Analytical performance issues: comparison of ATP bioluminescence and aerobic bacterial count for evaluating surface cleanliness in an Italian hospital

Impact of terminal cleaning in rooms previously occupied by patients with healthcare-associated infections

Healthcare associated infections (HAIs) are costly but preventable. A limited understanding of the effects of environmental cleaning on the riskiest HAI associated pathogens is a current challenge in HAI prevention. This project aimed to quantify the effects of terminal hospital cleaning practices on HAI pathogens via environmental sampling in three hospitals located throughout the United States. Surfaces were swabbed from 36 occupied patient rooms with a laboratory-confirmed, hospital- or community-acquired infection of at least one of the four pathogens of interest (i.e., Acinetobacter baumannii (A. baumannii), methicillin resistant Staphylococcus aureus (MRSA), vancomycin resistant Enterococcus faecalis/faecium (VRE), and Clostridioides difficile (C. difficile)). Six nonporous, high touch surfaces (i.e., chair handrail, bed handrail, nurse call button, desk surface, bathroom counter near the sink, and a grab bar near the toilet) were sampled in each room for Adenosine Triphosphate (ATP) and the four pathogens of interest before and after terminal cleaning. The four pathogens of interest were detected on surfaces before and after terminal cleaning, but their levels were generally reduced. Overall, C. difficile was confirmed on the desk (n = 2), while MRSA (n = 24) and VRE (n = 25) were confirmed on all surface types before terminal cleaning. After cleaning, only MRSA (n = 6) on bed handrail, chair handrail, and nurse call button and VRE (n = 5) on bathroom sink, bed handrail, nurse call button, toilet grab bar, and C. difficile (n = 1) were confirmed. At 2 of the 3 hospitals, pathogens were generally reduced by >99% during terminal cleaning. One hospital showed that VRE increased after terminal cleaning, MRSA was reduced by 73% on the nurse call button, and VRE was reduced by only 50% on the bathroom sink. ATP detections did not correlate with any pathogen concentration. This study highlights the importance of terminal cleaning and indicates room for improvement in cleaning practices to reduce surface contamination throughout hospital rooms.

Hygiene Assessment of Buffalo Milking Parlours in Campania Region, Italy: A Preliminary Study by Using ATP Luminometry and Bacteriological Investigation

Careful cleaning of a milking parlour and its equipment is fundamental to guarantee good raw milk quality and prevent the dissemination of bacteria and improve animal welfare. This study aimed to investigate, using an ATP-bioluminescence assay and bacteriological analysis, the bacterial contamination of milking parlours on milking parlour surfaces of buffalo farms in the Campania Region, evaluating the seasonal dynamics during the year 2022. Eight farms were selected by the Italian ClassyFarm system, which assesses the level of animal welfare and biosecurity according to risk analysis. Before sampling, all dairy farm owners filled out a questionnaire on milking management, animal hygiene, and health. The questionnaires evidenced similar cleaning procedures but an absence of a standardised cleaning protocol among the different farms. ATP bioluminescence results evidenced similar levels of contamination in all the selected buffalo farms, and the season comparison showed no significant differences. A variation in the percentages of bacterial isolates during the different seasons was observed, with a higher prevalence of Enterobacteriaceae (38%) in summer. A small number of samples exhibited an absence of bacterial growth. Identifying bacteria is crucial for understanding the microorganisms present in the milking parlour, yet employing ATP luminometry could offer broad and accurate applications in buffalo milking parlours. In conclusion, the use of ATP bioluminescence for evaluating the hygiene of a buffalo milking parlour could represent a further important advancement in dairy farming technology.

