JP2003274995A - Method for evaluation of antibacterial performance of air conditioning facility - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for the evaluation of the antibacterial performance of air-conditioning facilities to evaluate the performance in the real working environment and grasp the decrease of the number of bacterial cells with time. <P>SOLUTION: A test machine 1A treated with an antibacterial agent and a contrast machine 1B free from the antibacterial treatment are prepared beforehand. A definite quantity of bacterial liquid is applied to a prescribed surface position of each machine, the air conditioners are operated and the antibacterial performance of the agent is evaluated by the variations of the number of live bacterial cells in the test machine 1A and the contrast machine 1B. The number of live cell colonies are counted at the start of the evaluation test, at the end of the test and one or more points during the test to grasp the change of the number of the live cells with time. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating the antibacterial performance of an air conditioner equipped with an antibacterial agent at a real machine level.

[0002]

2. Description of the Related Art Indoor air pollution caused by microorganisms has become a serious problem, for example, causing hospital infections in office buildings, hospitals, special elderly facilities and the like. on the other hand,
Since microorganisms prefer an environment of high humidity, they are often present in air conditioners that have adhered particles such as dust, which are a nutrient source, and have high humidity during operation.

Therefore, in recent years, it has come to be performed that an air conditioner is subjected to antibacterial processing to impart antibacterial performance. In addition, along with this, it has become important to evaluate the antibacterial performance. The film adhesion method defined in JIS Z 2801 exists as the only method capable of quantitatively evaluating such antibacterial performance.

In the film contact method, as shown in FIG. 5, first, an antibacterial processed test piece and a non-processed test piece cut into a size of 5 cm × 5 cm are placed on separate petri dishes, and a test chamber and the like are placed. Use 2.5-10 × 10 ⁵ pieces / ml
After dropping 0.4 ml of the bacterial solution prepared so that each of the test pieces was placed on the test piece, a film cut into 4 cm × 4 cm was put on the test piece to adhere it to the test piece. Leave for 24 hours. Next, the film is peeled off, the bacterial solution adhering to the test piece is washed out with a liquid medium, and this is diluted (or smeared) with an agar medium and cultured at a temperature of 35 ° C. for 48 hours.

Then, the number of viable bacterial colonies generated on the medium is counted, and the common logarithmic value of each colony number is calculated.
As shown in (1), subtract the common logarithm of the colony count of the antibacterial processed test piece from the common logarithm of the colony count of the unprocessed test piece, and if this value (antibacterial activity value) is 2.0 or more, the antibacterial effect is obtained. If it is less than 2.0, it is judged that there is no antibacterial effect.

[0006]

[Equation 1]

In the above-mentioned film contact method, the reason why the common logarithmic value of the number of colonies of the antibacterial processed test piece is reduced is to extract only the effect of the antibacterial processing. In addition, in the case of the concentration of microorganisms, since it is usual to judge at the order level (digit level), the common logarithmic value is used for evaluation. Therefore, 2 × 10 ⁵ and 5 × 10 ⁵ are treated as the same density.

[0008]

However, the film adhesion method simply measures the number of viable bacteria at the end of the test for each of the antibacterial processed test piece and the unprocessed test piece. It is only to evaluate the performance. Also, antibacterial test time (24 hours)
Since the temperature and humidity conditions (37 ° C., 90% or more) are significantly different from the operating conditions of the air conditioning equipment, there is a problem in that the antibacterial performance on a real machine level cannot be grasped by this film contact method.

On the other hand, unlike general particles, the number of microorganisms fluctuates depending on the environment. Therefore, it is very important to understand the decreasing tendency of the number of microorganisms along with the time axis. But,
In the film adhesion method, although the antibacterial evaluation is quantified, it is possible to grasp the tendency of the decrease in the number of microorganisms only by making the test time uniformly 24 hours and evaluating only the number of decreased microorganisms at the end of the test. There was a problem I couldn't do.

In addition, the antibacterial agent meets the necessary conditions,
It can exert an antibacterial effect. However, the film contact method is only testing the material subjected to antibacterial treatment under uniform time and temperature / humidity conditions, and the conditions such as temperature / humidity at the time of actual operation of the air conditioning equipment and presence or absence of dew condensation are Not considered at all. Therefore, although the result is worth considering as a reference value, it is virtually meaningless.

