The study was conducted according to the guidelines of the Hygienic Standard for Disinfection in Hospitals (GB15982-1995, GB15982-2012), Architectural Technical Code for Hospital Clean Operating Department (GB50333-2002, GB50333-2013) and Regulation of Disinfection Technique in Healthcare Settings (WS/T 367-2012). In total of 199 provincial affiliated tertiary or secondary public hospitals were selected between 2007 and 2017. To assess the effectiveness of disinfection strategies used in hospitals, seven primary items, namely indoor air, work surface, hand hygiene, UV irradiation intensity, sterilization of medical items, use of disinfectants, and effects of steam sterilizer, were assessed.
The plate exposure method was used to measure the depositing bacterial concentration, which is a cleanliness indicator of indoor air disinfection. Monitoring was conducted in the morning shortly after cleaning and disinfection and before clinical use according to the standard guidelines. The doors and windows were closed, and nobody was allowed to stay in the wards. For laminar flow wards, the operating and surrounding zones were assessed individually according to the cleanliness class (Table 1). The plates in the laminar flow wards were placed within 0.8 meter from the floor for 30 minutes. The assessment of the general wards was based on the size of the area (m2). For general wards >30 m2, the nutrient agar plates were placed 80 cm above the floor with one plate in the centre and four at the two diagonal lines of the room, and the plates were kept 1 meter away from the wall. While in wards sized ≤30 m2, three points shaping a diagonal line were identified. The time for sampling was determined by the class the wards belong to (Table 2). Finally, the plates were covered and incubated for 24 hours (laminar flow wards) or 48 hours (general wards) at 37 °C. The total number of bacterial colonies was calculated as colony forming units (CFU)/plate combined with corresponding time.
Cleanliness class Operating zone
(CFU/30 minutes, φ90 plate)
(CFU/30 minutes, φ90 plate)
Reference operation Ⅰ 0.20 0.40 Implants, large organ transplants, surgical infections that can be life-threatening Ⅱ 0.75 1.50 Large operation associated with deep tissues and vital organs Ⅲ 2.00 4.00 Other surgeries Ⅳ 6.00 Infection and severely polluted surgery Architectural Technical Code for Hospital Clean Operating Department (GB50333).
Table 1. Depositing bacterial concentration standards for laminar flow wards
Class Environmental area Indoor air
Work surface (CFU/cm2) Hand hygiene (CFU/cm2) Ⅰ Laminar flow wards See Table 1 ≤5.0 ≤5.0 Other general clean wards ≤4.0
(30 minutes, φ90 plate)
Ⅱ General wards, delivery room, baby room, premature infant room, general protective isolation room, sterile area of supply room, burn ward, and intensive care unit (ICU) ≤4.0
(15 minutes, φ90 plate)
≤5.0 ≤5.0 Ⅲ Paediatric ward, gynaecological examination room, injection room, dressing room, treatment room, cleaning area of supply room, emergency room, laboratory, all kinds of ordinary wards, and rooms ≤4.0
(5 minutes, φ90 plate)
≤10.0 ≤10.0 Ⅳ Infectious disease section and ward ≤4.0
(5 minutes, φ90 plate)
≤10.0 ≤10.0 Hygienic Standard for Disinfection in Hospitals (GB15982).
Table 2. Standard benchmarks of indoor air, work surface, and hand hygiene
The selected work surface included those with high-frequency contact with staff and patients, which may be involved in cross-infection transmission routes that are distributed throughout the treatment rooms of patients and sleeping areas, such as treatment vehicles, bench boards, bedside cabinets, and bed frames, which were mostly stainless steel or laminate plastics. A sterile cotton swab immersed in a neutralizing agent solution was used to wipe each sample (100 cm2) on a defined square (5 cm×5 cm), and the cotton swab was rotated while wiping five times back and forth vertically and horizontally. The swab was vortexed in 10 mL phosphate-buffered solution with a neutralizing agent solution prior to being sown 1 mL in nutrient agar in duplicate. The total number of bacterial colonies (CFU/cm2) after incubation at 37 °C for 48 hours was counted subsequently.
The sampling and testing of hand hygiene were similar to those of work surface with minor changes. The two fingers were wiped twice from the fingers to the fingertips by rotating the swab simultaneously. A total area of 60 cm2 (30 cm2 each hand) of each individual was sampled. The following steps were conducted in the same way as those in the work surface testing, and each sample of hand hygiene was expressed as CFU/cm2.
The UV irradiation intensity was measured 1 meter vertically by an UV irradiation meter with the light turned on for 5 minutes. The UV-C irradiation was performed at 254 nm and the minimum standard value for UV light was 70 μW/cm2. The microbial contamination status of use of disinfectants was assessed to identify the total number of bacterial colonies. In total, 1 mL of disinfectant was added to 9 mL of corresponding neutralizing agent solution; this was then vortexed and inoculated 1 mL in nutrient agar in duplicate and incubated at 37 °C for 72 hours. The total number of bacterial colonies (CFU/mL) was counted and the benchmark of disinfectant for mucus should be ≤10 CFU/mL, whereas that of other disinfectants must be ≤100 CFU/mL. Sterile medical supplies were randomly selected for aseptic testing, and any microbiology testing was not permitted. The effect of steam sterilizer was detected using Bacillus stearothermophilus spore processed through a steam autoclave cycle and incubated for 7 days to obtain the readout.
