Transfusion-related sepsis due to Serratia liquefaciens in the United States

Evaluation of bacterial growth, effects on albumin, and coagulation factors in canine fresh frozen plasma administered as continuous rate infusion exposed to room temperature for 12 hours

OBJECTIVES

To determine the risk of bacterial growth and to analyze the stability of albumin and coagulation factors in canine fresh frozen plasma (FFP) units exposed to room temperature (24°C) administered as a continuous rate infusion (CRI) for 12 hours.

DESIGN

Ex vivo study.

SETTING

University teaching hospital and pet blood bank.

ANIMALS

None.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

An FFP CRI was simulated to replicate the standard routine procedure used in dogs. Plasma samples were collected before starting the CRI (H0), after 4 hours (H4), and after 12 hours (H12). Bacterial culture of FFP was performed and albumin concentration and specific activity levels for factors V, VII, VIII, and IX were measured and compared. All plasma culture results were negative. There were no statistically significant differences at any time point in the factor VIII activity (median 105.5% [range, 75.6%-142.0%] at H0; median 107.8% [range, 75.0%-172.7%] at H4; and median 112.1% [range, 81.7%-171.0%] at H12); factor IX activity (median 119.3% [range, 89.1%-175.9%] at H0; median 123.1% [range, 72.5%-172.7%] at H4; and median 118.3% [range, 86.6%-177.5%] at H12); or albumin concentration (median 21.0 g/L [range, 17.0-23.0 g/L] at H0 and median 20.0 g/L [range, 17.0-24.0 g/L] at H12). A slight but significant increase in factor V activity was observed when comparing H0 (median 107.0% [range, 71.0%-159.0%]) to H4 (median 117.7% [range, 71.0%-176.7%]) (P = 0.002) or H12 (median 116.2% [range, 71.0%-191.6%]) (P = 0.001). A slight but significant increase in factor VII activity was observed when comparing H0 (median 115.4% [range, 70.6%-183.7%]) to H4 (median 118.2% [range, 82.7%-194.6%]) (P = 0.005); H0 to H12 (median 128.7% [range, 86.4%-200.0%]) (P < 0.001); and H4 to H12 (P = 0.002).

CONCLUSIONS

FFP CRI at room temperature for 12 hours could be considered safe with regard to risk for bacterial growth and also effective by providing albumin and clotting factors.

Comparison of Bacterial Risk in Cryo AHF and Pathogen Reduced Cryoprecipitated Fibrinogen Complex

Until November 2020, cryoprecipitated antihaemophilic factor (cryo AHF) was the only United States Food and Drug Administration (FDA)-approved fibrinogen source to treat acquired bleeding. The post-thaw shelf life of cryo AHF is limited, in part, by infectious disease risk. Concerns over product wastage demand that cryo AHF is thawed as needed, with thawing times delaying the treatment of coagulopathic patients. In November 2020, the FDA approved Pathogen Reduced Cryoprecipitated Fibrinogen Complex for the treatment and control of bleeding, including massive hemorrhage, associated with fibrinogen deficiency. Pathogen Reduced Cryoprecipitated Fibrinogen Complex (also known as INTERCEPT^® Fibrinogen Complex, IFC) has a five-day post-thaw room-temperature shelf life. Unlike cryo AHF, manufacturing of IFC includes broad spectrum pathogen reduction (Amotosalen + UVA), enabling this extended post-thaw shelf life. In this study, we investigated the risk of bacterial contamination persisting through the cryoprecipitation manufacturing process of cryo AHF and IFC. Experiments were performed which included spiking plasma with bacteria prior to cryoprecipitation, and bacterial survival was analyzed at each step of the manufacturing process. The results show that while bacteria survive cryo AHF manufacturing, IFC remains sterile through to the end of shelf life and beyond. IFC, with a five-day post-thaw shelf life, allows the product to be sustainably thawed in advance, facilitating immediate access to concentrated fibrinogen and other key clotting factors for the treatment of bleeding patients.

Stability of ex vivo coagulation factor activity in never-frozen and thawed refrigerated canine plasma stored for 42 days

OBJECTIVE

The primary objective of this study was to document coagulation factor activity in canine "NEVER-FROZEN" and "THAWED" refrigerated plasma for the purposes of defining recommended expiration dates. We hypothesized that NEVER-FROZEN and THAWED refrigerated plasma would maintain >50% activity of coagulation factors V (FV), VII (FVII), VIII (FVIII), IX (FIX), X (FX), and von Willebrand factor antigen (vWF) and a concentration of fibrinogen above the lower bound of the reference interval (>0.982 g/L) for greater than 14 days but less than 42 days.

DESIGN

Prospective laboratory-based study.

SETTING

University teaching hospital blood bank.

ANIMALS

Ten canine plasma units derived from healthy client-owned blood donors.

INTERVENTIONS

Serial sampling (days 0, 1, 3, 5, 7, 10, 14, 17, 21, 24, 28, 32, 35, 39, 42) from NEVER-FROZEN and THAWED refrigerated canine plasma units was conducted for measurement of activities of FV, FVII, FVIII, FIX, FX, vWF, and fibrinogen concentrations using the ACL TOP 300. Plasma was defined as "suitable for transfusion" at a given time point if the entire 95% confidence interval for each factor was above 50% activity and above a fibrinogen concentration of 0.982 g/L.

MEASUREMENTS AND MAIN RESULTS

The lower bounds of the FVIII and vWF confidence intervals were above 50% up to and including day 32 for NEVER-FROZEN refrigerated plasma and day 28 for THAWED refrigerated plasma. Confidence intervals for FV, FVII, FIX, and FX remained above 50% activity at all time points. The lower bound of the fibrinogen concentration was <0.982 g/L on day 39 for NEVER-FROZEN refrigerated plasma and on day 35 for THAWED refrigerated plasma.

CONCLUSIONS

Refrigerated canine plasma from these 10 dogs retained coagulation factor activity above the limit that we defined as suitable for transfusion for up to 32 days when NEVER-FROZEN and 28 days when THAWED. Further studies should evaluate the clinical outcomes and effects on coagulation factor activity of dogs receiving refrigerated plasma transfusions.

