PTCDA growth on Ge(111)-[Formula: see text] surfaces: a scanning tunneling microscopy study

The initial stages of growth of PTCDA (3,4,9,10 perylene tetracarboxylic dianhydride) at room temperature (RT) on Ge(111)-[Formula: see text] surfaces have been studied by means of scanning tunneling microscopy (STM) under ultrahigh vacuum conditions. The results show that PTCDA molecules have a high mobility at RT on the well ordered areas of the semiconductor substrate, since nucleation is only observed in domain walls, steps and surface defects. However, no molecular ordering has been detected at submonolayer coverage. For higher coverages, the formation of three-dimensional (3D) molecular islands has been observed. These 3D islands present a crystalline nature as demostrated by molecularly resolved STM images. According to these STM measurements, PTCDA molecules are ordered in a herringbone structure, similar to the one observed in PTCDA bulk crystals. Moreover, the 3D crystallites are grown on top of a disordered molecular layer, which acts as a passivating layer.

[Risk factors for early rebleeding after esophageal variceal ligation in patients with liver cirrhosis]

Objective: To investigate the risk factors for early rebleeding after esophageal variceal ligation (EVL) through a multicenter retrospective study. Methods: A total of 3289 patients who were hospitalized and underwent EVL in 17 upper second-class hospitals or hospitals of higher classes from January 1999 to May 2015 were collected and screened according to the exclusion criteria. A total of 2531 patients were screened out, and a retrospective analysis was performed for their clinical data including age, sex, endoscopic findings, and results of laboratory examination (liver function, biochemical results, routine blood test, and coagulation function) to collect related data. According to the presence or absence of rebleeding within 1 month after EVL, the patients were divided into rebleeding group and non-rebleeding group. SPSS22.0 software was used for independent t-test and one-way analysis of variance, and P < 0.05 was considered statistically significant. Results: In the 2531 patients who underwent EVL, the rate of early rebleeding after EVL was 6.6%, and the mortality rate was 12.0%. The results showed that sex (P = 0.014), number of veins with varices (P = 0.203), prothrombin time (P = 0.001), prothrombin activity (P = 0.014), albumin (P = 0), total bilirubin (P = 0.011), aspartate aminotransferase (P = 0.004), white blood cell count (P = 0.342), hepatic encephalopathy (P = 0.021), ascites (P = 0.027), Child-Pugh class (P = 0), Child-Pugh score (P = 0), glue injection for gastric varices (P = 0.521), gastric varices (P = 0.32), shunt (P = 0.174), number of ligation points (P = 0.001), number of ligation times (P = 0.024), number of times of hematemesis before treatment (P = 0), number of times of tarry stool (P = 0.008), and volume of blood in hematemesis before treatment (P = 0) were risk factors for early rebleeding after EVL. The regression analysis showed that male sex, a Child-Pugh score of >7.2, and volume of blood in hematemesis before treatment were independent risk factors for early rebleeding after EVL, while an albumin concentration of > 31.5 g/L was the protective factor. Conclusion: EVL has a good therapeutic effect in esophageal variceal rebleeding. Among all the factors analyzed, male sex, a Child-Pugh score of > 7.2, and volume of blood in hematemesis before treatment are independent risk factors for early rebleeding after EVL, and an albumin concentration of > 31.5 g/L is a protective factor.

Bronchopleural fistula after lung ablation: Experience in two cases and literature review

BACKGROUND

Bronchopleural fistula (BPF) complicating lung tumor ablation is rare but severe. The purpose of this article was to study its characteristics and treatments.

MATERIALS AND METHODS

Two of 682 (0.3%) sessions of lung microwave ablation (MWA) were complicated with BPF and documented. Two electronic databases were searched for reported cases of BPF after lung tumor ablation. Case selection and data collection were done by 3 independent reviewers.

RESULTS

A 56-year-old man and a 61-year-old woman developed BPF after MWA and died. Thirteen cases (mean age 63.8, 61.5% male) of BPF with adequate information were identified from 8 articles. Of the 13 cases, 5 (38.5%) had pulmonary co-morbidity, 3 (23.1%) had a history of pulmonary surgery, 7 (53.8%) had a target tumor adjacent or abutting pulmonary pleura, and 6 (46.2%) developed severe infections. After chest tube placement, pleurodesis, endoscopic therapy, surgery, and other treatments, 12 were cured and 1 died of BPF and pneumonia.