The results were evaluated according to the standards (Tables 1 and 2). The data were transferred to Excel and STATISTICA 17.0 software (StatSoft Inc.). The qualified rates of indoor air, work surface, hand hygiene, UV irradiation intensity, and sterilization of medical items were analysed using the nonparametric comparative Chi-square test. A P value of <0.05 was considered significant. The data on use of disinfectants and the effects of steam sterilizer were analyzed descriptively.
Over the 11-year period, a total of 855 indoor air, 1 929 work surface, 2 864 hand hygiene, 1 259 UV, 1 619 sterilized medical items, 1 575 use of disinfectant, and 243 steam sterilizer samples were collected. The annual average qualified rates of indoor air, work surface, hand hygiene, UV, and sterilized medical items were (94.74±3.54)%, (97.25±1.65)%, (87.57±4.60)%, (95.00±4.50)%, and (98.76±1.14)%, respectively (Table 3). Differences in hand hygiene (χ2=49.37, P<0.001) and UV irradiation intensity (χ2=79.67, P<0.001) qualified rates were highly significant and variable, and the qualified rate for hand hygiene varied from 80.79% to 93.73%, and this was considered as the most variable factor. The differences in the other three items were less variable, with rates all >90%. In addition, few microbiological contaminated items were noted in disinfectant (3/1 575) and steam sterilizer (1/243). Overall, the data from this program indicated the effectiveness of hospital disinfection was improved by monitoring and administrative supervision over these years.
Year Indoor air Work surface Hand hygiene UV irradiation intensity Sterilized medical items 2007 91.67 (110/120) 95.34 (327/343) 80.79 (307/380) 85.14 (212/249) 98.13 (157/160) 2008 90.65 (97/107) 97.00 (226/233) 87.61 (304/347) 97.44 (152/156) 100.00 (179/179) 2009 92.08 (93/101) 99.00 (199/201) 86.18 (262/304) 95.18 (158/166) 96.97 (160/165) 2010 94.74 (90/95) 97.09 (167/172) 89.85 (292/325) 93.75 (150/160) 98.74 (157/159) 2011 94.44 (102/108) 99.47 (189/190) 93.73 (269/287) 100.00 (165/165) 99.44 (177/178) 2012 95.56 (43/45) 98.55 (136/138) 92.56 (224/242) 96.36 (53/55) 96.95 (127/131) 2013 100.00 (83/83) 96.32 (183/190) 88.65 (289/326) 98.61 (142/144) 99.48 (190/191) 2014 100.00 (71/71) 96.13 (149/155) 80.77 (189/234) 100.00 (93/93) 100.00 (154/154) 2015 98.21 (55/56) 97.24 (141/145) 90.43 (170/188) 100.00 (40/40) 98.00 (147/150) 2016 93.18 (41/44) 100.00 (100/100) 91.11 (123/135) 100.00 (17/17) 98.98 (97/98) 2017 100.00 (25/25) 95.16 (59/62) 82.29 (79/96) 100.00 (14/14) 100.00 (54/54) Total 94.74 (810/855) 97.25 (1 876/1 929) 87.57 (2 508/2 864) 95.00 (1 196/1 259) 98.76 (1 599/1 619) χ2 18.87 16.68 49.37 79.67 15.50 P 0.042 0.082 <0.001 <0.001 0.115 Note: qualified rate (qualified samples/total samples).
Table 3. Annual monitoring qualified rate of indoor air, work surface, hand hygiene, UV irradiation intensity and sterilized medical items
Effectiveness of hospital disinfection and experience learnt from 11 years of surveillance
- Received Date: 2018-11-12
- Accepted Date: 2019-02-27
Abstract: This survey was designed to assess the sanitation status of hospitals and the compliance of hospital staff to disinfection strategies within the past 11 years. A total of 199 provincial affiliated tertiary or secondary public hospitals from 2007 to 2017 were investigated and seven critical categories, namely indoor air, work surface, hand hygiene, ultraviolet (UV) irradiation intensity, use of disinfectants, sterilization of medical items, and effects of steam sterilizer, were monitored. The average qualified rates were (94.74±3.54)% (810/855), (97.25±1.65)% (1 876/1 929), (87.57±4.60)% (2 508/2 864), (95.00±4.50)% (1 196/1 259), and (98.76±1.14)% (1 599/1 619) for indoor air, work surface, hand hygiene, UV irradiation intensity, and sterilization of medical items, respectively. In terms of other categories, a few samples were not qualified: 3/1 575 for use of disinfectants and 1/243 for effects of steam sterilizer. The hospital disinfection monitoring and supervision program effectively improved the effectiveness of disinfection. Routine monitoring and supervision must be conducted to ensure a safe hospital treatment environment.