Improving infection control in a veterinary hospital: a detailed study on patterns of faecal contamination to inform changes in practice

BACKGROUND

The main purpose of this study was to investigate the cleanliness and microbial burden of a veterinary hospital to establish the extent of cross-contamination with faecal bacteria as an aid to reducing nosocomial infections. Enterococci and Escherichia coli were used as faecal indicator organisms as they can survive on inanimate surfaces for months and pose a threat to animal health. The study consisted of several elements: (i) a cross-sectional study to identify sites currently contaminated with faecal organisms that could be usefully included in a longitudinal study, (ii) a 3-week longitudinal study to identify sites from which faecal bacteria were repeatedly recovered, (iii) once-off monitoring of hand hygiene, (iv) a review of all hospitalised cases with confirmed E. coli or enterococcal infection during the 8-week study period to investigate possible hospital-acquired (HAI) infection and relationship with environmental contamination. Environmental surface and hand hygiene were assessed using 3M™ Clean-Trace™ ATP test, 3M™ Petrifilm™ plates and bacteriological culture of Enterococcus species and E. coli. Cross contamination was assessed using results of antimicrobial susceptibility testing.

RESULTS

In the cross-sectional study, 26 of 113 (24.5%) of sites sampled exceeded the accepted microbial threshold (2.5 CFU/cm²) and Enterococcus species were isolated from 31 (27.4%) and E. coli from 9 (7.9%) of 113 samples. Organic residue and microbial levels were high in the dog kennels even after cleaning and faecal organisms were also recovered from sites such as the dispensary, a student computer and staff common room. Four of 51 (7.8%) hand samples were contaminated with faecal bacteria. Nine sites were monitored on three occasions in the longitudinal study and a total of 23 Escherichia coli and 6 Enterococcus species were recovered. Seven of the nine sites were positive for faecal organisms on more than one occasion. There was no change in cleanliness or microbial burden over 3 weeks. Twenty-one of the 73 isolates (28.8%) recovered during all parts of the study were multi-drug resistant. Enterococci and E. coli isolates with similar resistance patterns were recovered from the environment in the large and small animal hospitals and from a small number of patients during the same timeframe, suggesting possible hospital acquired infections.

CONCLUSIONS

Results suggested that movement between the small and large animal hospital areas may have been responsible for cross-contamination and possible hospital-acquired infections. The data show that cross-sectional and longitudinal monitoring of faecal contamination across all hospital areas can play an important role in informing review of infection control protocols in veterinary hospital settings. Changes in practices in the hospital based on results generated are outlined.

Impact of Plastic-Wrap Properties and Cleaning Intervals on the Disinfection of Elevator Buttons

Fomite transmission is a possible route by which different pathogens spread within facilities. In hospital settings, elevator buttons are widely observed to be covered with various types of plastic wraps; however, limited information is available concerning the impact of different plastic materials on cleaning. Our study aimed to identify which plastic material is suitable for the coverage of elevator buttons and the optimal intervals for their cleaning. We tested six plastic covers, including polyethylene (PE), polymethylpentene (PMP), polyvinyl chloride (PVD), and polyvinylidene chloride (PVDC) plastic wraps; a thermoplastic polyurethane (TPU) keyboard cover; and a polyethylene terephthalate-ethylene vinyl acetate (PET-EVA) laminating film, which are plastic films. The bioburden on the elevator buttons at different time intervals was measured using an adenosine triphosphate (ATP) bioluminescence assay. Our results show that wraps made of PVDC had superior durability compared with those of PMP, PVC, and PVDC, in addition to the lowest detectable ATP levels among the six tested materials. Regarding different button locations, the highest ATP values were found in door-close buttons followed by door-open, and first-floor buttons after one- and three-hour intervals (p = 0.024 and p < 0.001, respectively). After routine disinfection, the ATP levels of buttons rapidly increased after touching and became more prominent after three hours (p < 0.05). Our results indicate that PVDC plastic wraps have adequate durability and the lowest residual bioburden when applied as covers for elevator buttons. Door-close and -open buttons were the most frequently touched sites, requiring more accurate and precise disinfection; therefore, cleaning intervals of no longer than three hours may be warranted.

Comparison of Improved Surgical Eight-Step Handwashing Combined with ATP Fluorescence in Detecting the Infection Rate at the Site of Seven-Step Surgical Handwashing and 30-Day Orthopaedic Surgery: A Randomized Study

OBJECTIVES

To compare the effects of two hand cleaning schemes on the prevention of surgical site infection in routine orthopaedic surgery. Compared with the standard surgical seven-step washing technique and detected by ATP fluorescence method, the handwashing effects of the improved surgical eight-step washing technique and the standard surgical seven-step washing technique were compared, so as to provide a basis for eliminating the handwashing blind area of the surgical seven step washing technique and improving the surgical handwashing method.