CONCLUSION

BPF is a rare but severe complication of lung ablation, and the management needs a multidisciplinary and individualized treatment strategy.

Comparison of coronary heart disease risk among four diagnostic definitions of metabolic syndrome

PURPOSE

Metabolic syndrome (MetS) is now well known as one of the major risk factors for coronary heart disease (CHD). Currently, there are several methods used to define MetS. The aim of this study was to determine to what extent current MetS definition reflects CHD risk using the probability of CHD in 10 years based on Framingham risk score algorithms.

METHODS

A total of 7575 adults, aged 16-93 years (2532 men and 5043 women), were recruited. We conducted a cross-sectional health survey in China using MetS criteria from four different definitions: modified National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III), International Diabetes Federation (IDF), Chinese and Japanese.

RESULTS

Differences in the prevalence of MetS by each definition were small in males (22.9-25.9 %), whereas in females, MetS was three times more prevalent using the IDF definition (29.1 %) versus the Japanese definition (9.7 %). Framingham risk scores in participants with MetS were significantly higher than in those without MetS by all definition criteria (p < 0.001). The CHD risk scores for participants with MetS by each definition showed similar values in males (range 11.5-12.1 %) with no significant differences among definitions. Conversely, in females with MetS the risk score for CHD was low (range 3.5-4.3 %) by each MetS definition.

CONCLUSIONS

These findings suggest that further studies are required to establish appropriate criteria of MetS in females.

[Unexpected cutaneous purpura in an infant]

A two-month-old boy visited the hospital due to unexpected cutaneous purpura and thrombocytopenia for 2 days. The physical examination revealed a purple mass on the back. The soft tissue color Doppler ultrasound showed rich blood signals in the tissue, and the results of bone marrow puncture indicated an increased number of megakaryocytes. After the treatment with hormone and gamma globulin, the platelet count rapidly increased and maintained at a normal level. Meanwhile, the boy was given oral administration of propranolol. He was followed up for 4 months and the volume of the mass on the back was reduced significantly. He had a definite diagnosis of hemangioma and immune thrombocytopenia. As for the patients with hemangioma complicated by thrombocytopenia, knowledge of Kasabach-Merritt syndrome should be enhanced and there should be a clarification of the association between thrombocytopenia and hemangioma. There should also be an alertness for thrombocytopenia of other causes.

Investigation of c ions formed by N-terminally charged peptides upon collision-induced dissociation

Tandem spectrometry is one of most powerful and versatile tools for peptide and protein structure elucidation. Low-energy CID is by far the most popular and readily accessible activation method to generate high fragmentation efficiency and complementary sequence information for protonated peptides. CID is classically characterized by amide bond cleavage and the formation of typical b/y ions where the observation of c ions is scarce. In this perspective special feature article, Prof. Xinhua Guo and co-workers evaluate the influence of changing an arginine residue for a deuterohemin group at the peptide N-terminal on the formation of c ions upon low-energy CID. Results demonstrate that the N-terminal fixed charge of peptides promotes the formation of c ions either by direct cleavage from precursor ions or through the further dissociation of uncommon b ions via a McLafferty-type rearrangement. Dr. Xinhua Guo is professor of chemistry at Jilin University (China). Her research interests are in fundamental and applied mass spectrometry more specifically understanding the behavior of biomolecule fragmentation.

Identification of molecular markers for oocyte competence in bovine cumulus cells

Cumulus cells (CCs) have an important role during oocyte growth, competence acquisition, maturation, ovulation and fertilization. In an attempt to isolate potential biomarkers for bovine in vitro fertilization, we identified genes differentially expressed in bovine CCs from oocytes with different competence statuses, through microarray analysis. The model of follicle size, in which competent cumulus-oocyte complexes (COCs) were recovered from bigger follicles (≥8.0 mm in diameter) and less competent ones from smaller follicles (1-3 mm), was used. We identified 4178 genes that were differentially expressed (P < 0.05) in the two categories of CCs. The list was further enriched, through the use of a 2.5-fold change in gene expression as a cutoff value, to include 143 up-regulated and 80 down-regulated genes in CCs of competent COCs compared to incompetent COCs. These genes were screened according to their cellular roles, most of which were related to cell cycle, DNA repair, energy metabolism, metabolism of amino acids, cell signaling, meiosis, ovulation and inflammation. Three candidate genes up-regulated (FGF11, IGFBP4, SPRY1) and three down-regulated (ARHGAP22, COL18A1 and GPC4) in CCs from COCs of big follicles (≥8.1 mm) were selected for qPCR analysis. The selected genes showed the same expression patterns by qPCR and microarray analysis. These genes may be potential genetic markers that predict oocyte competence in in vitro fertilization routines.

