Lesser-known or hidden reservoirs of infection and implications for adequate prevention strategies: Where to look and what to look for

In developing hygiene strategies, in recent years, the major focus has been on the hands as the key route of infection transmission. However, there is a multitude of lesser-known and underestimated reservoirs for microorganisms which are the triggering sources and vehicles for outbreaks or sporadic cases of infection. Among those are water reservoirs such as sink drains, fixtures, decorative water fountains and waste-water treatment plants, frequently touched textile surfaces such as private curtains in hospitals and laundry, but also transvaginal ultrasound probes, parenteral drug products, and disinfectant wipe dispensers. The review of outbreak reports also reveals Gram-negative and multiple-drug resistant microorganisms to have become an increasingly frequent and severe threat in medical settings. In some instances, the causative organisms are particularly difficult to identify because they are concealed in biofilms or in a state referred to as viable but nonculturable, which eludes conventional culture media-based detection methods. There is an enormous preventative potential in these insights, which has not been fully tapped. New and emerging pathogens, novel pathogen detection methods, and hidden reservoirs of infection should hence be given special consideration when designing the layout of buildings and medical devices, but also when defining the core competencies for medical staff, establishing programmes for patient empowerment and education of the general public, and when implementing protocols for the prevention and control of infections in medical, community and domestic settings.

The survival of influenza A(H1N1)pdm09 virus on 4 household surfaces

We investigated the survival of a pandemic strain of influenza A H1N1 on a variety of common household surfaces where multiple samples were taken from 4 types of common household fomite at 7 time points. Results showed that influenza A H1N1sw virus particles remained infectious for 48 hours on a wooden surface, for 24 hours on stainless steel and plastic surfaces, and for 8 hours on a cloth surface, although virus recovery from the cloth may have been suboptimal. Our results suggest that pandemic influenza A H1N1 can survive on common household fomites for extended periods of time, and that good hand hygiene and regular disinfection of commonly touched surfaces should be practiced during the influenza season to help reduce transmission.

The uremic toxin indoxyl sulfate acts as a pro- or antioxidant on LDL oxidation

Uremic toxins have been shown to play a role in chronic kidney disease (CKD) associated oxidative stress. Oxidative stress and inflammation have been associated with increased risk of cardiovascular disease in uraemia. The oxidative modification of LDL may play a role in early atherogenesis. Enhanced LDL oxidation has been found in uremic patients which may account for accelerated atherosclerosis observed in CKD. The uremic toxin indoxyl sulfate (IS) has been reported to exert oxidative and antioxidative activity. Thus, in the present study we have investigated the influence of IS on the atherogenic modifications of LDL exposed in vitro to different oxidising systems. The transition metal ion (Cu(2+)) and hemin/H2O2 induced lipid oxidation reactions monitored by conjugated diene formation, were inhibited by the presence of IS, which points to possible antioxidant effects by this uremic toxin. A protective effect of IS on LDL apoprotein modification by the exposure to the product of the myeloperoxidase/H2O2/Cl(-) system HOCl, was also observed as estimated by protein carbonyl formation. In contrast, a marked increase in conjugated dienes and lipid hydroperoxides was observed when lipid oxidation was initiated by the free radical generator AAPH in presence of IS. The GC-MS analysis revealed the formation of indole-2,3-dione and 6,12-dihydro-6,12-dioxo-indolo[2,1-b]quinazoline (tryptanthrin) in IS/AAPH reaction. A scheme for the generation of tryptanthrin from IS via indoxyl radicals is proposed, which may facilitate LDL lipid oxidation. Our observations add further insight in the Janus-faced properties of this important uremic toxin.

