Bacteriologic and endotoxin analysis of salvaged blood used in autologous transfusions during cardiac operations.

Autologous blood transfusion is a common method of reducing the need for heterologous blood transfusion during cardiac operations. Recently we investigated an outbreak of severe, nonsurgical postoperative bleeding among patients undergoing heart operations and receiving intraoperative transfusion of blood from a cell conservation device (Cell Saver System, Haemonetics Corp., Braintree, Mass.). As a result of this investigation, we conducted a prospective study to determine if bacterial or endotoxin contamination of the blood collected in the Cell Saver System and used for reinfusion during heart operations contributes to postoperative bleeding complications. Patients' blood samples were collected immediately before operation, at the end of cardiopulmonary bypass, 1 hour postoperatively, and from the Cell Saver System. All blood samples were cultured for bacteria, and all plasma samples were assayed for endotoxin. Preoperatively all patients having heart operations were without signs of infection, 33 of 37 blood cultures taken were negative, and none of the plasma samples had detectable endotoxin. After discontinuance of cardiopulmonary bypass but before delivery of blood from the Cell Saver System, bacteria and endotoxin were detected in 11 of 36 (30.6%) and five of 35 (14.3%) of the patients' blood samples, respectively. The blood aspirated from the open chest and collected by the Cell Saver System was culture positive in 30 of 31 (96.8%) samples, and seven of 29 (24.1%) contained endotoxin. One of 28 blood samples collected 1 hour postoperatively was culture positive, and five of 25 samples contained endotoxin. Of 61 total microorganisms isolated, 50 (82%) were coagulase-negative staphylococci, four (6.6%) aerobic diphtheroids, five (8.2%) anaerobic "diphtheroids" (Propionibacterium acnes), and two (3.2%) gram-negative bacilli. Plasma endotoxin concentrations ranged from 10 to 765 pg/ml. No signs of endotoxemia or unusual bleeding were observed intraoperatively or postoperatively in any of the 38 patients. Although blood collected in the Cell Saver System and used for reinfusion during heart operations often was contaminated with gram-positive bacterial commensals of the skin and low concentrations of endotoxin, no adverse effects were noted in the patients.

Candida parapsilosis bloodstream infections in neonatal intensive care unit patients: epidemiologic and laboratory confirmation of a common source outbreak.

BACKGROUND: Candida parapsilosis is a common cause of sporadic and epidemic infections in neonatal intensive care units (NICUs). When a cluster of C. parapsilosis bloodstream infections occurred in NICU patients in a hospital in Louisiana, it provided us with the opportunity to conduct an epidemiologic investigation and to apply newly developed molecular typing techniques. METHODS: A case-patient was defined as any NICU patient at Louisiana State University Medical Center, University Hospital, with a blood culture positive for C. parapsilosis during July 20 to 27, 1991. To identify risk factors for C. parapsilosis bloodstream infection, a cohort study of all NICU infants admitted during July 17 to 27, 1991, was performed. Electrophoretic karyotyping was used to assess the relatedness of C. parapsilosis isolates. RESULTS: The receipt of liquid glycerin given as a suppository was identified as a risk factor (relative risk, 31.2; 95% confidence intervals, 4.3 to 226.8). Glycerin was supplied to the NICU in a 16-oz multidose bottle. Bottles used at the time of the outbreak were not available for culture. All six available isolates from four case-patients had identical chromosomal banding patterns; six University Hospital non-outbreak isolates had different banding patterns. CONCLUSIONS: This study demonstrates the utility of combined epidemiologic and laboratory techniques in identifying a novel common source for a C. parapsilosis bloodstream infection outbreak and illustrates that extreme caution should be exercised when using multidose medications in more than one patient.

Bloodstream infections in neonatal intensive care unit patients: results of a multicenter study.

