and consequently a comparative test between the two plastics, in terms of light intensity reduction within GM500 cages, was carried out.

Results show no statistically significant differences in the light intensity recorded inside the cages, making the use of this new plastic feasible, acceptable and safe for the animals.

Individually Ventilated caging systems were developed to reduce the spread of infective agents and allergens (bio-containment), at the same time cutting dramatically the risk of animals? microbial contamination (bio-esclusion). A secondary goal was to maintain low ammonia and CO2 levels in the cages. Local temperature and relative humidity are another two key parameters usually monitored at room level. Air distributed within IVC systems is not conditioned in terms of temperature and relative humidity, because of this, local factors like cage animal density or ventilation set-up (Air Changes per Hour) can theoretically interfere when an inappropriate (too low) number of ACH is set. This study confirms the hypothesis of higher variability in terms of RH in ventilated cages when the setting is below 50 ACH.

After the successful verification of the engineering standard parameters, a new IVC system for rodents requires an intensive phase of trials to assess the performance standard of the equipment. Because efficiency of ventilation is the key point to accept or reject any new IVC project, tests are carried out to study the micro-environment in terms of some standard parameters: NH3, CO2, O2, CH4, temp. and RH. Water intake, body weight growth or stability once mice are at their growing plateau are also considered. Different strains of mice were used in this trial with the IVC GM500 confirming the suitability of this new caging system for the appropriate holding of mice over a period of two weeks without any bedding change.

Comparative testing between different IVC systems requires the definition of a protocol where any possible variable is reduced to a minimum. Namely bedding quantity per square cm or initial body weight of the animals. Other parameters like number of Air Changes per hour are, on the contrary,suggested by the manufacturers and may occasionally differ slightly. The test carried out on three different IVCs showed a substantially comparable efficiency of the ventilationin compliance with the suggested acceptable parameters of the international guidelines in terms of temperature and RH as well as for gases removal.

A dynamic physical relation exists between the cage micro-environment and the surrounding room macro-environment. When studying the micro-environment in IVCs the control of the room environment should be carried out at the same time. This is what was done in this comprehensive study in one of the most important and modern animal facilities in the UK. The report provides information on noise and light levels both in one of the largest rooms at MRC Harwell plus the standard micro-environmental parameters in the Sealsafe IVC system in use at that facility.

CO2 Concentration Study in a Individually Ventilated Cage under static condition over a period of 24 hours
When IVCs are moved from their rack or when a power failure occurs ventilation stops and modifications of the micro-environment are unavoidable.

The monitoring of the micro-environmental parameters and possible effects on physiological behaviours of mice was investigated over a period of 24 hours in a GM500 IVC with five adult males. Results show that mean CO2 concentration is maintained well below the accepted limit of 3% and that no influences on general health conditions are detectable.

Excellent results had already been recorded during the 24-hour test in terms of “controlled” environmental condition once the GM500 Sealsafe plus is maintained in static conditions.

Because of this it was decided to monitor the micro-environment for a longer period to verify any consistent modification that might affect mice physiology.

Results confirm the stability of CO2 over a period of 72 hours with no signs of discomfort in mice and/or changes in their natural behaviour (increased activity during the dark phase). Normal increase of body weight, comparable to that recorded in the control group, point favourably to the possibility of having groups of mice in the GM500 unventilated for 72 hours.

Bio-containment and Bio-esclusion should be peculiar characteristics of Individually Ventilated Cages bothr in ventilated and static conditions.

The use of 0.2µm filters in Tecniplast cages is one of the features that helps to achieve this goal. In an attempt to verify whether or not it is possible to improve the micro-environment during the static condition, two different Reemay filters with a variable porosity and with a limited ability to avoid the escape or the entrance of particles carrying a number of micro-organisms or allergens were tested.

No advantages in terms of micro-environmental conditions were detected during the 72-hour test vs the 0.2 µm filters in use on the GM500 IVC leading to the conclusion that the latter is the perfect solution for the goal of Bio-containment and Bio-esclusion.

What happens in a static metabolic cage in terms of microenvironment when housing a medium size rat for 24 hours?

The test carried out with a 3701M081 Tecniplast metabolic cage and a male adult Sprague Dawley rat shows negligible levels of ammonia and the expected influence of the room temperature and Relative Humidity on the cage environment.

Due to the adaptation period on a wire mesh cage before moving the rat into the metabolic test cage, food intake was not affected significantly.