Tumorigenic potential is restored during differentiation in fusion-reprogrammed cancer cells

Detailed understanding of the mechanistic steps underlying tumor initiation and malignant progression is critical for insights of potentially novel therapeutic modalities. Cellular reprogramming is an approach of particular interest because it can provide a means to reset the differentiation state of the cancer cells and to revert these cells to a state of non-malignancy. Here, we investigated the relationship between cellular differentiation and malignant progression by the fusion of four independent mouse cancer cell lines from different tissues, each with differing developmental potentials, to pluripotent mouse embryonic stem (ES) cells. Fusion was accompanied by loss of differentiated properties of the four parental cancer cell lines and concomitant emergence of pluripotency, demonstrating the feasibility to reprogram the malignant and differentiative properties of cancer cells. However, the original malignant and differentiative phenotypes re-emerge upon withdrawal of the fused cells from the embryonic environment in which they were maintained. cDNA array analysis of the malignant hepatoma progression implicated a role for Foxa1, and silencing Foxa1 prevented the re-emergence of malignant and differentiation-associated gene expression. Our findings support the hypothesis that tumor progression results from deregulation of stem cells, and our approach provides a strategy to analyze possible mechanisms in the cancer initiation.

Intrarenal macrophage infiltration induced by T cells is associated with podocyte injury in lupus nephritis patients

Proteinuria is the hallmark of clinical manifestation of disease activity in lupus nephritis (LN) patients, which arises from direct or indirect podocyte injury. This study is to explore the relationship between intrarenal T cell infiltration and podocyte injury in lupus nephritis (LN), and to understand the potential mechanisms of podocyte injury induced by intrarenal T cells. Sixty renal biopsies from patients diagnosed with LN were included in the present study. Histological changes in LN patients were detected by light and electron microscopy. Podocyte-specific nephrin expression in renal tissues was detected by immunofluorescence. Infiltration of T cells (CD3+ cells), infiltration of macrophages (CD68+ cells) and the expression of osteopontin (OPN) in renal tissues were examined by immunohistochemical staining. Pearson or Spearman’s tests were used to perform correlation analysis. Morphologic lesions of podocytes were more severe in LN patients than in normal control subjects. Compared with normal control subjects, nephrin expression was significantly decreased in LN patients. The expression level of nephrin was significantly lower in active LN patients than in the inactive group of patients ( P < 0.05). Compared with normal control subjects, the number of infiltrated intrarenal T cells and macrophages was significantly increased in LN patients. T cells were mainly distributed in renal interstitium, with very few being in glomeruli, while macrophages were mainly located in glomeruli. The number of intrarenal infiltrated T cells and macrophages in active LN patients was more than that in the inactive group ( P < 0.05). Compared with normal control subjects, OPN expression in LN patients was increased significantly. The expression level of OPN in active LN patients was significantly higher than that in the inactive group ( P < 0.05). Podocyte-specific nephrin was negatively correlated with 24-hour proteinuria, intrarenal T cells infiltration and intrarenal OPN expression in LN patients ( P < 0.001). Intrarenal macrophages had significantly positive correlation with intrarenal OPN expression ( P < 0.001). The present study provides possible links between intrarenal T cells, OPN, macrophages with reduced podocyte-nephrin and podocytopathy in systemic lupus erythematosus. In addition, infiltration of macrophages in glomeruli induced by OPN that is induced by T cells may be a crucial mechanism for podocyte injury.

Down-regulation of tumor suppressor PDCD4 expression in endometrium of adenomyosis patients

OBJECTIVE

Adenomyosis is a common benign gynecological disease which has some malignant behaviors. Programmed cell death 4 (PDCD4) is a newly identified tumor suppressor gene which lowly expresses in various cancers. However, the expression status of PDCD4 in endometrium of adenomyosis patients has not been investigated. The aim of this study is to assess the expression levels of PDCD4 in endometrium of normal controls and adenomyosis patients.