Therefore, the main object of the present invention is to make it possible to evaluate the antibacterial performance in the actual operating environment of the air conditioning equipment, and to grasp the tendency of the decrease in the number of bacteria along with the time axis. It is to provide a performance evaluation method.

[0012]

As an invention according to claim 1 for solving the above-mentioned problems, there is provided an antibacterial performance evaluation method for evaluating antibacterial performance for actual air-conditioning equipment.
Prepare a target machine that has been subjected to antibacterial processing, and a comparison machine that is not subjected to antibacterial processing, apply a fixed amount of bacterial solution to each predetermined surface position, and operate the air conditioning facility for a predetermined time Try to evaluate the antibacterial performance based on the variation of the number of viable bacteria in the comparator, and to count the number of viable colonies at the start of the evaluation test and the number of viable colonies at the end of the evaluation test, and at the start of the evaluation test By counting the number of viable bacterial colonies at one or more elapsed time between the end of the evaluation test and the end of the evaluation test, it is possible to grasp the fluctuation tendency of the viable bacterial number in relation to the elapsed time. A method for evaluating antibacterial performance of an air conditioning system is provided.

In the invention according to the above-mentioned claim 1, the target machine which has been subjected to the antibacterial treatment and the comparison machine which is not subjected to the antibacterial treatment are prepared respectively, and a predetermined amount of the bacterial solution is applied to the surface at a predetermined position to provide an air conditioning facility. It was operated to perform antibacterial performance evaluation. Therefore, it becomes possible to evaluate the antibacterial performance in the environment during the actual operation of the air conditioning equipment. As a result, for example, the antibacterial effect is expected to be different between the middle season and the summer, but it becomes possible to understand such a difference in antibacterial effect for each season.

Furthermore, while the microbial particles exhibit physical behavior similar to general particles, since they are living things, their numbers greatly fluctuate due to environmental factors, etc., and the tendency of their fluctuations also differs. Therefore, in the present invention, at the start of the test,
The number of viable colonies is counted not only at the end of the test but also at the stage during the test. As a result, it becomes possible to grasp the tendency of the variation of the bacteria along with the time axis.

As an invention according to claim 2, a common logarithmic value of the number of viable bacterial colonies is obtained at the start of the evaluation test, at the one or more elapsed times during the evaluation test, and at the end of the evaluation test, and each elapsed time is calculated. At each time and at the end of the evaluation test, the value obtained by subtracting the common logarithm at each elapsed time or at the end of the evaluation test from the common logarithm at the start of the evaluation test for each of the target machine and the comparison machine is calculated. An antibacterial performance evaluation method for air conditioning equipment according to claim 1, wherein a value obtained by subtracting the value in the comparator from the value is obtained as an integer value, and the antibacterial performance is ranked according to the size of the integer value. .

The invention according to the second aspect of the invention is a concrete clarification of the quantification method. The integer value serves as an index value for evaluating antibacterial performance, and it becomes possible to specifically evaluate the degree of antibacterial performance depending on which rank of the preset evaluation categories this value belongs to.

According to the present invention of claim 3, in applying the bacterial solution, agar is added to prevent the bacterial solution from flowing together with the dew condensation water to increase the viscosity. An antibacterial performance evaluation method for an air conditioning facility is provided.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an example of an air conditioning facility to be tested by the evaluation method according to the present invention.

The air-conditioning equipment 1 shown is a fan coil unit type air-conditioner, and at one end thereof, an outside air filter 2 is provided which allows the outside air O to pass through the inside of the equipment while removing dust and the like mixed therein. An outside air damper 3 adjacent to the outside air filter 2 controls the amount of outside air O passing through the inside of the equipment.

On the other hand, a mixing box 4 is provided adjacent to the outside air damper 3, and the return air R sucked into the mixing box 4 and the outside air O entering from the outside air damper 3 are mixed in the mixing box 4 with each other. It is supposed to be mixed in. Then, the mixed air, after passing through the plurality of filters 5 and 6, is adjusted to a desired temperature in the cold / hot water coil 7, and the humidifier 8
After the humidity is adjusted to an appropriate level, the air blower 9 supplies the air as the air supply G from the other end side.