Game animals as a reservoir of rarely recorded opportunistic bacteria

In Poland, the population of game animals, including wild boars, roe and deer, is constantly increasing. The tonsils of wild game animals are a place of large variety of microorganisms. The pathogenic bacteria present in them, such as E. coli, Y. enterocolitica and Salmonella sp. are the most common source of meat infection. The opportunistic bacteria R. aquatilis, P. fluorescens, S. liquefaciens, S. fonticola and S. plymuthica also play an important role in public health. S. liquefaciens may be an opportunistic pathogen and in people causes sepsis and inflammation of the cornea. The protease, nuclease, phospholipase A, flagella, elastase and toxins haemolysin and proteolysin are responsible for its ability to cause disease symptoms. S. plymuthica, a rod commonly found in the environment, produces a red dye. It is most often isolated from soil, water and food. In humans, it causes infections of burn wounds, soft leg tissue as well as post-operative wounds and bacteraemia. Typically, the environmental rod S. fonticola differs from other Serratia sp. by the lack of extracellular enzymes. It causes wound infections and bacteraemia resulting from urinary tract infections. Bacteria from the genus Serratia sp. show a natural resistance to glycopeptides, rifampicin and erythromycin. The aquatic rod R. aquatilis in humans causes opportunistic infections of the urinary tract, wounds, bacteraemia and endocarditis. It exhibits natural resistance to antibiotics from the group of cephalosporins, penicillins and macrolides and quinolones. It is conditioned by the presence of class 1 integrons and class A β-lactamases. The virulence factors of R. aquatilis are also LPS and adhesin. P. fluorescens in humans is responsible for bacteraemia. It also exhibits resistance to human serum thanks to outer membrane proteins and has T3SS, which effectively infects the host.

Pseudomonas poae-Associated Fatal Septic Transfusion Reaction, Peoria, Illinois, USA, 2017

In the United States, fatal transfusion-transmitted infections from red blood cell units are rare. Although this pattern mostly reflects how inhospitable refrigerated red blood cell units are to contaminant growth, fatalities caused by microorganisms that can grow at storage temperature (4°C), but not in standard clinical blood cultures at 37°C, are probably underestimated. We analyzed a fatal red blood cell transfusion in Peoria, Illinois, USA, that occurred in 2017. Samples from the patient's whole blood and the red blood cell unit remained culture-negative during the investigation, despite direct visualization of gram-negative bacilli within the unit immediately after transfusion. We identified the bacteria as Pseudomonas poae, a nonpathogenic pseudomonad carrying multiple cold-shock domain protein genes, and confirmed its cold tolerance and inability to grow at 37°C. Our work indicates transfusion reaction workups need to include testing for psychrophilic organisms, which could explain the cause of other apparently culture-negative transfusion reactions.

Existing and Emerging Blood-Borne Pathogens: Impact on the Safety of Blood Transfusion for the Hematology/Oncology Patient

Despite measures to mitigate risk of transfusion-transmitted infections, emerging agents contribute to morbidity and mortality. We outline the epidemiology, risk mitigation strategies, and impact on patients for Zika virus, bacteria, Babesia, and cytomegalovirus. Nucleic acid testing of blood has reduced risk of Zika infection and reduced transfusion-transmitted risk of Babesia. Other collection and testing measures have reduced but not eliminated the risk of sepsis from bacterially contaminated blood components. Cytomegalovirus has almost been eliminated by high-efficiency leukoreduction, but residual transmissions are difficult to distinguish from community-acquired infections and additional antibody testing of blood may confer further safety of susceptible recipients.

Transcriptomic responses of Serratia liquefaciens cells grown under simulated Martian conditions of low temperature, low pressure, and CO2-enriched anoxic atmosphere

Results from previous experiments indicated that the Gram-negative α-proteobacterium Serratia liquefaciens strain ATCC 27592 was capable of growth under low temperature (0 °C), low pressure (0.7 kPa), and anoxic, CO₂-dominated atmosphere–conditions intended to simulate the near-subsurface environment of Mars. To probe the response of its transcriptome to this extreme environment, S. liquefaciens ATCC 27592 was cultivated under 4 different environmental simulations: 0 °C, 0.7 kPa, CO₂ atmosphere (Condition A); 0 °C, ~101.3 kPa, CO₂ atmosphere (Condition B); 0 °C, ~101.3 kPa, ambient N₂/O₂ atmosphere (Condition C); and 30 °C, ~101.3 kPa, N₂/O₂ atmosphere (Condition D; ambient laboratory conditions). RNA-seq was performed on ribosomal RNA-depleted total RNA isolated from triplicate cultures grown under Conditions A-D and the datasets generated were subjected to transcriptome analyses. The data from Conditions A, B, or C were compared to laboratory Condition D. Significantly differentially expressed transcripts were identified belonging to a number of KEGG pathway categories. Up-regulated genes under all Conditions A, B, and C included those encoding transporters (ABC and PTS transporters); genes involved in translation (ribosomes and their biogenesis, biosynthesis of both tRNAs and aminoacyl-tRNAs); DNA repair and recombination; and non-coding RNAs. Genes down-regulated under all Conditions A, B, and C included: transporters (mostly ABC transporters); flagellar and motility proteins; genes involved in phenylalanine metabolism; transcription factors; and two-component systems. The results are discussed in the context of Mars astrobiology and planetary protection.

Stored Canine Whole Blood Units: What is the Real Risk of Bacterial Contamination?

Background

Bacterial contamination of whole blood (WB) units can result in transfusion‐transmitted infection, but the extent of the risk has not been established and may be underestimated in veterinary medicine.

Objectives

To detect, quantify, and identify bacterial microorganisms in 49 canine WB units during their shelf life.

Animals

Forty‐nine healthy adult dogs.

Methods

Forty‐nine WB units were included in the study. Immediately after collection, 8 sterile samples from the tube segment line of each unit were aseptically collected and tested for bacterial contamination on days 0, 1, 7, 14, 21, 28, 35, and 42 of storage. A qPCR assay was performed on days 0, 21, and 35 to identify and quantify any bacterial DNA.

Results

On bacterial culture, 47/49 blood units were negative at all time points tested, 1 unit was positive for Enterococcus spp. on days 0 and 1, and 1 was positive for Escherichia coli on day 35. On qPCR assay, 26 of 49 blood units were positive on at least 1 time point and the bacterial loads of the sequences detected (Propionobacterium spp., Corynebacterium spp., Caulobacter spp., Pseudomonas spp., Enterococcus spp., Serratia spp., and Leucobacter spp.) were <80 genome equivalents (GE)/μL.

Conclusions and Clinical Importance

Most of the organisms detected were common bacteria, not usually implicated in septic transfusion reactions. The very low number of GE detected constitutes an acceptable risk of bacterial contamination, indicating that WB units have a good sanitary shelf life during commercial storage.

