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To observe the disinfection effect of polyhexamethylene biguanide disinfectant on the surface of hospital objects.


Cotton swab sampling and bacterial quantitative culture were used. The effect of a polyhexamethylene biguanide disinfectant on the surface of objects in hospital wards was observed. And do parallel comparison with chlorine-containing disinfectant.


The disinfectant concentration of 1380 mg/L of polyhexamethylene biguanide and the effective chlorine 500 mg/L of chlorine-containing disinfectant were used to disinfect the surface of the objects for 30 min. The hygiene quality pass rate was 100%.

Sampling and testing 24 hours after disinfection. The sanitary pass rate of object surface disinfected by polyhexamethylene biguanide was maintained at 70%. The sanitary pass rate of object surfaces disinfected by chlorine-containing disinfectants was 43%. It basically returned to the level before disinfection.

There was a significant difference in the qualified rate of surface hygiene between the two groups 8 hours after disinfection.


The disinfecting effect of polyhexamethylene biguanide disinfectant on the object surface is better than that of chlorine-containing disinfectant with a concentration of 500 mg/L. The details need to be further researched.

Polyhexamethylenebiguanide belongs to the guanidine class of disinfectants. It has the characteristics of good bactericidal and inhibition effect and safe use. It is widely used in the field of sanitary disinfection.

Guanidine compounds are cationic type. It is a low-efficiency disinfectant. Most of them are used in compound configurations to improve their bactericidal effect. In this study, a new compound disinfectant composed of polyhexamethylene biguanide and nano-scale silicone was used. The field disinfection effect of this biguanide disinfectant on hospital object surfaces was observed to provide an evidence-based basis for future use.

1. Materials and Methods

1.1 Test materials

The test group used biguanide disinfectant, namely methylethoxysilane polyhexamethylene biguanide. The stock solution content was 1380 mg /L. Supplemented with organic silicon (methyl ethoxilane) complex. Chlorine-containing effervescent tablets (500 mg/L effective chlorine) were used for parallel comparison.

Neutralizers were 10 g/L glycine, 10 g/L saponin, 40 g/L lecithin, and 60 g/L Tween- 80 in D/E broth. These were used in the polyhexamethylene biguanide test. 5 g/L sodium thiosulfate, 5 g/L Tween-80, were used in the chlorinated disinfectant test. The neutralizing agents were validated by identification tests (procedure omitted).

The test was conducted in the intensive care unit (ICU) and surgical ward of a hospital. The disinfection targets were bed linen and medical supplies.

1.2 Test methods

1.2.1 Test requirements

Sampling points should be selected in accordance with the 2002 edition of Disinfection Technical Specifications. The test ward was cleaned and disinfected for 1 week before the test. Use bed sheets for patients staying more than 24 hours. Do not disinfect 24 hours before sampling. Specific sampling objects include bed units, treatment vehicles, keyboards or mice, monitors or micropumps and other high frequency contact surfaces.

1.2.2 Disinfection implementation methods

( 1) Pre-disinfection sampling.

Each selected sampling site was firstly sampled before disinfection and served as a control group.

( 2) Implementation of disinfection.

Disinfection was carried out with a new disinfectant or chlorinated disinfectant using polyhexamethylene bis(guanidine), wipe disinfection was carried out according to the conventional wipe disinfection method, and post-disinfection sampling was carried out at different times set after disinfection.

( 3) Sampling method.

Sampling was performed with cotton swabs soaked with sampling solution, and four consecutive areas of 5 cm × 5 cm were sampled.

( 4) Quantitative culture of bacteria.

The sample swab head was aseptically cut into a tube containing 10 mL of the corresponding neutralizing agent, shaken thoroughly and neutralized for 10 min. 1. 0 mL of the eluate was taken and inoculated into a sterile dish, and molten nutrient agar medium cooled to 45℃ was poured into each dish for culture, and live bacteria were counted.

( 5) Result determination.

ICU is a class II environment, the total number of bacteria on the surface of the object should be ≤5 CFU/cm2 for qualified disinfection; GSD (general surgery department) wards belong to class III environment, the number of bacteria on the surface of the object ≤10 CFU/cm2 for qualified disinfection.

1.3 Statistical analysis

Data were analyzed using SAS 9.2. χ2 test was used to compare the difference in the number of bacterial colonies passing on the surface of the object. The t-test compares the differences in the mean number of bacterial colonies.

