YY/T 0471.5-2017Test methods for primary wound dressings - Part 5: Bacterial barrier properties (English PDF)

2.1 Low-moisture Condition

Under low-moisture condition, 2 sides of dressings are not wet. Under this condition, dressings shall manifest no or minimal exudate on the wound; the external surface of dressings shall be under low-moisture condition.

2.2 Semi-wet Condition

Under semi-wet condition, 1 side of dressings is wet. Under this condition, there is exudate on the wound, but the external surface of dressings shall be under low-moisture condition, namely, "dry outside, wet inside"; or there is no or minimal exudate on the wound, and the external surface of dressings is expected to be under wet condition, namely, "wet outside, dry inside".

2.3 Wet Condition

Under wet condition, 2 sides of dressings are wet. Under this condition, there is exudate on the wound, and the external surface of dressings is expected to be under wet condition.

4.1 Challenge Inoculum Preparation

Pick Serratia Marcescens colony from the bevel of Serratia Marcescens working strain; conduct streak inoculation on the plate of nutrient agar medium.

4.2 Challenge Bacterial Solution Preparation

Pick single colony of Serratia Marcescens from the plate of challenge inoculum prepared in 4.1, inoculate it in nutrient broth medium. Through overnight culture at 26 °C, obtain challenge bacterial solution (concentration. around 109 CFU/mL), which can be adopted in bacterial barrier property test under semi-wet condition (wet outside, dry inside) and wet condition. Prepared challenge bacterial solution shall preferably be used on the same day.

5.1 Test Device

Please see the sketch map of bacterial barrier property test device under low-moisture 2 Standard strain released by domestically and internationally acknowledged strain preservation institutions, such as ATCC 8100, CICC 10187, etc.

5.2 Test Procedure

5.2.1 Sample clamping

Respectively take 3 samples, turn the internal surface of the samples towards the sampling room. Clamp the samples to the area between the challenge room and the sampling room. The mode of clamping shall be confirmed; guarantee that there is no leakage of challenge microorganism. In terms of relatively large sample, cut off the remaining part or wrap it around the test device; in terms of relatively small sample, raw materials of large samples can be adopted for testing, or an appropriate mode can be adopted to fill up the missing part for testing.

5.2.5 Challenge microbiological vitality examination

After the stipulated time, operate in accordance with 5.2.4. Wipe the external surface of the samples through the mouth of the challenge room to examine challenge microbiological vitality.

5.3 Result Judgment

On the plate of nutrient agar medium that is adopted for vitality examination, there shall be the growth of Serratia marcescens; otherwise, the test shall be deemed as invalid.

6 Bacterial Barrier Properties under Semi-wet Condition (Dry Outside, Wet Inside)

6.1 Test Device

Please see the sketch map of bacterial barrier property test device under semi-wet condition (dry outside, wet inside) in Figure 2 below.

6.2 Test Method

6.2.1 Sample clamping

Operate in accordance with 5.2.1.

6.2.2 Add challenge microorganism

Operate in accordance with 5.2.2.

6.2.3 Add nutrient broth medium

Fill up the sampling room with nutrient broth medium in the mode of sterile operation.

6.3 Result Judgment

On the plate of nutrient agar medium that is adopted for vitality examination, there shall be the growth of Serratia marcescens; otherwise, the test shall be deemed as invalid.

7 Bacterial Barrier Properties under Semi-wet Condition (Wet Outside, Dry Inside)

7.1 Test Device

Please see the sketch map of bacterial barrier property test device under semi-wet condition (wet outside, dry inside) in Figure 3 below. Challenge room shall be used to place challenge inoculum; sampling room shall be used to wipe samples.

7.2 Test Method

7.2.1 Sample clamping

Operate in accordance with 5.2.1.

7.2.2 Add challenge microorganism

Fill up the challenge room with challenge bacterial solution.

7.2.3 Sample challenge

Operate in accordance with 5.2.3.

7.3 Result Judgment

On the plate of nutrient agar medium that is adopted for vitality examination, there shall be the growth of Serratia marcescens; otherwise, the test shall be deemed as invalid.

If there is no growth of microorganism on the plate of nutrient agar that is adopted for the sampling analysis of the internal surface of the sample, it shall be deemed that the sample complies with the requirement of bacterial barrier properties under semi-wet condition (wet outside, dry inside).

8.1 Test Device

Please see the sketch map of bacterial barrier property test device under wet condition in Figure 4 below. Challenge room shall be used to place challenge inoculum; sampling room shall be used to place nutrient broth medium. Before test, adopt sterilization procedure that has already been confirmed to sterilize the test device for later usage.

8.2 Test Method

8.2.1 Sample clamping

Operate in accordance with 5.2.1.

8.2.2 Add challenge microorganism

Operate in accordance with 7.2.2.

8.2.3 Add nutrient broth medium

Operate in accordance with 6.2.3.

8.3 Result Judgment

On the plate of nutrient agar medium that is adopted for vitality examination, there shall be the growth of Serratia marcescens; otherwise, the test shall be deemed as invalid.

A.1 Applicable Object

Clinically speaking, infection is an important complication of wound. Primary wound dressings play a role as a mechanical barrier of wound. The bacterial barrier properties of primary wound dressings are tremendously important to the control of wound infection. However, this does not mean all the primary wound dressings are requested to manifest bacterial barrier properties. Certain types of wound with extremely low risks of infection might not need primary wound dressings with bacterial barrier properties.

Furthermore, the bacterial barrier properties of some primary wound dressings that need to be matched with secondary dressings are jointly provided by the two types of dressing, and merely conducting evaluation on the bacterial barrier properties of primary wound dressings might also lead to unilateral information. The evaluation of whether a specific primary wound dressing has the bacterial barrier properties depends on intensive study of risks of infection of different types of wound.