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T Pass

Publications and source records attributed to T Pass.

14 recordsLinked to original sources
PubMed1996

Culture of dialysis fluids on nutrient-rich media for short periods at elevated temperatures underestimate microbial contamination.

Recommended culture methods for monitoring bacterial contamination of H2O, dialysate and bicarbonate concentrate in dialysis centers in the USA involves culturing these fluids for 48 h at 37 degrees C. A variety of media and commercial culture methods are accepted for monitoring these fluids. Over a 3-month a comparison was made between an acceptable culture method, tryptic soy agar (TSA) employing the pour plate (PP) technique at 37 degrees C for 48 h, and PP cultures on standard methods agar (SMA) and R2A agar, incubated at ambient temperature (23 degrees C) for 48, 72, 168 h. Increases in the colony counts over time occurred for all three fluids. However, counts wee greater on SMA and R2A than on TSA. The increases over the standard 48-hour TSA cultures ranged as high as 10(4) times for 23 degrees C cultures at 7 days of incubation. Endotoxin levels even in the most contaminated samples were found to be below the acceptable 5 EU/ml recommended for reprocessor water. Bacterial colonies that appeared at 48, 72 and 168 h were isolated and identified. Pseudomonas, Moraxella, Acinetobacter and CDC group VI C-2 were among some of the common bacteria isolated. This study indicates that the media utilized, the time and temperature of incubation may result in a significant underestimation of the bacterial population of water and dialysis fluids, thus potentially placing the patient at a higher risk.

Bacteria↗
PubMed1992

Bacteriology of hemodialysis fluids: are current methodologies meaningful?

Reports of increasing endotoxic reactions in dialysis centers using high-flux dialyzers and high contamination in liquid bicarbonate concentrates have resulted in concern for the microbial contamination of dialysate. The influence of salt-supplemented media on the recovery of bacterial contaminants from the fluids used in hemodialysis has been examined. This study found a negative influence of a 2% NaCl supplementation of growth media for both purified water and dialysate. Salt-supplemented pour plate cultures of bicarbonate concentrate samples were not statistically different from nonsupplemented cultures (p = 0.2). The influence of the bicarbonate salt on recovery in the pour plates was not addressed. The different media recommended for monitoring microbial contamination of dialysis fluids were compared. As previously reported, both water and dialysate collected from a relatively large geographic area showed higher recoveries on Reasoner's R2A agar than on media recommended by the Association for Advancement of Medical Instrumentation (AAMI) standards (p < 0.0001). Standard methods agar (SMA) and trypticase soy agar (TSA) produced the next highest recovery for water and dialysate, respectively. The higher recoveries generally observed on R2A or SMA suggest that to provide better patient safety these media should be selected for monitoring bacterial contamination of water, and R2A, SMA, or TSA for dialysate. The variability in the species identified across the three fluids and variability in counts observed in the different fluids suggest that significant dialysate contamination may occur from sources other than the water and bicarbonate concentrates.

Bacteria↗
PubMed1990

Microbial and endotoxin contamination in water and dialysate in the central United States.

The purified water supplies and randomly selected dialysates of 51 chronic and acute dialysis centers in the central United States were surveyed to assess the relative risks to dialysis patients from microbial and endotoxin contamination. A culture medium more sensitive than those generally employed in routine quality assurance assays was used for recovery of bacteria from water. With this medium, 35.3% of the water samples and 19% of the dialysate samples were out of compliance with the Association for the Advancement of Medical Instrumentation (AAMI) standards: 200 and 2,000 colony forming units (CFU)/ml, respectively. There was no correlation observed between the type of water purification system or the frequency of disinfection of the system and the bacterial and endotoxin contamination levels. There was also no correlation found between the bacterial and fungal CFU per ml and the endotoxin concentration per ml (EU/ml). It is recommended that more sensitive culturing methods be used to provide adequate bacterial monitoring of dialysate center water supplies. Dialysis centers should monitor endotoxin in dialysate on a regular schedule and immediately after any endotoxemic-like patient reactions. Yeast and fungi were observed in 10% and 64% of the water systems, respectively. Dialysate was contaminated by yeast and fungi in 30% and 70% of the centers, respectively. The concentrations of these microbes in both fluids were much lower than bacteria. However, they were observed often enough to warrant further investigation of their impact on the well-being of dialysis patients.

Bacteria↗
PubMed1990

Endotoxin and bacterial contamination of dialysis center water and dialysate; a cross sectional survey.