The data of this study are in time order. The number of bacterial colonies before and after the test is not independent of each other. That is, the number of colonies at the previous time point affects the number of colonies at the next time point. Therefore, repeated-measures ANOVA was used to compare the disinfectant’s 24-hour disinfection effect, and P<0. 05 was considered a statistically significant difference

2 Results

90 high-frequency surfaces were selected for each of the two disinfectants, 40 in the ICU and 50 in the surgical ward. Samples were taken before, 0.5 h, 4 h, 8 h, and 24 h after disinfection, respectively. A total of 900 units were sampled.

2.1 Bacterial contamination before disinfection

The surface contamination of objects in the ICU ward was high before disinfection. The average bacterial count was 18 CFU /cm2. The average number of bacteria on the surface of GSD objects was 5 CFU /cm2. The total number of bacteria exceeding the standard on the surface of hospital ward objects before disinfection is shown in Table-1.

Table-1. Contamination of the surface of hospital ward objects before disinfection

Object surfaceSampling copies numberBacterial exceed the standard copies numberOver standard rate, %
Patient bed rails442352.27
Bedside table301240.00
Therapy Cart301653.33
Mouse and keyboard361233.33
Operation Panel401640.00

2.2 Disinfection effect

2.2.1 Comparison of disinfection effect

The results showed that the qualified rate of the surface sanitary quality was 100% when the two disinfectants were wiped for 30 minutes.

Samples were collected and tested 24 hours after disinfection. The qualified rate of surface hygiene of polyHexamethylene biguanidine disinfection was maintained at 70%. The qualified rate of surface hygiene after disinfection with chlorine disinfectant is about 43%. Return to pre-disinfection levels (Table 2).

There was a significant difference in the qualified rate of surface hygiene 8 h after disinfection between the two disinfectants (P < 0.05).

Table-2. Comparison of disinfection effect of two disinfectants

Time after disinfection, hBiguanides disinfectantChlorine-containing disinfectant
Sampling NumberPassing Rate, %Sampling NumberPassing Rate, %

2.2.2 Comparison of residual bacteria count after disinfection

The results showed that with the prolongation of disinfection time, the living bacteria on the surface of the object increased continuously.

The number of viable bacteria on the surface of the object disinfected by chlorine-containing disinfectant increased faster than that of biguanide disinfectant.

The difference between the two was statistically significant (P<0. 05), as shown in Table 3.

Table-3. Comparison of bacteria count on the surface of the object at different times after disinfection with two kinds of disinfectants

wards SectiondisinfectantDetected bacteria
0 h0.5 h4 h8 h24 h

3. Discussion

Research shows that polyhexamethylene guanidine compound disinfectant not only has a better inhibiting ability to object surface bacteria but also can effectively inhibit and kill airborne bacterial propagules and fungi, hand Staphylococcus aureus, Escherichia coli, and drug-resistant Acinetobacter baumannii.

The polyhexamethylene biguanide disinfectant used in this study is different from the traditional compound disinfectant. It is a kind of polymer nanometer sol polymerization material. It is composed of poly (hexamethylene bigguanidine) and methyl ethoxysilane.

Although the methyl ethoxylane in the formula has no bactericidal effect, it can form a hydrophobic and oily nanostructured film on the surface of the object. This not only prevents microbial penetration and growth. It also increases the adhesion of polyhexamethylbiguanidine. So as to further improve and prolong its antibacterial efficacy.

Some researches have shown that the compound disinfectant of polyhMMbiguanide and silicone has better antibacterial effect on carbapenem-resistant pathogens than double-chain quaternary ammonium salt and chlorine-containing compound disinfectant.

The present study showed that this bivalve disinfectant had an overall better ability to inhibit bacteria than the chlorinated disinfectant. This is consistent with other studies.

The study also showed that the disinfection effect of the bivalve disinfectant varied between wards. In the ICU, the new disinfectant was effective for 0.5 to 24 h. The bacterial count on the surface was lower than that of the chlorinated disinfectant. However, the difference was not statistically significant.

In the surgical ward, the retention and inhibition effect was better than that of chlorinated disinfectants. The difference was statistically significant. The reason may be that the surface contamination of ICU objects is higher than that of surgical wards. For example, the ICU ward has a lot of consultation activities. It is also possible that factors affecting the new disinfectant existed in the field test. Factors such as surface material, temperature, and air circulation.