Activity of a dry mist hydrogen peroxide system against environmental Clostridium difficile contamination in elderly care wards

Clostridium difficile causes serious healthcare-associated infections. Infection control is difficult, due in part to environmental contamination with C. difficile spores. These spores are relatively resistant to cleaning and disinfection. The activity of a dry mist hydrogen peroxide decontamination system (Sterinis((R))) against environmental C. difficile contamination was assessed in three elderly care wards. Initial sampling for C. difficile was performed in 16 rooms across a variety of wards and specialties, using Brazier's CCEY (cycloserine-cefoxitin-egg yolk) agar. Ten rooms for elderly patients (eight isolation and two sluice rooms) were then resampled following dry mist hydrogen peroxide decontamination. Representative isolates of C. difficile were typed by polymerase chain reaction ribotyping. C. difficile was recovered from 3%, 11% and 26% of samples from low, medium and high risk rooms, respectively. In 10 high risk elderly care rooms, 24% (48/203) of samples were positive for C. difficile, with a mean of 6.8 colony-forming units (cfu) per 10 samples prior to hydrogen peroxide decontamination. Ribotyping identified the presence of the three main UK epidemic strains (ribotypes 001, 027 and 106) and four rooms contained mixed strains. After a single cycle of hydrogen peroxide decontamination, only 3% (7/203) of samples were positive (P<0.001), with a mean of 0.4 cfu per 10 samples ( approximately 94% reduction). The Sterinis((R)) hydrogen peroxide system significantly reduced the extent of environmental contamination with C. difficile in these elderly care rooms. This relatively quick and user-friendly technology might be a more reliable method of terminally disinfecting isolation rooms, following detergent cleaning, compared to the manual application of other disinfectants.     

Lack of enhanced effect of a chlorine dioxide-based cleaning regimen on environmental contamination with Clostridium difficile spores

Spores of Clostridium difficile may play a significant role in transmission of disease within the healthcare environment and are resistant to a variety of detergents and cleaning fluids. A range of environmental cleaning agents has recently become available, many of which claim to be sporicidal. We investigated the effect of changing to a chlorine dioxide-based cleaning regimen on C.?difficile environmental contamination and patient infection rates. The prevalence of environmental contamination was unaffected with a rate of 8% (9/120) before and 8% (17/212) following the change. Rates of patient infection were also unchanged during these periods.     

Importance of environmental decontamination--a critical view

The level of evidence supporting different disinfection and cleaning procedures performed in healthcare settings worldwide is low. With respect to environmental surfaces, the final assessment of whether use of disinfectants rather than detergents alone reduces nosocomial infection rates in different clinical settings still awaits conclusive study. It must be kept in mind that the effect of surface disinfection is only transient microbial contamination will have reached its former level within a few hours. While resistance to biocides is generally not judged to be as critical as antibiotic resistance, scientific data support the need for proper use, i.e. avoidance of widespread application, especially in low concentrations and in consumer products. The decontamination ability of the substances used; prevention of resistance; and safety for patients, personnel and the environment; are the cornerstones that interact with each other. Future work should focus on this complex background. Targeted disinfection of environmental surfaces (those frequently touched) is an established component of infection control activities to prevent the spread of nosocomial (multi-resistant) pathogens, but of lesser importance than proper hand hygiene. However, since the use of disinfectants may pose a danger to staff, patients and the environment, prudent use combined with the application of proven safety precautions is important. Since emerging resistant pathogens will challenge healthcare facilities in future even more than today, well-designed studies addressing the role of disinfection in the healthcare-setting are needed.     

The emerging nosocomial pathogens Cryptosporidium, Escherichia coli O157:H7, Helicobacter pylori, and hepatitis C: epidemiology, environmental survival, efficacy of disinfection, and control measures.