Ammonia-Oligotrophic and Diazotrophic Heavy Metal-Resistant Serratia liquefaciens Strains from Pioneer Plants and Mine Tailings

Mine tailings are man-made environments characterized by low levels of organic carbon and assimilable nitrogen, as well as moderate concentrations of heavy metals. For the introduction of nitrogen into these environments, a key role is played by ammonia-oligotrophic/diazotrophic heavy metal-resistant guilds. In mine tailings from Zacatecas, Mexico, Serratia liquefaciens was the dominant heterotrophic culturable species isolated in N-free media from bulk mine tailings as well as the rhizosphere, roots, and aerial parts of pioneer plants. S. liquefaciens strains proved to be a meta-population with high intraspecific genetic diversity and a potential to respond to these extreme conditions. The phenotypic and genotypic features of these strains reveal the potential adaptation of S. liquefaciens to oligotrophic and nitrogen-limited mine tailings with high concentrations of heavy metals. These features include ammonia-oligotrophic growth, nitrogen fixation, siderophore and indoleacetic acid production, phosphate solubilization, biofilm formation, moderate tolerance to heavy metals under conditions of diverse nitrogen availability, and the presence of zntA, amtB, and nifH genes. The acetylene reduction assay suggests low nitrogen-fixing activity. The nifH gene was harbored in a plasmid of ∼60 kb and probably was acquired by a horizontal gene transfer event from Klebsiella variicola.

Detection of bacterial contamination and DNA quantification in stored blood units in 2 veterinary hospital blood banks

Blood transfusions in veterinary medicine have become increasingly more common and are now an integral part of lifesaving and advanced treatment in small and large animals. Important risks associated with transfusion of blood products include the transmission of various infectious diseases. Several guidelines suggest what infectious agents to screen for in canine and feline transfusion medicine. However, while the risk of bacterial contamination of blood products during storage and administration has not been documented in veterinary medicine, it has emerged as a cause of morbidity and mortality in human transfusion medicine. Clinical experience shows that the majority of blood component bacterial contaminations are caused by only a few species. Unlike other types of bacteria, psychrotolerant species like Pseudomonas spp. and Serratia spp. can proliferate during the storage of blood units at 4°C from a very low titer at the time of blood collection to a clinically significant level (> 10(5) CFU/mL) causing clinical sepsis resulting from red blood cell concentrate transfusions in human medicine. The purpose of this report was to describe the detection and quantification procedures applied in 4 cases of bacterial contamination of canine and feline blood units, which suggest the need for further investigations to optimize patients' safety in veterinary transfusion medicine.

Whole-Genome Sequence of Serratia liquefaciens HUMV-21, a Cytotoxic, Quorum-Sensing, and Biofilm-Producing Clinical Isolate

A clinical isolate of Serratia liquefaciens (strain HUMV-21) was obtained from a skin ulcer of an adult patient. We report here its complete genome assembly using PacBio single-molecule real-time (SMRT) sequencing, which resulted in a single circular chromosome with 5.3 Mb. About 5,844 protein-coding genes are predicted from this assembly.

Biofilm Formation and Quorum-Sensing-Molecule Production by Clinical Isolates of Serratia liquefaciens

Serratia spp. are opportunistic human pathogens responsible for an increasing number of nosocomial infections. However, little is known about the virulence factors and regulatory circuits that may enhance the establishment and long-term survival of Serratia liquefaciens in the hospital environment. In this study, two reporter strains, Chromobacterium violaceum CV026 and VIR24, and high-resolution triple-quadrupole liquid chromatography-mass spectrometry (LC-MS) were used to detect and to quantify N-acyl-homoserine lactone (AHL) quorum-sensing signals in 20 S. liquefaciens strains isolated from clinical samples. Only four of the strains produced sufficient amounts of AHLs to activate the sensors. Investigation of two of the positive strains by high-performance liquid chromatography (HPLC)-MS confirmed the presence of significant amounts of short-acyl-chain AHLs (N-butyryl-l-homoserine lactone [C4-HSL] and N-hexanoyl-l-homoserine lactone [C6-HSL]) in both strains, which exhibited a complex and strain-specific signal profile that included minor amounts of other short-acyl-chain AHLs (N-octanoyl-l-homoserine lactone [C8-HSL] and N-3-oxohexanoyl-l-homoserine lactone [OC6-HSL]) and long-acyl-chain (C10, C12, and C14) AHLs. No correlation between biofilm formation and the production of large amounts of AHLs could be established. Fimbria-like structures were observed by transmission electron microscopy, and the presence of the type 1 fimbrial adhesin gene fimH in all strains was confirmed by PCR. The ability of S. liquefaciens to adhere to abiotic surfaces and to form biofilms likely contributes to its persistence in the hospital environment, increasing the probability of causing nosocomial infections. Therefore, a better understanding of the adherence properties of this species will provide greater insights into the diseases it causes.

Guidelines for the Prevention of Intravascular Catheter–Related Infections

Background:

Although many catheter-related blood-stream infections (CRBSIs) are preventable, measures to reduce these infections are not uniformly implemented.

Objective:

To update an existing evidenced-based guideline that promotes strategies to prevent CRBSIs.

Data Sources:

The MEDLINE database, conference proceedings, and bibliographies of review articles and book chapters were searched for relevant articles.

Studies Included:

Laboratory-based studies, controlled clinical trials, prospective interventional trials, and epidemiologic investigations.

Outcome Measures:

Reduction in CRBSI, catheter colonization, or catheter-related infection.

Synthesis:

The recommended preventive strategies with the strongest supportive evidence are education and training of healthcare providers who insert and maintain catheters; maximal sterile barrier precautions during central venous catheter insertion; use of a 2% chlorhexidine preparation for skin antisepsis; no routine replacement of central venous catheters for prevention of infection; and use of antiseptic/antibiotic-impregnated short-term central venous catheters if the rate of infection is high despite adherence to other strategies (ie, education and training, maximal sterile barrier precautions, and 2% chlorhexidine for skin antisepsis).

Conclusion:

Successful implementation of these evidence-based interventions can reduce the risk for serious catheter-related infection.