For identification of risk factors for bloodstream infection (BSI) among neonatal intensive care unit patients, prospective 6-month studies in three neonatal intensive care units were conducted. BSI was diagnosed in 42 of 376 (11.2%) enrolled infants. Pathogens included coagulase-negative staphylococci, Candida sp., Group B streptococci and Gram-negative species. Patients with BSIs were more likely to die during their neonatal intensive care unit stay than were patients who did not acquire BSIs (6 of 42 vs. 11 of 334, P = 0.007). BSI rate was highest in infants with birth weight < 1500 g (relative risk (RR) = 6.8, P < 0.001), those treated with H-2 blockers (RR = 4.2, P < 0.001) or theophylline (RR = 2.8, P < 0.001) and those with admission diagnoses referable to the respiratory tract (RR = 3.7, P < 0.001). Infants who developed BSI were more severely ill on admission than other infants (median physiologic stability index 13 vs. 10 (P < 0.001) and were of lower gestational age (28 vs. 35 weeks, P < 0.001). In logistic regression analysis, risk of BSI was independently associated only with very low birth weight, respiratory admission diagnoses and receipt of H-2 blockers. Risk of isolation of a pathogen from blood culture was independently associated with Broviac, umbilical vein or peripheral venous catheterization > 10, 7 or 3 days, respectively, at one insertion site. Rate of isolation of a pathogen was higher (9 of 59 (15%)) within 48 hours of a measurable serum interleukin 6 concentration than an interleukin 6 level of 0 pg/ml (10 of 159 (6%), P = 0.04).(ABSTRACT TRUNCATED AT 250 WORDS)

Microbial growth and endotoxin production in the intravenous anesthetic propofol.

OBJECTIVE: In this study, we measured microbial growth and endotoxin production in the intravenous anesthetic propofol using 10 different microbial strains; 6 isolated from outbreak cases and 4 from laboratory stock cultures. DESIGN: In each trial, endotoxin-free glass tubes containing 10 ml propofol were inoculated with 10(0)-10(3) CFU/ml of the test organism and incubated at 30 degrees C for 72 hours. SETTING: In May and June 1990, the Centers for Disease Control received reports of 5 outbreaks in 5 states of postsurgical patient infections and/or pyrogenic reactions. Epidemiologic and laboratory investigations implicated extrinsic contamination of an intravenous anesthetic, propofol, as the probable source of these outbreaks. RESULTS: After 24 hours, 9 of the 10 cultures increased in viable counts by 3 to 6 logs. At least 1 ng/ml of endotoxin was produced within 24 hours by Escherichia coli, Enterobacter cloacae, and Acinetobacter calcoaceticus subspecies anitratus. CONCLUSIONS: Propofol can support rapid microbial growth and endotoxin production. To avoid infectious complications, scrupulous aseptic technique should be used when preparing or administering this anesthetic.

Bacterial contamination of platelets at a university hospital: increased identification due to intensified surveillance.

BACKGROUND: A cluster of bacterial contamination of platelets occurred at a university hospital in a one-month period. This unusual clustering allowed us to examine the likely mechanism of contamination and clinical sequelae. METHODS: We reviewed medical records of patients receiving random donor platelet transfusions to determine numbers of platelets transfused, reactions reported, and episodes of bacterial contamination. We also reviewed procedures at the collecting blood agencies and the hospital blood bank. RESULTS: Four patients received bacterially contaminated platelets during June and July 1991. The rates of reported platelet transfusion reactions increased significantly (P < 0.001) from September 1989 through July 1991 (study period); in addition, the rate of contamination of platelets during June and July 1991 was 23-fold higher than during the previous 21 months (P < 0.001). Surveillance methodology changed dramatically during the study period, contributing to the recognition of the current cluster. Pathogens isolated from the contaminated platelet pools were Bacillus cereus, Staphylococcus epidermidis, or Pseudomonas aeruginosa in titers ranging from 10(6) to 10(8) colony forming units/mL. Four constituent individual platelet units identified as the probable cause of the outbreak (including one postepidemic episode) were significantly older (mean age, 4.8 days) than 106 randomly selected individual platelet units (mean age, 3.7 days; P = 0.04). Platelet pools were transfused an average of 2.5 hours after pooling. Review of blood collection and platelet preparation practices did not identify breaks in procedure or technique that could have caused contamination. CONCLUSIONS: Increased awareness of platelet transfusion reactions by clinical staff and routine culturing of all platelets associated with transfusion reactions will identify contaminated platelets. Identification of contaminated platelets is necessary to treat affected patients appropriately and to determine the prevalence of and risk factors for contaminated platelets (Infect Control Hosp Epidemiol 1994;15:82-87).

A cluster of severe postoperative bleeding following open heart surgery.

