Outbreak of hepatitis C virus infection in a hemodialysis unit: potential transmission by the hemodialysis machine?

OBJECTIVE: To identify the routes of transmission during an outbreak of infection with hepatitis C virus (HCV) genotype 2a/2c in a hemodialysis unit. DESIGN: A matched case-control study was conducted to identify risk factors for HCV seroconversion. Direct observation and staff interviews were conducted to assess infection control practices. Molecular methods were used in a comparison of HCV infecting isolates from the case-patients and from patients infected with the 2a/2c genotype before admission to the unit. SETTING: A hemodialysis unit treating an average of 90 patients. PATIENTS: A case-patient was defined as a patient receiving hemodialysis with a seroconversion for HCV genotype 2a/2c between January 1994 and July 1997 who had received dialysis in the unit during the 3 months before the onset of disease. For each case-patient, 3 control-patients were randomly selected among all susceptible patients treated in the unit during the presumed contamination period of the case-patient. RESULTS: HCV seroconversion was associated with the number of hemodialysis sessions undergone on a machine shared with (odds ratio [OR] per additional session, 1.3; 95% confidence interval [CI95], 0.9 to 1.8) or in the same room as (OR per additional session, 1.1; CI95, 1.0 to 1.2) a patient who was anti-HCV (genotype 2a/2c) positive. We observed several breaches in infection control procedures. Wetting of transducer protectors in the external pressure tubing sets with patient blood reflux was observed, leading to a potential contamination by blood of the pressure-sensing port of the machine, which is not accessible to routine disinfection. The molecular analysis of HCV infecting isolates identified among the case-patients revealed two groups of identical isolates similar to those of two patients infected before admission to the unit. CONCLUSIONS: The results suggest patient-to-patient transmission of HCV by breaches in infection control practices and possible contamination of the machine. No additional cases have occurred since the reinforcement of infection control procedures and the use of a second transducer protector.     

An outbreak of gram-negative bacteremia in hemodialysis patients traced to hemodialysis machine waste drain ports.

OBJECTIVE: To investigate an outbreak of gram-negative bacteremias at a hemodialysis center (December 1, 1996-January 31, 1997). DESIGN: Retrospective cohort study. Reviewed infection control practices and maintenance and disinfection procedures for the water system and dialysis machines. Performed cultures of the water and dialysis machines, including the waste-handling option (WHO), a drain port designed to dispose of saline used to flush the dialyzer before patient use. Compared isolates by pulsed-field gel electrophoresis. SETTING: A hemodialysis center in Maryland. RESULTS: 94 patients received dialysis on 27 machines; 10 (11%) of the patients had gram-negative bacteremias. Pathogens causing these infections were Enterobacter cloacae (n = 6), Pseudomonas aeruginosa (n = 4), and Escherichia coli (n = 2); two patients had polymicrobial bacteremia. Factors associated with development of gram-negative bacteremias were receiving dialysis via a central venous catheter (CVC) rather than via an arterio-venous shunt (all 10 infected patients had CVCs compared to 31 of 84 uninfected patients, relative risk [RR] undefined; P<.001) or dialysis on any of three particular dialysis machines (7 of 10 infected patients were exposed to the three machines compared to 20 of 84 uninfected patients, RR = 5.8; P = .005). E cloacae, P aeruginosa, or both organisms were grown from cultures obtained from several dialysis machines. WHO valves, which prevent backflow from the drain to dialysis bloodlines, were faulty in 8 (31%) of 26 machines, including 2 of 3 machines epidemiologically linked to case-patients. Pulsed-field gel electrophoresis patterns of available dialysis machine and patient E cloacae isolates were identical. CONCLUSIONS: Our study suggests that WHO ports with incompetent valves and resultant backflow were a source of cross-contamination of dialysis bloodlines and patients' CVCs. Replacement of faulty WHO valves and enhanced disinfection of dialysis machines terminated the outbreak.     