Interaction of macrophages with a cytotoxic Serratia liquefaciens human isolate

Macrophages play key roles in host defense by recognizing, engulfing, and killing microorganisms. Understanding the response of macrophages to pathogens may provide insights into host defenses and the tactics used by pathogens to circumvent these defenses. In the present study, we investigated the interaction between a clinical isolate of Serratia liquefaciens and macrophages. S. liquefaciens strain HUMV-3250 triggers a fast and potent cytotoxic effect upon infection. This process requires the presence of live bacteria, adherence, and protein synthesis but not phagocytosis/bacterial internalization. Moreover, cytotoxicity assays, analysis of DNA integrity, immunofluorescence, and confocal, scanning, and time-lapse microscopy revealed that macrophage viability decreased rapidly with time upon challenge, and depends on the MOI used. Treatment of macrophages with caspase-1 inhibitors, or with specific inhibitors of phagocytosis, did not alter the infection outcome. Moreover, human macrophages exhibited similar cytotoxic changes after infection with this strain. Macrophages responded to this cytotoxic strain with a robust pattern of pro-inflammatory gene expression. However, phagocytosis attempts to engulf live bacteria were unsuccessful, and the phagocytes were unable to kill the bacteria. We conclude that macrophage cell death occurs rapidly as a result of necrotic events after close contact with S. liquefaciens. These results likely have important implications for understanding Serratia pathogenesis and host response to infection.

Red blood cell transfusion risks in patients with end-stage renal disease

Prior to the introduction of recombinant human erythropoietin (EPO), red blood cell (RBC) transfusions were frequently required when iron and anabolic steroids failed to improve the clinical symptoms of anemia associated with hemoglobin (Hb) levels that were commonly less than 7 g/dl. After the approval of EPO in the United States in 1989, the Hb levels of patients on hemodialysis dramatically improved and the need for RBC transfusions decreased significantly. The need for RBC transfusion remains for patients who require an immediate increase in their RBC mass due to symptomatic anemia and is likely to increase due to changes in the management of anemia in dialysis patients resulting from clinical trials data, regulatory changes, and new reimbursement policies for EPO. The safety of the blood supply has greatly improved over the last few decades, and the risk of transfusion-transmitted diseases has now been dramatically reduced. Noninfectious complications of transfusion currently cause the majority of morbidity and mortality associated with transfusion in the United States. Transfusion also brings a risk of alloimmunization, a particular concern for dialysis patients waiting for kidney transplantation. Knowledge of the risks of RBC transfusions will help clinicians better assess the risks and benefits of transfusing patients with ESRD. This article reviews the modern day infectious and noninfectious risks of allogeneic RBC transfusions.

Serratia infections: from military experiments to current practice

Serratia species, in particular Serratia marcescens, are significant human pathogens. S. marcescens has a long and interesting taxonomic, medical experimentation, military experimentation, and human clinical infection history. The organisms in this genus, particularly S. marcescens, were long thought to be nonpathogenic. Because S. marcescens was thought to be a nonpathogen and is usually red pigmented, the U.S. military conducted experiments that attempted to ascertain the spread of this organism released over large areas. In the process, members of both the public and the military were exposed to S. marcescens, and this was uncovered by the press in the 1970s, leading to U.S. congressional hearings. S. marcescens was found to be a certain human pathogen by the mid-1960s. S. marcescens and S. liquefaciens have been isolated as causative agents of numerous outbreaks and opportunistic infections, and the association of these organisms with point sources such as medical devices and various solutions given to hospitalized patients is striking. Serratia species appear to be common environmental organisms, and this helps to explain the large number of nosocomial infections due to these bacteria. Since many nosocomial infections are caused by multiply antibiotic-resistant strains of S. marcescens, this increases the danger to hospitalized patients, and hospital personnel should be vigilant in preventing nosocomial outbreaks due to this organism. S. marcescens, and probably other species in the genus, carries several antibiotic resistance determinants and is also capable of acquiring resistance genes. S. marcescens and S. liquefaciens are usually identified well in the clinical laboratory, but the other species are rare enough that laboratory technologists may not recognize them. 16S rRNA gene sequencing may enable better identification of some of the less common Serratia species.

Effect of platelet additive solution on bacterial dynamics and their influence on platelet quality in stored platelet concentrates

BACKGROUND

Platelet additive solutions (PASs) are an alternative to plasma for the storage of platelet concentrates (PCs). However, little is known about the effect of PAS on the growth dynamics of contaminant bacteria. Conversely, there have been no studies on the influence of bacteria on platelet (PLT) quality indicators when suspended in PAS.

STUDY DESIGN AND METHODS

Eight buffy coats were pooled, split, and processed into PCs suspended in either plasma or PAS (SSP+, MacoPharma). PCs were inoculated with 10 and 100 colony-forming units (CFUs)/bag of either Serratia liquefaciens or Staphylococcus epidermidis. Bacterial growth was measured over 5 days by colony counts and bacterial biofilm formation was assayed by scanning electron microscopy and crystal violet staining. Concurrently, PLT markers were measured by an assay panel and flow cytometry.

RESULTS

S. liquefaciens exhibited an apparent slower doubling time in plasma-suspended PCs (plasma-PCs). Biofilm formation by S. liquefaciens and S. epidermidis was significantly greater in PCs stored in plasma than in PAS. Although S. liquefaciens altered several PLT quality markers by Days 3 to 4 postinoculation in both PAS- and plasma-PCs, S. epidermidis contamination did not produce measurable PLT changes.

CONCLUSIONS

S. liquefaciens can be detected more quickly in PAS-suspended PCs (PAS-PCs) than in plasma-PCs by colony counting. Furthermore, reduced biofilm formation by S. liquefaciens and S. epidermidis during storage in PAS-PCs increases bacteria availability for sampling detection. Culture-based detection remains the earliest indicator of bacterial presence in PAS-PCs, while changes of PLT quality can herald S. liquefaciens contamination when in excess of 10(8) CFUs/mL.

Quorum sensing in Serratia

Many bacteria use cell-cell communication to monitor their population density, synchronize their behaviour and socially interact. This communication results in a coordinated gene regulation and is generally called quorum sensing. In gram-negative bacteria, the most common quorum signal molecules are acylated homoserine lactones (AHLs), although other low-molecular-mass signalling molecules have been described such as Autoinducer-2 (AI-2). The phenotypes that are regulated in Serratia species by means of AHLs are remarkably diverse and of profound biological and ecological significance, and often interconnected with other global regulators. Furthermore, AHL- and AI-2-mediated systems (less profoundly studied) are continuously being discovered and explored in Serratia spp., many having interesting twists on the basic theme. Therefore, this review will highlight the current known quorum sensing systems in Serratia spp., including the important nosocomial pathogen Serratia marcescens.

