N-acetylcysteine prevents catheter occlusion and inflammation in catheter associated-urinary tract infections by suppressing urease activity.

Introduction: Proteus mirabilis is a key pathobiont in catheter-associated urinary tract infections (CA-UTIs), which is well known to form crystalline biofilms that occlude catheters. Urease activity alkylates urine through the release of ammonia, consequentially resulting in higher levels of Mg2+ and Ca2+ and formation of crystals. In this study, we showed that N-acetyl cysteine (NAC), a thiol antioxidant, is a potent urease inhibitor that prevents crystalline biofilm formation. Methods: To quantify urease activity, Berthelot's method was done on bacterial extracts treated with NAC. We also used an in vitro catheterised glass bladder model to study the effect of NAC treatment on catheter occlusion and biofilm encrustation in P. mirabilis infections. Inductively-coupled plasma mass spectrometry (ICP-MS) was performed on catheter samples to decipher elemental profiles. Results: NAC inhibits urease activity of clinical P. mirabilis isolates at concentrations as low as 1 mM, independent of bacterial killing. The study also showed that NAC is bacteriostatic on P. mirabilis, and inhibited biofilm formation and catheter occlusion in an in vitro. A significant 4-8log10 reduction in viable bacteria was observed in catheters infected in this model. Additionally, biofilms in NAC treated catheters displayed a depletion of calcium, magnesium, or phosphates (>10 fold reduction), thus confirming the absence of any urease activity in the presence of NAC. Interestingly, we also showed that not only is NAC anti-inflammatory in bladder epithelial cells (BECs), but that it mutes its inflammatory response to urease and P. mirabilis infection by reducing the production of IL-6, IL-8 and IL-1b. Discussion: Using biochemical, microbiological and immunological techniques, this study displays the functionality of NAC in preventing catheter occlusion by inhibiting urease activity. The study also highlights NAC as a strong anti-inflammatory antibiofilm agent that can target both bacterial and host factors in the treatment of CA-UTIs.

Adenosine triphosphate (ATP) sampling algorithm for monitoring the cleanliness of surgical instruments.

BACKGROUND: Timely detection of cleaning failure is critical for quality assurance within Sterilising Service Units (SSUs). Rapid Adenosine Triphosphate (ATP) testing provides a real time and quantitative indication of cellular contaminants, when used to measure surface or device cleanliness. The aim of this study was to investigate the use of an ATP algorithm and to whether it could be used as a routine quality assurance step, to monitor surgical instruments cleanliness in SSUs prior to sterilisation. METHODS: Cleanliness monitoring using rapid ATP testing was undertaken in the SSUs of four hospitals located in the western (Amazonia) region of Brazil. ATP testing was conducted (Clean Trace, 3M) on 163 surgical instruments, following manual cleaning. A sampling algorithm using a duplicate swab approach was applied to indicate surgical instruments as (i) very clean, (ii) clean, (iii) equivocal or (iv) fail, based around a 'clean' cut-off of 250 Relative Light Units (RLU) and a 'very clean' <100 RLU. RESULTS: The four cleanliness categories were significantly differentiated (P≤0.001). The worst performing locations (hospitals A & C) had failure rates of 39.2% and 32.4%, respectively, and were distinctly different from hospitals B & D (P≤0.001). The best performing hospitals (B & D) had failure rates of 7.7% and 2.8%, respectively. CONCLUSION: The ATP testing algorithm provides a simple to use method within SSUs. The measurements are in real time, quantitative and useful for risk-based quality assurance monitoring, and the tool can be used for staff training. The four-tiered approach to the grading of surgical instrument cleanliness provides a nuanced approach for continuous quality improvement within SSU than does a simple pass/fail methodology.

Using a simplified ATP algorithm to improve data reliability and improve cleanliness standards for surface and medical device hygiene.