METHODS

A total of 800 consecutive patients who underwent clean and clean-contaminated orthopaedic surgery between January 1, 2020 and December 31, 2020. Twenty orthopaedic doctors in the operating room of our research team were randomly divided into the improved eight-step washing technique group (improved group) and the traditional seven-step washing technique group (traditional group), with 10 people in each group. Each person was randomly sampled 40 times, 400 people in each group, a total of 800 people, and completed by stages in 12 months. Main Outcome Measures. The infection rate of surgical site 30 days after operation was the primary end point. The qualified rate of fingertip culture was combined with ATP fluorescence in the two groups and three new culture areas in the two groups: the lateral edge of the palm, the medial edge of the palm, and the nail groove of the middle finger and the nail root were secondary end points.

RESULTS

The 2 protocols were comparable in regard to surgical site infection risk factors. The infection rate of surgical site in the traditional group was 10 cases (2.50%) in 400 cases and 0 cases (0%) in the improved group. Three culture areas were added: the qualified rate of lateral edge of palm, medial edge of palm, and nail groove and nail root of middle finger, and the nosocomial infection rate of surgical incision between the two groups was statistically significant (P < 0.05). There was no significant difference in the qualified rate of fingertip culture (P > 0.05). The handwashing scheme in this study meets the recommended duration of hand disinfection and has good tolerance, and the skin dryness and skin irritation after using aqueous solution are similar.

CONCLUSIONS

The improved surgical eight-step washing technique combined with ATP fluorescence detection is helpful to eliminate the "blind area" of handwashing. It is also necessary to add three training areas. Handwashing and training are more scientific, rigorous, and effective. They are effective in reducing orthopaedic surgical infection and have application value. They can safely replace the traditional surgical seven-step washing technique, which is worthy of clinical promotion.

The correlation between ATP measurement and microbial contamination of inanimate surfaces

Background

The objective of this study was to determine the correlation between adenosine triphosphate (ATP) measurements and microbial contamination using a standardized method. Secondarily, analyzing reproducibility of ATP measurements and aerobic colony counts (ACC’s) on the same surface.

Methods

ATP measurements and ACC’s were conducted on 10 pre-defined fomites in a hospital and nursing home setting. Per fomite two ATP measurements and two agar plate measurements were conducted, each measurement was conducted on a 25 cm² surface. Both measurements were compared and analyzed for correlation.

Results

In total 200 paired measurements were conducted, 200 ATP measurements and 200 ACC’s. The mean of all ATP measurements tested on the same surface was calculated, as was for all 200 ACC’s. There was a strong correlation between the mean of two ATP measurements on two different sites on the same fomite (R = 0.800, p < 0.001) as well as between two ACC measurements on the same fomite (R = 0.667, p < 0.001). A much weaker correlation was found between RLU values and ACC’s (R = 0.244, p < 0.001).

Conclusions

Reproducibility of ATP measurements and ACC’s on the same fomite was good. However, the correlation between RLU values and ACC’s on hospital surfaces was much lower. This may be explained by the wide variety of biological material that is measured with ATP, of which the bacterial load is only one of many components. ATP measurement can be used to give a quantifiable outcome for the rating of cleanliness in health care facilities, however the results cannot be translated into the level of microbial contamination.

Antimicrobial susceptibility of bacterial pathogens isolated from healthcare workers' cellphones

OBJECTIVE

To evaluate bacterial isolates, antibiotic susceptibility, and disease transmission risk in healthcare workers using cellphones.

METHODS

A total of 70 cellphones were received from the hospital staff. Samples were collected from the phones with a sterile cotton swab moistened with physiological saline solution. Samples were inoculated in a bacteriological culture medium and incubated at 37.5°C for 24-48hours. Identification of microorganisms was performed by traditional methods and VITEK 2 device. Kirby-Bauer disk diffusion method was used to determine antibiotic susceptibility.

