TRANSFUSION COMPLICATIONS: Bacterial contamination of pediatric whole blood transfusions in a Kenyan hospital

BACKGROUND: Hospitalized children in sub‐Saharan Africa frequently receive whole blood transfusions for severe anemia. The risk from bacterial contamination of blood for transfusion in sub‐Saharan Africa is not known. This study assessed the frequency of bacterial contamination of pediatric whole blood transfusions at a referral hospital in Kenya. STUDY DESIGN AND METHODS: This was an observational study. Over the course of 1 year, bacteriologic cultures were performed on 434 of the 799 blood packs issued to children by the blood bank of Coast Provincial General Hospital, Mombasa. Clinical outcome was not assessed. RESULTS: Forty‐four bacterial contaminants were isolated from 38 blood packs—an overall contamination frequency of 8.8% (95% confidence interval, 6.1%‐11.4%). Sixty‐four percent of the bacteria isolated were Gram‐negative. Many of the isolates are usually found in the environment and the most likely source of contamination was considered to be the hospital blood bank. CONCLUSION: Bacterial contamination of whole blood may be a significant but unrecognized hazard of blood transfusion for children in sub‐Saharan Africa. Further work is needed to clarify the extent of the problem and its clinical consequences. Increased awareness and adherence to basic principles of asepsis in the hospital blood bank may be important immediate interventions.     

胰岛素注射液开启后有效期内细菌污染调查

目的了解胰岛素注射液开瓶后细菌污染现况,以确定胰岛素开瓶后安全使用时间。方法通过现场抽样和细菌培养方法,对本医院20个临床科室胰岛素注射液开启时间、使用次数以及细菌污染情况进行了调查。结果胰岛素注射液瓶开启后第4d即出现污染;开启后第5 d～第9 d,污染率平均为14.29%;开启后第10 d以上,污染率即达到20%以上。污染率的上升与开启后持续时间和抽吸药物的次数有密切关系,时间越长、抽吸次数越多,污染率越高。结论胰岛素注射液瓶开启后容易受到细菌污染,随试验延长和抽吸次数增加,污染率增加,应尽量缩短开启后持续使用时间,还需要研究无菌保存措施。     

赣州市医疗机构消毒工作质量的检测

为了解赣州市医疗机构消毒工作质量,对室内空气、医护人员手、医疗用品等采样,检测细菌污染状况。结果,室内空气细菌总数超标率为19.86％～79.79％,医护人员手、物体表面、使用中消毒液细菌总数超标率分别为10.42％-77.78％、2.63％-42.86％、1.11％-11.34％,灭菌医疗用品不合格率达2.92～36.92％。个体医疗机构环境与物品细菌污染较严重。说明应加强对医疗机构（尤其是个体医疗机构）消毒工作的管理。     

Potential Infection Control Risks Associated with Ultrasound Equipment – A Bacterial Perspective

Ultrasound equipment used in trans-abdominal (TA) and trans-vaginal (TV) examination may carry bacterial contamination and pose risks to infection control during ultrasound examination. We aimed to describe the prevalence of bacterial contamination on ultrasound probes, gel, machine keyboard and cords and examined the effectiveness of low- and high-level disinfection techniques. This study was performed at a public hospital and a private practice. A total of 171 swabs were analyzed and bacterial species were identified using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) analysis and polymerase chain reaction (PCR). Sixty percent of TA probes and 14% of TV probes had evidence of bacterial contamination after an ultrasound examination. Low-level disinfection was partially effective, but 4% of probes were still contaminated by spore-forming species. Some heated gel samples were highly contaminated with the environmental bacterium Brevundimonas aurantiaca, suggesting the gel was conducive to bacterial growth. Ultrasound machines, probe cords and gels were identified as potential sources of bacterial contamination and need to be cleaned and changed regularly to minimize risks of infection.     