New and emerging infectious diseases pose a threat to public health and may be responsible for nosocomial outbreaks. Cryptosporidium parvum and Escherichia coli are gastrointestinal pathogens that have caused nosocomial infections via person-to-person transmission, environmental contamination, or contaminated water or food. Helicobacter pylori has been transmitted via inadequately disinfected endoscopes. Finally, hepatitis C may be acquired by healthcare personnel by percutaneous or mucous membrane exposure to blood or between patients by use of contaminated blood products or via environmental contamination. Rigorous adherence to Standard Precautions, Contact Precautions for patients with infectious diarrhea, disinfection of environmental surfaces, and appropriate disinfection of endoscopes are adequate to prevent nosocomial acquisition of these pathogens.     

Acquisition of Clostridium difficile from the hospital environment

An outbreak of antibiotic-associated colitis that occurred on a ward of a Michigan hospital during February-April, 1984, was studied by bacteriophage-bacteriocin typing. Stools from the seven involved patients yielded Clostridium difficile isolates of types B1537 or Cld7;B1537. C. difficile was recovered from 31.4% of environmental cultures obtained on the ward, and the majority of isolates were types B1537 or Cld7;B1537. When the ward was disinfected with unbuffered hypochlorite (500 parts per million (ppm) available chlorine), surface contamination decreased to 21% of initial levels and the outbreak subsequently ended. Phosphate buffered hypochlorite (1,600 ppm available chlorine, pH 7.6) was even more effective; its use resulted in a 98% reduction in surface contamination. These findings suggest that environmental contamination with C. difficile is important in the epidemiology of antibiotic-associated colitis, and that hypochlorite is effective in eliminating C. difficile from the hospital environment.     

Environmental contamination and airborne microbial counts: a role for hydroxyl radical disinfection units?

Environmental contamination is thought to play a role in the spread of infection in hospitals and there has been increased interest in novel air disinfection systems in preventing infection. In this study the efficacy of a hydroxyl radical air disinfection system (Inov8 unit) in reducing the number of airborne bacteria was assessed in a clinical setting. Environmental contamination was assessed using settle plates and air samples in three settings: (1) non-clinical room; (2) non-clinical room with defined activity; and (3) single intensive care unit cubicle. A comparison of air counts and environmental contamination rates was made with the Inov8 units on and off. The Inov8 unit produced an overall reduction in both air sample and settle plate counts in each setting (P<0.001, Wilcoxon signed-rank test). There was a mean reduction in air sample counts of 26%, 39% and 55% for settings 1, 2 and 3 respectively. The corresponding reductions in settle plate counts were 35%, 62% and 54%. These results suggest that this type of novel air disinfection may have a role in improving air quality and reducing environmental contamination within clinical isolation rooms. Further work is required to assess the effect on specific pathogens, and to establish whether this will reduce the risks of patients and/or healthcare workers acquiring such pathogens from the environment.     

How useful are microbial filters in respiratory apparatus?

Following an outbreak of hepatitis C in surgical patients in Australia, it has been suggested that transmission can take place as a result of contaminated anaesthetic circuits. It has therefore been recommended that filters should be placed between patients and breathing systems with a new filter being used for each patient. Although nosocomial pneumonia is a major manifestation of hospital-acquired infection, it is unclear whether contamination of ventilator circuits is implicated in the aetiology of this condition. Some data suggest that bacteria cannot survive well in anaesthetic circuits and several studies have failed to demonstrate significant contamination of circuits in clinical situation. Several outbreaks of pneumonia related to contaminated anaesthetic equipment have been described, but many of these were controlled by appropriate decontamination of the respiratory equipment. Although ventilator filters are used by the majority of intensive care units and filters do have the ability to filter bacteria and viruses, there are few data suggesting that the use of filters reduce the rate of pulmonary infections in long-term ventilated patients. Furthermore, to change filters between operations would have significant financial implications, and there is no conclusive evidence that they would reduce cross infection. Until more data are available on the role of filters in both long-term ventilated patients and operations, standard hygienic measures such as appropriate disinfection protocols are still the most effective way of reducing ventilator-associated infections.     