A comparative test between three filters with a different porous size was carried out in order to verify any possible advantage in static condition for one of them.

In general, all 3 filters worked in line with the purpose they are designed for, limiting the growth of CO2 to an acceptable level, sufficient to guarantee the survival in good clinical condition of mice. In previous tests where no filter was available (top 100% solid) the 8.8% CO2 concentration was reached in approximately two hours.

The 1µm GORE and the 2024 REEMAY® filters did not provide any advantage in terms of gases growth concentration control vs the 0.2 µm PALL filter.

The choice of the latter is highly justified in terms of both animal and human welfare.

The role played by substrates in modulating NH3 growth as a consequence of moisture content and proliferation of Urease positive bacteria is huge.

In this study stock males, stock females and breeding pairs were used to monitor ammonia growth in cages filled with Corn Cob, Alphadry or Wood Chip. As expected, clear differences were found in the concentration of ammonia at the end of the 14-day period between males and females housing cages.

A consistent higher increase of ammonia was detected in Wood chip group vs the other two substrate groups. Room relative humidity also played a role in modulating the increase or decrease of this gas.

The objective of this test was to verify the containment performances of a ferret cage purposely designed for use in ABSL3 facilities.

By means of smoke, simulating the presence of large quantities of particles inside the cage we monitored under different conditions, static or ventilating, the containment capability of the ferret cage once the side port used for the bag-in bag out procedure is open.

Importance of the test is in relation with the need to guarantee that in case of accidental opening of that specific port with no bags on and during standard operations, particles carrying hazardous pathogens are retained in the enclosure and not disperded in the outside environment.

Results show no statistically significant differences between the mean count of particles just in front of the port either open or close with the system running in negative pressure mode.

Dynamic Containment Cage represent a new frontier for staff protection working with rats treated with hazardous chemicals, pathogens or simply when Laboratory Animal allergy is an issue.  The objective of the test was to monitor the modification of a number of environmental parameters in the DCC cage system with rats over a period of two weeks. It was also objective of the test to monitor the body weight growth, food intake and bedding weight increase during the housing of rats in the DCC cage. Results indicate the possibility to maintain adult rats in the cage without changing the bedding for up to 12 days with no detection of ammonia a perfect control and stability of the key environmental parameters .

Alternative to wet showering, air showers are becoming more and more popular in animal facilities as barrier to limit introduction of pathogens.   Reduction of particles from Tyvek suit artificially contaminated with talc has been studied in conjunction with a Tecniplast air shower.   Size of particles taken into consideration vary from 0,3 to 5 microns, because representative of most micro-organism classes.   Seven repetitions of the test were carried out and a final efficiency of particles removal of 94,7% was recorded.

The Risk analysis procedure for noise and ultrasounds generated by a Multimagic II machine is described in this report. The innovative installation of an Ultrasound generator FISA CM Electronics inside the cap collection crates tank require the evaluation of the noise related risk for the 98/37/EC Machine directive Safety Requirement Number 1.5.8.  The machine once levelled on the floor and positioned far away from any possible external noise source and electromagnetic field was tested for sound pressure levels (machine off and on) and ultrasound emission at the same 8 positions for 30 seconds each.  Results assure that ultrasounds are dampened enough before being reflected outside the vanes of the machine, vibrations are not perceivable on external machine panels and sound level is in compliance with the 98/37/EC Directive.

Kronos is a fully automated system for the complete handling of dirty bottles for watering of laboratory animals. A washing machine, connected to the Kronos, is designed to wash water bottles and their caps in parallel wash chambers that are closed at each end by a guillotine door.   The objective of the study was to assess the washing efficiency of the IWT bottle washing machine operating with the combination of a standard cleaning action due to a detergent/disinfectant agent and the thermal disinfection phase at different temperature and exposure time, in terms of the bacterial load knock down when the water contained in the bottles is preliminary infected with a defined load of 4 different bacterial species in their vegetative form. All cycles were repeated twice each and did show the 100% killing of the infective agents.

An IWT rack washer series 900 was challenged with a load of “eggs holders” artificially contaminated with a complex cocktail of bacteria (106 cfu/ml), mould, yeasts (104 cfu/ml) and the Acholeplasma laidlawii (102 cfu/ml). The rack washer was operated with a solution of NaOH 2% during the washing phase followed by 60 sec thermal disinfection at 82°C.  There was no growth of bacteria, mould, yeast or Acholeplasma from the swabs confirming the efficiency of the cycle and the coverage of the load during the washing action.