Isolation of bacterial cerebrospinal fluid culture contaminants at a major military medical center

In recent decades, bacterial meningitis rates have decreased secondary to the success of routine vaccinations. Ironically, the decreased incidence may contribute to the challenge of establishing accurate and timely diagnoses. Studies have suggested that in immunocompetent patients with normal cerebrospinal fluid (CSF) white blood cell counts (WBC), positive CSF cultures may be disregarded as presumed contaminants, making the initial CSF WBC increasingly relevant. This single-institution retrospective study sought to integrate clinical data with positive cultures in an era when CSF contaminants may be more commonly isolated in culture than true pathogens. A total of 7715 adult and pediatric CSF samples from 1995 to 2009 were obtained at a major military medical center. Clinical and laboratory data from 121 positive bacterial cultures were reviewed. Our bacterial CSF contamination rate (false positives) was 0.91% (70/7715). True-positive (TP) CSF cultures totaled 51 (0.66%). Among TPs, 16% (8/51) demonstrated normal CSF cell counts. The notably low 15-year CSF contamination rate of 0.91%, suggests that positive cultures are likely to represent true infection in our institution. We believe efforts to decrease the contamination rate are among the most cost-effective, while targeted clinical re-evaluation for all patients with positive CSF cultures remains vital. In light of this data, a targeted approach to re-evaluating positive cultures while incorporating the clinical context remains prudent.     

学校食堂餐（用）具细菌污染状况的调查

经检测，平南县中、小学学生食堂餐（用）具细菌总数超标率达４０．２８％～８１．２５％，大肠菌群检出率为２４．５９％～５３．７０％。私立学校或无消毒设备与药品的食堂餐（用）具细菌污染较严重。     

喉头喷雾器污染状况调查与5种消毒方法消毒效果的比较

目的调查喉头喷雾器使用前后的污染状况,探讨理想的消毒方法以降低医院感染发生率.方法分别用酒精、酒精灯烧烤、氧化电位水、碘伏和碘酒＋酒精5种消毒方法对喉头喷雾器消毒,操作方法按＂消毒技术规范＂规定方法进行,并比较5种方法的消毒效果.结果使用前的喷雾器有细菌存在;使用后的喷雾器存在严重的污染,有大量的细菌,除了有口咽部和鼻腔分布的正常菌群外,还有较多的致病菌;5种方法消毒效果均较明显,酒精灯烧烤法与碘酒＋酒精法优于氧化电位水冲洗、碘伏和酒精擦拭3种消毒方法.结论要重视喉头喷雾器污染状况,并选用合适方法进行严格消毒,防止侵 入性操作引起医源性医院感染的发生.酒精灯烧烤法与碘酒＋酒精擦拭法是较理想的消毒方法.     

使用中洗手液染菌情况调查

目的了解使用中洗手液污染情况及原因。方法采用现场采样和细菌检验技术,对该医院临床科室使用中洗手液染菌情况进行抽样调查。结果共抽检该医院11个临床科室123份洗手液,不合格25份,其中细菌总数超标4份,检出条件致病菌21份,超标率20.33%。在洗手液中检出铜绿假单胞菌最多,占71%,大肠埃希菌占19%,肺炎克雷伯菌和金黄色葡萄球菌各占5%。该医院不同科室使用中洗手液细菌污染超标率最高者为重症监护病房,其次是普通病区和手术室。结论该医院用于手卫生的洗手液不规范使用导致细菌污染超标严重,检出铜绿假单胞菌最多,应用感应式取液器及规范的消毒措施可提高合格率。     

Evaluation of a reporting system for bacterial contamination of blood components in the United States

BACKGROUND: The transfusion of blood components contaminated with bacteria may have serious clinical consequences, but few data are available on the incidence of these events. A national effort to assess the frequency of blood component bacterial contamination associated with transfusion reaction (the BaCon Study) was initiated to better estimate their occurrence. STUDY DESIGN AND METHODS: Standard reporting criteria, data collection forms, and a standardized reporting protocol were developed in collaboration with the American Red Cross, AABB, and the Department of Defense. Episodes reported to the BaCon Study were compared with those reported to the FDA's national reporting systems to estimate the extent to which all serious reactions associated with bacterial contamination were captured. RESULTS: During the first 2 years, 38 episodes meeting study criteria were reported; 21 were laboratory-confirmed. The estimated proportion of episodes reported to the BaCon Study (i.e., completeness of coverage) was lower than that reported to the FDA during the same period (0.33 vs. 0.68), but the positive predictive value was higher (0.66 vs.0.28). CONCLUSION: Despite the complexity of obtaining reports from a large number of United States hospitals and transfusion centers, the feasibility and usefulness of the BaCon Study were shown. This study was the only national study in the United States to monitor adverse clinical events associated with bacterial contamination of blood components. By building on hospital-based reporting of transfusion-related adverse events, the BaCon Study serves as a model for the study of other complications associated with blood and blood components.     