Value of lysozyme agar incorporation and alkaline thioglycollate exposure for the environmental recovery of Clostridium difficile

Clostridium difficile is an increasingly prevalent nosocomial pathogen. Environmental contamination by spores is believed to be a major factor propagating the spread of C. difficile. Various approaches including the use of bile salts have been described to enhance the recovery of C. difficile from clinical and environmental specimens. We found that lysozyme (5 mg/L) incorporated into a selective medium containing bile salts significantly increased the recovery of C. difficile from swabs of 197 environmental sites (11% versus 24% samples positive, P< 0.01). Furthermore, in a separate series of experiments additional use of cooked meat broth enrichment significantly enhanced the recovery of C. difficile (35% versus 45%, P = 0.009). Conversely, we found that pre-exposure to alkaline thioglycollate did not improve the yield of C. difficile. Lysozyme incorporation markedly increases the recovery of C. difficile from environmental samples probably by stimulation of spore germination. Our findings suggest that previous attempts to determine the level of environmental C. difficile contamination have markedly underestimated the true prevalence of this pathogen.     

Prospective evaluation of environmental contamination by Clostridium difficile in isolation side rooms.

We determined prospectively the frequency, persistence and molecular epidemiology of Clostridium difficile environmental contamination after detergent-based cleaning in side rooms used to isolate patients with C. difficile diarrhoea. Approximately one-quarter of all environmental sites in side rooms sampled over four-week periods were contaminated with C. difficile. The overall side room prevalence of environmental C. difficile declined from 35% initially, to 24% in week 2, 18% in week 3, and 16% in week 4. The bed frame was the most common site from which C. difficile was recovered, although the floor was the most contaminated site in terms of total numbers of colonies. C. difficile was recovered significantly more frequently from swabs plated directly on to C. difficile selective media containing lysozyme than from enrichment broth (P< 0.001), emphasizing the benefit of lysozyme supplementation. The great majority of C. difficile isolates (87% of all isolates, 84% of patient isolates) was indistinguishable from the UK epidemic strain (PCR ribotype 1). It thus could not be determined whether environmental contamination was a cause or a consequence of diarrhoea. Our findings highlight the need for improved approaches to hospital environmental hygiene, and call into question current UK guidelines that recommend detergent-based cleaning to remove environmental C. difficile. In particular, improved cleaning of frequently touched sites in the immediate bed space area is required.     

Environmental contamination makes an important contribution to hospital infection

Meticillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) are capable of surviving for days to weeks on environmental surfaces in healthcare facilities. Environmental surfaces frequently touched by healthcare workers are commonly contaminated in the rooms of patients colonized or infected with MRSA or VRE. A number of studies have documented that healthcare workers may contaminate their hands or gloves by touching contaminated environmental surfaces, and that hands or gloves become contaminated with numbers of organisms that are likely to result in transmission to patients. Pathogens may also be transferred directly from contaminated surfaces to susceptible patients. There is an increasing body of evidence that cleaning or disinfection of the environment can reduce transmission of healthcare-associated pathogens. Because routine cleaning of equipment items and other high-touch surfaces does not always remove pathogens from contaminated surfaces, improved methods of disinfecting the hospital environment are needed. Preliminary studies suggest that hydrogen peroxide vapour technology deserves further evaluation as a method for decontamination of the environment in healthcare settings.     

