Objective To investigate the in vitro antimicrobial activity of antimicrobial peptide RP557 and its mechanism, and to evaluate its safety. Methods The minimum inhibitory concentration (MIC) of RP557 against various clinical isolates was determined using the microdilution broth method. The bactericidal mechanism of RP557 against Gram-negative bacteria was analyzed through time-kill assays, biofilm inhibition, outer and inner membrane disruption, and ion leakage detection. The safety of RP557 at the animal level was assessed through histopathological examination and hepatic and renal function tests. Results MIC values of RP557 were≤32 µg/mL against multidrug-resistant and hypervirulent Gram-negative and Gram-positive clinical isolates. Biofilm formation could be completely inhibited at 1×MIC. Treatment with 2×MIC induced a 1.5-fold increase in outer membrane disruption, 10-fold increase in inner membrane damage, and significant Na⁺/K⁺ leakage. No significant differences in hepatic/renal function indices or lung histopathology scores were observed in mice after 400 µg/mL aerosol exposure compared to controls. Conclusion RP557 induces bacterial death through a dual-membrane disruption mechanism. At certain exposure doses, it shows no toxic side effects, highlighting its potential as a novel bactericidal agent.

Objective To evaluate the disinfection effect of two disinfectants on bacteria in the dust accumulated in centralized air-conditioning return air filters, and to explore the effect of air conditioner filter cleaning and disinfection methods on the total number of relevant indoor air bacteria. Methods During the period from 2018 to 2024, the dust accumulated in the return air filters of centralized air-conditioning units in some wards of three tertiary hospitals in Wuhan was sampled, and the total number of bacteria was calculated. Simulated on-site and on-site disinfection tests were conducted on air-conditioning filters using a chlorine disinfectant with an effective chlorine level of 500 mg/L and a complex quaternary ammonium salt disinfectants with a level of 3 000 mg/L, and the disinfection effects were evaluated. Changes in bacterial counts in indoor air before and after direct rinsing of air-conditioning filters with tap water and after disinfection and then rinsing were detected using the plate exposure method and the air sampler method in the dirty washroom of a hospital department. Results The amount of dust accumulated in the air conditioner return air filters was positively correlated with the total number of bacteria, with a correlation coefficient of 0.77. The results of the simulated on-site disinfection test showed that the concentration of chlorine-containing disinfectant and compound quaternary ammonium salt disinfectant failed to disinfect the filter when the concentration decreased to 31.20 mg/L and 1 820.70 mg/L, respectively. The results of on-site disinfection test showed that when the concentration of chlorine-containing disinfectant and compound quaternary ammonium salt disinfectant were lower than 50 mg/L and 2 000 mg/L, respectively, the filter disinfection failed. Both the plate exposure method and the air sampler method showed that the direct use of tap water to rinse the filters significantly increased the total number of airborne bacteria in the room of interest. After disinfecting and then rinsing the filter with tap water, the total number of indoor air bacteria was similar to that before cleaning. Conclusion Chlorine disinfectant (effective chlorine 500 mg/L) and compound quaternary ammonium salt disinfectant (3 000 mg/L) can effectively kill bacteria in the dust of centralized air-conditioning return air filter after 5 minutes disinfection. The use of pre-sanitization followed by cleaning reduces bacterial contamination of the relevant indoor air environment.

Objective To establish and optimize a high performance liquid chromatography-tandem mass spectrometry method for the determination of five disinfection byproducts in drinking water, and compare it with ion chromatography. Methods The samples were separated by an 0.22 m microporous membrane on a Dionex IonPac AS16 column (2 mm ×250 mm, 9 m), and then treated with acetonitrile-0.7 mol /L methylamine (60:40)，electrospray ion source and negative ion mode. At the same time, the samples were separated through 0.45 m microporous filter membrane by Metrosep A Supp 18-250 column. The leached solution was 9 mmol/L KOH, 1.25 mmol/L Na₂CO₃ and 1% sulfuric acid, then analyzed by ion chromatogram. Results The linear correlation coefficient (r) of the five disinfection byproducts of the two methods was >0.999 4. The detection limit was 0.001-0.004 mg/L, and the determination limit was 0.003-0.001 2 mg/L. The average recovery rate was 89.4%-105.4%. The relative standard deviation was 1.0%-5.4%. Both method were used to test 30 samples of drinking water, in which no bromates or hypochlorites were detected. The mean values of dichloroacetic acid measured by HPLC-MS/MS and IC were 0.032 and 0.034 mg/L, and the mean values of chlorate were 0.069 and 0.066mg/L, respectively(P>0.05). The detection rates of trichloroacetic acid were 90.0% and 53.3%, respectively (P<0.05). Conclusion The two methods have their own advantages and disadvantages. The appropriate method should be selected according to actual situation.