An international survey of bacterial contamination and householders’ knowledge, attitudes and perceptions of hygiene

This prospective, multinational study was conducted in 20 homes in eight cities or regions in different countries to determine the level of microbiological contamination of common surfaces and items, and investigate the attitudes and perceptions of householders towards cleaning and hygiene. Environmental Health Practitioners took eight standardised swabs in each home. The swabs were cultured for a range of micro-organisms. Householders ( n=160) were also interviewed regarding their cleaning habits and perceptions of hygiene. Overall, 28% of surfaces or items tested in the study had ‘moderate bacterial growth’ or ‘heavy bacterial growth’. Kitchen cloths were the most contaminated items, with 86% having moderate bacterial growth or heavy bacterial growth; kitchen taps were the second most contaminated items, with 52% having moderate bacterial growth or heavy bacterial growth. High proportions (>50%) of kitchen cloths contained coliforms, Enterobacteriaceae and Pseudomonas spp. The visual appearance of surfaces and items frequently (30%) did not correspond to their level of contamination with micro-organisms. The majority of householders (65%) cleaned to make the house ‘look clean, smell nice and remove germs’; however, householders’ perceptions of the cleanliness of their homes frequently did not correspond to microbiological reality. In conclusion, further research and education are needed regarding hygiene in the home.

The role of surface disinfection in infection prevention

Background: The Rudolf Schuelke Foundation addresses topics related to hygiene, infection prevention and public health. In this context a panel of scientists from various European countries discussed “The Role of Surface Disinfection in Infection Prevention”. The most important findings and conclusions of this meeting are summarised in the present consensus paper.

Aim: Although the relevance of surface disinfection is increasingly being accepted, there are still a number of issues which remain controversial. In particular, the following topics were addressed: Transferral of microbes from surface to patients as a cause of infection, requirements for surface disinfectants, biocidal resistance and toxicity, future challenges.

Methods and findings: After discussion and review of current scientific literature the authors agreed that contaminated surfaces contribute to the transmission of pathogens and may thus pose an infection hazard. Targeted surface disinfection based on a risk profile is seen as an indispensable constituent in a multibarrier approach of universal infection control precautions. Resistance and cross-resistance depend on the disinfectant agent as well as on the microbial species. Prudent implementation of surface disinfection regimens tested to be effective can prevent or minimize adverse effects.

Conclusions: Disinfection must be viewed as a holistic process. There is a need for defining standard principles for cleaning and disinfection, for ensuring compliance with these principles by measures such as written standard operating procedures, adequate training and suitable audit systems. Also, test procedures must be set up in order to demonstrate the efficacy of disinfectants including new application methods such as pre-soaked wipes for surface disinfection.

[Experiences with outbreaks of nosocomial infections]

Ten years after the publication of the recommendation: "Outbreak management and structural proceedings in case of cumulative occurrence of nosocomial infections" of the federal commission of hospital hygiene, these recommendations are now being re-evaluated. To date, the recommendations have proven valid and have maintained their significance for an effective management. However, besides new hygienic-microbiological methods and an increased sensitivity of the perception of nosocomial outbreaks by the public, by politicians and by the press, it is necessary to consider new issues in this field. Outbreaks are tragic events placing an extraordinary burden on all persons involved, which can have significant consequences. Therefore, it is necessary to ensure prompt outbreak management by experienced professionals who must combine a systematic on-site inspection, hygienic-microbiological investigation and typing methods used with epidemiological approaches. To assure these requirements, the support of independent reference centres such as universal hygiene institutes should be guaranteed. Politicians should be involved only after a scientific evaluation of the details of the outbreak has been made. A national documentation centre, e.g. at the Robert Koch Institute, should be established, thereby making experiences with outbreaks widely available.

Recommendations and requirements for soap and hand rub dispensers in healthcare facilities

Hand hygiene is one of the most important measures to prevent transmission of infectious agents and plays a major role in prevention of infection in any type of healthcare setting. While requirements for the efficacy of hand disinfectants are defined in European testing norms such as the EN 1500 for hygienic hand disinfection or EN 12791 for surgical hand preparation, no specific recommendations for hand rub dispensers and liquid soap dispensers have been given yet. Therefore, the intention of the present recommendation on soap and hand rub dispensers in healthcare facilities is to close this gap and to enhance future improvement of dispenser functionality and design. Regardless of manufacture and design of a hand rub or liquid soap dispensers the following requirements shall be met in healthcare facilities:

Triggering the dispenser must be possible without using hands. Sensor- or elbow-operated dispensers both fulfill this requirement. Dispensers must be only refillable in a modality where the content, be it a hand rub or liquid soap, cannot be contaminated. This is achieved best by using replaceable cartridge systems. Refilling through “top-up” must not be possible. The disperser should allow usage of different types of cartridges made by different manufacturers. Dispensers must be operated and maintained such that a microbial contamination of the pump nozzle may easily be avoided. It must be possible to identify the products used in a dispenser easily and without any manipulation. Identifying the type of product, be it a hand rub or a liquid soap, as well as reading the product's name and critical manufacturers' warnings must be possible at any time. The disperser must allow identification of the level of the used product without any further manipulation at any time. The design of the dispenser must allow easy cleaning and disinfection the outside and inside of the dispenser. The manufacturer of the dispenser must provide the user with information on applicable chemicals and cleaning products. It must be possible to reprocess the dispenser and all of its permanent parts by applying machine based thermal disinfection at an A₀-value of minimum 60 (e.g. 80°C/1 minute). Automatically portioning dispensers shall not fail during 200 hubs. The maximal allowed failure rate shall not exceed 1% (2 out of 200 consecutive hubs). A dispenser used for alcohol based hand rubs must allow keeping the alcohol concentration constant over a time period of 3 months. The maximum acceptable decrease in the concentration of the alcohol shall not exceed 5%. Liquid soap and hand rub dispensers with single-use pumps, ideally already mounted on the cartridge and to be discharged with the empty cartridge, are preferable. If pumps are used on the next consecutive cartridge, the manufacturer must provide the user with a detailed introduction for cleansing and reprocessing before further use. Because of forensic reasons it is recommended to place a good readable sign on the dispenser indicating e.g. “Apply alcohol based hand rubs only on the hand! Do not drink, avoid spraying into the eye or application on mucous membranes”. It is regarded as an additional benefit, if the dispenser is able to document the consumption of hand rub or the frequency of hubs either mechanically or electronically.

Reliability of fiber post bonding to root canal dentin after simulated clinical function in vitro

The aim of this study was to investigate the effect of thermomechanical loading (TML) on the bond strength of fiber posts luted with three different resin cements. Sixty-six extracted human anterior teeth were endodontically treated and restored with fiber posts (RelyX Fiber Posts, 3M ESPE) using three commercially available resin cements and three corresponding core build-up materials (n=22 each): Panavia F 2.0/Clearfil DC Core Automix (Kuraray), Variolink II/Multicore Flow (Ivoclar Vivadent), and RelyX Unicem/Filtek Z250 (3M ESPE). Twelve specimens of each group received all-ceramic crowns and were subjected to TML. The other 10 specimens were stored in saline solution for 24 hours. The roots were sectioned and bond strength was measured using a push-out test. Adhesive interfaces of two specimens of each group subjected to TML were analyzed using field emission scanning electron microscopy (FESEM). Bond strengths of fiber posts were significantly affected by the type of resin cement (p<0.0005) and TML (p<0.0005; two-way analysis of variance). TML significantly reduced bond strengths for all materials ((6.0 (6.2) MPa)) compared with initial bond strengths ((14.9 (10.4) MPa)). RelyX Unicem resulted in significantly higher bond strengths before ((18.3 (10.3) MPa)) and after TML ((9.8 (7.5) MPa)) compared with the other materials (p<0.0005; Tukey HSD). Using FESEM, Variolink II and Panavia F demonstrated a hybrid layer partly detached from the underlying resin cement, whereas no hybrid layer was observed for RelyX Unicem. The decrease in bond strength after TML suggests that retention of fiber posts may be reduced after clinical function. Therefore, endodontically treated teeth that are restored using fiber posts may benefit from additional reinforcement via coronal restorations using adequate ferrules and/or adhesive techniques.