血液透析患者丙型肝炎病毒感染的预防

目的 调查血透患者丙肝病毒(HCV)感染情况及影响因素，探讨预防HCV感染的措施。方法 在未采取HCV感染预防措施的1990—1992年间、采取HCV感染预防措施的1997—1999年间及使用一次性透析器后的2001—2002年间，采用日本Kuraray公司提供的抗HCV—14试剂盒，以间接酶免疫测定法检测长期维持性血透患者抗体。结果 HCV的1年阳转率1991—1992年为42．2％，1998—1999年为22．8％，2001年--2002年为9％；输血量越多，透析时间越长，丙肝的感染率越高。结论 多次输血是血透患者高丙肝病毒感染的主要原因，透析过程中的医院感染也是不容忽视的重要因素。减少输血量，加强对血透患者HCV感染者的管理，严格消毒隔离，透析器一次使用等可有效控制血液透析(HD)患者高HCV感染状态。     

An outbreak of hepatitis C virus in a haemodialysis unit: molecular evidence of patient-to-patient transmission

Hepatitis C virus (HCV) infection remains a major problem in haemodialysis units despite the risk decrease provided by anti-HCV screening of blood. The exact mode of transmission of HCV in the dialysis units remains unclear. To identify the route of the virus and the mechanisms of transmission an investigation into the outbreak of HCV infection in a haemodialysis unit on a molecular level was held: 12 newly infected patients and 14 already infected were investigated by sequencing the 5' untranslated region of the viral genome. The results showed that 3 strains infected new cases and these strains matched those sequenced in already infected patients. Transmission occurred between patients treated on the same shift and also between different rooms. Console and blood or blood product contamination was excluded. Our study gave molecular evidence of patient-to-patient transmission of HCV in a haemodialysis unit. Our data underline the importance of the strict enforcement of standard precautions to prevent HCV transmission and failure of the isolation of anti-HCV positive patients as preventive measure.     

Prevalence and associated factors to hepatitis C in hemodialysis patients in Brazil

OBJECTIVE: The prevalence of hepatitis C virus (HCV) is higher in patients on hemodialysis than in the general population, probably due to greater exposure to risk situations. The purposes of the study were to determine anti-HCV antibodies prevalence among hemodialysis patients and dialysis clinics and patients factors associated with HCV transmission. METHODS: A cross-sectional study was conducted in 752 hemodialysis patients in all 12 dialysis clinics of Fortaleza, Brazil, and were screened using third generation ELISA. Sociodemographic, clinical, and epidemiological data of 663 patients were collected through interviews. Nosocomial factors were assessed using a specific questionnaire tool. Statistical analysis was conducted using Student's t test, odds ratio and multivariate analysis. RESULTS: The prevalence of anti-HCV was 52% (390/746; ranged from 6% to 72%). The anti-HCV positivity was higher in patients who had previous peritoneal dialysis (OR=1.76; 95% CI 1.12-2.76) and blood transfusion (OR=2.75; 95% CI 1.25-6.03). Dialysis age has been associated with anti-HCV positivity (OR=1.47; 95% CI 1.35-1.61). Clinics practices associated with anti-HCV positivity were: previous preparing of heparin (OR=2.92; 95% CI 1.23-6.92), failure in gloves use or change (OR=5.73; 95% CI 1.75-18.72), unsatisfactory dialysis machine disinfection (OR=2.79; 95% CI 1.57-4.96), and patient isolation in dialysis room (OR=0.18; 95% CI 0.05-0.61). CONCLUSIONS: The results show high anti-HCV prevalence among hemodialysis patients and the association of nosocomial factors with new HCV infection cases.     

Confirmation of nosocomial hepatitis C virus infection in a hemodialysis unit.

OBJECTIVES: To investigate a hepatitis C virus (HCV) outbreak in a hemodialysis unit and determine the source of transmission. METHODS: We have prospectively investigated the epidemiology of hemodialysis-related HCV infection in a single unit since 1989. In September 2000, acute hepatitis C (AH-C) was diagnosed in 5 patients by alanine aminotransferase elevation and HCV genotype 1b viremia without antibody to HCV. We surveyed the epidemiologic situation and performed polymerase chain reaction sequence analysis of the HCV 5'-noncoding (5'NC) region in the patients for comparison with 9 patients with chronic HCV genotype 1b viremia. RESULTS: Sequence analysis of the 5'NC region showed the consistency in the 5 independent clones from each AH-C patient and those from each chronic HCV viremia patient and no quasispecies over time in the clones of any of 14 analyzed patients. All AH-C patients had the same sequencing of the 6 variations in the region with the only other patient. A saline ampoule, used for heparin solution during hemodialysis, had a recap function. It was difficult to determine whether the ampoule was new or had already been used. The source-patient often underwent hemodialysis before the AH-C patients and most of their hemodialysis-related medicine was prepared during the source-patient's treatment. These findings suggested a high possibility that the AH-C patients shared a single heparin-saline solution ampoule contaminated by HCV from the source-patient. CONCLUSION: Nosocomial HCV infection occurred as a result of poor infection control practice when a patient with chronic HCV viremia received treatment prior to other hemodialysis patients.     