The bacterial and endotoxin levels of purified water and effluent dialysate were examined in a cross section of dialysis centers in the central United States. All samples were collected within a four-hour drive of the University of Louisville and were collected, processed and analyzed by our personnel, to eliminate variability in sample handling. A medium capable of higher bacteria recovery from aqueous environments than those ordinarily employed in clinical assays was used. Endotoxins were determined by a quantitative colorimetric assay. By the more sensitive bacterial assay 53% of the centers had bacterial counts above the AAMI standard of 200 colony-forming units per ml (CFU/ml) for water and 35% of the centers had bacterial counts above the 2000 CFU/ml standard for dialysate in at least one sampling period. The samples showed 35% and 19% of water and dialysate above the standards, respectively. While there are no standards for endotoxin concentrations in water used to prepare dialysate, 2% of the centers had endotoxin levels in their water above five endotoxin units per ml (5 EU/ml = 1 ng/ml in our assay kit), the limit set by the AAMI standards for reprocessor water. Both bacterial and endotoxin levels tended to be elevated in dialysate, with the highest levels of endotoxin in dialysates posing an obvious potential risk when high-flux dialyzers are used.

Bacteria↗
PubMed1989

Bacterial contamination of hemodialysis center water and dialysate: are current assays adequate?

Many dialysis centers depend on clinical laboratories or a commercially available dip culture to determine the contamination levels in water and dialysate. To determine whether these standard clinical culture procedures adequately quantitate bacterial contamination in hemodialysis center water and dialysate, test results of two routine clinical media was compared, trypticase soy agar (TSA) and plate count agar (PCA), with those of nutrient-poor R2A medium. Dialysate samples demonstrated significant differences in media, the temperature of incubation, and plating techniques (pour plate versus spread plates). Purified water for dialysis demonstrated significant differences only for media; however, temperature was an important variable. Selective growth on R2A agar of some water- and dialysate-contaminating species was studied by velvet disk and loop transfer of colonies. A strong selectivity for water-borne bacteria was demonstrated by R2A agar; the bacteria that did not grow on TSA and PCA have been identified.

Bacteriological Techniques↗
PubMed1987

Case-mix, severity systems provide DRG alternatives.

Since their adoption, diagnosis related groups (DRGs) have been criticized for relying too much on the principal discharge diagnosis, for not taking the secondary diagnoses into account, and for ignoring the severity of a patient's illness or illnesses. Four case-mix and severity systems, Disease Staging, Patient Management Categories, MedisGroups, and Computerized Severity of Illness, offer alternatives to DRGs by either classifying patients into diagnostic categories or producing overall case severity scores. While most hospitals are likely to continue using DRGs or whatever successor is prescribed by regulation, some may find it useful to look seriously at these alternatives as a means of measuring the consumption of healthcare resources.

Diagnosis-Related Groups↗
PubMed1981

Hitchcock's birds, or the increased rate of exposure to histoplasma from blackbird roost sites.

A statewide survey of populations in proximity to blackbird roost sites to determine exposure to histoplasmosis from such sites has demonstrated that a site harboring Histoplasma capsulatum, even though undisturbed, adds significantly to the exposure rate of proximal populations. Disturbance of such a site increases the exposure rate dramatically with or without concurrent clinical cases of histoplasmosis.

Adult↗
PubMedDate not supplied

Dialysate contamination and back filtration may limit the use of high-flux dialysis membranes.

Endotoxins, or fragments thereof, can reach the blood stream of dialysis patients, transported by diffusion and connection across the intact high-flux membrane. This transfer depends upon the phenomenon of back filtration. Back filtration generally occurs under conventional high-flux dialysis conditions with membranes having an ultrafiltration coefficient in blood (UF-C) above 20 ml/hr/m2/mmHg. The clinical consequences of back filtration vary from center to center depending primarily on the quality of dialysate. We therefore surveyed the bacterial and endotoxin levels of purified water and effluent dialysate in a cross section of dialysis centers in the central United States. Using a high recovery medium, we found that 53% of the centers had bacterial counts above the Association for the Advancement of Medical Instruments standard in water (20% cfu/ml) and 35% above the standard in dialysate (2,100 cfu/ml). Endotoxin concentrations higher than 5.0 EU/ml in both water and dialysate were found in 4% and 11.8% of the centers, respectively. Since high-flux membranes are believed to be of benefit for long-term dialysis patients, manufacturers will have to offer dialysate preparation systems with additional safety features. The proper membrane design will be a key to the success of such systems.

Colony Count, Microbial↗