Disinfection of the hospital water supply: a hidden risk to dialysis patients

Identification and Quantification of Aqueous Disinfectants Using an Array of Carbon Nanotube-Based Chemiresistors

Disinfection of water is essential to prevent the growth of pathogens, but at high levels, it can cause harm to human health. Therefore, accurate monitoring of disinfectant concentrations in water is essential to ensure safe drinking water. The use of multiple disinfectants at different stages in water treatment plants makes it necessary to also identify the type and concentrations of all of the disinfectant species present. Here, we demonstrate an effective approach to identify and quantify multiple disinfectants (using the example of free chlorine and potassium permanganate) in water using single-walled carbon nanotube (SWCNT)-based reagent-free chemiresistive sensing arrays. Facile fabrication of chemiresistive devices makes them a popular choice for the implementation of sensor arrays. Our sensing array consists of functionalized and unfunctionalized (blank) SWCNT sensors to distinguish the disinfectants. The distinct responses from the different sensors at varying concentrations and pH can be fitted to the mathematical model of a Langmuir adsorption isotherm separately for each sensor. Blank and functionalized sensors respond through different mechanisms that result in varying responses that are concentration- and pH-dependent. Chemometric techniques such as principal component analysis (PCA) and partial least-squares-discriminant analysis (PLS-DA) were used to analyze the sensor data. PCA showed an excellent separation of the analytes over five different pHs (5.5, 6.5, 7.5, 8.5, and 9.5). PLS-DA provided excellent separability as well as good predictability with a Q2 of 94.26% and an R2 of 95.67% for the five pH regions of the two analytes. This proof-of-concept solid-state chemiresistive sensing array can be developed for specific disinfectants that are commonly used in water treatment plants and can be deployed in water distribution and monitoring facilities. We have demonstrated the applicability of chemiresistive devices in a sensor array format for the first time for aqueous disinfectant monitoring.

Assessment of endotoxin levels of water in hemodialysis centers in Iraq

The significance of endotoxin-free, sterile dialysis fluid for long-term, high-quality hemodialysis treatment is obvious and highly desired[MF1] . The current study aimed to determine endotoxin for the water quality used in twenty hemodialysis treatment centers. Eighty samples (40 x dialysates and 40 x dialysis water) were tested for endotoxin using the LAL gel clot method. The results revealed a variation in the quality of the produced water that makes it unaccepted compared to the international standard (ANSI/AAMI/ISO-23500). Endotoxin levels were higher than (0.25 EU/ml) in 40% of dialysis water and 30% of dialysate water, higher than the recommended international standards. The results conclude that systematic water quality monitoring in hemodialysis services is essential for patient safety and health problems. Keywords: Endotoxin; Water quality; Dialysis fluid; LAL test; Hemodialysis patient

Delftia acidovorans pseudo outbreak in portable reverse osmosis machines: Interventions to ensure safe and cost-effective hemodialysis

INTRODUCTION

Reverse osmosis (RO), a major advance in hemodialysis (HD) safety, effectively clears most water organisms. Delftia acidovorans is an environmental water-borne pathogen that is rarely reported to cause human infections. We report a pseudo outbreak caused by colonization of RO machines with D acidovorans with no reported human infections and interventions to improve HD safety.

METHODS

Repeated positive RO product water cultures triggered our hospital to initiate an investigation, RO machines were examined for mechanical integrity by biomedical engineers. Cultures of product water as well as RO parts were done. Testing for bacterial relatedness after identification was performed. An investigation was conducted in a systematic fashion to determine the cause and the extent of the problem.

RESULTS

Upon formal review of policies and procedures, there were minor deficiencies. Rectifying these deviations from policies did not stop the repeated positive water cultures. A 7-step investigation and correction was successfully conducted. City water testing with filtration and concentration methods was positive for D acidovorans. Major renovation of the HD unit with replacement of all RO machines and a 2-step water filtration resulted in elimination of the pseudo outbreak.

CONCLUSION

City water was the source of biofilm formation of D acidovorans in RO machines that was not possible to eradicate. Application of incoming water filters was an effective preventive strategy. Replacement of RO machines after 4 failed disinfection attempts is the most cost-effective strategy as well for persistent positive water cultures. The HD remains RO water culture negative 2 years after changes.

Microbiological Analysis of Hemodialysis Water in a Developing Country

Microbiological control of hemodialysis fluid is important for the prevention of hemodialysis-associated illness. Bacterial populations inhabiting a distribution system for hemodialysis water were studied over a 4 month period in five hospitals (one in Tehran, and the others at Alborz). All the samples from the four hospitals at Alborz had colony counts of ≥100 CFU/ml, which at different points of sampling were higher than the maximum recommended values. A total of 80 samples taken at different points in each hospital's hemodialysis distribution system were collected, and 229 planktonic bacteria isolated on R2A medium. No growth was detected by culturing the samples on Blood agar or Mueller-Hinton agar, according to routine procedures currently used in the five hospitals. A representative of isolates from each of 45 different morphotypes were identified using 16S RNA sequencing. A diverse bacterial community, containing predominantly gram-positive members of Kocuria, Arthrobacter and Staphylococcus and Mycobacterium, was detected. Bacteria from the genera Acinetobacter, Burkholderia, Halomonas, Herbaspirillum, Pseudomonas, and Sphingomonas were identified, which has been described in the build-up of biofilms. Some of the species reported here may represent a health risk to patients receiving hemodialysis treatment. In conclusion, it is recommended that standard protocols for evaluation of microbial contamination be used for regular monitoring and identification of culturable bacteria.