血液透析患者感染丙型病毒性肝炎因素的Logistic回归分析

目的 分析影响维持性血液透析患者感染丙型肝炎的危险因素。方法 收集120例血透患者的临床资料。采用第二代ELISA法检测血抗-HCV;临床资料包括;年龄、性别、血透时间,每周透析时间,输血和血制品史和量,合并HBV感染,肾脏移植史、CAPD史,ALT异常史,肝炎史、结核史以及医院感染史等。结果 单因素分析表明HCV感染与透析时间,每周透析时间,输血、血制品史和量、肾移植史、医院感染史,ALT增高中显著性相关,Logistic逐步回归分析证实HCV感染的原因为输血和医源性传播。结论 结果提示订采取严格的预防措施,减少输血和隔离抗-HCV阳性患者,对控制HCV感染意义重大。     

A cluster of hepatitis C virus infections associated with ozone-enriched transfusion of autologous blood in Rome, Italy.

OBJECTIVE: To describe an outbreak of hepatitis C virus (HCV). DESIGN: Retrospective cohort study. SETTING: Outpatient department of a hospital in Rome, Italy. PATIENTS: All 42 patients exposed to ozone therapy by autohemotherapy or intramuscular injection from January to June 2001. METHODS: Epidemiologic investigation, serologic analysis, and virus genotyping. RESULTS: Thirty-one (74%) of the patients agreed to participate in the study. Three (9.7%) had symptoms of HCV infection. This incidence rate was higher than the rate of 1.4 per 100,000 per year in the regional population. Six patients were positive for HCV antibodies and HCV RNA for a prevalence rate of 19.4%, which was much higher than the estimate of 0.9% in the population. Virus genotype 1b was found in two case-patients (one symptomatic) and 2c in four case-patients (two symptomatic), one of whom was known to have an HCV infection since 1986 and could have been the source of infection. The infected patients were all being exposed to ozone-enriched transfusions of autologous blood. Although the specific mode of transmission between patients was not detected, transmission probably occurred during one of the three busiest therapeutic sessions in the 6-month period. CONCLUSIONS: Transmission of HCV infection may occur during medical procedures with limited bleeding. Standard precautions must be applied in any healthcare setting; restricting the number of individuals treated during each therapeutic session could be an effective way of avoiding accidental transmission of infection.     

A large nosocomial outbreak of hepatitis C and hepatitis B among patients receiving pain remediation treatments.

BACKGROUND AND OBJECTIVE: In August 2002, the Oklahoma State Department of Health received a report of six patients with unexplained hepatitis C virus (HCV) infection treated in the same pain remediation clinic. We investigated the outbreak's extent and etiology. DESIGN, SETTING, AND PARTICIPANTS: We conducted a retrospective cohort study of clinic patients, including a serologic survey, interviews of infected patients, and reviews of medical records and staff infection control practices. Patients received outpatient pain remediation treatments one afternoon a week in a clinic within a hospital. Cases were defined as HCV or hepatitis B virus (HBV) infections among patients who reported no prior diagnosis or risk factors for disease or reported previous risk factors but had evidence of acute infection. RESULTS: Of 908 patients, 795 (87.6%) were tested, and 71 HCV-infected patients (8.9%) and 31 HBV-infected patients (3.9%) met the case definition. Multiple HCV genotypes were identified. Significantly higher HCV infection rates were found among individuals treated after an HCV-infected patient during the same visit (adjusted odds ratio [AOR], 6.2; 95% confidence interval [CI95], 2.4-15.8); a similar association was observed for HBV (AOR, 2.9; CI95, 1.3-6.5). Review of staff practices revealed the nurse anesthetist had been using the same syringe-needle to sequentially administer sedation medications to every treated patient each clinic day. CONCLUSIONS: Reuse of needles-syringes was the mechanism for patient-to-patient transmission of HCV and HBV in this large nosocomial outbreak. Further education and stricter oversight of infection control practices may prevent future outbreaks.     

血液透析患者肝炎病毒医院感染原因及预防

目的研究血液透析（HD）患者肝炎病毒感染的危险因素，探讨其预防措施。方法将170例透析前无肝炎病史的患者随机分为实验组和对照组，实验组使用一次性管道透析器及分机透析，对照组使用重复透析器及共用透析机进行治疗，并调查透析次数与感染肝炎病毒的关系。结果实验组乙、丙肝感染率为13．8％，对照组感染率为61．9％，差异有统计学意义（P〈0．01），且随着透析次数的增加，感染率也明显上升。结论重复使用透析器、共用透析机及透析次数多等是透析患者感染病毒性肝炎的重要因素，严格消毒隔离措施，使用一次性透析器、分区隔离及专机透析等是降低HD患者肝炎病毒感染率的有效措施。     

Outbreak of hemodialysis vascular access site infections related to malfunctioning permanent tunneled catheters: making the case for active infection surveillance.