BACKGROUND: An algorithm has been improved to mitigate variability in cleanliness measurements of various surfaces using rapid Adenosine Triphosphate (ATP) testing. A cleaning intervention step (CIS) verifies the cleanability of those surfaces. METHODS: ATP testing was performed on surfaces which were pre-approved as "clean" and ready for re-use. Adjacent (duplicate) ATP sampling was undertaken on 421 environmental surfaces, medical devices and other implements. The CIS was conducted on 270 surfaces using an aseptic technique and disposable cleaning wipes. RESULTS: The two initial ATP results were plotted against each other with a 100 RLU threshold grading the results as clean (2x < 100RLU), dirty (2x > 100RLU) or equivocal (1x < 100RLU and 1x > 100RLU). Of the surfaces sampled, 68.5 % were clean (288/421), 13.5 % were dirty (57/421) and 18 % were equivocal (76/421). The duplicate testing demonstrated a false negative rate of 10 % (44/421) where the first swab was <100 RLU and the second swab >100 RLU. For the equivocal group, the gap between the two swabs was >100 RLU for 7.5 % of surfaces (33/421). The CIS was conducted on 270 of the surfaces tested and showed that cleaning could be improved (P=<0.001) on 88.5 % of surfaces (239/270). CONCLUSION: The simplified ATP testing algorithm provides real-time discrimination between surface cleanliness levels and improved certainty over surface hygiene. The duplicate swab sampling approach mitigates uncontrolled variability in the results and the CIS provides a nuanced understanding of the measurable cleanliness of any surface.

Evaluating bio-burden of frequently touched surfaces using Adenosine Triphosphate bioluminescence (ATP): Results from the Researching Effective Approaches to Cleaning in Hospitals (REACH) trial.

BACKGROUND: Environmental cleaning is an important approach to reducing healthcare-associated infection. The aim of this short research paper is to describe changes in the efficacy of post-discharge cleaning by examining the amount of bio-burden on frequent touch points (FTPs) in patient areas, using a validated Adenosine Triphosphate (ATP) bioluminescence sampling method. In so doing, we present findings from a secondary outcome of a recent trial, the Researching Effective Approaches to Cleaning in Hospitals (REACH) study. METHODS: The REACH study used a prospective, stepped-wedge randomised cluster design. Cross sectional ATP sampling was conducted at three of the 11 participating hospitals. At each hospital, during the control and intervention phase of the study, six Frequent Touch Points (FTPs) were sampled: toilet flush, bathroom tap, inside bathroom door handle, patient call button, over bed tray table, and bed rails. RESULTS: Across the three hospitals, 519 surfaces in 49 rooms (control phase) and 2856 surfaces in 251 rooms (intervention phase) were sampled. Bedroom FTP cleaning improved across all three hospitals. The cleaning of bathroom FTPs was generally high from the outset and remained consistent throughout the whole study period. Average cleaning outcomes for bathroom FTPs were consistently high during the control period however outcomes varied between individual FTP. Changes in cleaning performance over time reflected variation in intervention effectiveness at the hospital level. CONCLUSION: Findings confirm improvement in cleaning in the FTPs in bedrooms, demonstrating improvements in discharge cleaning aligned with the improvements seen when using fluorescent marking technology as a marker of performance.

A new sampling algorithm demonstrates that ultrasound equipment cleanliness can be improved.

BACKGROUND: Australia has established guidelines on cleaning for reusable ultrasound probes and accompanying equipment. This is a preliminary study investigating cleanliness standards of patient-ready ultrasound equipment in 5 separate health care facilities within a major city. METHODS: The cleanliness was assessed using rapid adenosine triphosphate (ATP) testing used with a sampling algorithm which mitigates variability normally associated with ATP testing. Each surface was initially sampled in duplicate for relative light units (RLUs) and checked for compliance with literature recommended levels of cleanliness (<100 RLUs). Triplicate sampling was undertaken where necessary. A cleaning intervention step (CIS) followed using a disposable detergent wipe, and the surface was retested for ATP. RESULTS: There were 253 surfaces tested from the 5 health care facilities with 26% (66/253) demonstrating either equivocal or apparent lack of cleanliness. The CIS was conducted on 148 surfaces and demonstrated that for >91% (135/148) of surfaces, the cleaning standards could be improved significantly (P > .001). For 6% (9/148) of devices and surfaces, the CIS needed to be repeated at least once to achieve the intended level of cleanliness (<25 RLUs). CONCLUSIONS: This study indicates that ATP testing is an effective, real-time, quality assurance tool for cleanliness monitoring of ultrasound probes and associated equipment.

