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1.  Clostridium difficile infection after adult autologous stem cell transplantation: A multicenter study of epidemiology and risk factors 
We sought to describe the epidemiology of Clostridium difficile infection (CDI) among adult recipients of autologous hematopoietic stem cell transplantation (auto HSCT) within the first year after HSCT in centers with variable epidemiology of hyper-toxigenic strains. A multicenter, retrospective nested case-control study was conducted among 873 auto HSCT recipients at Johns Hopkins Hospital (JHH, Baltimore, MD) and Hôpital Maisonneuve-Rosemont (HMR, Montreal, Canada) between 1/2003-12/2008. Despite center differences in the prevalence of NAP-1 strains over the time period (21-43% JHH; 80-84% HMR), the 1-year incidence of CDI was similar (6.2% JHH; 5.7% HMR). The median time to infection was 11 days (interquartile range [IQR] 1 to 27). In case control analysis, the following were predictors for CDI: grade 2 or higher mucositis (odds ratio [OR]: 3.00, P=0.02) and receipt of a 4th generation cephalosporin (OR: 2.76, P=0.04). Mucositis was the strongest predictor of risk for CDI in multivariate analysis (adjusted OR [AOR]: 2.77; P=0.03). CDI is a common and early complication of auto HSCT. Treatment-related gastrointestinal mucosal damage, in addition to the potentially modifiable risk of antimicrobial exposure, influence risk for CDI early post-auto HSCT.
PMCID: PMC3806308  PMID: 23916741
Clostridium difficile; stem cell transplantation; mucositis; antibiotics; NAP-1
2.  Incidence of invasive aspergillosis following remission–induction chemotherapy for acute leukemia: a retrospective cohort study in a single Canadian tertiary care centre 
CMAJ Open  2014;2(2):E86-E93.
The decision to use universal primary antimould prophylaxis to prevent invasive aspergillosis in patients with acute leukemia depends on the incidence of infection at individual centres. We determined our institution’s incidence of invasive aspergillosis among patients who received remission–induction chemotherapy for acute leukemia to evaluate the potential benefits of primary antimould prophylaxis.
We conducted this retrospective cohort study at a Canadian tertiary care centre. From the central pharmacy registries, we retrieved records for all adult patients for whom remission–induction chemotherapy for acute leukemia was prescribed between 2008 and 2010. We retrieved clinical, microbiologic, pathologic and radiologic data from the patients’ medical charts. The primary outcome was a diagnosis of probable or proven invasive aspergillosis up to 180 days after resolution of aplasia.
We retrieved records for 123 patients with acute leukemia. Twenty-two of these patients did not receive the prescribed chemotherapy and were excluded from the analysis. Of the 101 patients included, 77 (76.2%) had acute myeloid leukemia. Overall, 136 courses of chemotherapy were administered, with more than 1 course administered to 26 (25.7%) of the 101 patients. In 9 of the patients (8.9%; 95% confidence interval 4.2%–16.2%), invasive aspergillosis was diagnosed (3 proven and 6 probable cases) a median of 19 (range 11–34) days after initiation of chemotherapy. In 7 (78%) of these 9 patients, invasive aspergillosis occurred during the first course of chemotherapy. Three patients died within the first year after diagnosis of invasive aspergillosis.
We found a high incidence (8.9%) of invasive aspergillosis at our centre. This finding triggered the introduction of targeted antimould prophylaxis for patients with acute leukemia who were undergoing remission–induction chemotherapy.
PMCID: PMC4114061  PMID: 25077134
3.  Transcriptional profiling of the effects of 25-hydroxycholesterol on human hepatocyte metabolism and the antiviral state it conveys against the hepatitis C virus 
Hepatitis C virus (HCV) infection is a global health problem. A number of studies have implicated a direct role of cellular lipid metabolism in the HCV life cycle and inhibitors of the mevalonate pathway have been demonstrated to result in an antiviral state within the host cell. Transcriptome profiling was conducted on Huh-7 human hepatoma cells bearing subgenomic HCV replicons with and without treatment with 25-hydroxycholesterol (25-HC), an inhibitor of the mevalonate pathway that alters lipid metabolism, to assess metabolic determinants of pro- and antiviral states within the host cell. These data were compared with gene expression profiles from HCV-infected chimpanzees.
Transcriptome profiling of Huh-7 cells treated with 25-HC gave 47 downregulated genes, 16 of which are clearly related to the mevalonate pathway. Fewer genes were observed to be upregulated (22) in the presence of 25-HC and 5 genes were uniquely upregulated in the HCV replicon bearing cells. Comparison of these gene expression profiles with data collected during the initial rise in viremia in 4 previously characterized HCV-infected chimpanzees yielded 54 overlapping genes, 4 of which showed interesting differential regulation at the mRNA level in both systems. These genes are PROX1, INSIG-1, NK4, and UBD. The expression of these genes was perturbed with siRNAs and with overexpression vectors in HCV replicon cells, and the effect on HCV replication and translation was assessed. Both PROX1 and NK4 regulated HCV replication in conjunction with an antiviral state induced by 25-hydroxycholesterol.
Treatment of Huh-7 cells bearing HCV replicons with 25-HC leads to the downregulation of many key genes involved in the mevalonate pathway leading to an antiviral state within the host cell. Furthermore, dysregulation of a larger subset of genes not directly related to the mevalonate pathway occurs both in 25-HC-treated HCV replicon harbouring cells as well as during the initial rise in viremia in infected chimpanzees. Functional studies of 3 of these genes demonstrates that they do not directly act as antiviral gene products but that they indirectly contribute to the antiviral state in the host cell. These genes may also represent novel biomarkers for HCV infection, since they demonstrate an outcome-specific expression profile.
PMCID: PMC2651120  PMID: 19149867

Results 1-3 (3)