OBJECTIVE: To describe an outbreak of infections with permanent cuffed hemodialysis catheters recognized through ongoing surveillance and related to a specific malfunctioning permanent catheter. DESIGN: The outbreak was suspected from the results of prospective infection surveillance and confirmed by a retrospective cohort study using medical records for patients receiving dialysis between April 1, 1999, and March 31, 2000. SETTING: Integrated network of six outpatient hemodialysis facilities in southern Idaho and eastern Oregon. PATIENTS: Outpatients receiving long-term hemodialysis. RESULTS: During the 18 months prior to the outbreak, the overall infection rate was 4.1 infections per 1,000 dialysis sessions with a catheter rate of 8.9 per 1,000 dialysis sessions. During the 7 months of the outbreak, the overall rate increased to 5.8 per 1,000 dialysis sessions, whereas the catheter rate increased to 18.1 per 1,000 dialysis sessions. Reports of malfunctioning "Brand A" catheters prompted discontinuation of their placement. A manufacturer recall occurred in April 2000. During the 14 months after the outbreak, the overall infection rate decreased to 3.3 per 1,000 dialysis sessions and the catheter rate to 10.8 per 1,000 dialysis sessions. A 12-month retrospective cohort study recognized 96 patients with an identifiable catheter brand and 48 infections. Of these, 27 (56%) occurred in patients with Brand A catheters. The relative risk for infection when compared with other catheter brands was 1.96 (95% confidence interval, 1.32 to 2.92; P < .001). CONCLUSIONS: Ongoing infection surveillance in hemodialysis facilities can identify specific device-related outbreaks of infections and promote interventions to reduce infectious complications and promote patient safety. Surveillance for vascular access site infections is recommended as a routine activity in hemodialysis facilities.     

维持性血液透析患者庚型肝炎病毒感染的研究

目的 了解血液透析患者庚型肝炎病毒(HGV)感染情况，探讨其危险因素。方法 采用酶联免疫法(ELISA)和逆转录—套式PCR法分别检测44例血透患者的抗—HGV抗体和HGVRNA。结果 血透患者HGV感染率为13．6％，HGV阳性组与阴性组相比输血次数较多、透析时间较长，但差异无显著性；而单独HGV阳性组与全阴性组相比透析时间明显延长，HGV感染与年龄、HBV感染、HCV感染及肝功能损害无显著相关。结论 血透患者HGV感染率明显高于普通人群，严格消毒措施、预防交叉感染、减少输血、血源中HGV筛查，对减少透析中庚型肝炎病毒感染至关重要。     

Investigation of an outbreak of multidrug-resistant Acinetobacter baumannii in trauma intensive care unit

Between January and June 2002, an outbreak of multidrug-resistant Acinetobacter baumannii occurred in a trauma intensive care unit (TICU) at the Hamad Medical Corporation, Qatar. The outbreak involved 21 patients whose infection/colonization was hospital acquired. All the strains were resistant to all tested antibiotics except amikacin. An A. baumannii strain with a similar antibiogram was isolated from the environment, equipment and hands of healthcare workers (HCWs). The technique of open suctioning probably resulted in aerosilization and contamination of the immediate patient environment. This allowed the hands of HCWs to be contaminated with the outbreak strain, with subsequent transmission to other patients and their environment. Lack of proper hand hygiene between patients and equipment contact facilitated this transmission. A review of hand hygiene practices, extensive environmental cleaning, a closed suctioning system, education and review of other infection-control practices, contributed to the termination of the outbreak.     

Multifacility Outbreak of Middle East Respiratory Syndrome in Taif,Saudi Arabia

Middle East respiratory syndrome (MERS) coronavirus (MERS-CoV) is a novel respiratory pathogen first reported in 2012. During September 2014–January 2015, an outbreak of 38 cases of MERS was reported from 4 healthcare facilities in Taif, Saudi Arabia; 21 of the 38 case-patients died. Clinical and public health records showed that 13 patients were healthcare personnel (HCP). Fifteen patients, including 4 HCP, were associated with 1 dialysis unit. Three additional HCP in this dialysis unit had serologic evidence of MERS-CoV infection. Viral RNA was amplified from acute-phase serum specimens of 15 patients, and full spike gene-coding sequencing was obtained from 10 patients who formed a discrete cluster; sequences from specimens of 9 patients were closely related. Similar gene sequences among patients unlinked by time or location suggest unrecognized viral transmission. Circulation persisted in multiple healthcare settings over an extended period, underscoring the importance of strengthening MERS-CoV surveillance and infection-control practices.     