Characterization of microbial community composition, antimicrobial resistance and biofilm on intensive care surfaces.

BACKGROUND: Organisms causing healthcare associated infections can be sourced from the inanimate environment around patients. Residing in a biofilm increases the chances of these organisms persisting in the environment. We aimed to characterise bacterial environmental contamination, genetically and physiologically, and relate this to general intensive care unit (ICU) cleanliness. METHODS: Cleanliness was determined by adenosine triphosphate (ATP) measurements of 95 high-touch objects. Bacteriological samples were obtained from the same sites (n=95) and from aseptically removed sections (destructive samples, n=20). Bacterial enrichment culture was conducted using tryptone soya broth prior to plating on horse blood agar, MacConkey agar, and screening chromogenic agar for identification of multidrug resistance organism (MDRO). Bacterial load and microbial diversity were determined using quantitative PCR (qPCR) and next generation DNA sequencing respectively. Confocal laser scanning microscopy and scanning electron microscopy were used to visually confirm the biofilm presence. RESULTS: Many intensive care surfaces (61%) were highly contaminated by biological soil as determined by ATP bioluminescence testing. The degree of biological soiling was not associated with bacterial contamination as detected by qPCR. Bacterial load ranged from 78.21 to 3.71×108 (median=900) bacteria/100cm2. Surface swabs from 71/95 sites (75%) were culture-positive; of these 16 (22.5%) contained MDRO. The most abundant genera were Staphylococcus, Propionibacterium, Pseudomonas, Bacillus, Enterococcus, Streptococcus and Acinetobacter. Biofilm was visually confirmed by microscopy on 70% (14/20) of items. CONCLUSION: Bacterial biofilms and MDROs were found on ICU surfaces despite regular cleaning in Saudi Arabia, suggesting that biofilm development is not controlled by current cleaning practices.

A pilot study into locating the bad bugs in a busy intensive care unit.

BACKGROUND: The persistence of multidrug-resistant organisms (MDROs) within an intensive care unit (ICU) possibly contained within dry surface biofilms, remains a perplexing confounder and is a threat to patient safety. Identification of residential locations of MDRO within the ICU is an intervention for which new scientific approaches may assist in finding potential MDRO reservoirs. METHOD: This study investigated a new approach to sampling using a more aggressive environmental swabbing technique of high-touch objects (HTOs) and surfaces, aided by 2 commercially available adenosine triphosphate (ATP) bioluminometers. RESULTS: A total of 13 individual MDRO locations identified in this pilot study. The use of ATP bioluminometers was significantly associated with the identification of 12 of the 13 individual MDRO locations. The MDRO recovery and readings from the 2 ATP bioluminometers were not significantly correlated with distinct cutoffs for each ATP device, and there was no correlation between the 2 ATP devices. CONCLUSION: The specific MDRO locations were not limited to the immediate patient surroundings or to any specific HTO or type of surface. The use of ATP testing helped rapidly identify the soiled locations for MDRO sampling. The greatest density of positive MDRO locations was around and within the clinical staff work station.

The perennial problem of variability in adenosine triphosphate (ATP) tests for hygiene monitoring within healthcare settings.

OBJECTIVE: To investigate the reliability of commercial ATP bioluminometers and to document precision and variability measurements using known and quantitated standard materials. METHODS: Four commercially branded ATP bioluminometers and their consumables were subjected to a series of controlled studies with quantitated materials in multiple repetitions of dilution series. The individual dilutions were applied directly to ATP swabs. To assess precision and reproducibility, each dilution step was tested in triplicate or quadruplicate and the RLU reading from each test point was recorded. Results across the multiple dilution series were normalized using the coefficient of variation. RESULTS: The results for pure ATP and bacterial ATP from suspensions of Staphylococcus epidermidis and Pseudomonas aeruginosa are presented graphically. The data indicate that precision and reproducibility are poor across all brands tested. Standard deviation was as high as 50% of the mean for all brands, and in the field users are not provided any indication of this level of imprecision. CONCLUSIONS: The variability of commercial ATP bioluminometers and their consumables is unacceptably high with the current technical configuration. The advantage of speed of response is undermined by instrument imprecision expressed in the numerical scale of relative light units (RLU).