Nosocomial outbreak of severe Pseudomonas aeruginosa infections in haematological patients

From June to September 1988, an outbreak of Pseudomonas aeruginosa infections in neutropenic patients admitted to the Haematological Wards of Ospedali Riuniti in Bergamo, Italy, was detected. Out of 11 cases of P. aeruginosa infections, 8 were bacteremic. Of these, 7 died within few days of onset (mortality rate: 87.5%). Consequently, possible sources of infection were investigated, and moist areas of the hospital environment were shown to be highly contaminated by P. aeruginosa. A clinical and microbiological follow-up of patients admitted to the Haematological Wards was performed for a 10 month period following the outbreak. Adequate measures for cleaning and disinfection were shown to reduce the frequency of P. aeruginosa hospital infections.     

多药耐药铜绿假单胞菌在神经外科暴发的调查

目的 回顾性分析神经外科铜绿假单胞菌(PAE)下呼吸道感染医院暴发原因及控制措施,探求引起多药耐药PAE感染可能存在的危险因素.方法 对PAE感染患者以流行病学方法进行调查、分析,辅以环境监测及细菌鉴定.结果 该次PAE医院感染暴发主要以消毒不严格的螺纹管及雾化管道所致,呼吸机螺纹管及雾化管道PAE检出率为100.0％,患者家属的手PAE检出率为80.0％;由于环境中PAE感染源的持续存在以及抗菌药物长时间、联合应用促进了多药耐药PAE的感染.结论 将PAE感染患者统一隔离,并采取严格的消毒措施、加强护理,严格抗菌药物的使用等,有效控制PAE医院感染的再扩大.     

Nosocomial outbreak of Pseudomonas aeruginosa infections related to a flexible bronchoscope

An outbreak of Pseudomonas aeruginosa infections affecting 17 patients was detected in the 27-bed intensive care unit (ICU) of a community hospital from 1 July to 30 September 2003. An ambidirectional cohort study was conducted to identify the risk factors for infection. Nosocomial infections were defined using the criteria of the Centers for Disease Control and Prevention. Random arbitrary polymorphic DNA-polymerase chain reaction was used for genotypic characterization. Logistic regression analyses demonstrated that case patients were more likely than non-cases to have had a longer stay in the ICU, and to have undergone mechanical ventilation and antimicrobial treatment. The multi-variate analysis identified recent bronchoscopy [risk ratio (RR) 3.8, 95% confidence interval (CI) 2.5-3.9] and exposure to an infected patient (RR 2.9, 95% CI 1.1-3.7) as independent risk factors. Molecular analysis showed that of the nine isolates available, four patients had a similar strain. The factor with the strongest influence on the risk of death was infection with P. aeruginosa (RR 2.1, 95% CI 1.0-2.4, P=0.04). A combined infection control strategy was implemented, including strict compliance with isolation precautions and recommendations for cleaning and disinfecting bronchoscopes, and a sharp reduction in the incidence of P. aeruginosa infection followed. It is thought that this outbreak was caused by patient-to-patient transmission and infection from a common source, i.e. the flexible bronchoscope.     

Questions on causality and responsibility arising from an outbreak of Pseudomonas aeruginosa infections in Norway

In 2002, Norway experienced a large outbreak of Pseudomonas aeruginosa infections in hospitals with 231 confirmed cases. This fuelled intense public and professional debates on what were the causes and who were responsible. In epidemiology, other sciences, in philosophy and in law there is a long tradition of discussing the concept of causality. We use this outbreak as a case; apply various theories of causality from different disciplines to discuss the roles and responsibilities of some of the parties involved. Mackie's concept of INUS conditions, Hill's nine viewpoints to study association for claiming causation, deterministic and probabilistic ways of reasoning, all shed light on the issues of causality in this outbreak. Moreover, applying legal theories of causation (counterfactual reasoning and the "but-for" test and the NESS test) proved especially useful, but the case also illustrated the weaknesses of the various theories of causation. We conclude that many factors contributed to causing the outbreak, but that contamination of a medical device in the production facility was the major necessary condition. The reuse of the medical device in hospitals contributed primarily to the size of the outbreak. The unintended error by its producer – and to a minor extent by the hospital practice – was mainly due to non-application of relevant knowledge and skills, and appears to constitute professional negligence. Due to criminal procedure laws and other factors outside the discourse of causality, no one was criminally charged for the outbreak which caused much suffering and shortening the life of at least 34 people.     