Consensus report: E. coli O104:H4 (HUSEC041) and the potential threat to European water supplies

Among the 3rd Seminar for PhD students working on Water and Health which was held in Cannes on 27–29 June 2011, experts from a number of universities and research institutes took the opportunity to discuss the emergence of Escherichia coli O104:H4 in Europe. Especially, possible threats for European water suppliers were considered. The consensus is summarized in this report. The main conclusion was that E. coli O104:H4 would not pose a substantial risk to well managed water supplies, especially where regular monitoring of indicator E. coli is negative. However, this may not apply for small and very small water systems which are quite common in Europe. New strategies like the Water Safety Plan approach are needed to protect also small scale drinking water systems and private wells in Europe. Water used in the processing of foods likely to be eaten raw, especially sprouts, should be of drinking water quality.

[Hygiene in schools - an important issue for the public health services]

According to the Protection against Infection Act (IfSG), schools have to identify their arrangements of standard operating procedures (SOPs) for hygienic conditions, and the public health departments are obliged to check the hygienic conditions in schools. Here, practical experience with these topics in Frankfurt/Main, Germany, is presented.Although all schools had been informed about their duties according to IfSG in 2001, only 44% (80/180 schools) of them were able to present their SOPs when requested to do so by the public health department in 2006. Complaints about bad sanitary hygiene in schools have to be confirmed, often even in recently redeveloped facilities, because of vandalism. The equipment of washing basins was improved very well during the influenza pandemic in 2009. In 2010, however, a tendency to deterioration had been observed. With data on high levels on indoor contamination (particles and CO2) in class rooms in 2006, the city increased the frequency of cleaning and launched a programme on proper ventilation in classrooms. However, a study on ventilation in 29 schools in 2009 resulted in very high levels of CO2; obviously the recommendation to ventilate the classrooms every break are neglected. Large studies on drinking water quality exhibited good data, with the exception of high Legionella contaminations in hot water systems supplying the showers in gymnasiums. Major redevelopment measures were necessary.Hygienic conditions in schools should be improved urgently. The public health departments should increase their consulting services as well as their control visits in schools - with the aim to improve hygiene in schools. Responsibility of the schools as well as of the individuals in the schools is demanded as well. More public attention to this topic seems mandatory, may be via a "signal light - red-yellow-green" for schools?

[Strategies for prevention of healthcare associated infection]

In light of the hazard of healthcare associated infection (HAI) and pandemic increase of multiresistant pathogens the prevention and control of HAI by implementing infection control strategies in a structured and systemic manner are becoming increasingly important in order to assure patient safety.A well balanced implementation of primary, secondary, and tertiary prevention in the format of a multibarrier concept together with surveillance of outcome measures are critical elements for a good hygiene practice. Criteria for structure-quality are optimal planned facility interieur supporting the clinical work-flow, adequate staffing of infection control practitioners and nurses, management of processes supporting infection prevention measures together with facility specific SOPs, and Surveillance and monitoring of the outcome together with feed-back to staff. Finally, any healthcare facility must be prepared for acute crisis such as outbreak management or management of critical incidences related to HAIs.

Disinfection aboard cruise liners and naval units: formation of disinfection by-products using chlorine dioxide in different qualities of drinking water

The world-wide deployment of cruise liners and naval units has caused an increased need for the disinfection of drinking water. The main cause for this is the unknown quality of drinking water in foreign harbours--besides the formation of bio-films due to the climatically disadvantageous conditions in the operational area. Water conduits on board are currently disinfected with calcium hypochlorite in case of microbiological contamination. Chemical and physical analyses after disinfection with calcium hypochlorite have shown that organic by-products consisting of trihalomethanes develop in considerable amounts during disinfection. Furthermore, the method is susceptible to handling errors and thus often leads to insufficient disinfection results. Hitherto, the use of other disinfection methods allowed by government regulations, especially chlorine dioxide, is not widely spread. Unlike disinfection with calcium hypochlorite, chlorine dioxide does not lead to the formation of trihalomethanes. Typical disinfection by-products (DBP) are the anions chlorite and chlorate, which are formed in oxidative processes. The formation conditions of these anions have not yet been elucidated. For this reason, the probability of the generation of inorganic by-products after disinfection with chlorine dioxide has been determined, and their occurrence in drinking water on board has been examined with respect to a possible correlation between water quality and the formation of chlorate and chlorite. Therefore, a chromatographic method was developed and validated in order to determine the periodical development of chlorate and chlorite from chorine dioxide in purified water at different pH-values as well as in actual drinking water samples from water conduits on board. The formation of the by-products chlorite and chlorate after disinfection with chlorine dioxide is influenced neither by pH-value nor by chemical properties of the disinfected water. Considering the examined conditions, chlorine dioxide is suitable for usage on board due to its simple handling and the low potential of producing by-products.