血液透析机消毒作用的探讨

在一些透析部门中,对血液透析机的消毒不仅在每天治疗结束后进行,而且还在每次透析治疗后也对透析机执行消毒。在第一项15个透析单位（5个单位每次透析治疗结束后执行消毒和10个单位仅在每天治疗结束后消毒）参加的多方面研究当中发现,上述两种对血液透析机消毒的方式,对于发生丙型肝炎病毒（HCV）的阴转阳率并没有影响,而透析单位加强一般性预防措施,对降低HCV的阴转阳率有重要作用。在第二项研究中,对四台金宝的血液透析机平均分两一组,执行上述两种对血透机的消毒方式（即：两台在每次透析治疗结束后消毒,两台在每天治疗结束后消毒）,分别检测这两组血液透析机的透析液中的细菌与内毒素的含量,结果发现它们指标参数并无明显差异。结论：血液透析机在每次透析治疗结束后消毒,对预防HCV的感染并非起到重要作用,并且对透析液中细菌和内毒素的含量无显著影响。     

腹膜透析患者HCV感染标志检测及临床意义

目的：评价维持性腹膜透析（腹透）患丙丙型肝炎病毒（HCV0感染状况及其临床意义。方法：采用第二代酶链免疫吸附试验（ELISA2）和逆转录聚合酶链反应（RT－PCR）检测60例腹透患者血清抗－HCV和HCVRNA,按HCV标志阳性与阴性分组比较有关临床因素。结果：60例患者中,抗－HVCIgM阳性7例（11．7％）,抗－HCVIgG阳性10例（16．7％）,HCVRNA阳性13例（21．7％）,三项中任一项阳性15例（25．0％）;阳笥组与阴性组相比,两组在性别、年龄、肾功能、HBV标志、EPO（促红细胞生成素）应用上无明显差异,而在平均透时间、输血史、ALT异常、血液透析史、肾移植史方面有显著性差异。结论：腹透患者中HCV感染较为严重,输血为腹透患者感染HCDV的主要途径,但也存在与透析环境有关的传播的可能。     

Epidemic parenteral exposure to volatile sulfur-containing compounds at a hemodialysis center.

OBJECTIVE: To determine the cause of acute illness on August 30, 2000, among patients at an outpatient dialysis center (center A). DESIGN: We performed a cohort study of all patients receiving dialysis on August 30, 2000; reviewed dialysis procedures; and analyzed dialysis water samples using microbiologic and chemical assays. SETTING: Dialysis center (center A). PATIENTS: A case-patient was defined as a patient who developed chills within 5 hours after starting hemodialysis at center A on August 30, 2000. RESULTS: Sixteen (36%) of 44 patients at center A met the case definition. All case-patients were hospitalized; 2 died. Besides chills, 15 (94%) of the case-patients experienced nausea; 12 (75%), vomiting; and 4 (25%), fever. Illness was more frequent on the second than the first dialysis shift (16 of 20 vs 0 of 24, P < .001); no other risk factors were identified. The center's water treatment system had received inadequate maintenance and disinfection and a sulfurous odor was noted during sampling of the water from the reverse osmosis (RO) unit. The water had elevated bacterial counts. Volatile sulfur-containing compounds (ie, methanethiol, carbon disulfide, dimethyldisulfide, and sulfur dioxide) were detected by gas chromatography and mass spectrometry in 8 of 12 water samples from the RO unit and in 0 of 28 samples from other areas (P < .001). Results of tests for heavy metals and chloramines were within normal limits. CONCLUSIONS: Parenteral exposure to volatile sulfur-containing compounds, produced under anaerobic conditions in the RO unit, could have caused the outbreak. This investigation demonstrates the importance of appropriate disinfection and maintenance of water treatment systems in hemodialysis centers.     

954例血液透析患者血透前丙肝抗体检测结果分析

目的:分析HCV在维持性血液透析患者中的感染情况。方法:采用ELISA法对维持性血液透析患者血透前进行Anti-HCV检测,共检测954例。结果:954例中,阳性79例,阳性率8.28%。结论:在维持性血液透析患者中,HCV感染率明显高于正常人群;严格的消毒措施和对阳性病例进行隔离透析,降低HCV医源性传播有非常积极的意义。