METHODS

The expression of PDCD4 in endometrium of normal controls and eutopic or ectopic endometrium of patients with adenomyosis was evaluated with quantitative real-time PCR, western blot and immunohistochemistry. In addition, the levels of serum estradiol and progesterone in normal controls and adenomyosis patients were detected using electrochemiluminescence immunoassay.

RESULTS

The results showed that PDCD4 mainly expressed in the cytoplasma of glandular epithelium of control endometrium and varied during the cycle changes of endometrium, which may be regulated by changing concentrations of progesterone in the menstrual cycle. Compared with the proliferative phase of control endometrium, PDCD4 expression was down-regulated in proliferative phase of eutopic endometrium or ectopic endometrium, and there was no cyclic variation of PDCD4 expression in eutopic endometrium of adenomyosis patients due to progesterone resistance.

CONCLUSION

These results suggest that PDCD4 may be involved in the pathogenesis of adenomyosis, which will provide a novel strategy for the early diagnosis and new therapeutic target of adenomyosis.

Correlation between protein 4.1R and the progression of heart failure in vivo

We aimed to assess the protein 4.1R (4.1R) expression of the membrane skeleton in cardiomyocytes and to determine the potential role of 4.1R in the pathogenesis of heart failure (HF). Forty-two male mice were randomly divided into two groups: an HF group (N = 22) and control group (N = 20). The HF model was established by abdominal subcutaneous injection of 5 mg⋅kg(-1)⋅day(-1) isopropyl adrenaline to the mice for 14 days. Electrocardiography was carried out and cardiac function was assessed by ultrasonic cardiogram. The left ventricular weight index (LVMI) was measured after mice were sacrificed, and the pathological changes of the heart were observed by hematoxylin and eosin staining. The expression of 4.1R in cardiomyocytes was analyzed by immunohistochemistry, immunofluorescence, and reverse transcription polymerase chain reaction. The echocardiographs showed that the left ventricular end-diastolic dimension (LVEDD) and left ventricular end-systolic dimension (LVESD) were significantly higher in the HF group than in the controls (P < 0.05), while the left ventricle shortening fraction was remarkably lower than that in the controls (P < 0.05). Electrocardiography showed faster heart rates in the HF group than in the control group (P < 0.05). Both the LVMI and the myocardial tissue pathological score were significantly higher (P < 0.01) in the HF group than in the controls. 4.1R localized mostly to the plasma membrane and was distributed discretely in the cytosol of myocardial cells. The proportion of 4.1R-positive cells was significantly higher in the HF group (P < 0.01) than in the controls, which was confirmed by the positive mRNA expression of 4.1R. 4.1R localized mostly to the plasma membrane of myocardial cells and was upregulated with the progression of HF. This suggests that 4.1R may be associated with HF progression and therefore 4.1R represents a promising therapeutic target in HF.

Prediction and preliminary screening of HLA-A*0201-restricted epitope peptides of human GPC3

In response to the limited therapeutic option for hepatocellular carcinoma (HCC), immunotherapy as a promising approach points out a new direction to the cure of tumours through specific recognition and elimination of tumour cells by the immunity-enhanced autologous immunocytes of patients. Few effective tumour antigens, however, are alternative in addition to alpha fetoprotein or tumour cell lysates. Recent studies have demonstrated that glypican-3 (GPC3) is not only a promising diagnostic marker, but also ideal therapeutic target to HCC. In this study, potential HLA-A*0201 GPC3 peptides were screened with three epitope prediction software, the binding affinity of 13 predicted epitopes with high scores was determined by T2 cells binding assay and four optimal epitopes were identified. This is the first study in which the optimal HLA-A*0201 GPC3 epitopes were screened from a large number of candidates predicted by three software. The optimized HLA-A*0201 GPC3 peptides will provide new epitope candidates for HCC immunotherapy.