RESULTS

A total of 26 species and 170 microorganisms were isolated from 66 cellphones from which bacterial growths were obtained: coagulase-negative staphylococci (n=63, 37%) (most commonly Staphylococcus epidermidis: 25/63), Micrococcus luteus (n=25, 14.7%), Tetracoccus (n=24, 14.1%), Kocuria spp. (n=24, 14.1%), Corynebacterium diphtheriae (n=7, 4.1%), Leuconostoc mesenteroides (n=5, 3.0%), S. aureus (n=4, 2.3%), Enterococcus spp. (n=5, 2.9%), Acinetobacter spp. (n=7, 4.1%), Klebsiella pneumoniae (n=2, 1.2%), Actinomyces spp. (n=1, 0.6%), Pseudomonas aeruginosa (n=1, 0.6%), Morganella morganii (n=1, 0.6%), and Alcaligenes faecalis (n=1, 0.6%). Gram-positive isolates were all susceptible to the antibiotics used, whereas Gram-negative isolates were all resistant to ceftazidime.

CONCLUSION

Hands and/or cellphones of healthcare staff can be contaminated with various types of microorganisms. We recommend proper hand washing and disinfection to prevent bacterial pathogens spread within the hospital.

Assessing the Performance of a Real-Time Total Adenylate (ATP+ADP+AMP) Detection Assay for Surface Hygiene Monitoring in Food Manufacturing Plants and Commercial Kitchens

ABSTRACT

Environmental hygiene monitoring in the food processing environment has become important in current food safety programs to ensure safe food production. However, conventional monitoring of surface hygiene based on visual inspection and microbial counts is slow, tedious, and thus unable to support the current risk-based management system. Therefore, this study was conducted to assess the performance of a real-time total adenylate assay that detected ATP+ADP+AMP (A3) for food contact surface hygiene in 13 food processing plants and two commercial kitchens in Malaysia. The A3 value was compared with the microbial count (aerobic plate count [APC]) on food contact surfaces. Receiver-operating characteristic (ROC) analysis was performed to assess the reliability of the data and to determine the optimal threshold value for hygiene indication of food contact surfaces. Overall, the A3 value demonstrated a weak positive relationship with APC. However, the A3 value significantly correlated with APC for food processing environments associated with raw meat and raw food ingredients such as fruit that harbor a high microbial load. ROC analysis suggested an optimal threshold for the A3 value of 500 relative light units to balance the sensitivity and specificity at 0.728 and 0.719, respectively. The A3 assay as a hygiene indicator for food contact surfaces had an efficiency of 72.1%, indicating its reliability as a general hygiene indicator.

HIGHLIGHTS

Utility of rapid tests to assess the prevalence of indicator organisms (Aerobic plate count, Enterobacteriaceae, coliforms, Escherichia coli, and Listeria spp.) in apple packinghouses

The 2014 listeriosis outbreak caused by caramel-coated apples was linked to apples cross-contaminated within an apple packing facility. This outbreak has increased the focus on effective cleaning and sanitation methods that must be validated and monitored during apple packing. Thus, rapid and reliable testing methods are necessary for assessing cleanliness in the apple packing industry. The objectives of this study were to assess the prevalence of common indicator organisms [Aerobic plate count (APC), Enterobacteriaceae, coliforms, Escherichia coli, and Listeria spp.] on food contact surfaces (zone 1) in apple packinghouses and to evaluate the utility and accuracy of currently used rapid tests (ATP and glucose/lactose residue swabs). Food contact surfaces were sampled over a 100 cm² area in five commercial apple packinghouses to evaluate populations of indicator organisms APC, Enterobacteriaceae, coliforms, E. coli (n = 741), and rapid test readings (n = 659). Petrifilm plates were used for the quantification of APC, Enterobacteriaceae, and coliform/E. coli. Rapid tests [ATP swabs (UltraSnap) and glucose/lactose residue swabs (SpotCheck Plus)] were processed on-site. A larger area (0.93 m²) was sampled for the detection of Listeria spp. (n = 747), following a modified protocol of the FDA's Bacteriological Analytical Manual method, and confirmed with PCR and gel electrophoresis via the iap gene. No significant association was found between either rapid test and populations of APC, Enterobacteriaceae, coliforms, E. coli, and Listeria spp. detection. However, recovery of APC (log CFU/100 cm²) was higher with a failed glucose/lactose residue swab surface hygiene result (3.1) than a passed result (2.9) (p = 0.03). Populations of APC, Enterobacteriaceae, and coliforms were significantly different at each unit operation during the packing process (p ≤ 0.05). This study concluded that ATP and glucose/lactose residue rapid tests were poorly suited for determining microbial load since they were not related to populations of any common indicator organisms or the detection of Listeria spp. These findings emphasize the need to utilize a rapid test, which can be a good indicator of residual matter on a surface, along with traditional microbiological methods to assess cleaning and sanitation practices in apple packinghouses.