Objective To evaluate the dynamic disinfection efficacy of a 222 nm ultraviolet (UV) sterilizer on high-frequency contact surfaces and airborne bacteria in a respiratory intensive care unit (RICU). Methods Seven isolated rooms within the RICU of a tertiary hospital in Zhejiang, China, were selected. Rooms were assigned to either a control group (Room 2, 4, 6) receiving routine cleaning and ventilation, or an intervention group (Room 1, 3, 5, 7) receiving additional disinfection using a 222 nm UV sterilizer. Environmental samples were collected continuously for 3 days, with air and surface samples taken every 2 hours from 8:00 to 16:00 daily, totaling 1 050 samples. Bacterial colony counts and detection rates of Acinetobacter baumannii (AB) and Klebsiella pneumoniae (KP) were measured. Results The intervention group showed significantly lower mean colony counts on both surfaces and in air samples compared to the control group (P<0.05). Surface bacterial load was reduced from (161.63±464.17) cfu/cm² to (54.64±220.59) cfu/cm², while airborne bacterial load decreased from (215.14±303.88) cfu/m² to (150.65±106.52) cfu/m². The detection rates of AB and KP also decreased significantly in both surface and air samples. Conclusion The 222 nm ultraviolet sterilizer demonstrates significant disinfecting efficacy in the RICU environment. It effectively reduces microbial contamination on surfaces and in the air. Notably, it exhibits more stable and sustained efficacy for air disinfection. This device serves as a robust supplementary measure to routine disinfection protocols.

Objective To investigate and analyze the disinfection measures and efficacy of drinking water in rural of Zhoukou City, so as to provide a basis for ensuring rural drinking water safety. Methods Data on disinfection facilities and disinfectant usage in rural drinking water systems from 2020 to 2023 were collected. Residual disinfectant levels and total bacterial counts in drinking water were analyzed. Disinfection efficacy was evaluated according to GB 5749-2006 Standards for Drinking Water Quality. Results From 2020 to 2023, a total of 183, 183, 181 and 180 rural water treatment plants were monitored annually. The proportion of plants using disinfection facilities as required increased from 64.48% in 2020 to 74.44% in 2023 (χ²=3.571, P=0.059). Chlorine dioxide and sodium hypochlorite remained the predominant disinfectants, with the proportion of plants using sodium hypochlorite rising from 26.78% in 2020 to 43.89% in 2023 (χ²=6.808, P=0.009). Pass rates of residual disinfectant for sodium hypochlorite, chlorine dioxide and liquid chlorine treated samples were 67.04%, 89.23% and 90.83%. Chlorine dioxide-treated samples showed the lowest total bacterial count compliance (93.80%) (χ²=10.465, P=0.005). Residual disinfectant compliance was lower in finished water than in terminal water (χ²=4.579, P=0.032). Microbial compliance was higher in finished water than in terminal water (χ²=6.645, P=0.010). Residual disinfectant compliance was higher in the wet season than in the dry season (χ²=5.385, P=0.020). Microbial compliance was lower in the wet season than in the dry season (χ²=19.273, P<0.001). Residual disinfectant compliance was higher in conventionally treated reservoir water than in disinfected deep well water (χ²=9.166, P=0.002) (χ²=1.212, P=0.271). Conclusion Rural drinking water in Zhoukou City exhibits a high compliance rate for residual disinfectant levels. Disinfectant type, water sample type, season, water supply method, and water source classification exert varying degrees of influence on disinfection efficacy.

Objective To study the stability and antibacterial effect of a segmented fermentation citrus antibacterial solution by yeast, Lactobacillus plantarum and acetic acid bacteria, and to evaluate its safety. Methods The pH, thermal stability, heavy metal content and microbial contamination indexes of the citrus fermentation broth were determined, and the inhibitory effect of the citrus fermentation broth on Staphylococcus aureus, Escherichia coli and Candida albicans was detected by quantitative suspension method, and the skin irritation test was carried out in New Zealand rabbits. Results The pH of the fermentation broth was 3.25. The heavy metal and microbial contamination test results met the hygiene standards; the average antibacterial rates of 27 g/L for 10 min against Escherichia coli, Staphylococcus aureus, and Candida albicans were 90.44%, 84.42%, and 53.47%, respectively. The antibacterial rates of the fermentation broth against Candida albicans before and after stability experiments for 20 minutes were 94.46% and 93.43%, respectively. Skin irritation test results on New Zealand rabbits showed no irritation. Conclusion The citrus antibacterial solution produced through multi-bacterial fermentation has good antibacterial effects and safety for use.