OBJECTIVE: To investigate a cluster of postoperative bleeding following open heart surgery. DESIGN: A cohort and case/control study. SETTING: Palo Alto Veterans Administration Medical Center, Palo Alto, California. PARTICIPANTS: Six (21.4%) of 28 patients undergoing open heart surgery who developed severe, nonsurgical, postoperative bleeding from July 1 through August 30, 1988 (outbreak period). All case-patients had chest tube drainage of greater than or equal to 1000 ml within 4 hours of surgery but did not have identifiable bleeding vessel(s) on exploration. RESULTS: Upon comparison of the pre-outbreak (January 1986 through June 1988) and the outbreak period, a significant increase was found in the incidence of postoperative nonsurgical bleeding (5/440 versus 6/28, p = .0006), but not of postoperative surgical bleeding (8/440 versus 0/28, p = 1.0). Of all patients undergoing open heart surgery during the outbreak period, case patients were found to be older (67.8 versus 60.6, p = .02) and to have received a larger volume of hetastarch (HES), a synthetic colloidal plasma-volume expander (mean = 19.4 ml/kg versus 14.1 ml/kg, p = .02). CONCLUSIONS: We conclude that the use of large volumes of HES during surgery in the elderly open heart surgery patient may increase the risk for severe, nonsurgical postoperative bleeding, probably caused by alterations of the coagulation system. As the incidence of open heart surgery increases among the elderly, surgeons and anesthesiologists should be alert to possible adverse reactions from exposures not associated with adverse reactions in younger patients.

Microbiologic evaluation of needleless and needle-access devices.

OBJECTIVE: This study was carried out to determine whether needleless intravenous access devices are more likely to allow microorganisms to enter the fluid pathway than intravenous needle-access devices. METHODS: A laboratory study was conducted with two needleless and one intravenous needle-access devices and Enterococcus faecium as a bacterial challenge. Inocula of E. faecium were prepared on the basis of the numerical estimates of 1000 to 10,000 colony-forming units (CFU)/cm2 of bacterial flora on dry regions of skin (arms, legs, and hands). The septum of each access device was inoculated with 10 to 20 microliters of a 10(4) to 10(5) CFU/ml challenge suspension, which was allowed to dry on the surface of the septum. In the first part of the experiment, the needleless or needle-access cannula of each device was used to puncture the corresponding septum without previously disinfecting the top of the septum. In the second part, the contaminated septum was punctured after disinfecting the septum with a 70% isopropyl alcohol wipe. After each puncture, trypticase soy broth was flushed through the fluid pathway of the intravenous access device, collected, and cultured by the membrane filtration technique. The septum of each injection-site cap and the needleless or needle-access cannula were sampled with sterile premoistened swabs. Swabs were cultured on blood agar plates. RESULTS: The rate of fluid pathway contamination was 100% (40/40) for one of the needleless intravenous access devices and 80% (20/25) for the other when septa were contaminated with E. faecium and not disinfected before puncture. The rate for the intravenous needle-access device was 72% (18/25). When the septa of the three different devices tested were disinfected with 70% isopropyl alcohol, E. faecium was isolated on only one septum from all devices tested in part two (1/74, 1.3%). CONCLUSIONS: These laboratory studies demonstrate that there is no statistically significant difference in the rate of fluid pathway contamination between needleless and intravenous needle-access devices. However, if the septa of either needleless or needle systems are not disinfected before puncture, a high rate of fluid pathway contamination may occur.

Comparison of the microbial barrier properties of a needleless and a conventional needle-based intravenous access system.

BACKGROUND: Sporadic reports of increased infection rates involving concerning access systems, especially in home-care setting, have raised questions concerning the safety of all needleless systems. Addressing this concern, Baxter Healthcare Corporation and the Centers for Disease Control an d Prevention performed parallel laboratory studies comparing the microbial barrier properties of the Interlink (trademark of Baxter Healthcare Corporation, Deerfield, Ill) needleless system with a conventional intravenous access system. METHODS: Studies of needleless and conventional systems evaluated fluid path contamination introduced through injection site septa, which were intentionally inoculated with high levels of bacteria and subsequently punctured with a without alcohol swabbing disinfection before access. RESULTS: With disinfection, the combined effects of the disinfection technique and the barrier properties of the septa prevented the transfer of organisms into the fluid path in 94% to 96% of needleless test articles and 96% to 100% of conventional test articles. Without disinfection, the barrier properties of the septa alone prevented the transfer of organisms into the fluid path in 20% to 69% of needleless test article and 10% to 28% of conventional test articles. CONCLUSIONS: The data demonstrate the needless system performs as well as the conventional intravenous access system with respect to the risk of microbial contamination and reinforce the need for appropriate septum disinfection before accessing either system.