Genotypes and infection sites in an outbreak of multidrug-resistant Pseudomonas aeruginosa

There is little published evidence regarding whether heparin lock solutions containing preservatives prevent catheter-related infections. However, adverse effects from preservative-containing flushes have been documented in neonates, leading many hospitals to avoid their use altogether. Infection control records from 1982 to 2008 at St. Jude Children's Research Hospital (SJCRH) were reviewed regarding the incidence of catheter-related infections and the use of preservative-containing intravenous locks. In addition, the antimicrobial activities of heparin lock solution containing the preservatives parabens (0.165%) or benzyl alcohol (0.9%), and 70% ethanol were examined against Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Bacillus cereus, Pseudomonas aeruginosa and Candida albicans, and compared with preservative-free saline with and without heparin. Growth was assessed after exposure to test solutions for 0, 2, 4 and 24h at 35 °C. The activities of preservatives were assessed against both planktonic (free-floating) and sessile (biofilm-embedded) micro-organisms using the MBEC Assay. Infection control records revealed two periods of increased catheter-related infections, corresponding with two intervals when preservative-free heparin was used at SJCRH. Heparin solution containing preservatives demonstrated significant antimicrobial activity against both planktonic and sessile forms of all six microbial species. Ethanol demonstrated the greatest antimicrobial activity, especially following short incubation periods. Heparin lock solutions containing the preservatives parabens or benzyl alcohol, and 70% ethanol demonstrated significant antimicrobial activity against both planktonic and sessile micro-organisms commonly responsible for catheter-related infections. These findings, together with the authors' historical infection control experience, support the use of preservatives in intravenous lock solutions to reduce catheter related infections in patients beyond the neonatal period.     

Nosocomial outbreak of Pseudomonas aeruginosa endophthalmitis.

We describe an outbreak of nosocomial endophthalmitis due to a common source, which was determined to be trypan blue solution prepared in the hospital's pharmacy service. We assume that viable bacteria probably gained access to the trypan blue stock solution during cooling after autoclaving. The temporal cluster of Pseudomonas aeruginosa endophthalmitis was readily perceived on the basis of clinical and microbiological findings, and an exogenous source of contamination was unequivocally identified by means of DNA fingerprinting.     

Control of an outbreak of carbapenem-resistant Pseudomonas aeruginosa in a haemato-oncology unit

An outbreak of a multidrug-resistant Pseudomonas aeruginosa producing metallo-β-lactamase (MBLPA) in a haemato-oncology unit was controlled using multidisciplinary interventions. The present study assesses the effects of these interventions by active surveillance of the incidence of MBLPA infection at the 1,240-bed tertiary care Kyoto University Hospital in Kyoto, Japan. Infection control strategies in 2004 included strengthening contact precautions, analysis of risk factors for MBLPA infection and cessation of urine collection. However, new MBLPA infections were identified in 2006, which prompted enhanced environmental cleaning, routine active surveillance, and restricting carbapenem usage. Between 2004 and 2010, 17 patients in the unit became infected with indistinguishable MBLPA strains. The final five infected patients were found by routine active surveillance, but horizontal transmission was undetectable. The MBLPA outbreak in the haemato-oncology unit was finally contained in 2008.     

Pseudomonas aeruginosa and Pseudomonas putida outbreak associated with contaminated water outlets in an oncohaematology paediatric unit