Objective To determine the optimal pre-treatment protocol for engraved areas on instruments during cleaning and disinfection through orthogonal experiment design. Methods A total of 180 pieces 14 cm hemostatic forceps with engraved markings collected from the decontamination area of a central sterile supply department (CSSD) between May and August 2024 were selected. Using L₆(3×2) orthogonal design, six experimental groups were established with three pre-treatment methods (A₁: no pre-treatment; A₂: 30 s rinse under running water; A₃: enzymatic immersion for 1 min followed by brushing) and two mechanical cleaning methods (B₁: fully automatic spray washer; B₂: vacuum boiling cleaning machine), with 30 instruments per group. Cleaning efficacy was evaluated through visual inspection and protein residue testing, with analysis of factors influencing cleaning quality. Results Range analysis revealed that pre-treatment method (Factor A) had greater impact on cleaning quality than mechanical cleaning method (Factor B). The optimal combination was enzymatic immersion with brushing + vacuum boiling cleaning machine (A₃B₂). While no statistically significant difference existed between A2 and A3 in cleaning efficacy, the 30 s water rinse demonstrated higher time efficiency. Conclusion Pretreatment selection for engraved sites should be based on contamination level, with vacuum boiling cleaning machine recommended as the preferred cleaning method.

Objective To understand the current situation of disinfection work in some medical institutions in Xinxiang City from 2023 to 2024, and to provide scientific basis for effectively improving the disinfection quality and infection control work of medical institutions in the city. Methods A retrospective analysis was conducted to statistically analyze the disinfection quality monitoring data of Xinxiang City from 2023 to 2024. Results From 2023 to 2024, a total of 86 medical institutions were monitored for disinfection quality, with 1 275 samples collected and 1 151 qualified samples. The total qualified rate was 90.27%, and there was a statistically significant difference in the qualified rate between the years(χ²=0.036, P<0.05); Among different types of medical institutions, tertiary hospitals had the highest qualification rate (93.28%) and private hospitals and clinics had the lowest qualification rate (85.85%). The difference in the overall qualification rate of disinfection quality was statistically significant (χ²=12.958, P<0.05); Among different monitoring items, the overall pass rates of pressure steam sterilizers (100.00%), medium risk medical equipment (100.00%), low-risk medical equipment (96.94%), and disinfectants in use (96.91%) were relatively high, while the overall pass rates of medical staff hands (77.41%) and medical institution sewage (80.70%) were relatively low. There was no significant difference in the qualified rate of each monitoring item between the two years (P > 0.05). Conclusion The overall disinfection quality of medical institutions in Xinxiang City is good from 2023 to 2024, but there are still deficiencies in medical water, hand hygiene, and sewage discharge. The disinfection quality of private medical institutions needs to be strengthened.

Objective To understand the basic situation and quality of disinfection in kindergartens in Jining City, and to provide scientific basis for prevention and control of infectious diseases in kindergartens. Methods The basic situation and quality of disinfection in 49 kindergartens in Jining city were investigated and monitored by questionnaire survey and sampling, and the data were analyzed. Results In 2023, 49 kindergartens in 11 counties and districts under the jurisdiction of Jining city were investigated, of which 17 were public and 32 were private. The disinfection skills training was mainly based on the internal training of kindergartens, accounting for 83.67%. A total of 1 882 samples were detected, and 1 479 qualified, with a qualified rate of 78.59%; The commonly used disinfectants were mainly chlorine-containing disinfectants and alcohol-based disinfectants. The qualified rates of tableware and staff hands disinfection were relatively low, at 72.53% and 58.31%, respectively. Different surfaces, different staff hands hygiene, different counties and districts, different sizes and different establishment times had statistical significance in the qualified rate of disinfection (P<0.05). Conclusion In 2023, the disinfection quality of kindergartens in Jining City is overall low, especially the hands hygiene of staff. It is necessary to strengthen the assessment, supervision and management of disinfection quality in key areas and articles.

Objective To assess the overall disinfection quality in medical institutions of Dongying City and to provide evidence for enhancing infection control through improved disinfection practices. Methods From 2019 to 2023, complete random sampling was used to select medical institutions at all levels in Dongying City. On-site sampling and microbiological testing were performed on environmental surfaces, hygienic hands, surgical hands, operating-room air, and medical water. Total bacterial count and fecal coliforms were measured. Results Of 3 018 samples, 2 587 (85.72 %) were qualified. Annual disinfection qualification rates differed significantly (χ²= 33.007, P< 0.001). Tertiary hospitals showed higher qualification rates than secondary and primary ones. Among the tested items, pressure-steam sterilizers achieved the highest qualification rate (100.00 %), followed by post-disinfection endoscope rinse water (98.15 %), whereas hygienic hands had the lowest (75.64 %). Conclusion The qualification rate for hand hygiene among healthcare workers in Dongying City remains low. Priority should be given to improving hand-disinfection quality, with intensified monitoring and training on disinfection techniques.