Hospital-acquired infections related to contaminated substances

Drug-related outbreaks are frequently reported from various medical departments. A systematic review was performed to describe characteristics of these outbreaks and to determine the most frequent occasions in which contamination of substances for patient care take place. Articles were assessed by a search of the outbreak database, a search of PubMed, and hand search of reference lists from relevant articles. Articles published before 1990 were excluded. Data on affected patients, hospital-acquired infections, substances, pathogens and graded information about the location of the contamination incidence were extracted. A total of 2250 patients in 128 articles were included, mostly from intensive care units or haematological departments. Septicaemia was the most frequent hospital-acquired infection. Most often articles report contamination of blood products and heparin-sodium chloride solutions. The most frequent pathogens were hepatitis A virus, Yersinia enterocolitica, and Serratia spp. for blood products and Burkholderia cepacia and Enterobacter spp. for substances other than blood products. Mortality was highest if red blood cells or total parenteral nutrition formulas were contaminated. In 64 of the outbreaks multi-dose vials had been used against the manufacturers' recommendations. Thus, drug-related outbreaks are likely to occur particularly when basic hygiene measures are disobeyed. A large proportion of drug-related nosocomial infections could have been prevented, for example, by avoiding the use of multi-dose vials.

Transfusion-transmitted Klebsiella pneumoniae fatalities, 1995 to 2004

Transfusion-transmitted bacterial sepsis is the third most common cause of transfusion-related fatalities reported to the Food and Drug Administration. Between October 1, 1995, and September 30, 2004, there were 665 reported transfusion fatalities. Eighty-five (13%) deaths were due to transfusion-transmitted bacterial infections, of which 58 (68%) were due to gram-negative organisms. The most common gram-negative organism associated with transfusion-transmitted deaths after receipt of platelets was Klebsiella pneumoniae. This article summarizes retrospectively the case series of deaths due to transfusion-transmitted K pneumoniae infection, reported to the Food and Drug Administration, 1995 to 2004. There were 12 deaths due to transfusion-transmitted K pneumoniae infection with 7 (58%) of the 12 cases occurring in 2002. Eleven deaths were caused by the transfusion of contaminated platelets and 1 death attributed to contaminated red blood cells. Extensive review of the seven 2002 fatality reports did not identify a common (shared) lot for items used during collection or processing of the blood product. In conclusion, in cases of suspected transfusion-transmitted septicemia, broad spectrum antibiotic coverage including coverage of gram-negative organisms should be considered. Strict adherence to infection control measures while collecting, processing, and handling all blood and blood components in both the clinical settings and in the laboratory should be followed. Further development of simple and effective test procedures for detecting bacteria in the blood is needed.

Hemolysis during percutaneous mechanical thrombectomy can mimic a hemolytic transfusion reaction

BACKGROUND

Interventional radiologists have developed percutaneous mechanical thrombectomy (PMT) devices to remove intravascular thrombi. Hemolysis, secondary to thrombus destruction from these devices, has been described in radiology journals, but similar reports appear to be lacking in the transfusion medicine literature. Two cases of hemolysis after PMT are described that involved the transfusion service, one of which was reported as a hemolytic transfusion reaction.

CASE REPORTS

The first patient received 4 units of red cells (RBCs) during a thrombectomy and subsequent placement of a transjugular intrahepatic portosystemic shunt. The patient developed hemoglobinuria, and it was reported to the blood bank as a possible hemolytic transfusion reaction. After RBC mismatch and bacterial contamination were excluded, the hemolysis was attributed to thrombectomy-related mechanical hemolysis. In the second case, a hemolyzed sample was sent to the blood bank for a type and cross-match. Upon requesting that the sample be redrawn, it was learned that the sample was obtained after PMT.

CONCLUSION

Patients who have undergone PMT can have clinical and laboratory findings suggestive of hemolytic transfusion reactions. Although interventional radiologists are familiar with these side effects, the blood bank profession needs to be aware that these procedures cause nonimmune hemolysis and must consider this possibility when evaluating transfusion reactions in these patients.

Bacterial contamination of blood components

Blood for transfusion is a potential source of infection by a variety of known and unknown transmissible agents. Over the last 20 years, astounding reductions in the risk of viral infection via allogeneic blood have been achieved. As a result of this success, bacterial contamination of blood products has emerged as the greatest residual source of transfusion-transmitted disease. This paper summarizes the current status of detection, prevention, and elimination of bacteria in blood products for transfusion.

Two novel real-time reverse transcriptase PCR assays for rapid detection of bacterial contamination in platelet concentrates

The incidence of platelet bacterial contamination is approximately 1 per 2,000 units and has been acknowledged as the most frequent infectious risk from transfusion. In preliminary studies, the sterility of platelet concentrates (PCs) was tested with an automated bacterial blood culturing system and molecular genetic assays. Two real-time reverse transcriptase PCR (RT-PCR) assays performed in a LightCycler instrument were developed and compared regarding specificity and sensitivity by the use of different templates to detect the majority of the clinically important bacterial species in platelets. Primers and probes specific for the conserved regions of the eubacterial 23S rRNA gene or the groEL gene (encoding the 60-kDa heat shock protein Hsp60) were designed. During the development of the 23S rRNA RT-PCR, problems caused by the contamination of reagents with bacterial DNA were noted. Treatment with 8-methoxypsoralen and UV irradiation reduced the level of contaminating DNA. The sensitivity of the assays was greatly influenced by the enzyme system which was used. With rTth DNA polymerase in a one-enzyme system, we detected 500 CFU of Escherichia coli or Staphylococcus epidermidis/ml. With a two-enzyme system consisting of Moloney murine leukemia virus RT and Taq DNA polymerase, we detected 16 CFU/ml. With groEL mRNA as the target of RT-PCR under optimized conditions, we detected 125 CFU of E. coli/ml, and no problems with false-positive results caused by reagent contamination or a cross-reaction with human nucleic acids were found. Furthermore, the use of mRNA as an indicator of viability was demonstrated. Here we report the application of novel real-time RT-PCR assays for the detection of bacterial contamination of PCs that are appropriate for transfusion services.

Risk and prevention of transfusion-related sepsis

PURPOSE OF REVIEW

Transfusion-related sepsis is both the oldest recognized and most common transfusion-associated infectious risk. Despite an increased awareness and recognition of this problem, particularly with room-temperature stored platelets, strategies to prevent or reduce the occurrence of this problem have proved daunting.

RECENT FINDINGS

With the recent FDA approval of culture methods for platelet bacterial testing and the promulgation of accreditation standards by the College of American Pathologists and American Association of Blood Banks to limit and detect platelet bacterial contamination, it is anticipated that the frequency of this problem will now begin to diminish.