New hospital disinfection processes for both conventional and prion infectious agents compatible with thermosensitive medical equipment

With the detection of prions in specific tissues in variant and sporadic Creutzfeldt–Jakob diseases, efficient decontamination for human transmissible spongiform encephalopathy (TSE) agents, that is compatible with medical equipment, has become a major issue. We previously described the cleavage of prions on exposure to copper (Cu) and hydrogen peroxide (H₂O₂) and have used this property to develop efficient prion decontamination processes. To validate this approach, in-vitro assays on genuine human and animal prions using both brain homogenates and steel wires to mimic contamination of medical equipment were conducted. In-vivo experiments using steel wire in the hamster 263 K model were then used to evaluate the effect on prion infectivity. Assays on classical pathogens following international norms completed these prion experiments. In-vitro data confirmed the full decontamination efficacy of H₂O₂/Cu on different TSE strains. Combination of Cu with peracetic acid, used for endoscope disinfection, also revealed improved prion decontamination. Animal assay demonstrated efficacy on TSE infectivity of H₂O₂/Cu alone or in combination with detergents (reduction factor ≥5.25 log₁₀). Assays on classical pathogens confirmed the disinfection properties of the different processes. Taken together, these new disinfection processes are efficient for both conventional and prion infectious agents and are, compatible with thermosensitive medical equipment. They can be adapted to hospitals' and practitioners' routine use, and they present reduced risks for the environment and for healthcare professionals.     

Molecular epidemiology of endemic Clostridium difficile infection

This is the first study to provide a comprehensive insight into the molecular epidemiology of endemic Clostridium difficile and particularly that associated with a recently recognized epidemic strain. We DNA fingerprinted all C. difficile isolates from the stools of patients with symptomatic antibiotic-associated diarrhoea and from repeated samples of the inanimate ward environment on two elderly medicine hospital wards over a 22-month period. Notably, C. difficile was not recoverable from either ward immediately before opening, but was found on both wards within 1-3 weeks of opening, and the level of environmental contamination rose markedly during the first 6 months of the study period. C. difficile infection (CDI) incidence data correlated significantly with the prevalence of environmental C. difficile on ward B (r = 0.76, P < 0.05) but not on ward A (r = 0.26, P > 0.05). We found that RAPD and RS-PCR typing had similar discriminatory power, although, despite fingerprinting over 200 C. difficile isolates, we identified only six distinct types. Only two distinct C. difficile strains were identified as causing both patient infection and ward contamination. Attempts to determine whether infected patients or contaminated environments are the prime source for cross-infection by C. difficile had limited success, as over 90% of C. difficile isolates were the UK epidemic clone. However, a non-epidemic strain caused a cluster of six cases of CDI, but was only isolated from the environment after the sixth patient became symptomatic. The initial absence of this strain from the environment implies patient-to-patient and/or staff-to-patient spread. In general, routine cleaning with detergent was unsuccessful at removing C. difficile from the environment. Understanding the epidemiology and virulence of prevalent strains is important if CDI is to be successfully controlled.     

Hygienic analysis of the experience in dicyclopentadiene production from petrochemical raw materials

The labour conditions at an experimental dicyclopentadiene (DCPD) processing line was characterized by a combined action of occupational hygienic factors, mostly contamination of the working zone air with chemical substances. Both to the degree of its hazardousness and concentration levels in the working zone air, DCPD was predominant agent in the gaseous discharges. The DCPD discharge in the air was due to improper pump packing gland hermetization, manual sample taking, inadequate decontamination of the equipment prior to preventive maintenance, as well as to the desorption by the construction elements surfaces. DCPD contamination of the workers' skin and overalls was also revealed.     

A molecular characterization of Clostridium difficile isolates from humans, animals and their environments.

It is generally accepted that most patients with Clostridium difficile-associated diarrhoea acquire the organism from the environment. Recently we demonstrated that household pets may constitute a significant reservoir of C. difficile through gastrointestinal carriage in up to 39% of cats and dogs. These findings suggested that direct transmission from household pets, or contamination of the environment by them, may be a factor in the pathogenesis of C. difficile-associated diarrhoea. To investigate this possibility, we examined isolates of C. difficile from humans, pets and the environment by restriction enzyme analysis (REA) and restriction fragment length polymorphism (RFLP) typing using enhanced chemiluminescence. Both REA and RFLP typing methods used Hind III digests of chromosomal DNA. A total of 116 isolates of C. difficile from pets (26), veterinary clinic environmental sites (33), humans (37) and hospital environmental sites (20) was examined. REA was far more discriminatory than RFLP typing and for all isolates there were 34 REA types versus 6 RFLP types. There was good correlation between the REA types found in isolates from pets and from the veterinary clinic environment, and between isolates from humans and from those found in the hospital environment. There was, however, no correlation between REA type of C. difficile found in pets and isolates of human origin. We conclude that there may still be a risk of humans acquiring C. difficile from domestic pets as these findings may be the result of geographical variation.     