National surveillance of dialysis associated diseases in the United States, 1991.

To determine trends in a number of hemodialysis associated diseases and practices, the Centers for Disease Control and Prevention in collaboration with the Health Care Financing Administration performed a mail survey of chronic hemodialysis centers in the United States in 1991. Of 2,123 centers surveyed, 2,046 (96%), representing 155,877 patients and 40,298 staff members, responded. The 1991 survey found that certain hemodialysis practices are increasing in frequency, including use of bicarbonate dialysate and high-flux dialysis and reuse of disposable dialyzers (in 1991, 71% of centers reused dialyzers). Hepatitis B surface antigen (HBsAg) was present at low frequency in patients (incidence = 0.2%, prevalence = 1.3%) and staff (incidence = 0.04%, prevalence = 0.3%). Among centers that had > or = HBsAg positive patient, the incidence of hepatitis B virus (HBV) infection was lower in those centers that used a separate room for dialysis of HBsAg positive patients. Reuse of dialyzers, blood lines, transducer filters, or dialyzer caps was not associated with an increased risk of acquiring HBV infection among either patients or staff. Antibody to HBsAg was present in 21% of patients and 53% of staff, and was significantly related to levels of hepatitis B vaccine coverage. Pyrogenic reactions in the absence of septicemia were reported by 20% of centers and associated with the reuse of dialyzers. Human immunodeficiency virus (HIV) was known to be present in 1.2% of patients; 29% of centers reported providing hemodialysis to one or more HIV infected patients.

National surveillance of hemodialysis associated diseases in the United States, 1990.

To determine trends in several hemodialysis associated diseases and practices, the Centers for Disease Control (CDC), in collaboration with the Health Care Financing Administration (HCFA), performed a mail survey of chronic hemodialysis centers in the United States in 1990. Of 1,995 centers surveyed, 1,882 (94%) representing 140,608 patients and 36,907 staff members responded. As in recent years, the 1990 survey found that certain hemodialysis practices are increasing in frequency, including treatment of water with reverse osmosis and deionizer units; use of bicarbonate dialysate and high-flux dialysis; and reuse of disposable dialyzers (in 1990, 70% of centers reused dialyzers). Hepatitis B surface antigen (HBsAg) was present at low frequency in patients (incidence, 0.2%; prevalence, 1.2%) and staff (incidence, 0.04%; prevalence, 0.3%). Antibody to hepatitis B surface antigen was present in 20% of patients and 58% of staff, and was significantly related to levels of hepatitis B vaccine coverage. Pyrogenic reactions in the absence of septicemia were reported by 20% of centers and were associated with use of high-flux dialyzer membranes and reuse of dialyzers (particularly in centers where the maximum number of reuses was 40 or more). Septicemia among hemodialysis patients was reported by 49% of centers. Twenty-six percent of centers reported providing hemodialysis for patients infected with human immunodeficiency virus (HIV), and 1.1% of dialyzed patients had known HIV infection.

National surveillance of dialysis associated diseases in the United States, 1993.

To determine trends in a number of hemodialysis associated diseases and practices, the Centers for Disease Control and Prevention, in collaboration with the Health Care Financing Administration, performed a mail survey of 2,304 chronic hemodialysis centers in the United States in 1993. By the end of 1993, at least three doses of hepatitis B vaccine were administered to 29% of patients and 76% of staff at responding centers. Hepatitis B surface antigen was present at low frequency in patients (incidence = 0.1%, prevalence = 1.2%) and staff members (incidence = 0.2%, prevalence = 0.3%). The 1993 incidence of hepatitis B virus infection among patients was higher at centers that accepted hepatitis B surface antigen positive patients but did not use a separate room and dialysis machine for treatment of these patients, government and profit (versus nonprofit) centers, and centers in four End Stage Renal Disease Networks. The prevalence of antibody to hepatitis C virus was 9.7% among patients and 1.6% among staff members. Pyrogenic reactions in the absence of septicemia were reported by 21% of centers and associated with use of high flux dialysis. Human immunodeficiency virus infection was known to be present in 1.5% of patients; 34% of centers reported providing hemodialysis to one or more human immunodeficiency virus infected patients.