In the air conditioner 1, the adhered particulate matter that serves as a nutrient source for the microorganisms is present, and the humidity during air conditioning is high, so that the environment where the microorganisms easily propagate is created.

In this example, a method of performing antibacterial processing on the coil fins of the cold / hot water coil 7 and evaluating the antibacterial effect will be described in detail with reference to the flow chart of FIG.

First, a target machine 1A having antibacterial processing on the coil fin and a comparison machine 1B not having antibacterial processing are prepared respectively, and both the coil fin 7A having antibacterial processing and the unprocessed coil fin 7B are prepared. Apply the bacterial solution to the surface of. At this time, since the coil fins 7A and 7B are linear when viewed from the front, the bacterial solution cannot be evenly applied as it is. Therefore, the coil fins 7A and 7B are bent to have a planar shape when viewed from the front so that the bacterial solution can be easily applied to the surface. The bent coil fin 7
On the surfaces of A and 7B, a frame of equal area is made of thread.

Then, the inner surface of the frame is lightly wiped with absorbent cotton soaked in ethanol for 2 to 3 times and dried, and the prepared bacterial solution is evenly applied to each frame with a absorbent cotton swab. It is desirable that the bacterial solution is an actual target bacterium or Escherichia coli (indicator bacterium). In addition, the concentration is 5-10 × 10 ⁵ (CFU / m
l) is preferable.

Immediately after the application, the surface to which the bacterial solution is applied is wiped with a sterilized cotton swab (ST15 manufactured by Elmex Co., Ltd.) soaked in a sterilized phosphate buffer solution to obtain a test sample for wiped bacteria. From this test sample, as shown in FIG. 3, a fixed amount was taken out by a dispenser 10, inoculated into a contact slide medium 11 for general bacteria, cultured at 35 ° C. for 24 to 48 hours, and then grown. Count the number of colonies 12 of.

Immediately after application of the test sample for bacteria immediately after application,
After the operation of the target machine 1A and the comparator 1B is started and a predetermined time has elapsed (h ₁ , h ₂ , h _n ...), and at the time of the end of inspection h _E , the surface of the coil fin is in accordance with the procedure described above. The bacterial solution is wiped off from the sample to prepare a bacterial test sample, which is cultured under the same conditions, and the number of colonies of the grown bacteria is counted.

The antibacterial performance was evaluated immediately after applying the bacterial solution.
The number of adherent bacteria (the number of colonies) of the target device 1A and the comparison device 1B is calculated.
Apply A1 (CFU / ml) and B1 (CFU / ml) respectively, and apply the bacterial solution.
H _iThe number of adherent bacteria on the target device 1A and the comparison device 1B after a lapse of time
Antibacterial performance as A2 (CFU / ml) and B2 (CFU / ml) respectively
The index (API) is calculated from the following formula (2). The antibacterial performance
The index (API) is rounded off to the nearest whole number.

[0028]

[Equation 2]

The above-mentioned antibacterial performance index (API) is evaluated in three stages, and if API = 1, the antibacterial performance may be evaluated. If API = 2, it is evaluated as having antibacterial performance, and if API ≧ 3, it is evaluated as having strong antibacterial performance. However, if there is a large decrease in the number of bacteria in the comparator 1B, is the decrease in the number of bacteria in the target device 1A due to the antibacterial performance of the antibacterial agent? Since it is not possible to judge whether it is true, set log (B1 / B2) ≤ 2 as a test satisfaction condition.

In this example, the case where the fin coil of the fan coil unit type air conditioner is subjected to the antibacterial treatment has been described as an example, but the evaluation method according to the present invention can be applied to other parts of the air conditioner, Air handling unit type air conditioner,
It can also be applied to drain pans, humidifiers, room air conditioners, and other commercially available antibacterial goods.

[0031]

[Examples] MRSA (Methicillin resista), which is a test strain and is considered to be a causative bacterium of nosocomial infection, is used by using one target device 1A that has been subjected to antibacterial processing and one comparison device 1B that has not been subjected to antibacterial
ntstaphylococcus aureus, methicillin-resistant Staphylococcus aureus). Bacterial solution was cultivated for 24 hours at 35 ° C using Brain Heart Infusion medium, and the test strains stored frozen were adjusted to a concentration of 5-10 × 10 ⁵ (CFU / ml) with sterile phosphate buffer. What was prepared in 1. was used as the test bacterial solution. In addition, 0.15% agar was added to prevent the test bacterial solution from flowing along with the dew condensation water on the coil surface to increase the viscosity.

