Adenosine Triphosphate Bioluminescence for Hygiene Monitoring in Health Care Institutions

ATP Bioluminescence for Assessing the Efficacy of the Manual Cleaning Procedure during the Reprocessing of Reusable Surgical Instruments

Achieving sterilization by adopting proper practices is essential to ensure that surgical instruments do not transmit microorganisms to patients. As the effectiveness of sterilization mandates effective cleaning, it is necessary to verify the success of cleaning procedures. In this study, we used the adenosine triphosphate (ATP) bioluminescence method for assessing the efficacy of the manual cleaning procedure during the reprocessing of reusable surgical instruments. The ATP bioluminescence assay was performed on 140 surgical instruments of 12 different types, both before being cleaned (baseline) and after each of the cleaning procedures (i.e., decontamination, manual washing, drying, and visual inspection). For each instrument, two swabs were used as follows: one to sample the entire surface (test point 1) and the other to sample the most difficult part of the surface to clean (test point 2). Overall, for each type of instrument, there was a decrease in contamination ranging from 99.6 to >99.9% (log reduction from 2.40 to 3.76). Thus, in order to standardize the assessment of cleanliness, it may be useful to introduce the bioluminescence method into the daily routine or, at least, at regular time intervals as a complementary check combined with visual inspection. This would allow real-time verification of the achievement of an adequate level of cleanliness.

[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.

Implications of Adenylate Metabolism in Hygiene Assessment: A Review

The assessment of a hygienic state or cleanliness of contact surfaces has significant implications for food and medical industries seeking to monitor sanitation and exert improved control over a host of operations affecting human health. Methods used to make such assessments commonly involve visual inspections, standard microbial plating practices, and the application of ATP-based assays. Visual methods for inspection of hygienic states are inherently subjective and limited in efficacy by the accuracy of human senses, the degree of task-specific work experience, and various sources of human bias. Standard microbial swabbing and plating techniques are limited in that they require hours or even days of incubation to generate results, with such steps as enrichment and colony outgrowth resulting in delays that are often incompatible with manufacturing or usage schedules. Rapid in conduct and considered more objective in operation than visual or tactile inspection techniques, swabbing surfaces using ATP-based assessments are relied on as routine, even standard, methods of hygienic assessment alone or in complement with microbial and visual inspection methods. Still, current ATP methods remain indirect methods of total hygiene assessment and have limitations that must be understood and considered if such methods are to be applied judiciously, especially under increasingly strict demands for the verification of hygiene state. Here, we present current methods of ATP-based bioluminescence assays and describe the limitations of such methods when applied to general food manufacturing or health care facilities.

Turning tryptophanase into odor-generating biosensors

An odor-based sensor system that exploits the metabolic enzyme tryptophanase (TPase) as the key component is reported. This enzyme is able to convert an odorless substrate like S-methyl-L-cysteine or L-tryptophan into the odorous products methyl mercaptan or indole. To make a biosensor, TPase was biotinylated so that it could be coupled with a molecular recognition element, such as an antibody, to develop an ELISA-like assay. This method was used for the detection of an antibody present in nM concentrations by the human nose. TPase can also be combined with the enzyme pyridoxal kinase (PKase) for use in a coupled assay to detect adenosine 5'-triphosphate (ATP). When ATP is present in the low μM concentration range, the coupled enzymatic system generates an odor that is easily detectable by the human nose. Biotinylated TPase can be combined with various biotin-labeled molecular recognition elements, thereby enabling a broad range of applications for this odor-based reporting system.

The uses and abuses of rapid bioluminescence-based ATP assays

Bioluminescence-based ATP testing of solid surfaces has become well established in the food processing industry as part of general hazard analysis and critical control points (HACCP) measures. The rise in healthcare associated infections (HAIs) at the turn of the century focussed attention on the environment as a potential reservoir of the agents responsible for such infections. In response to the need for objective methods of assessing the efficiency of cleaning in healthcare establishments and for rapid methods for detecting the presence of the pathogens responsible for HAIs, it was proposed that ATP testing of environmental surfaces be introduced. We examine the basis behind the assumptions inherent in these proposals. Intracellular ATP levels are shown to vary between microbial taxa and according to environmental conditions. Good correlations between microbial numbers and ATP levels have been obtained under certain specific conditions, but never within healthcare settings. Notwithstanding, ATP testing may still have a role in providing reassurance that cleaning regimes are being carried out satisfactorily. However, ATP results should not be interpreted as surrogate indicators for the presence of microbial pathogens.

Application of ATP bioluminescence for evaluation of surface cleanliness of milking equipment

The ATP bioluminescence method was used to evaluate the cleanliness of milking equipment surfaces (teat cup rubbers, teat dip containers, milk receivers, and pipeline joints) in dairy farms in Galicia (northwest Spain) with parlour, pipeline tie-stall or bucket tie-stall milking systems. The cleanest surfaces were teat cup rubbers. The use of non-chlorinated water for cleaning, and of pipeline or bucket tie-stall milking systems, was associated with high ATP bioluminescence values. However, ATP bioluminescence values only explained 12% of the variability in bulk-tank bacterial count; this is attributable to the importance of other factors (notably the correct functioning of the tank cooling system) for maintenance of low bacterial count.