National surveillance of dialysis associated diseases in the United States, 1992.

To determine trends in a number of hemodialysis associated diseases and practices, the Centers for Disease Control and Prevention, in collaboration with the Health Care Financing Administration, completed a mail survey of chronic hemodialysis centers in the United States in 1992. Of 2,321 centers surveyed, 2,170 (93%) representing 170,028 patients and 43,535 staff members responded. In 1992, 2,049 (94%) centers used bicarbonate dialysate as the primary method of dialysis, 765 (35)% used high flux dialysis, and 1,569 (72%) reused dialyzers, continuing the trends toward increased use of these methods. Central (subclavian or jugular) venous catheters were used in > or = 1 patient as permanent vascular access for hemodialysis at 69% of dialysis centers. Hepatitis B surface antigen was present at low frequency in patients (incidence = 0.1%, prevalence = 1.2%) and staff members (incidence - 0.03%, prevalence = 0.3%). Among centers that had > or = 1 hepatitis B surface antigen positive patient, the incidence of hepatitis B virus infection was lower in those centers that used a separate room for dialysis of patients positive for hepatitis B surface antigen. From 1991 to 1992, reported hepatitis B vaccine coverage increased from 17% to 24% among patients and from 56% to 69% among staff members; in absolute terms, these were the largest single year increases since introduction of hepatitis B vaccine. The prevalence of antibody to hepatitis C virus was 8.1% among patients and 1.6% among staff members. Pyrogenic reactions in the absence of septicemia were reported by 19% of centers and associated with use of high flux dialysis. New dialyzer syndrome was reported by 24% of centers, most frequently by centers using regenerated cellulose or cuprophan membranes. Human immunodeficiency virus was known to be present in 1.5% of patients; 34% of centers reported providing hemodialysis to one or more patients infected with HIV.

Environmental health impact in the hospital laundry.

The task of surveying the hospital laundry is often dismissed by public health officials as unnecessary because the laundry cycle is generally considered to be capable of destroying all pathogens. Even though a properly operated laundry can produce a relatively bacteria free product, there are a number of variables that have an impact on the bacterial quality of the linen before it reaches the patient. It is vital that surveillance personnel understand these factors during processing, transporting, or sorting linen so that the final product is aesthetically, chemically, and bacteriologically acceptable for patient use. At the U. S. Public Health Service Hospital laundry in New Orleans, surveillance by the Environmental Health Department has identified potential problem areas. Operational improvements have been instituted at this laundry that would not have been possible without a thorough understanding of the laundry cycle. The authors describe the laundry cycle, including potential problem areas; identify useful microbial and chemical surveillance methods; and discuss process control procedures. This information will help the environmental health worker in discussions with laundry personnel regarding contamination control and operational efficiency.

Occupational exposure to ethylene oxide: effects and control.

Ethylene oxide (EO) is widely used in the health care industry as a gas sterilant for medical products that cannot withstand the high temperature and humidity associated with conventional steam sterilization. As a consequence, approximately 100,000 health care workers are exposed to residual EO each year. The acute toxicity of exposure to EO has been well documented, and recent concern about the mutagenic potential of occupational exposure to EO has resulted in an effort to further reduce workplace exposure levels to EO. The Environmental Protection Agency has issued a rebuttal presumption against registration of EO as a pesticide and the American Conference of Governmental Industrial Hygienists (ACGIH) has proposed a sharp reduction in the threshold limit value permitted for EO. Recognizing the need for environmental health personnel to become more familiar with this workplace hazard, it is appropriate to briefly review the toxic effects of acute and chronic exposure to EO residuals. The authors describe a gas sterilization system successfully utilized at the U.S. Public Health Service Hospital in New Orleans, La., which has demonstrated exposure concentrations well below the EO threshold limit value recently proposed by the ACGIH, while preserving the principal goal of assuring the sterility of reusable medical products which cannot be subjected to steam sterilization.

Microbiological and endotoxin assays of hemodialysis fluids.