The washing machine connected to the Kronos is designed to wash water bottles and their caps in wash chambers that are closed at each end by a guillotine door. Minimal configuration and operating conditions were applied and monitored in this trial. Cycleswith and withoutdetergentsin the washing water were compared. Minimal operating condition due to absence of thermal disinfection was the additional challenging factor.  Bottles and caps were infected with four bacteria singly or mixed together inoculated in sterile water bottles. The interesting results are described in the report.

The efficiency of a tunnel washer to evaluate the degree of cleanliness can be the assessment of the residual bacteriological load on the cages after a cycle when their surface is artificially contaminated with highly concentrated solutions of different micro-organisms. An IWT tunnel washer 10 m long was challenged in its performances by two different type of cages severely infected with four bacteria, one mould, one yeast and their mixture. A complete reduction from two to five log occurred after the cycle which means the achievement of No Growth end point expected vs the positive control.

In vivo tests on washing equipments take to results that are only applicable to the specific working condition of the facility where they are carried out. The report describe the organization and the outcome of a test carried out at an important animal facility where a 9 m IWT tunnel washer working with alkaline detergent only is installed.  The pre-washing microbiological load of Type II Polysulphone cages was ascertained and the following decrease after the cycle was monitored on a number of cages out of 117 washed during standard operations of that unit. The continuous monitoring of temperatures achieved by the different sections of the tunnel washer during the test is also described.

Can a tunnel washer perform as a Washer Disinfector? Is it possible for a tunnel washer to comply with the Health Technical Memorandum 2030 (NHS Estates, Agency of the Department of Health, UK) requirements? In this trial a successful attempt to give a positive answer to these questions was carried out. Modulating the drying temperature, the exposure time and monitoring the surface of a type II polysulphone cage (GM 500, Tecniplast) by means of a Wireless Thermo Recorder RTR-52/53 was possible to define the appropriate parameters of cycles that allow to satisfy the guidelines requirements.

The test was carried out on a standard Tecniplast ISOSLIM unit, connected in loop to a Clarus L H2O2 vapour generator with the target to decontaminate in loop the exhaust portion of Air Handling Unit with vaporized hydrogen peroxide. A suitable cycle was developed and the pertaining SOPs released.

This study was carried out to demonstrate the efficacy of a decontamination cycle within an IWT decontamination lock working in conjunction with a CLORDISYS Chlorine Dioxide gas generator. The characteristics of the decontamination cycles for a standard load were defined monitoring the 100% sporicidal and bactericidal efficacy by means of BIs.  On completion of the cycle, no growth occurred either in TSA, SDA or in spores’ culture media meanwhile the compatibility with the stainless steel did not show any side effect.

Following the first installation of a rack washer XL, a test was put in place to define cycles characteristics in terms of timing and quantity of hydrogen peroxide generated by a Clarus C vapour generator to achieve the 100% sporicidal efficacy assessed by means of BIs. The test was carried out at customer site in cooperation with Bioquell. A suitable decontamination cycle capable to guarantee 100% killing have been developed and validated.

This study was carried out to demonstrate the efficacy of a decontamination cycle within IWT decontamination lock working in conjunction with a Steris VHP1000ED H2O2 vapour generator. The characteristics of the decontamination cycles for a standard load were defined monitoring the 100% sporicidal and bactericidal efficacy by means of BIs and on completion of the cycle, no growth occurred either in TSA, SDA or in spores’ culture media.

A study, requested by a customer, was carried out to validate standard loads to be processed within the decontamination lock recently installed in the facility. Definition of cycles characteristics in terms of phase-time, quantity of hydrogen peroxide and standard loads structure monitoring the 100% sporicidal efficacy by means of BIs demonstrated the efficacy of the cycle and its compatibility with a load composed by electronic equipments such as desk top computer, LCD screen, keyboard and mouse.

Following the first installation of a decontamination lock with the catalyst filter on board, tests were put in place for the definition of cycles characteristics in terms of timing and quantity of hydrogen peroxide generated by a Clarus C vapour generator to achieve the 100% sporicidal efficacy assessed by means of BIs. The test, apart from showing the efficacy of the filtration unit in terms of short cycle time, demonstrated the efficacy of the new design of the decontamination chamber and the 100% killing rate.