SUMMARY

As methods to reduce and/or inactivate pathogens emerge, it is hoped that transfusion-related sepsis will essentially disappear.

Severe Serratia liquefaciens sepsis following vitamin C infusion treatment by a naturopathic practitioner

A 66-year-old female patient developed severe Serratia liquefaciens sepsis following vitamin C infusion treatment by a naturopathic practitioner. The clinical course of the infection was characterized by several complications, and the direct costs of the hospital stay amounted to about 40000 Euro. Genotypically identical S. liquefaciens was isolated from the residue of the infusate given to the patient, as well as from the washbasin overflow and from two other infusion bottles. A careful inspection of the dispensing facilities and review of procedures used to prepare the infusate revealed several indications of poor hygiene. However, the source of contamination could not be fully clarified. This case report raises questions about the local facilities and personal qualifications required for naturopathic practitioners to conduct invasive procedures and demonstrates that lapses in hygiene can lead to severe morbidity and high cost.

Natural antibiotic susceptibility of strains of Serratia marcescens and the S. liquefaciens complex: S. liquefaciens sensu stricto, S. proteamaculans and S. grimesii

The natural susceptibility of 77 strains of Serratia marcescens and 41 strains of the S. liquefaciens complex (S. liquefaciens sensu stricto (n=21), S. grimesii (n=10), S. proteamaculans (n=10)) to 70 antibiotics was examined using a microdilution procedure in Isosensitest broth (all strains) and cation-adjusted Mueller Hinton broth (some strains). All species were naturally resistant to benzylpenicillin, oxacillin, cefaclor, cefazolin, cefuroxime, numerous macrolides, lincosamides, streptogramins, glycopeptides, rifampicin and fusidic acid. Uniform natural sensitivity was found to most aminoglycosides, several acylureidopenicillins, ticarcillin, newer cephalosporins, carbapenems, aztreonam, quinolones and antifolates. Species-related differences in susceptibility affecting clinical assessment criteria were found for several agents. S. marcescens was less susceptible to some aminoglycosides than species of the S. liquefaciens group. It was the only species that was uniformly naturally resistant to tetracycline, amoxycillin, amoxycillin/clavulanate and loracarbef. Species of the S. liquefaciens group were naturally resistant and intermediate or naturally intermediate to the latter agents. Differences in susceptibility among the species of the S. liquefaciens complex were generally small. S. proteamaculans was most susceptible to sulphamethoxazole. S. liquefaciens sensu stricto was less susceptible than S. grimesii and S. proteamaculans to tetracyclines, chloramphenicol and nitrofurantoin; it was the only species uniformly naturally resistant to fosfomycin. This study suggested that all species examined probably express chromosomally-encoded AmpC beta-lactamases, but the amount of enzyme may vary from species to species. The naturally-occurring low-level expression of the S. marcescens aminoglycoside 6'-acetyltransferase AAC(6')-Ic and its absence in other Serratia spp. was supported by the data. All species of the S. liquefaciens complex should be considered as probable agents of human diseases.

Guidelines for the prevention of intravascular catheter-related infections

BACKGROUND

Although many catheter-related bloodstream infections (CRBSIs) are preventable, measures to reduce these infections are not uniformly implemented.

OBJECTIVE

To update an existing evidenced-based guideline that promotes strategies to prevent CRBSIs.

DATA SOURCES

The MEDLINE database, conference proceedings, and bibliographies of review articles and book chapters were searched for relevant articles.

STUDIES INCLUDED

Laboratory-based studies, controlled clinical trials, prospective interventional trials, and epidemiologic investigations.

OUTCOME MEASURES

Reduction in CRBSI, catheter colonization, or catheter-related infection.

SYNTHESIS

The recommended preventive strategies with the strongest supportive evidence are education and training of healthcare providers who insert and maintain catheters; maximal sterile barrier precautions during central venous catheter insertion; use of a 2% chlorhexidine preparation for skin antisepsis; no routine replacement of central venous catheters for prevention of infection; and use of antiseptic/antibiotic-impregnated short-term central venous catheters if the rate of infection is high despite adherence to other strategies (ie, education and training, maximal sterile barrier precautions, and 2% chlorhexidine for skin antisepsis).

CONCLUSION

Successful implementation of these evidence-based interventions can reduce the risk for serious catheter-related infection.

Guidelines for the Prevention of Intravascular Catheter–Related Infections

These guidelines have been developed for practitioners who insert catheters and for persons responsible for surveillance and control of infections in hospital, outpatient, and home health-care settings. This report was prepared by a working group comprising members from professional organizations representing the disciplines of critical care medicine, infectious diseases, health-care infection control, surgery, anesthesiology, interventional radiology, pulmonary medicine, pediatric medicine, and nursing. The working group was led by the Society of Critical Care Medicine (SCCM), in collaboration with the Infectious Disease Society of America (IDSA), Society for Healthcare Epidemiology of America (SHEA), Surgical Infection Society (SIS), American College of Chest Physicians (ACCP), American Thoracic Society (ATS), American Society of Critical Care Anesthesiologists (ASCCA), Association for Professionals in Infection Control and Epidemiology (APIC), Infusion Nurses Society (INS), Oncology Nursing Society (ONS), Society of Cardiovascular and Interventional Radiology (SCVIR), American Academy of Pediatrics (AAP), and the Healthcare Infection Control Practices Advisory Committee (HICPAC) of the Centers for Disease Control and Prevention (CDC) and is intended to replace the Guideline for Prevention of Intravascular Device–Related Infections published in 1996. These guidelines are intended to provide evidence-based recommendations for preventing catheter-related infections. Major areas of emphasis include 1) educating and training health-care providers who insert and maintain catheters; 2) using maximal sterile barrier precautions during central venous catheter insertion; 3) using a 2% chlorhexidine preparation for skin antisepsis; 4) avoiding routine replacement of central venous catheters as a strategy to prevent infection; and 5) using antiseptic/antibiotic impregnated short-term central venous catheters if the rate of infection is high despite adherence to other strategies (i.e., education and training, maximal sterile barrier precautions, and 2% chlorhexidine for skin antisepsis). These guidelines also identify performance indicators that can be used locally by health-care institutions or organizations to monitor their success in implementing these evidence-based recommendations.

Guidelines for the prevention of intravascular catheter-related infections

BACKGROUND

Although many catheter-related bloodstream infections (CR-BSIs) are preventable, measures to reduce these infections are not uniformly implemented.