The potential for exposure of dialysis patients to greater levels of microbial and endotoxin contamination has increased dramatically during the last decade with the increase in reuse of hemodialyzers, and the use of bicarbonate dialysate and high flux dialysis. To help prevent pyrogenic reactions and bacteremia in hemodialysis patients caused by microbial and endotoxin contamination of hemodialysis fluids, the Association for the Advancement of Medical Instrumentation (AAMI) has promulgated standards for maximum allowable concentrations of bacteria and endotoxin in these fluids. Each dialysis center should develop microbiological and endotoxin surveillance policies and procedures for the types of hemodialysis fluids to assay, frequency and manner of sample collection, assay techniques, and methods for recording and interpreting results to ensure compliance with the AAMI standards. These necessary components of a comprehensive surveillance program are discussed in depth in this article. A safer environment will be provided for each dialysis patient if appropriate microbiological assay procedures are followed and the results are consistently within the AAMI microbiological and endotoxin standards.

Pyrogenic reactions associated with the reuse of disposable hollow-fiber hemodialyzers.

We investigated 18 pyrogenic reactions (PRs) that occurred between July 1 and 13, 1987, in 16 patients receiving long-term hemodialysis at one dialysis center in Illinois. We defined a case of PR as the onset of chills or fever (oral temperature, greater than or equal to 37.8 degrees C) in a patient who was afebrile and had no signs or symptoms of infection before a dialysis treatment. Pyrogenic reactions to dialysis sessions during the epidemic period (July 1 through 14) were associated with the use of a reused dialyzer (risk ratio, 6.2; 95% confidence interval, 0.8 to 45). The water used to rinse the dialyzers after use and to dilute the germicide for disinfecting the dialyzers contained high concentrations of endotoxins (greater than 6 ng/mL) and bacteria (greater than 10(4) colony forming units/mL). After reuse of dialyzers was discontinued at the center, the PR rate fell to pre-epidemic levels. We concluded that PRs were associated with reuse of dialyzers, probably contaminated with endotoxins. Active surveillance for PRs among patients undergoing long-term hemodialysis should be routine at all dialysis centers; an increase in PRs should prompt timely review of water treatment and dialyzer reprocessing systems.

Efficacy of chemical dosing methods for isolating nontuberculous mycobacteria from water supplies of dialysis centers.

Investigations of nontuberculous mycobacterium (NTM) infections associated with various environmental sources have been hampered by the lack of adequate techniques for selective isolation of these organisms from environmental fluids. This study compared chemical dosing techniques for recovery of NTM from water samples collected from 115 randomly selected dialysis centers. Cell suspensions of NTM group II and IV isolates and gram-negative bacteria were exposed to solutions containing sodium hypochlorite (0.2 micrograms/ml of free available chlorine), formaldehyde (1, 0.75, or 0.5%), oxalic acid (1.25%), cetylpyridinium chloride (25 micrograms/ml), or cetyltrimethylammonium bromide (100 micrograms/ml). Results of standard membrane filtration assays with laboratory test strains and water samples from dialysis centers showed that 5 min of exposure to 1% formaldehyde effectively reduced gram-negative bacterial populations and allowed increased recovery of NTM in environmental fluids containing mixed microbial populations.

National surveillance of dialysis-associated diseases in the United States, 1989.