Comparison of the effect of detergent versus hypochlorite cleaning on environmental contamination and incidence of Clostridium difficile infection

To determine how best to decontaminate the hospital environment of Clostridium difficile, we carried out a cross-over study on two elderly medicine wards to determine whether cleaning with a hypochlorite disinfectant was better than using neutral detergent in reducing the incidence of C. difficile infection (CDI). We examined 1128 environmental samples in two years, 35% of which grew C. difficile. There was a significant decrease of CDI incidence on ward X, from 8.9 to 5.3 cases per 100 admissions (P<0.05) using hypochlorite, but there was no significant effect on ward Y. On ward X the incidence of CDI was significantly associated with the proportion of culture-positive environmental sites (P<0.05). On ward Y the only significant correlation between CDI and C. difficile culture-positive environmental sites was in patient side-rooms (r=0.41, P<0.05). The total daily defined doses of cefotaxime, cephradine and aminopenicillins were similar throughout the trial. These results provide some evidence that use of hypochlorite for environmental cleaning may significantly reduce incidence of CDI, but emphasize the potential for confounding factors.     

Environmental reservoirs of methicillin-resistant Staphylococcus aureus in isolation rooms: correlation with patient isolates and implications for hospital hygiene

Strategies to control and prevent the spread of methicillin-resistant Staphylococcus aureus (MRSA) include early identification of positive patients through screening, patient isolation, hand hygiene, nasal and skin decontamination, and the adequate cleaning and decontamination of clinical areas. However, many national and other guidelines provide few details on environmental decontamination regimens, partly because the role of the environment in the spread of MRSA is not well documented. We prospectively studied the environment of the isolation rooms of 25 MRSA patients for up to four weeks, sampling horizontal surfaces and the air using settle plates as well as an air sampler, while continuing regular daily cleaning according to the hospital protocol. We then typed 20 patient isolates and the corresponding environmental isolates (N=35) to assess the similarity of strains. A high proportion of samples were positive for MRSA; 269/502 (53.6%) surface samples, 70/250 (28%) air samples and 102/251 (40.6%) settle plates. Over half of the surface samples taken from the beds and the mattresses were positive for MRSA. Identical or closely related isolates were recovered from the patient and their environment in 14 (70%) patients, suggesting possible environmental contamination of the isolation rooms, possibly contributing to endemic MRSA. More effective and rigorous use of current approaches to cleaning and decontamination is required as well as consideration of newer technologies to eradicate MRSA and other hospital-acquired pathogens.     

Evaluation of the PotoClean(®) decontamination technology for reprocessing of water supply lines in dental units during routine work