[Evaluation of Hygiene in Dry Powder Steroid Drug Inhalers Used by Elderly Asthma Patients]

Dry powder inhalers (DPI) are frequently used by asthmatic patients, and the usage rate increases every year. The pharmacists at our hospital provided initial inhalation instructions on how the inhaler must be used but did not elaborate on the cleaning of the device. Therefore, the cleaning status of the inhaler is unknown, and there is a possibility of bacterial growth. This study investigated the cleaning status and hygiene of steroid drug inhalers used by elderly asthma patients. We administered a questionnaire to investigate the inhaler cleaning status after inhalation, and conducted a cross-sectional survey on hygiene using ATP measurement and bacterial culture examination. Considering the responses by 53 patients, it became clear that the ATP values of patients who answered "never cleaned" after inhalation were significantly higher than those who answered "cleaned every time". Moreover, some bacteria were detected in 62% of inhalers; 4 patients' inhalers contained bacteria other than normal oral microbial flora. In conclusion, because the inhalers used by elderly patients are in poor hygienic conditions, we must give cleaning instructions accordingly. We believe that it is necessary to give proper medical instructions along with instructions on the cleaning method with dry cloth.

Taking Screenshots of the Invisible: A Study on Bacterial Contamination of Mobile Phones from University Students of Healthcare Professions in Rome, Italy

Mobile phones (MPs) are commonly used both in the personal and professional life. We assessed microbiological contamination of MPs from 108 students in healthcare professions (HPs), in relation to their demographic characteristics and MPs handling habits, collected by means of a questionnaire. Cultural and biochemical tests were performed, and statistical analyses were carried out. Staphylococci were present in 85% of MPs, Enterococci in 37%, Coliforms in 6.5%; E. coli was never detected. Staphylococcus epidermidis was the most frequently isolated staphylococcal species (72% of MPs), followed by S. capitis (14%), S. saprophyticus, S. warneri, S. xylosus (6%), and by S. aureus (4%). Heterotrophic Plate Counts (HPC) at 37 °C, ranged from 0 to 1.2 × 10⁴ CFU/dm² (mean = 362 CFU/dm²). In univariate analysis, the male gender only was significantly associated with higher HPCs and enterococcal contamination. Multiple linear regression models explained only 17% and 16% of the HPC 37 °C and staphylococcal load variability, respectively. Developing specific guidelines for a hygienic use of MPs in clinical settings, for preventing cross-infection risks, is advisable, as well as introducing specific training programs to HP students. MPs decontamination procedures could also be implemented in the community.

Evaluation of different detector types in measurement of ATP bioluminescence compared to colony counting method for measuring bacterial burden of hospital surfaces

The ATP bioluminescence method has been increasingly employed as a rapid, on-site detection method in nosocomial infections control. In this study, we used a paired design of monitoring methods, the colony counting method (C) and the ATP bioluminescence method, to evaluate environmental surfaces after disinfection. The ATP bioluminescence method included three detector types (B, P, and N). Every surface after disinfection was performed by combining two types of monitoring methods or detectors. There was no statistically significant difference in theATP content per surface siteamong samples from intensive care units (ICUs)and internal medicine wards using B (p = 0.435) and P (p = 0.260). According to the Spearman’s rank correlation coefficients, with the exception of the correlation between the ATP content values detected by B and P, the correlation between the values generated by the remaining methods/detectors was weak or lacking, whereasthe differences between the detectors were statistically significant. Therefore, there are differences between the ATP bioluminescence method and the colony counting method, also between different detectors.