To determine trends in a variety of dialysis-associated diseases and practices, the Centers for Disease Control surveyed 1,867 chronic hemodialysis centers in the United States in 1989 in conjunction with the annual facility survey performed by the Health Care Financing Administration. The response rate to a mailed questionnaire was 92%. These 1,726 centers represented 122,734 patients and 32,486 staff members. The following results were found. 1) During the last 14 years, the incidence of hepatitis B virus (HBV) infection decreased from 3.0 to 0.1% among patients, and from 2.6 to 0.1% among staff members. Over the same time, the prevalence of hepatitis B surface antigen (HBsAg) positivity declined from 7.8 to 1.4% among patients and from 0.9 to 0.3% among staff members. Hepatitis B vaccine was given by 92% of the centers. By the end of 1989, 19% of susceptible patients and 55% of susceptible staff members had received all three doses of hepatitis B vaccine. From 1982 to 1989, as a result of receiving vaccine, the prevalence of antibody to HBsAg (anti-HBs) increased from 12 to 19% among patients and from 18 to 54% among staff. The incidence of non-A, non-B hepatitis in 1989 was reported to be 0.7% among patients and 0.1% among staff members. 2) Twenty-two percent of the centers reported pyrogenic reactions in the absence of septicemia among their patients, and 51% reported septicemia. 3) The reported incidence of dialysis dementia among hemodialysis patients was 0.2%, with a case fatality rate of 23%. 4) In 1989, 68% of centers reported that they reused disposable dialyzers; these centers treated 73% of the dialysis patient population. Among centers that reused disposable dialyzers, the average number of reuses ranged from 1 to 50 (mean, 12) and the maximum number of times a disposable dialyzer was ever reused ranged from 3 to 150 (mean, 28). Chemical germicides used for reprocessing dialyzers included formaldehyde, Renalin (a peracetic acid-hydrogen peroxide-based germicide), and glutaraldehyde-based germicides. Reuse of disposable dialyzers was not associated with any increased risk of acquiring HBV infection among either patients or staff. However, pyrogenic reactions occurring in clusters were reported more frequently in centers that reused conventional dialyzer membranes compared with centers that did not. This increased risk was associated only with centers that used Renalin or glutaraldehyde for reprocessing (not formaldehyde) and occurred with both automated and manual reprocessing systems.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of incubation time and temperature on microbiologic sampling procedures for hemodialysis fluids.

To prevent pyrogenic reactions and bacteremia in hemodialysis patients, the Association for the Advancement of Medical Instrumentation and the Centers for Disease Control recommend culturing of hemodialysis fluids (water and dialysate) at least once a month. The recommendations for total microbial counts are (i) less than or equal to 200 CFU/ml in water used to prepare dialysate or reprocess hemodialyzers and (ii) less than or equal to 2,000 CFU/ml for the dialysate. In accordance with the Association for the Advancement of Medical Instrumentation recommendations all cultures should be incubated at 37 degrees C for 48 h on suitable culture media, such as Trypticase soy agar, standard methods agar, or one of several commercially available assay systems. There have been suggestions that lower temperatures and longer incubation might improve the recovery of bacteria from water and dialysate. In this study bacterial recovery from various dialysis fluids (water, bicarbonate dialysate, and bicarbonate concentrate) at 30 and 37 degrees C was compared. Duplicate sets of samples were membrane filtered (pore size, 0.45 microns); one set was incubated at 30 degrees C and the other was incubated at 37 degrees C for 72 h. The number of visible colonies was counted every 24 h by using a dissecting microscope. No significant difference was observed in specimens incubated at 37 degrees C for 48 h compared with those incubated at 30 degrees C for 72 h. Also, bacterial recovery was significantly better when samples of bicarbonate dialysate or bicarbonate concentrate were plated on Trypticase soy agar as opposed to standard methods agar.

An outbreak of fatal fluoride intoxication in a long-term hemodialysis unit.

OBJECTIVE: To determine the cause of an outbreak of acute illness and death in a long-term hemodialysis unit. DESIGN: A retrospective cohort and case-control study of patients receiving hemodialysis and a laboratory study of a model deionization system to purify water for hemodialysis. SETTING: An outpatient hemodialysis unit of a university hospital. PATIENTS: 12 patients who became severely ill after hemodialysis treatment and 20 patients who did not become ill after receiving hemodialysis treatment in the same unit. MEASUREMENTS: Medical and dialysis unit records were reviewed to identify and characterize cases. Fluids for dialysis were tested for toxic substances, and fluoride was measured in patients' serum. Resistivity and fluoride were measured in effluent from a model deionization system operated in the same way as the system associated with illness. RESULTS: During five consecutive hemodialysis shifts, 12 of 15 patients receiving dialysis treatment in one room became acutely ill, with severe pruritus, multiple nonspecific symptoms, and/or fatal ventricular fibrillation (3 patients). None of 17 patients treated in the adjacent room became ill (P < 0.0001). Death was associated with longer hemodialysis time and increased age compared with other patients who became ill. Serum concentrations of fluoride in the sick patients were markedly increased to as high as 716 mumol/L, and the source of fluoride was the temporary deionization system used to purify water for hemodialysis only in the affected room. Operation of a model deionization system showed how fluoride was adsorbed and then displaced in a massive efflux. CONCLUSIONS: Because deionization systems are used widely in hemodialysis and can cause fatal fluoride intoxication, careful design and monitoring are essential.