Objective To understand the current situation of hand hygiene among medical staff at all levels of hospitals in Urumqi, and to identify weak links, improve the level of infection control, so as to provide a basis for further strengthening hand hygiene work. Methods From 2015 to 2023, sample and monitor the hand hygiene of medical staff in some hospitals in Urumqi, and compare the differences in qualification rates. Results From 2015 to 2023, a total of 955 hygiene hand samples and 372 surgical hand samples were collected. Among hospitals of different levels, the second level hospital had the highest qualified rates for hand hygiene (90.85%), while the first level hospital had the highest qualified rates for surgical hands (100%). Among medical personnel in different positions, the qualified rates of nurses' hand hygiene (90.90%) and surgical hands (98.26%) were higher than those of doctors' hand hygiene (83.86%) and surgical hands (95.94%) (χ²=10.014, P=0.002; χ²=10.473, P=0.006). Among different departments, the neonatal department had the highest qualified rate of hand hygiene (95.24%). The lowest qualified rates of hand hygiene measures were different hand hygiene methods(75%). Conclusion The overall qualified rate of hand hygiene among medical personnel in Urumqi is good, while the qualified ratesof hand hygiene among doctors is relatively low. It is necessary to further strengthen the training and supervision of hand hygiene among doctors and first level medical institutions, and to popularize effective hand hygiene measures in all departments to improve the overall quality of hand hygiene.

Objective To analyze the distribution and drug resistance of pathogenic bacteria in patients undergoing radical surgery for colorectal cancer in a tertiary teaching hospital, and to provide a basis for the prevention and treatment of hospital infections in clinical patients undergoing radical surgery for colorectal cancer. Methods Retrospective collection of data on all patients undergoing radical resection of colorectal cancer admitted to the colorectal department of a tertiary teaching hospital in Shandong Province from February 2019 to September 2023 was carried out. The distribution and drug resistance of pathogenic bacteria in 58 patients undergoing radical resection of colorectal cancer complicated with hospital acquired infections were analyzed. Results A total of 67 pathogenic bacteria were detected, including 55 Gram negative bacteria (82.09%), 11 Gram positive bacteria (16.42%), and 1 fungus (1.49%). The drug sensitivity results showed that Escherichia coli had a high resistance rate to ampicillin, cefazolin, and compound sulfamethoxazole (all≥ 60.00%), a low resistance rate to ertapenem, piperacillin/tazobactam, amoxicillin/clavulanic acid, and cefoperazone/sulbactam (all 4.00%), and sensitive to amikacin, imipenem, and tigecycline. Pseudomonas aeruginosa had a high resistance rate (60.00%) to ampicillin, a low resistance rate (10.00%) to amikacin, ceftazidime, cefepime, levofloxacin, and cefoperazone/sulbactam, and sensitive to ciprofloxacin, meropenem, tobramycin, imipenem, and piperacillin/tazobactam. The resistance rates of Enterococcus faecalis and Enterococcus faecalis to linezolid and vancomycin were relatively low. Conclusion The infection sites of hospital acquired infections are mainly in the abdomen and digestive system. The main pathogenic bacteria causing infections are gram-negative bacteria, which are resistant to various commonly used antibiotics.

Objective To evaluate the application outcomes of a care bundle management model in Central Sterile Supply Departments (CSSD). Methods From July 2023 to June 2024, 800 surgical instruments were assigned chronologically to two groups with 400 in each group: routine management group (July-December 2023) and care bundle management group (January-June 2024). The comprehensive capabilities of the staff in the disinfection supply room, the management quality of the operating room equipment, and the staff's satisfaction with quality management were compared between the two groups. Results Compared to routine management, the care bundle model significantly enhanced CSSD staff competencies including service awareness, risk alert capability, self-protection, and error prevention (all P<0.05). Instrument processing compliance rates of collection, cleaning, sterilization, and packaging were increased(P<0.05). Instrument loss, damage, documentation errors, and delayed delivery were decreased(P<0.05). The scores for environmental conditions, processes, layout, and equipment were significantly improved (P< 0.05). Conclusion The cluster management model significantly enhances the management efficiency of disinfection supply centers.