Viewing the Interaction Between Double Strand Deoxyribonucleic Acid and Graphene Oxide via Atomic Force Microscopy

The interaction between DNA and graphene-oxide (GO) is fundamental and of significance to a number of biomedical applications. It is fairly clear that π-π stacking effect accounts for the strong interaction between ssDNA and GO, while little is known on the mechanics of the relative weak interaction between dsDNA and GO. Here we employ AFM to investigate the coupling behavior of dsDNA-GO duplex and reveal preference adsorption of DNAon GO. The results show that dsDNA tends to aggregate on GO surface. Additionally, it is observed that GO also tend to stack into multi-layer structure in the presence of dsDNA, indicating dsDNA can simultaneously interact with two sides of the GO sheet. Such a structure is, however, unstable and can easily collapse by rinsing or heating.

Core-resonant double photoemission from palladium films

We studied the core-resonant double photoemission process from palladium films with linearly polarized synchrotron radiation. We excited either the 3d or 4p core level and focused on the Auger transitions which leave two holes in the valence band. We find that the two-dimensional energy distributions are markedly different for the 3d and 4p decay. The 3d decay can be understood by a sequential emission of the two electrons while the 4p decay proceeds in a single step. Despite the large differences in the two-dimensional energy spectra we find the shape of the energy sum spectra rather similar. For the description of the 4p decay we propose a model which uses available single electron spectra, but suggest an alternative interpretation of these data. With this we are able to explain the range over which the available energy is shared. Key assumptions of the model are verified by our experiments on the 3d decay.

Artificial pneumothorax for pain relief during microwave ablation of subpleural lung tumors

BACKGROUND

When microwave ablation (MWA) is used for subpleural lesions, severe pain was the common side effect under the local anesthesia conditions during the procedure and postprocedure. To study the pain relief effect of artificial pneumothorax in the treatment of subpleural lung tumors with MWA.

MATERIALS AND METHODS

From February 2012 to October 2014, 37 patients with 40 subpleural lung tumors underwent MWA, including 17 patients of 19 sessions given artificial pneumothorax prior to MWA (group-I), and 20 patients of 21 sessions without artificial pneumothorax (group-II). Patient's pain assessment scores (10-point visual analog scale [VAS]) at during-procedure, 6, 12, 24, and 48 h after the MWA procedure and mean 24 h morphine dose were compared between the two groups. Complications of the artificial pneumothorax were also summarized.

RESULTS

Pain VAS were 0.53, 0.65, 1.00, 0.24, and 0.18 at during-procedure, 6, 12, 24, and 48 h for group-I and 5.53, 2.32, 2.82, 1.21, and 0.21 for group-II, respectively. Pain VAS in group I was significantly decreased at during-procedure, 6, 12, and 24 h after the MWA (P < 0.001). No statistical pain VAS difference was observed at 48 h after the MWA between the two groups (P > 0.05). The mean 24 h morphine dose was 5.00 mg in group-I and 12.63 mg in group-II (P = 0.000). "Artificial pneumothorax" related complications occurred in two patients from group-I, including one pleural effusion and one minor hemoptysis. No patient in group-I and group-II died during the procedure or in 30 days after MWA.

CONCLUSION

Artificial pneumothorax is a safe and effective method for pain relief during MWA of subpleural lung tumors.

Abstract AS31: MEK inhibition reverses antiestrogen resistance in ovarian cancer (OVCA) via alteration of cell cycle pathways and MAPK/estrogen regulated gene expression

BACKGROUND: It is estimated that 67% of epithelial OVCAs are estrogen receptor (ER) positive. However, the response to anti-estrogen therapy in OVCA remains marginal. The Ras/Raf/MEK/MAPK pathway is hyperactivated in 40% of OVCAs. We have previously shown that estrogens further activate kinases such as Src, ER and Src kinase binding in the cytoplasm suggesting a non-genomic role or ER in OVCA. We postulated that estrogens further activate MAPK signaling and combination ER blockade with MEK inhibition would block cross-talk and increase the efficacy of ER blockade.

METHODS: The effects of treatment with MEK inhibitor (AZD6244) and anti-estrogen (Fulvestrant), each alone or together, on cell cycle and cell survival were evaluated in ER+ OVCA lines in vitro. Drug effects on xenograft tumor growth were assayed in vivo in NOD/SCIDs. Reverse phase protein lysate array (RPPA) analysis and gene expression analysis (GEA) were performed to evaluate biomarkers of drug response. Finally, a previously reported MAPK gene signature identified in breast cancer was analyzed in the OVCA lines treated with AZD6244 and combination treatment. And using alteration of gene expression upon MEKi treatment as suggestive of MAPK regulation, we define a MAPK gene signature originating from ovarian cancer cells.