ATP bioluminescence assay for evaluating cleaning practices in operating theatres: applicability and limitations

Background

Environmental cleaning practice plays an important role in reducing microbial contamination in hospital surfaces and contributes to prevent Healthcare Associated Infections. Adenosine Triphosphate (ATP) bioluminescence assay is a commonly used method for assessing environmental cleanliness on healthcare surfaces. This study tested the feasibility of using ATP-bioluminescence assay for evaluating the efficiency of cleaning procedures in the operating theatre settings, comparing the ATP-bioluminescence test with the traditional culture method.

Methods

The surfaces of 10 operating rooms of two public hospitals (140 samples in total) were examined “at rest”, in two moments of the same daily session: before the first scheduled operation (Pre), and before the second, after a clean environment was re-established (Post). Surface contamination was assessed using the cultural method to detect Total Viable Counts (TVC36°C) and ATP-bioluminescence assay (RLU).

Results

The examined surfaces presented very low TVCs (geometric means: 1.8 CFU/plate; IC95%: 1.6–2.0), always compliant with the relative reference standards. No statistical correlation was found between ATP values and TVCs. However, considering the results in terms of general evaluation of hygienic quality of surfaces, the two methods were consistent in identifying the most contaminated areas (Hospital A > Hospital B; Pre > Post; most contaminated surfaces: scialytic lamp). Furthermore, the ATP mean values showed a progressive increase from surfaces with TVC = 0 to surfaces with TVC > 15 CFU/plate.

Conclusions

Although not an alternative to cultural methods, the ATP-bioluminescence-assay can be a useful tool to measure the efficiency of cleaning procedures also in environments with very low microbial counts. Each health facility should identify appropriate reference values, depending on the devices used and on the basis of the analysis of the data collected through spatial and temporal sampling series. By providing a rapid feedback, the ATP-assay helps to increase the awareness of operators and allows immediate action to be taken in critical situations.

Effectiveness of Surface Cleaning and Disinfection in a Brazilian Healthcare Facility

Background

Failures in the processes of cleaning and disinfecting health service surfaces may result in the spread and transfer of pathogens that are often associated with healthcare-related infections and outbreaks.

Aims

To assess the effectiveness of environmental surface cleaning and disinfection in a hospital clinic.

Method

The study was conducted in a nursing ward with 45 beds. A total of 80 samples from five high-touch surfaces were evaluated before and after cleaning and disinfection, using the following methods: visual inspection, adenosine triphosphate bioluminescence assay, aerobic colony count, Staphylococcus aureus colony count, and evaluation of resistance to methicillin. The data analysis used nonparametric comparative and correlative tests to observe any differences in the pre- and post- cleaning and disinfection results for the surfaces assessed.

Results

Effective cleaning and disinfection had a significant effect on only two surfaces when measured for the presence of adenosine triphosphate, the inner bathroom door handle (p=0.007) and the toilet bowl (p=0.01). When evaluated for Staphylococcus aureus colony count, the toilet flush handle also demonstrated a significant effect (p=0.04).

Conclusion

The effectiveness of cleaning and disinfection of the surfaces tested was not satisfactory. An educational intervention is recommended for the cleaning and disinfection staff and the nursing team at the healthcare facility.

Relevance to Clinical Practice

The data in the study revealed that daily hospital cleaning and disinfection in the sampled sites are not sufficient in medical and surgical wards. Hospital cleanliness must be reevaluated from the point of view of materials, such as an adequate supply of clean cloths, in addition to establishing more precise cleanliness protocols and accurate monitoring systems.

Effectiveness of ATP bioluminescence to assess hospital cleaning: a review

INTRODUCTION

Contamination of hospital surfaces plays an important role in the transmission of several healthcare-associated microorganisms, therefore methods for evaluating hospital surfaces' cleaning gain particular importance. Among these, there are visual inspection, quantitative microbiology, fluorescent markers and adenosine triphosphate (ATP) bioluminescence. The latter seems to provide interesting features, detecting the presence of ATP on surface (as Relative Light Units, RLU), a proxy of organic matter and microbial contamination. Several studies have investigated the effectiveness of this technology; with this research, we aim to summarize the most significant results.