A frame of 5 cm × 10 cm (50 cm ² ) was made with a thread on each of the fin coils 7A and 7B of the target machine 1A and the comparative machine 1B, and one hour immediately after the application of the bacterial solution in order to grasp the change with time of the antibacterial performance. After 3 hours and 5 hours (inspection end time)
In addition, a sample was taken, and a part (10 μl) of the sample was inoculated into a contact slide medium for general bacteria and incubated at 35 ° C for 24 hours.
After culturing for ˜48 hours, the number of grown bacterial colonies was counted.

The results of the evaluation test are shown in FIG. From the figure, it can be seen that the target device 1A has a viable cell count of 0 after 5 hours, and exhibits a strong bactericidal performance rather than an antibacterial effect. Also, 3
When the antibacterial performance index (API) is calculated after time, API = log
(A1 / A2) −log (B1 / B2) = log (516000/11000) −log (416000 /
538000) = 2, indicating that the target device 1A has antibacterial performance. In addition, the number of viable bacteria after 5 hours also decreased in the comparator 1B, which is considered to be a result of a part of the bacteria flowing out by dew condensation water.

[0034]

As described above in detail, according to the present invention, it becomes possible to evaluate the antibacterial performance in the actual environment when the air conditioning equipment is operating, and to grasp the tendency of the decrease in the number of bacteria along with the time axis.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an air conditioning facility to be tested by an evaluation method according to the present invention.

FIG. 2 is a flow chart of an evaluation method according to the present invention.

FIG. 3 (A) is a diagram in which a test sample is inoculated into a medium by a dispenser 10, and (B) is a diagram showing a state in which a colony 12 has grown in the medium.

FIG. 4 is a graph showing the change over time in the viable cell count according to the example.

FIG. 5 is a flow chart of a film contact method.

[Explanation of symbols]

1 ... Air conditioning equipment, 2 ... Outside air filter, 3 ... Outside air damper, 4
… Mixing box, 5/6… Filter, 7… Cold / hot water coil, 8…
Humidifier, 9 ... Blower, 10 ... Dispenser, 11 ... Contact slide medium, 12 ... Colony

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2G045 AA28 BB20 CB21 FB04 GC22                       JA01                 2G052 AA00 AB16 AC19 AD32 AD52                       CA03 CA04 EB12 GA29                 3L051 BC10                 4B063 QA01 QA06 QQ05 QR69 QR74                       QS24 QX01

Claims (3)

[Claims] 1. An antibacterial performance evaluation method for evaluating antibacterial performance of an actual air-conditioning facility, wherein an antibacterial processed target machine and a non-antibacterial processed comparison machine are prepared respectively. Apply a certain amount of bacterial solution to a predetermined surface position, operate the air conditioning equipment for a predetermined time to evaluate the antibacterial performance based on the fluctuation of the viable cell count in the target machine and the comparison machine, and start the evaluation test The number of live bacterial colonies at the time and the number of live bacterial colonies at the end of the evaluation test, and the number of live bacterial colonies at one or more elapsed times between the start of the evaluation test and the end of the evaluation test. Thus, the method for evaluating the antibacterial performance of an air conditioning facility is characterized in that the fluctuation tendency of the viable cell count is grasped in relation to the elapsed time. 2. The above 1 during the evaluation test at the start of the evaluation test.
Or, at multiple elapsed times and at the end of the evaluation test, calculate the common logarithm of the number of viable colonies, and at each elapsed time and at the end of the evaluation test, use the target device and the comparator at the start of the evaluation test. The value obtained by subtracting the common logarithmic value at each elapsed time or at the end of the evaluation test from the logarithmic value is obtained, and the value obtained by subtracting the above value in the comparator from the above value in the target machine is obtained as an integer value. The antibacterial performance evaluation method for an air conditioner according to claim 1, wherein the antibacterial performance is ranked in accordance with the degree. 3. The antibacterial performance evaluation method for air conditioning equipment according to claim 1, wherein upon application of the bacterial solution, agar is added to prevent the bacterial solution from flowing together with the dew condensation water to increase the viscosity. .