An international trial of quantitative PCR for monitoring Legionella in artificial water systems

AIMS

  To perform an international trial to derive alert and action levels for the use of quantitative PCR (qPCR) in the monitoring of Legionella to determine the effectiveness of control measures against legionellae.

METHODS AND RESULTS

  Laboratories (7) participated from six countries. Legionellae were determined by culture and qPCR methods with comparable detection limits. Systems were monitored over ≥10 weeks. For cooling towers (232 samples), there was a significant difference between the log mean difference between qPCR (GU l(-1) ) and culture (CFU l(-1) ) for Legionella pneumophila (0·71) and for Legionella spp. (2·03). In hot and cold water (506 samples), the differences were less, 0·62 for Leg. pneumophila and 1·05 for Legionella spp. Results for individual systems depended on the nature of the system and its treatment. In cooling towers, Legionella spp. GU l(-1) always exceeded CFU l(-1) , and usually Legionella spp. were detected by qPCR when absent by culture. The pattern of results by qPCR for Leg. pneumophila followed the culture trend. In hot and cold water, culture and qPCR gave similar results, particularly for Leg. pneumophila. There were some marked exceptions with temperatures ≥50°C, or in the presence of supplementary biocides. Action and alert levels for qPCR were derived that gave results comparable to the application of the European Guidelines based on culture. Algorithms are proposed for the use of qPCR for routine monitoring.

CONCLUSIONS

  Action and alert levels for qPCR can be adjusted to ensure public health is protected with the benefit that remedial actions can be validated earlier with only a small increase in the frequency of action being required.

SIGNIFICANCE AND IMPACT OF THE STUDY

  This study confirms it is possible to derive guidelines on the use of qPCR for monitoring the control of legionellae with consequent improvement to response and public health protection.

Infection prevention during anaesthesia ventilation by the use of breathing system filters (BSF): Joint recommendation by German Society of Hospital Hygiene (DGKH) and German Society for Anaesthesiology and Intensive Care (DGAI)

An interdisciplinary working group from the German Society of Hospital Hygiene (DGKH) and the German Society for Anaesthesiology and Intensive Care (DGAI) worked out the following recommendations for infection prevention during anaesthesia by using breathing system filters (BSF). The BSF shall be changed after each patient. The filter retention efficiency for airborne particles is recommended to be >99% (II). The retention performance of BSF for liquids is recommended to be at pressures of at least 60 hPa (=60 mbar) or 20 hPa above the selected maximum ventilation pressure in the anaesthetic system. The anaesthesia breathing system may be used for a period of up to 7 days provided that the functional requirements of the system remain unchanged and the manufacturer states this in the instructions for use.THE BREATHING SYSTEM AND THE MANUAL VENTILATION BAG ARE CHANGED IMMEDIATELY AFTER THE RESPECTIVE ANAESTHESIA IF THE FOLLOWING SITUATION HAS OCCURRED OR IT IS SUSPECTED TO HAVE OCCURRED: Notifiable infectious disease involving the risk of transmission via the breathing system and the manual bag, e.g. tuberculosis, acute viral hepatitis, measles, influenza virus, infection and/or colonisation with a multi-resistant pathogen or upper or lower respiratory tract infections. In case of visible contamination e.g. by blood or in case of defect, it is required that the BSF and also the anaesthesia breathing system is changed and the breathing gas conducting parts of the anaesthesia ventilator are hygienically reprocessed.Observing of the appropriate hand disinfection is very important. All surfaces of the anaesthesia equipment exposed to hand contact must be disinfected after each case.