METHODS

A systematic review was conducted. The keywords (namely, "ATP", "bioluminescence", "hospital" and "surfaces") were searched in PubMed/MEDLINE and Scopus databases, in order to find relevant data, from January 2000 to October 2014. After the selection, we globally considered 27 articles.

RESULTS

Most of the studies were conducted in United Kingdom and in USA. Different threshold RLU benchmark values were identified by analyzed studies. Fourteen of these researches compared the ATP bioluminescence with microbiological methods, 11 identified a significant correlation between the two methods, although poor or not complete for 5.

DISCUSSION

ATP bioluminescence is not a standardized methodology: each tool has different benchmark values, not always clearly defined. At the moment, we can say that the technique could be used to assess, in real time, hospital surfaces where cleanliness is required, but not sterility.

Determination of ATP-activity as a useful tool for monitoring microbial load in aqueous humidifier samples

Air humidifier water tanks are potential sources of microbial contaminants. Aerosolization of these contaminants is associated with the development of airway and lung diseases; therefore, implementation of preventive strategies including monitoring of the microbial contamination is recommended. So far, culture-based methods that include measuring colony forming units (CFU) are widely used to monitor microbial load. However, these methods are time consuming and have considerable drawbacks. As a result, alternative methods are needed which provide not only clear and accurate results concerning microbial load in water samples, but are also rapid and easy to use in the field. This paper reports on a rapid test for ATP quantification as an alternative method for microbial monitoring, including its implementation, validation and application in the field. For this purpose, 186 water samples were characterized with different methods, which included ATP analysis, culture-based methods, endotoxin activity (common and rapid test), pyrogenic activity and number of particles. Half of the samples was measured directly in the field and the other half one day later in the laboratory. The results of both tests are highly correlated. Furthermore, to check how representative the result from one sample of a water source is, a second sample of the same water tank were collected and measured. Bioluminescence results of the undiluted samples covered a range between 20 and 25,000 relative light units (RLU) and correlated with the results obtained using the other methods. The highest correlation was found between bioluminescence and endotoxin activity (rs=0.79) as well as pyrogenic activity (rs=0.75). Overall, the results of this study indicate that ATP measurement using bioluminescence is a suitable tool to obtain rapid, reproducible and sensitive information on the microbial load of water samples, and is suitable to use in the field. However, to use ATP measurement as an indicator of water quality, criteria of assessment has to be discussed.

Controlling hospital-acquired infection: focus on the role of the environment and new technologies for decontamination

There is increasing interest in the role of cleaning for managing hospital-acquired infections (HAI). Pathogens such as vancomycin-resistant enterococci (VRE), methicillin-resistant Staphylococcus aureus (MRSA), multiresistant Gram-negative bacilli, norovirus, and Clostridium difficile persist in the health care environment for days. Both detergent- and disinfectant-based cleaning can help control these pathogens, although difficulties with measuring cleanliness have compromised the quality of published evidence. Traditional cleaning methods are notoriously inefficient for decontamination, and new approaches have been proposed, including disinfectants, steam, automated dispersal systems, and antimicrobial surfaces. These methods are difficult to evaluate for cost-effectiveness because environmental data are not usually modeled against patient outcome. Recent studies have reported the value of physically removing soil using detergent, compared with more expensive (and toxic) disinfectants. Simple cleaning methods should be evaluated against nonmanual disinfection using standardized sampling and surveillance. Given worldwide concern over escalating antimicrobial resistance, it is clear that more studies on health care decontamination are required. Cleaning schedules should be adapted to reflect clinical risk, location, type of site, and hand touch frequency and should be evaluated for cost versus benefit for both routine and outbreak situations. Forthcoming evidence on the role of antimicrobial surfaces could supplement infection prevention strategies for health care environments, including those targeting multidrug-resistant pathogens.