OBJECTIVE

To update an existing evidenced-based guideline that promotes strategies to prevent CR-BSIs.

DATA SOURCES

The MEDLINE database, conference proceedings, and bibliographies of review articles and book chapters were searched for relevant articles.Studies Included: Laboratory-based studies, controlled clinical trials, prospective interventional trials, and epidemiological investigations.

OUTCOME MEASURES

Reduction in CR-BSI, catheter colonization, or catheter-related infection.

SYNTHESIS

The recommended preventive strategies with the strongest supportive evidence are education and training of healthcare providers who insert and maintain catheters; maximal sterile barrier precautions during central venous catheter insertion; use of a 2% chlorhexidine preparation for skin antisepsis; no routine replacement of central venous catheters for prevention of infection; and use of antiseptic/antibiotic impregnated short-term central venous catheters if the rate of infection is high despite adherence to other strategies (i.e. education and training, maximal sterile barrier precautions and 2% chlorhexidine for skin antisepsis).

CONCLUSION

Successful implementation of these evidence-based interventions can reduce the risk for serious catheter-related infection.

Guidelines for the prevention of intravascular catheter-related infections. The Hospital Infection Control Practices Advisory Committee, Center for Disease Control and Prevention, U.S

These guidelines have been developed for practitioners who insert catheters and for persons responsible for surveillance and control of infections in hospital, outpatient, and home health-care settings. This report was prepared by a working group comprising members from professional organizations representing the disciplines of critical care medicine, infectious diseases, health-care infection control, surgery, anesthesiology, interventional radiology, pulmonary medicine, pediatric medicine, and nursing. The working group was led by the Society of Critical Care Medicine (SCCM), in collaboration with the Infectious Disease Society of America (IDSA), Society for Healthcare Epidemiology of America (SHEA), Surgical Infection Society (SIS), American College of Chest Physicians (ACCP), American Thoracic Society (ATS), American Society of Critical Care Anesthesiologists (ASCCA), Association for Professionals in Infection Control and Epidemiology (APIC), Infusion Nurses Society (INS), Oncology Nursing Society (ONS), Society of Cardiovascular and Interventional Radiology (SCVIR), American Academy of Pediatrics (AAP), and the Healthcare Infection Control Practices Advisory Committee (HICPAC) of the Centers for Disease Control and Prevention (CDC) and is intended to replace the Guideline for Prevention of Intravascular Device-Related Infections published in 1996. These guidelines are intended to provide evidence-based recommendations for preventing catheter-related infections. Major areas of emphasis include 1) educating and training health-care providers who insert and maintain catheters; 2) using maximal sterile barrier precautions during central venous catheter insertion; 3) using a 2% chlorhexidine preparation for skin antisepsis; 4) avoiding routine replacement of central venous catheters as a strategy to prevent infection; and 5) using antiseptic/antibiotic impregnated short-term central venous catheters if the rate of infection is high despite adherence to other strategies (ie, education and training, maximal sterile barrier precautions, and 2% chlorhexidine for skin antisepsis). These guidelines also identify performance indicators that can be used locally by health-care institutions or organizations to monitor their success in implementing these evidence-based recommendations.

Electrochemiluminescent detection of bacteria in blood components

Transfusion-transmitted bacterial infections cause significant patient morbidity and mortality. This study aimed to improve the sensitivity of a nucleic acid-based electrochemiluminescence (ECL) assay for pretransfusion bacterial testing of cellular blood components. The approach is dependent on the detection of bacterial 16S ribosomal RNA (rRNA). The modifications studied included the use of a chaotrope-based lysis buffer with high-energy mechanical cell disruption by RiboLysis, increased ruthenium (Ru2+) labelling per 16S rRNA molecule and concomitant use of fluorescent nucleic acid dyes (CyQUANT, Syto 17 red and Syto 61 red). The methodological changes made did lead to more effective bacterial cell disruption and enhanced ECL signal generation. Nevertheless, assay sensitivity was only slightly improved at approximately 10(4)-10(5) colony forming units per mL (CFU mL(-1)) and the results were highly inconsistent. The method is still not sensitive to the required 10(2) CFU mL(-1) and remains impractical for routine use in blood centres.

Management of intravascular devices to prevent infection

Intravenous therapy is an essential part of clinical care used in a wide variety of healthcare settings. Thus, intravenous catheters have become indispensable to clinical practice. However, catheter-related-bloodstream infections (CR-BSIs) are a major source of morbidity and mortality, especially in hospital patients. Strategies to prevent infection need to change and develop to reflect the advances in technology and delivery of health care. Current guidance recommends a number of strategies to reduce the incidence of CR-BSIs. These include applying the principles of asepsis, the choice of catheter material, the site of insertion and when to replace equipment used. This article reviews the guidelines for current clinical practice.

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.

Transfusion-related bacterial sepsis

Transfusion-associated bacterial sepsis is a persistent problem in transfusion medicine, posing a greater threat than the combined risks of receiving a blood product contaminated with HIV-1 or 2, hepatitis C virus (HCV), hepatitis B virus (HBV), and human T-cell lymphtrophic virus (HTVL) -I or -II. This article provides a brief overview of the current incidence, clinical presentation, associated blood products and organisms, and the most feasible and effective methods available to reduce the potential risk of transfusion-associated sepsis. Because bacterial contamination of blood products is the most frequent cause of transfusion-transmitted infectious disease, and as no single existing strategy can completely eliminate its risk, it is important that clinical suspicion be high, and any partial solutions additively be implemented.

Multiplex PCR for detection of Enterobacteriaceae in blood

BACKGROUND

Rapid and sensitive methods are needed to detect the small numbers of bacteria that may sometimes contaminate units of blood during collection. A multiplex 5'-nuclease TaqMan PCR assay (PE Applied Biosystems) was used to detect several bacterial species that may contaminate blood.

STUDY DESIGN AND METHODS

Oligonucleotide primers were made for regions of the 16S rRNA gene conserved in four different bacterial species: Yersinia enterocolitica and Serratia, Klebsiella, and Enterobacter species. Two probes were designed: SL-1 detected Serratia, Klebsiella, and Enterobacter species, and YE-3 detected Y. enterocolitica.

RESULTS

When TaqMan PCR was performed with chromosomal DNA isolated from pure cultures of Serratia liquefaciens, Klebsiella oxytoca, Klebsiella pneumoniae, Enterobacter cloacae, and Enterobacter agglomerans, the limit of detection with probe SL-1 was 1 to 2 CFUs. For S. marcescens, the sensitivity was 8 CFUs. The limit of detection for Y. enterocolitica with probe YE-3 was 2 CFUs. When total chromosomal DNA was extracted from whole-blood samples spiked with different numbers of Y. enterocolitica, S. liquefaciens, E. cloacae, or K. pneumoniae bacteria, the TaqMan PCR detected 12 to 16 organisms in 1 mL of blood.