This paper describes an outbreak of Pseudomonas aeruginosa and Pseudomonas putida that occurred in an oncohaematology paediatric unit between January and April 2005. Eight children had nosocomial infections due to P. aeruginosa (N=5) or P. putida (N=3), which were recovered from central venous catheter blood cultures (N=4), the catheter exit site alone (N=2), or the catheter exit site and the catheter tip (N=2). Subsequent investigation showed that contaminated water outlets represented the possible source of spread. Studies of nursing and environmental cleaning practices revealed two modes of catheter contamination. A reduction in the size of the catheter dressing at the exit site gave less protective cover during showers, and a detergent-disinfectant diluted with tap water had contaminated perfusion bottles. Repetitive intergenic consensus polymerase chain reaction indicated two discrete patterns for P. aeruginosa and one for P. putida. The water network was chlorinated, and disposable seven-day filters were fitted on all taps and showers. Due to the deleterious effects of chlorination on the water network and the cost of the weekly filter change, a water loop producing microbiologically controlled water was installed. In addition, the concentration of the detergent-disinfectant was increased and refillable sprayers were replaced with ready-to-use detergent-disinfectant solution for high-risk areas. Following these measures, no Pseudomonas spp. have since been isolated in clinical or environmental samples from the ward.     

Cell-to-cell signaling and Pseudomonas aeruginosa infections.

Pseudomonas aeruginosa is a bacterium responsible for severe nosocomial infections, life-threatening infections in immunocompromised persons, and chronic infections in cystic fibrosis patients. The bacterium''s virulence depends on a large number of cell-associated and extracellular factors. Cell-to-cell signaling systems control the expression and allow a coordinated, cell-density-dependent production of many extracellular virulence factors. We discuss the possible role of cell-to-cell signaling in the pathogenesis of P. aeruginosa infections and present a rationale for targeting cell-to-cell signaling systems in the development of new therapeutic approaches.     

西安地区耐亚胺培南铜绿假单胞菌感染危险因素

目的分析某地区耐亚胺培南铜绿假单胞菌（IRPA）感染的危险因素,为控制IRPA感染提供参考。方法 随机选取西安地区4所三级医院2013年2-10月IRPA感染患者103例（病例组）,同期对亚胺培南敏感的铜绿假单胞菌感染患者103例（对照组）,对IRPA感染危险因素进行分析。结果单因素分析结果显示：高龄、住院时间≥4周、慢性肺部疾病、入住重症监护室、机械通气、分离出IRPA前2周使用过亚胺培南或美罗培南等碳青霉烯类抗生素、早期联合应用抗菌药物是IRPA感染的相关危险因素;选取单因素分析有统计学意义的变量进行logistic多因素回归分析,结果显示,住院时间≥4周（OR95%CI：1.44~139.73）、机械通气（OR95%CI：2.96~267.75）以及分离出IRPA前2周使用过亚胺培南或美罗培南（OR95%CI：2.65~154.34）是IRPA感染的独立危险因素。结论该地区医院应针对IRPA感染危险因素进行干预,以期降低IRPA感染的风险。     

耐亚胺培南铜绿假单胞菌术后医院感染危险因素分析

目的 分析手术后发生耐亚胺培南铜绿假单胞菌(IRPA)感染特征的差异性,为临床治疗提供参考依据.方法 2011年1月—2012年11月于医院手术室行手术后确诊为IRPA感染的432例患者为IRPA组,并将同期无IRPA感染的94 495例患者作为非IRPA组,对两组患者感染特征的差异性进行对比分析.结果 手术后IRPA感染患者年龄＞59岁占95.0％,平均术后住院(4.79±26.57)d,首位的基础疾病为脑血管疾病,占15.05％,其次为烧伤和胰腺疾病,分别占14.58％和13.89％；手术后IRPA感染中侵入性操作使用频率远高于非IRPA医院感染者.结论 IRPA医院感染患者群集中在老年患者,以脑部疾病患者为主,术后感染部位多集中于泌尿道感染,临床应针对上述感染特征采取有效的干预措施,以减少IRPA感染的发生.     

基层医院铜绿假单胞菌多药耐药性分析

目的 了解基层医院铜绿假单胞菌(PAE)的临床分布及多药耐药情况,以指导临床正确选用抗菌药物. 方法 对2006年6月-2008年6月临床感染的81株PAE及耐药情况进行回顾性分析. 结果 81株PAE中有68株来自呼吸道感染(83.9%),以神经外科为最多(33株,40.7%),其次为神经内科(13株,16.0%);药敏结果显示,81株PAE均对≥12种抗菌药物耐药,对β-内酰胺类、氨基糖苷类(阿米卡星,庆大霉素)、喹诺酮类(左氧氟沙星,环丙沙星)、磺胺甲噁唑/甲氧苄啶呈高度耐药,均>69.0%,对亚胺堵南耐药率也达43.2%,四代头孢菌素的头孢吡肟耐药率为59.3%,三代头孢菌素的头孢他啶耐药率为90.1%. 结论 在基层医院,PAE感染以呼吸道为主,对临床常用抗菌药物旱高度多药耐药,应引起临床重视.     