医疗机构消毒质量监测

为了解医疗机构消毒质量,对部分医疗机构环境及物品污染情况进行了调查。结果,医院污水消毒排放超标率为52.94％,室内空气超标率为39.75％,物体表面细菌超标率为5.93％,医护人员手细菌超标率为10.29％,一次性使用医疗用品污染超标率为2.91％,使用中消毒剂细菌超标率为1.564％,紫外线灯辐照度和压力蒸汽灭菌器均为100％合格。调查结果反映出医疗机构消毒质量存在问题,暴露出各级医疗机构重治轻防的弱点。     

Bacterial contamination of platelet concentrates: results of a prospective multicenter study comparing pooled whole blood-derived platelets and apheresis platelets

BACKGROUND: The GERMS Group initiated a prospective multicenter study to assess prevalence and nature of bacterial contamination of pooled buffy-coat platelet concentrates (PPCs) and apheresis platelet concentrates (APCs) by routine screening with a bacterial culture system. STUDY DESIGN AND METHODS: In nine centers overall, 52,243 platelet (PLT) concentrates (15,198 APCs, 37,045 PPCs) were analyzed by aerobic and anaerobic cultures (BacT/ALERT, bioMérieux). RESULTS: In 135 PLT concentrates (PCs; 0.26%), bacteria could be identified in the first culture (0.4% for APCs vs. 0.2% for PPCs; p < 0.001). In 37 (0.07%) of these PC units, the same bacteria strain could be identified in a second culture from the sample bag and/or the PC unit. The rate of confirmed-positive units did not differ significantly between APC (0.09%; 1/1169) and PPC units (0.06%; 1/1544). Bacteria from skin flora (Propionibacterium acnes, Staphylococcus epidermidis) were the most prevalent contaminants. Median times to first positive culture from start of incubation were 0.7 and 3.7 days in aerobic and anaerobic cultures for confirmed-positive units. With a "negative-to-date" issue strategy, most PC units (55%) had already been issued by time of the first positive culture. CONCLUSION: The rate of confirmed bacterial contamination of PC units was low. Nevertheless, clinicians must be aware of this risk. The risk of bacterial contamination does not warrant universal preference of APCs. It must be questioned whether routine bacterial screening by a culture method can sufficiently prevent contaminated products from being transfused due to the delay until a positive signal in the culture system and due to false-negative results.     

Skin disinfection with a single‐step 2% chlorhexidine swab is more effective than a two‐step povidone‐iodine method in preventing bacterial contamination of apheresis platelets

BACKGROUND: Skin commensal bacteria account for most septic reactions after apheresis platelet (PLT) transfusion. Consequently, we evaluated the effectiveness of two skin disinfection methods in preventing bacterial contamination of PLT collections. STUDY DESIGN AND METHODS: Three regional blood centers evaluated a one‐step 2% chlorhexidine/70% isopropyl alcohol (2% CHX/IPA) skin disinfection method (trial group), while 32 blood centers (control group) continued to use a two‐step povidone‐iodine (P‐I) method. Aerobic quality control bacterial culture results and adverse donor events were compared between April 1, 2009, and December 31, 2009. RESULTS: The rate of initial positive bacterial cultures was significantly lower in the trial regions compared to control regions in 2009 (143 vs. 321 per million: odds ratio [OR] 0.44, 95% confidence interval [CI] 0.23‐0.86]). Trial regions also tended to have lower rates of both true‐positive cultures (100 vs. 214 per million: OR 0.47, 95% CI 0.21‐1.03) and false‐positive (contamination) cultures (43 vs. 96 per million: OR 0.45, 95% CI 0.14‐1.49). No differences were seen in the corresponding periods in 2007 and 2008 when all centers used P‐I skin preparation. Allergic reactions were reported after 89 of 73,247 apheresis procedures (0.12%) in the trial regions representing a 16‐fold increase (OR 15.9, 95% CI 9.9‐25.6) compared to control regions. CONCLUSION: The 2% CHX/IPA single‐step skin swabs are more effective in preventing bacterial contamination of apheresis PLT components than a two‐step P‐I skin disinfection method and may reduce the risk of septic transfusion reactions. Skin irritation and allergic reactions were more likely among donors in trial regions, but reactions were generally mild and self‐limiting.     