RESULTS: RPPA analysis of high grade serous tumors from the TCGA (n=408) demonstrates that over 70% of tumors have phosphorylated MEK and MAPK, and patients with ER+ cancers and high pMAPK or pMEK (top50%), have a worse overall survival than those with low pMAPK or pMEK. Estrogen (E2) increases phosphorylation of MEK in ER+ OVCA cells. Fulvestrant caused minimal growth arrest after treatment demonstrating intrinsic resistance. AZD6244 caused loss of pMAPK, partial G1 cell cycle arrest and a modest increase in p27 levels in a dose dependent manner after treatment. However, responsiveness of OVCA cells to fulvestrant increased by addition of AZD6244 in vitro, with synergistic cell cycle arrest mediated by p27 binding to Cyclin E/cdk2 and much greater inhibition of MAPK activity. Gene enrichment analysis showed an increase in the ERB4/MAPK gene set with Fulv alone and the addition of AZD6244 showed that the top 20 gene sets downregulated were all related to replication and cell cycle (ie FOXM1, CyclinE). RPPA confirmed that combination was more effective in decreasing cell cycle promoting proteins (ie FOXM1, Cyclin B1) and upregulating p27. AZD6244 treatment of OVCA lines resulted in differential expression of about ¼ of the breast cancer defined MAPK gene expression signature, and of these, fulvestrant addition to MEK inhibition (MEKi) differentially affected 19 genes, reflective of these being E2 regulated genes. Similarly, of the total MEKi affected genes, a subset were differentially regulated by the addition of fulvestrant indicating putative E2 regulation underlying these genes. Xenograft data showed the greatest decrease in tumor volume with the drug combination compared to either drug alone.

CONCLUSION: Given the majority of primary OVCAs express high MEK/MAPK activity may underlie failure of anti-estrogen therapy. MEK inhibition reverses anti-estrogen resistance in our OVCA models. These data support further pre-clinical and clinical evaluation of combined fulvestrant and MEK inhibition in OVCA.

Citation Format: K. Hew, P. Miller, J. Sun, Z. Wei, G. Zhang, Y. Lu, G. Mills, J. Slingerland, MD, PhD, D. El-Ashry, F. Simpkins. MEK inhibition reverses antiestrogen resistance in ovarian cancer (OVCA) via alteration of cell cycle pathways and MAPK/estrogen regulated gene expression [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr AS31.

Tracking a hospital outbreak of KPC-producing ST11 Klebsiella pneumoniae with whole genome sequencing

An outbreak of carbapenem-resistant Klebsiella pneumoniae strains emerged at a hospital, and was tracked in order to understand the spread of these infectious pathogens. A total of 66 K. pneumoniae strains were collected from sterile samples in 2012. The MICs of 20 antimicrobial agents were determined for all strains. Molecular typing was performed with pulsed-field gel electrophoresis (PFGE). Twelve blaKPC-producing K. pneumoniae strains isolated from ten patients were selected for whole genome sequencing. Phylogenetic reconstruction of these 12 strains was performed by the use of single-nucleotide polymorphism (SNP) row sequences of each draft genome sequence. Plasmids from the 12 strains were separated by S1 digestion and PFGE. The 12 K. pneumoniae strains isolated from the ten patients were deemed to be representative of the hospital outbreak, owing to their similar PFGE patterns. These 12 blaKPC-producing strains conferred multidrug resistance, which contrasted with the remaining 54, more susceptible, strains in the hospital. Differences in SNPs between each draft genome of the blaKPC-producing strains partitioned the 12 outbreak strains into three separate clades. The patients with each clade shared close hospital units. All 12 strains harboured at least one multidrug resistance plasmid. Strains showing high-level resistance may facilitate nosocomial dissemination and result in an infectious pathogen outbreak. Although the 12 blaKPC-producing K. pneumoniae strains possessed similar PFGE patterns, SNP variations throughout the genome allowed the strains to be divided into three clades. These results suggest that three independent transmission events led to hospital-wide dissemination of the outbreak strains.