铜绿假单胞菌耐药性变迁分析

目的 了解医院铜绿假单胞菌耐药性变迁,为合理使用抗菌药物提供依据.方法 采用K-B法测定细菌药敏试验,对2004年1月-2007年12月的所有铜绿假单胞菌药敏试验结果使用WHONET软件进行分析,结果氨苄西林、头孢唑林、头孢替坦的耐药率均100.0%,头孢他啶、头孢哌酮、头孢哌酮/舒巴坦、哌拉西林的耐药率均较低,其中头孢哌酮/舒巴坦的耐药率最低,2007年为3.2%,左氧氟沙星的耐药率逐年递增,而环丙沙星的耐药率,由15.6%下降至9.6%,庆大霉素由20.0%下降至16.4%,而阿米卡星的耐药率由11.1%下降至4.8%,亚胺培南和美罗培南的耐药率均约10.0%.结论 铜绿假单胞菌的耐药性基本稳定,临床医师在治疗时应根据药敏结果和抗菌药物的药理学特点合理选用抗菌药物,以提高疗效并减少耐药菌株产生.     

重症患者气管切开后铜绿假单胞菌感染的调查

目的了解医院重症患者气管切开后出现呼吸道铜绿假单胞菌感染的情况,探讨预防及控制医院感染的措施。方法对2008年1月-2009年12月38例行气管切开术的重症患者资料进行回顾性分析。结果所有患者均做痰细菌培养及药物敏感试验,培养阳性率为100.00%;38例患者共送检痰标本90次,培养出病原菌11种共146株,以革兰阴性杆菌为主,119株,占81.5%,革兰阳性菌21株,占14.4%,真菌6株,占4.1%。结论铜绿假单胞菌已成为重症患者气管切开后呼吸道医院感染的首要致病菌,加强消毒隔离措施及气道护理,根据药敏试验联合使用抗菌药物是预防与控制感染的重要手段。     

Nosocomial infections caused by multiresistant Pseudomonas aeruginosa.

A case-control study was done to evaluate factors associated with nosocomial infections by multiresistant Pseudomonas aeruginosa (MRPA). Results showed that MRPA was associated with the use of immunosuppressive and antimicrobial drugs. Five typing methods indicated that the MRPA infections were due to multiple strains rather than a single strain.     

铜绿假单胞菌医院感染的调查与耐药性分析

目的探讨铜绿假单胞菌医院感染的分布情况及耐药性。方法收集2015年1月-2016年12月铜绿假单胞菌医院科室临床分离株170株,采用琼脂扩散法(K-B法)对170株铜绿假单胞菌进行药敏试验,分析铜绿假单胞菌的标本来源分布及对15种常用抗菌药物的药敏率,并探讨抗菌药物单独用药与联合用药对铜绿假单胞菌的治疗效果。结果铜绿假单胞菌标本来源主要为呼吸道标本,检出率为59.4%,其次为尿液,检出率为12.4%,且铜绿假单胞菌医院感染主要集中在ICU、神经外科、呼吸内科等科室;药物敏感试验显示铜绿假单胞菌对临床中常用的15种抗菌药物均有严重耐药性,其中对氨苄西林/舒巴坦的耐药率最高,达到74.7%,其次为头孢噻肟,耐药率为70.6%,对环丙沙星的耐药率最低,为18.8%;6组联合抗菌药物协同累加率为43.52%~88.47%,联合抗菌治疗效果最佳为头孢他啶与环丙沙星,达到92.9%,其次为环丙沙星与哌拉西林他唑巴坦钠的联合,达到78.8%,抗菌药物联合应用敏感率与单独用药敏感率呈现显著差异(P<0.05)。结论铜绿假单胞菌有较高的耐药性,应加强临床监测与控制,对铜绿假单胞菌给予抗菌药物联合给药,增强体外抗菌活性。