普通病房床单位细菌污染调查

目的了解综合性医院普通病房床单位的污染状况及消毒情况,降低床单位传播医院感染的机会。方法采用微生物学采样和检测方法,对5个病区普通病房的50张床单位进行了调查和监测。结果普外科床单位污染率为90%以上,内科床单位污染率为55%以上。床单位组件中,以枕芯污染率最高,为84.0%;棉胎污染率为78.0%,床垫的污染率为72.0%。病人住院1周以内的床单位平均污染率为27.8%,住院2周以上的床单位平均污染率达到80%以上。经臭氧床单位消毒机消毒30 m in,对床单位表层和深层的自然菌消除率均达99%以上。结论医院普通床单位污染严重,外科床单位污染率最高;随着患者住院时间的延长,床单位污染程度逐渐加重,应进行床单位消毒。     

Bacterial contamination of ready-to-use 1-L feeding bottles and administration sets in severely compromised intensive care patients

OBJECTIVE: In intensive care patients, enteral feeding requires sterile feedings because of infectious complications and adequate supplements to meet nutritional needs. Heretofore, prepacked, large-volume formula containers were developed, but bacterial contamination occurred in 4% to 15%. Our objective was to investigate the microbial contamination rate of 1-L feeding bottles and newly designed administration sets over hanging times of 24 hrs in the intensive care unit (ICU). DESIGN AND SETTING: A prospective observational cohort study of patients admitted to the ICU of a university hospital. PATIENTS: All consecutive patients fed via a nasojejunal tube for at least 4 days. MEASUREMENTS: Cultures of feeding bottles, administration sets, and gastric and tracheobronchial aspirates at day 0, 1, 2, 4, and 7. RESULTS: A total of 4% of feeding bottles and 74% of infusion sets contained >10(2) colony forming units (CFU)/mL. Gastric and bronchial aspirates were positive in 90% and 92%, respectively. Bacterial counts of feeding bottles were 10(2)-10(5) CFU/mL, and the main bacteria isolated included Enterobacter cloacae, Klebsiella oxytoca, and enterococci. One third of all cultured bacteria in feeding bottles, administration sets, stomach, and lungs belonged to the Enterobacteriaceae family, which was held responsible for the nosocomial infections in the ICU. None of the 1-L feeding bottles with a hanging time of 19-24 hrs was contaminated. Only bottles that had to be exchanged because of need for a faster rate of infusion proved to be contaminated, apparently without clinical consequences. With time and the increasing severity of disease, the administration sets became contaminated at an increasingly faster rate and with higher bacterial counts mainly through retrograde growth of endogenous bacteria. The final step of bottle contamination might have been the bacterial transfer by nurses' hands. CONCLUSION: Despite an almost ideal design of the enteral nutrition delivery system, a 4% contamination rate of initially sterile feedings with clinically relevant bacteria and the fact that only manipulated systems showed bacterial growth are of concern.     

Liquid nitrogen freezers: a potential source of microbial contamination of hematopoietic stem cell components

BACKGROUND: The recent report of hepatitis B transmission between hematopoietic progenitor and putative stem cell (HPC) components stored in liquid nitrogen led to the questioning of whether evidence existed for similar contamination by bacterial or fungal elements. STUDY DESIGN AND METHODS: Microbial contamination rates were reviewed for 704 HPC components from 255 patients over an 18-month period. Five liquid nitrogen freezers were surveyed for microbial contamination. The literature was reviewed to ascertain the published experience of other laboratories with HPC component contamination first documented on thawing. RESULTS: Seven (1.2%) of 583 thawed components were found to be contaminated with a variety of environmental or waterborne organisms, despite a meticulous protocol to prevent contamination during thawing. All of these components had been sterile on cryopreservation. Literature review revealed a similar incidence of post-thaw contamination from other centers. Microbial survey of liquid nitrogen freezers revealed low-level contamination in four of five. The organisms represented were similar to those cultured from thawed HPC components. One freezer was heavily contaminated by Aspergillus species. CONCLUSION: Liquid nitrogen freezers are not sterile, and both the liquid and vapor phases are potential sources of microbial contamination of HPC components. While low-level contamination by environmental organisms may be common, the occurrence of heavy contamination by potential pathogens such as Aspergillus species suggests that monitoring of liquid nitrogen sterility may be indicated. Strategies to assess and prevent microbial transmission from liquid nitrogen to HPC components need further development.     