Evaluation and control of microbial and chemical contamination in dialysis water plants of Italian nephrology wards

BACKGROUND

Patients receiving haemodialysis are exposed to a large volume of dialysis fluid. The Italian Society of Nephrology (ISN) has published guidelines and microbial quality standards on dialysis water (DW) and solutions to ensure patient safety.

AIM

To identify microbial and chemical hazards, and evaluate the quality of disinfection treatment in DW plants.

METHODS

In 2015 and 2016, water networks and DW plants (closed loop and online monitors) of nine dialysis wards of Italian hospitals, hosting 162 dialysis beds overall, were sampled on a monthly basis to determine the parameters provided by ISN guidelines. Chlorinated drinking water was desalinated by reverse osmosis and distributed to the closed loop which feeds all online monitors. Disinfection with peracetic acid was performed in all DW plants on a monthly basis.

FINDINGS

Over the 24-month study period, seven out of nine DW plants (78%) recorded negative results for all investigated parameters. Closed loop contamination with Burkholderia cepacia was detected in a DW plant from January 2015 to March 2015. Pseudomonas aeruginosa was isolated from March 2016 to May 2016 in the closed loop of another DW plant. These microbial contaminations were eradicated by shock disinfection with sodium hypochlorite and peracetic acid, followed by water flushing.

CONCLUSION

These results highlight the importance of chemical and physical methods of DW disinfection. The maintenance of control measures in water plants hosted in dialysis wards ensures a microbial risk reduction for all dialysis patients.

Diagnosis, Treatment, and Prevention of Hemodialysis Emergencies

Given the high comorbidity in patients on hemodialysis and the complexity of the dialysis treatment, it is remarkable how rarely a life-threatening complication occurs during dialysis. The low rate of dialysis emergencies can be attributed to numerous safety features in modern dialysis machines; meticulous treatment and testing of the dialysate solution to prevent exposure to trace elements, toxins, and pathogens; adherence to detailed treatment protocols; and extensive training of dialysis staff to handle medical emergencies. Most hemodialysis emergencies can be attributed to human error. A smaller number are due to rare idiosyncratic reactions. In this review, we highlight major emergencies that may occur during hemodialysis treatments, describe their pathogenesis, offer measures to minimize them, and provide specific interventions to prevent catastrophic consequences on the rare occasions when such emergencies arise. These emergencies include dialysis disequilibrium syndrome, venous air embolism, hemolysis, venous needle dislodgement, vascular access hemorrhage, major allergic reactions to the dialyzer or treatment medications, and disruption or contamination of the dialysis water system. Finally, we describe root cause analysis after a dialysis emergency has occurred to prevent a future recurrence.

Candida parapsilosis complex water isolates from a haemodialysis unit: biofilm production and in vitro evaluation of the use of clinical antifungals

Candida parapsilosis, currently divided into three distinct species, proliferates in glucose-rich solutions and has been associated with infections resulting from the use of medical devices made of plastic, an environment common in dialysis centres. The aims of this study were (i) to screen for Candida orthopsilosis and Candida metapsilosis (100 environmental isolates previously identified as C. parapsilosis), (ii) to test the ability of these isolates to form biofilm and (iii) to investigate the in vitro susceptibility of Candida spp biofilms to the antifungal agents, fluconazole (FLC) and amphotericin B (AMB). Isolates were obtained from a hydraulic circuit collected from a haemodialysis unit. Based on molecular criteria, 47 strains were re-identified as C. orthopsilosis and 53 as C. parapsilosis. Analyses using a formazan salt reduction assay and total viable count, together with microscopy studies, revealed that 72 strains were able to form biofilm that was structurally similar, but with minor differences in morphology. A microtitre-based colorimetric assay used to test the susceptibility of fungal biofilms to AMB and FLC demonstrated that the C. parapsilosis complex displayed an increased resistance to these antifungal agents. The results from these analyses may provide a basis for implementing quality controls and monitoring to ensure the microbiological purity of dialysis water, including the presence of yeast.

Multidisciplinary evaluation for severity of hazards applied to hemodialysis devices: an original risk analysis method

BACKGROUND AND OBJECTIVES

Risk analysis for medical devices is a crucial process to grant adequate levels of safety. Identification of device exposure-related hazards is one of the main objectives.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Hazard analysis for hemodialysis devices has been performed by a multidisciplinary team involving engineers and clinical experts. A potential harm list was identified from clinical and technical experience, postproduction information, and literature. Various hazardous situations (circumstances when the use of the dialysis device may lead to described harms) were described. Such hazardous situations were correlated to the extent of the deviation of a specific device parameter from expected ranges. The clinical severity that was relevant to any specific harm was categorized for each hazardous situation using a descriptive and numerical scale with five levels (from negligible [i.e., discomfort only] to catastrophic [i.e., potentially lethal]).

RESULTS

Harms in which the deviation of a parameter strictly coincides with the clinically measured effect on the patient are defined as "direct." Otherwise, when another clinical parameter must be involved to quantify severity, the related harm is considered "indirect." Two complete examples of multidisciplinary evaluation for severity of hazards (MESH) are given for a direct harm (air embolism) and for an indirect harm (hypothermia). For other harms, the maximum value of severity involved is provided.

CONCLUSIONS

MESH represents a possible example of risk management for dialysis equipment in which, although the manufacturer is directly responsible, a multidisciplinary task force may contribute to a better link between engineering and clinical perspectives.