An assessment of cleaning regimes and standards in butchers' shops

Cleaning regimes and standards in retail butchers taking part in the Accelerated HACCP project initiative, were assessed by means of visual inspection, examination of cleaning schedules and ATP bioluminescence assays of selected food and hand contact sites. There was a wide variation in surface ATP results, both within and between butchers' shops, but overall they indicated that food and hand contact surfaces were heavily soiled during food production and service. Although separate preparation equipment/utensils were provided, staff undertook raw and cooked product handling throughout the day, with the concomitant danger of contaminating hand and food contact surfaces. The extent of soiling was generally underestimated when assessed visually, the technique used most commonly by the food retail trade and inspection authorities. Periodic or interim cleaning practices produced a significant improvement in cleanliness assessed visually and with ATP assay; however, these results were generally less satisfactory than those obtained by the use of best practice protocols. A lack of written cleaning schedules and records, training in the correct use of cleaning products and awareness of the importance of cleaning hand contact sites were identified as common defects. The results are discussed in relation to the establishment of an effective HACCP system and recommendations for improving cleaning standards are given.

An evaluation of hospital cleaning regimes and standards

A four-part study assessing cleanliness in up to 113 environmental surfaces in an operating theatre and a hospital ward is reported. Surfaces were assessed visually, using microbiological methods and ATP bioluminescence. Results from a preliminary random survey indicated variability in cleanliness. These results were then used to select sites for monitoring before and after routine cleaning, over a 14-day period. Using published microbiological and ATP specifications 70 and 76% of these sites were unacceptable after cleaning. Visual assessment was a poor indicator of cleaning efficacy with only 18% considered unacceptable. Sites most likely to fail in the ward were in the toilet and kitchen, areas which are frequently implicated in the spread of infectious intestinal disease. Operating theatre sites had lower ATP results but 61% of sites would be considered unacceptable. There was no significant difference in general microbiological or ATP results overall before and after routine cleaning. Although some important hand contact sites showed no significant difference, overall there was a significant decrease in staphylococcal and enterobacteria counts in the ward but not in the operating theatre after cleaning. The routine cleaning programmes used did not include a biocide and cleaning using a hypochlorite based sanitizer gave much lower values. The results are discussed in relation to infection control, cleaning audits and cleaning schedules: an integrated cleaning monitoring programme using ATP bioluminescence in conjunction with visual and microbiological assessments is recommended.

Evaluation of two methods for monitoring surface cleanliness-ATP bioluminescence and traditional hygiene swabbing

The minimum bacterial detection limits and operator reproducibility of the Biotrace Clean-Tracetrade mark Rapid Cleanliness Test and traditional hygiene swabbing were determined. Areas (100 cm2) of food grade stainless steel were separately inoculated with known levels of Staphylococcus aureus (NCTC 6571) and Escherichia coli (ATCC 25922). Surfaces were sampled either immediately after inoculation while still wet, or after 60 min when completely dry. For both organisms the minimum detection limit of the ATP Clean-Tracetrade mark Rapid Cleanliness Test was 10(4) cfu/100 cm2 (p < 0.05) and was the same for wet and dry surfaces. Both organism type and surface status (i.e. wet or dry) influenced the minimum detection limits of hygiene swabbing, which ranged from 10(2) cfu/100 cm2 to >10(7) cfu/100 cm2. Hygiene swabbing percentage recovery rates for both organisms were less than 0.1% for dried surfaces but ranged from 0.33% to 8.8% for wet surfaces. When assessed by six technically qualified operators, the Biotrace Clean-Tracetrade mark Rapid Cleanliness Test gave superior reproducibility for both clean and inoculated surfaces, giving mean coefficients of variation of 24% and 32%, respectively. Hygiene swabbing of inoculated surfaces gave a mean CV of 130%. The results are discussed in the context of hygiene monitoring within the food industry.

Evaluation of adenosine triphosphate-bioluminescence hygiene monitoring for trouble-shooting fluid milk shelf-life problems

An ATP-bioluminescence hygiene monitoring system was used to evaluate food contact surfaces in four fluid milk plants experiencing shelf-life problems. Postpasteurization surfaces, including gaskets, pipe fittings, valves, filler parts, and hand-washed items, were evaluated. Swab results, measured in relative light units proportional to total recovered ATP, were compared with results from the standard method of microbiological swab contact for adjacent sites of equal area. Microbiological procedures included standard plate count, coliform count, and Gram-negative bacteria count. Standard plate counts were < 1, 1 to 50, and > 50 cfu in 65, 22, and 13% of swabbed sites of < 100 RLU (relative light units); in 9, 36, and 55% of sites of 100 to 150 RLU; and in 22, 18, and 60% of sites of > 50 RLU, respectively. Thirteen sites were found with standard plate counts > 10,000 cfu per site and identified with the hygiene monitoring system (> 150 RLU). Gram-negative bacteria were the dominant bacterial type in a majority of these samples. Gram-negative bacteria were detected in a total of 22 sites tested; mean counts were 2100 cfu per site for Gram-negative bacteria and 20 cfu per site for coliform bacteria. Although limited to use on accessible sites, the hygiene monitoring system proved to be an effective, rapid tool for identifying the possible sources of postpasteurization contamination in the fluid milk plants evaluated.