CONCLUSION

The 5'-nuclease TaqMan PCR assay takes only 3 hours to perform and has the potential to detect very small numbers of bacteria.

Determinants of transfusion-associated bacterial contamination: results of the French BACTHEM Case-Control Study

BACKGROUND

Transfusion-associated bacterial contamination (TABC), probably the most frequent transfusion-transmitted infection, may induce serious adverse events. Systematic information and documentation on determinants are lacking.

STUDY DESIGN AND METHODS

The BACTHEM Study is a French matched case-control study assessing TABC determinants. Included were cases of TABC reported in France in a 2-year period, as determined from uniform definitions. Information on recipient-, blood component-, and donor-related potential determinants was collected on site. ORs were estimated by conditional logistic regression.

RESULTS

Of the 158 cases of suspected TABC reported, 41 that involved transfusion with 25 RBCs and 16 platelet concentrates were included. Gram-negative rods accounted for nearly half of the bacteria species involved and for all six deaths. In comparison with the risk of TABC for patients receiving RBCs for anemia, the risk was higher for patients receiving RBCs for pancytopenia (OR, 7.3; 95% CI, 1.3-41.0) and for those receiving platelets for thrombocytopenia (OR, 5.3; 95% CI, 1.2-24.1). Other potential determinants were platelet transfusion for pancytopenia (OR, 4.5; 95% CI, 0.5-40.0), immunosuppressive treatment (OR, 2.8; 95% CI, 0.7-10.6), shelf-life of more than 1 day for platelets or 8 days for RBCs (OR, 2.6; 95% CI, 0.7-9.6), and more than 20 previous donations by donors (OR, 1.9; 95% CI, 0.7-5.3).

CONCLUSION

This first comparative study revealed TABC determinants that suggest approaches for prevention.

Non-infectious complications of transfusion therapy

Blood transfusion is considered safe when the infused blood is tested using state of the art viral assays developed over the past several decades. Only rarely are known viruses like HIV and hepatitis C transmitted by transfusion when blood donors are screened using these sensitive laboratory tests. However, there are a variety of transfusion risks which still remain that cannot be entirely eliminated, many of which are non-infectious in nature. Predominantly immune-mediated complications include the rapid intravascular or slow extravascular destruction (hemolysis) of transfused red cells or extravascular removal of platelets by pre-formed antibodies carried by the transfusion recipient. Alternatively, red cells can be damaged when exposed to excessive heat or incompatible intravenous fluids before or during the transfusion. Common complications of blood transfusion that at least partly involve the immune system include febrile non-hemolytic and allergic reactions. While these are usually not life-threatening, they can hamper efforts to transfuse a patient. Other complications include circulatory overload, hypothermia and metabolic disturbances. Profound hypotensive episodes have been described in patients on angiotensin-converting enzyme (ACE) inhibitors who receive platelet transfusions through bedside leukoreduction filters. These curious reactions appear to involve dysmetabolism of the vasoactive substance bradykinin. Products contaminated by bacteria during blood collection and transfused can cause life-threatening septic reactions. A long-term complication of blood transfusion therapy unique to chronically transfused patients is iron overload. Less common - but serious - reactions more specific to blood transfusion include transfusion-associated graft-versus-host disease and transfusion-associated acute lung injury. Many of these complications of transfusion therapy can be prevented by adhering to well-established practice guidelines. In addition, individuals who administer blood transfusions should recognize these complications in order to be able to quickly provide appropriate treatment.

Serratia liquefaciens bloodstream infections from contamination of epoetin alfa at a hemodialysis center

BACKGROUND

In a one month period, 10 Serratia liquefaciens bloodstream infections and 6 pyrogenic reactions occurred in outpatients at a hemodialysis center.

METHODS

We performed a cohort study of all hemodialysis sessions on days that staff members reported S. liquefaciens bloodstream infections or pyrogenic reactions. We reviewed procedures and cultured samples of water, medications, soaps, and hand lotions and swabs from the hands of personnel.

RESULTS

We analyzed 208 sessions involving 48 patients. In 12 sessions, patients had S. liquefaciens bloodstream infections, and in 8, patients had pyrogenic reactions without bloodstream infection. Sessions with infections or reactions were associated with higher median doses of epoetin alfa than the 188 other sessions (6500 vs. 4000 U, P=0.03) and were more common during afternoon or evening shifts than morning shifts (P=0.03). Sessions with infections or reactions were associated with doses of epoetin alfa of more than 4000 U (multivariate odds ratio, 4.0; 95 percent confidence interval, 1.3 to 12.3). A review of procedures revealed that preservative-free, single-use vials of epoetin alfa were punctured multiple times, and residual epoetin alfa from multiple vials was pooled and administered to patients. S. liquefaciens was isolated from pooled epoetin alfa, empty vials of epoetin alfa that had been pooled, antibacterial soap, and hand lotion. All the isolates were identical by pulsed-field gel electrophoresis. After the practice of pooling epoetin alfa was discontinued and the contaminated soap and lotion were replaced, no further S. liquefaciens bloodstream infections or pyrogenic reactions occurred at this hemodialysis facility.

CONCLUSIONS

Puncturing single-use vials multiple times and pooling preservative-free epoetin alfa caused this outbreak of bloodstream infections in a hemodialysis unit. To prevent similar outbreaks, medical personnel should follow the manufacturer's guidelines for the use of preservative-free medications.

Rapid identification of Yersinia enterocolitica in blood by the 5' nuclease PCR assay

Yersinia enterocolitica accounts for 50% of the clinical sepsis episodes caused by the transfusion of contaminated red blood cells. A 5' nuclease TaqMan PCR assay was developed to detect Y. enterocolitica in blood. Primers and a probe based on the nucleotide sequence of the 16S rRNA gene from Y. enterocolitica were designed. Whole-blood samples were spiked with various numbers of Y. enterocolitica cells, and total chromosomal DNA was extracted. When the TaqMan PCR assay was performed, as few as six bacteria spiked in 200 microliter of blood could be detected. The assay was specific and did not detect other Yersinia species. The TaqMan assay is easy to perform, takes 2 h, and has the potential for use in the rapid detection of Y. enterocolitica contamination in stored blood units.