单中心腹膜透析相关性腹膜炎致病菌及病因分析

目的 分析单中心腹膜透析相关性腹膜炎(PDAP)的病因、致病菌分布和耐药性,为PDAP防治提供参考依据。方法 回顾性分析94例次PDAP住院患者的一般资料、细菌培养及耐药性分析、疗效及转归。结果 94例次PDAP患者中,最常见的感染原因是以G+菌感染为主的操作性污染（53.19%）、其次为G-菌感染为主的肠源性感染（27.66%）。94例次患者透析液病原菌培养阳性65例次,阳性率为69.15%。65例次培养分离出菌株67株,其中G+菌45株（67.16%）,G-菌20株（29.85%）,真菌2株（2.99%）。本中心最主要的致病菌是G+菌,以表皮葡萄球菌多见,而G-菌以大肠埃希杆菌最为常见。G+菌对青霉素（91.11%）、红霉素（91.11%）和苯唑西林（88.89%）耐药率高,对利奈唑胺和万古霉素无耐药。G-菌对亚胺培南、美罗培南未出现耐药,而对头孢他啶（10.00%）、头孢吡肟（5.00%）耐药率均较低。真菌对氟康唑、两性霉素B、5 氟尿嘧啶、伊曲康唑均无耐药。治疗后51例次治愈（78.46%）,退出14例次（21.54%）,退出患者中有1例死亡,病死率1.54%,13例次拔管改血透。G+菌与G-菌感染的患者比较治愈率与退出率差异均无统计学意义（P＞0.05）。2例真菌感染采取尽早拔管,转为血液透析。结论 本中心需加强腹膜透析患者教育,提高培养阳性率,PDAP的主要致病菌仍然以G+菌为主,头孢菌素一代联合三代仍然可作为本中心初始经验用药。     

一次使用性医疗用品的质量检测

经检测，１９９６年３～５月我院存放的来自１２个厂家的一次使用性医疗用品，包装破损率达１３．４９％，真菌污染率为６．５１％。抽测１０６副一次使用性输液（血）器，细菌内毒素阳性率为４．７２％。抽测５０副一次使用性注射器，无菌率１００％，未检出细菌内毒素。     

Bacterial contamination of whole-blood-derived platelets: the introduction of sample diversion and prestorage pooling with culture testing in the American Red Cross

BACKGROUND: Bacterial sepsis following whole blood–derived platelet (WBP) transfusion has remained a substantial patient risk, primarily due to a lack of practical and effective means to limit or detect bacterial contamination. We describe the risk of reported septic reactions to WBPs and the introduction of prestorage‐pooled whole blood–derived platelets (PSPs) collected using initial sample diversion and cultured for bacterial contamination. STUDY DESIGN AND METHODS: Product qualification and quality control (QC) testing with the Acrodose PL system (Pall Medical) were evaluated in four regional blood centers. Bacterial contamination risk was assessed by review of reported septic transfusion reactions to WBPs and by aerobic QC culture of leukoreduced PSPs utilizing automated microbial detection system cultures (BacT/ALERT 3D, bioMérieux). RESULTS: Before implementing PSPs (January 2003‐December 2006), we distributed 2,535,043 WBP units and received 20 reports of septic reactions including 2 fatalities (7.9 per million [1:126,752] reactions and 0.79 per million [1:1,267,522] fatalities). In October 2006, PSPs were effectively implemented with a product qualification success rate of 99.6 percent and a mean yield of 4.0 × 10¹¹ platelets (PLTs) per pool. Whole blood collection sets with sample diversion technology were introduced during the operational trial and decreased the rate of confirmed‐positive bacterial culture of PSPs from 2111 (1:474) to 965 (1:1036) per million (odds ratio, 0.46; 95% confidence interval, 0.22‐0.95). No septic reactions to PSPs were reported (25,936 PSP units distributed). CONCLUSION: Sample diversion and bacterial culture are effective methods to reduce bacterial risk with WBP transfusion. Bacterial contamination of PSPs was assessed at 5.8‐fold our current rate for apheresis PLTs utilizing comparable culture protocols.     

喉头喷雾器污染状况调查与消毒方法的研究

目的 调查喉头喷雾器使用前后的污染状况,探讨有效的消毒方法以降低医院感染发生率。方法按《消毒技术规范》规定方法进行采样及消毒,并进行统计。结果使用后的喷雾器存在严重的污染,有大量的细菌,除了有口咽部和鼻腔分布的正常菌群外,还有较多的致病菌。酒精灯烧烤和乙醇擦拭两种消毒方法优于氧化电位水冲洗。结论要重视喉头喷雾器污染状况,防止侵入性操作引起医源性医院感染的发生;酒精灯烧烤与乙醇擦拭是较理想的消毒方法。