Background: A frequent problem in dental units is the microbial contamination of water and biofilm formation in the water supply lines. After random identification of a bacterial contaminated dental unit (310 cfu/ml) in a practise with 3 dental units we implemented the present study to evaluate the efficacy of the PotoClean(?) technology, based on anodic oxidation. Method: The efficacy of a regular low concentrated permanent decontamination (1 mg Cl/L) with an additional intensive decontamination by PotoClean(?) (three times 20 mg Cl/ml for 2 h) on three dental units was tested over 7 months. Microbial contamination, total chlorine concentration and redox potential have been analyzed. Dental unit A and B was 15 years old, unit C 5 years.Results: After 3 intensive decontaminations, in dental unit A and B the number of bacteria and moulds could be reduced less than 7 d. Thereafter the bacteria counts increased again during the subsequent 7 month period and the amount of moulds was with some exceptions 300 cfu/ml, although PotoClean(?) was constantly added in the system (1 mg Cl/L). After further 7.5 month only with low concentrated permanent disinfection (1 mg Cl/L) both units were successful decontaminated. Dental unit C represented an object which was easier to decontaminate because of the advanced construction (prevention of water stagnation) and the shorter useful life. At the beginning of the decontamination it was no bacterial contamination, but moulds were contained (300 cfu/ml). Already after the first intensive decontamination, no further bacteria and moulds could be detected.Discussion: An important factor for the efficacy of PotoClean(?) was the age of the units and their construction. For a new generation of dental units PotoClean(?) was effective during the whole period of monitoring. For two old types of dental unit with massive biofilm development the successful decontamination needed more than 7 month. Conclusion: The PotoClean(?) technology has resulted in even old-type turbines with intensive biofilm formation to complete decontamination. In a recent turbine design already after the first intensive decontamination with PotoClean(?) and its continuous use (1 mg Cl/L) no more contamination by bacteria and moulds were detectable.     

纳米光催化空气消毒机对手术室空气消毒效果的探讨

目的探讨医院手术室应用纳米光催化空气消毒机进行手术间空气动态消毒的效果。方法采用纳米光催化空气消毒机动态和紫外线照射空气消毒方法进行比较。结果静态下纳米光催化空气消毒后,手术室空气菌落数为0 CFU/m3,紫外线消毒后手术间菌落数为33.3 CFU/m3;动态下不同组间,F=220.423,P=0.000,P<0.01;纳米光催化空气消毒机动态消毒效果明显优于紫外线照射消毒法。结论应用纳米光催化空气消毒机进行手术室的空气持续动态消毒,是一种比较有效的空气消毒方法。     

Benefits of automated surface decontamination of a radioiodine ward

A floor-washing robot has been acquired to assist physicists with decontamination of radioiodine therapy ward rooms after discharge of the patient at Sir Charles Gairdner Hospital. The effectiveness of the robot in decontaminating the ward has been evaluated. A controlled experiment was performed by deliberately contaminating a polyvinyl chloride flooring offcut with 131I followed by automated decontamination with the robot. The extent of fixed and removable contamination was assessed before and after decontamination by two methods: (1) direct Geiger-Mueller counting and (2) beta-counting wipe tests. Surface contamination was also assessed in situ on the ward by Geiger-Mueller counting and wipe testing. Contamination maps confirmed that contamination was removed rather than spread around by the robot. Wipe testing revealed that the robot was successful in clearing approximately 60-80% of removable contamination. The robotic floor-washing device was considered suitable to provide effective automated decontamination of the radioiodine ward. In addition, the robot affords other benefits: the time spent by the physicists decontaminating the room is greatly reduced offering financial and occupational safety and health benefits. The robot has also found utility in other decontamination applications in the healthcare environment.     

Disinfectology as a subject of differentiation in hygiene science

The paper provides a rationale for the need for developing the decontamination - actively health-promoting area of hygiene science and practice to neutralize (decontaminate) different pathogens just in the environment where they enter during its inadequate, ineffective, or quite impossible protection from contamination. As of now, there are no physical decontamination technologies or ineffective attempts to make harmless chemical pathogens in the environment; at the same time it is stated that there are scientifically grounded biological decontamination and disinfectology technologies to neutralize biological pathogens just in the environment and on its different objects. To solve these problems requires hygienic competence, particularly the substantiation of hygienic standards for disinfectants in the environment and the elaboration of hygienically safe regimens of their application. In this connection, disinfectology is the most hygienic branch of all antiepidemic ones of preventive medicine. The development of disinfectology as a fruitful alliance of hygiene and epidemiology allowed a system of governmental management and control of unspecific prophylaxis to be developed and introduced in Russia, which contributes to a reduction in or at least stabilization of the incidence of infectious diseases in the country.