Analysis of Gram-positive bacterial infection in patients following liver transplantation

Background  Liver transplantation is the most effective treatment for patients with end-stage liver failure, however infection after transplantation is a serious clinical complication. The purpose of this research was to investigate the molecular epidemiology and the influence of multidrug-resistant Gram-positive infection in patients, following liver transplantation, to provide reference for clinical treatment and prevention of Gram-positive bacterial infection.

Methods  We isolated and detected bacteria from phlegm, throat swabs, urine, wound or wound secretions, blood, and fecal samples from 221 liver transplant patients in our hospital from January 2007 to April 2010. All isolated bacterial strains were identified and tested by minimal inhibitory concentration (MIC) drug-sensitive detection using the BioMerieux ATB bacterial identification instrument and repetitive extragenic palindromic-polymerase chain reaction (REP-PCR) detection of bacterial homology. Risk factors were calculated by multivariate Logistic regression analysis.

Results  We collected 250 specimens from 221 patients hospitalized following liver transplantation surgery, of which 29 patients developed multiple infections. Sixty-five Gram-positive bacterial strains were isolated from different specimens from 53 infectious patients. We detected 29 multidrug-resistant Gram-positive strains from 29 patients (44.62%), including 20 Staphylococcus aureus (S. aureus) strains (68.97%) and nine Enterococcus strains (31.03%). All 20 S. aureus strains were highly resistant to aminoglycosides (gentamicin), cephalosporins (cefoxitin), quinolones (ciprofloxacin and levofloxacin), lincomycins (clindamycin), penicillin, and erythromycin. The resistance rate reached 100% in some cases. The S. aureus strains were highly sensitive to vancomycin and oxazolidinone (linezolid), with MIC50 <2 µg/ml for both. The nine Enterococci strains were also highly resistant to aminoglycosides, quinolones, and penicillins, and highly sensitive to vancomycin (MIC50 <2 µg/ml) and oxazolidinone (MIC50 <1 µg/ml). Using REP-PCR detection, S. aureus was divided into five genotypes with 14 B-type strains. Enterococcus was divided into 11 genotypes, with two D-type strains, two G-type strains, and two K-type strains. The risk factors for Gram-positive bacterial infection in patients following liver transplantation were preoperative use of antibiotics (OR=3.949, P=0.004), high intra-operative blood input (OR=1.071, P=0.005), and postoperative renal failure (OR=5.427, P=0.043).

Conclusions  S. aureus and Enterococcus were the main pathogens causing infection following liver transplantation in patients with drug-resistant Gram-positive bacterial infection. The isolated strains were resistant to multiple antibiotics. B-type S. aureus strains were predominant. Reasonable use of antibiotics, decreasing intra-operative blood input, and preventing post-operative renal failure may reduce Gram-positive bacterial infections and the appearance of drug-resistant strains following liver transplantation.

     

Downregulating activated epidermal growth factor receptor has no effect on RBM5 expression

Background  We were interested in determining how the tumor suppressor gene RBM5 is regulated in lung cancers. Previous studies suggested that the gene expression is related to histological subtype and smoking exposure, since in small cell lung cancers the RBM5 gene is deleted whereas in non-small cell lung carcinomas (NSCLC) RBM5 expression is reduced. Of particular interest was the recent finding that in lung adenocarcinomas, a histological subtype of NSCLC, smoking exposure correlated with mutational activity in the transforming growth factor alpha (TGF-a) signaling pathway. Lung adenocarcinomas from smokers were associated with activating KRAS mutations, whereas lung adenocarcinomas from never-smokers were associated with activating epidermal growth factor receptor (EGFR) mutations. We hypothesized that inhibition of RBM5 in lung adenocarcinomas is achieved indirectly via these activating mutations. The objective of the research described herein was to determine if EGFR activation and RBM5 expression are negatively correlated.

Methods  EGFR expression in the lung adenocarcinoma cell line NCI-H1975 was inhibited using small interfering RNA. RBM5 expression was examined by real-time quantitative polymerase chain reaction and Western blotting.

Results  Reduced EGFR expression did not correlate with any change in RBM5 expression at either the RNA or protein level.

Conclusion  These results suggest that RBM5 expression is not directly regulated by EGFR in non-smoker related lung adenocarinomas, and that some other mechanism operates to inhibit either the expression or function of this potential tumour suppressor in lung cancers that retain the RBM5 gene.

     

Molecular basis of weak D and DEL in Han population in Anhui Province, China

Background  Rh blood group system is the most complex and immunogenetic blood group system. Prevalent RHD alleles varied in different populations. The purpose of this study is to determine the molecular basis of weak D and DEL phenotype in Anhui Chinese Han population.

Methods  The D antigen was determined with IgM monoclonal anti-D conformed to the guidelines for donor testing in China. Weak D samples were identified by an indirect antiglobulin test. DEL phenotype was determined by adsorption and elution test. All the RHD 10 exons were screened by PCR with sequence-specific priming or sequenced for the first-time donors who typed weak D, DEL or D negative by serologic test.

Results  Of all the 30 799 blood donors, 155 blood samples were found D negative with IgM anti-D; 34 blood samples were found D positive by indirect antiglobulin test or absorption elution test. RHD alleles were identified by nucleotide sequencing. Total 4 RHD alleles were found including two new. One hundred and twenty of 155 (77.4%) of the serologically D negative samples lacked the RHD gene. One D negative was RHD(615del2). Thirty-two of 155 (20.6%) carried RHD(K409K) among them one carrying 1227G>A and 845G>A. Two of 155 (1.3%) was weak D type 15.

Conclusions  In this study at the molecular level, all DEL phenotype is RHD(K409K); weak D type 15 is the prevalent weak D allele in Anhui Chinese Han population. Additionally, an improved more efficient method was adopted to amplify all the RHD exons in one PCR program. Our study added to the understanding of molecular mechanisms underlying D antigen expression in Anhui Han population and provided useful information for adopting suitable genotyping strategies in routine use.     

Community-Acquired Methicillin-Resistant Staphylococcus aureus in Children With No Identified Predisposing Risk

Context.— Community-acquired methicillin-resistant Staphylococcus aureus (MRSA) infections in children have occurred primarily in individuals with recognized predisposing risks. Community-acquired MRSA infections in the absence of identified risk factors have been reported infrequently. Objectives.— To determine whether community-acquired MRSA infections in children with no identified predisposing risks are increasing and to define the spectrum of disease associated with MRSA isolation. Design.— Retrospective review of medical records. Patients.— Hospitalized children with S aureus isolated between August 1988 and July 1990 (1988-1990) and between August 1993 and July 1995 (1993-1995). Setting.— The University of Chicago Children's Hospital. Main Outcome Measures.— Prevalence of community-acquired MRSA over time, infecting vs colonizing isolates, and risk factors for disease. Results.— The number of children hospitalized with community-acquired MRSA disease increased from 8 in 1988-1990 to 35 in 1993-1995. Moreover, the prevalence of community-acquired MRSA without identified risk increased from 10 per 100000 admissions in 1988-1990 to 259 per 100000 admissions in 1993-1995 (P<.001), and a greater proportion of isolates produced clinical infection. The clinical syndromes associated with MRSA in children without identified risk were similar to those associated with community-acquired methicillin-susceptible S aureus. Notably, 7 (70%) of 10 community-acquired MRSA isolates obtained from children with an identified risk were nonsusceptible to at least 2 drugs, compared with only 6 (24%) of 25 isolates obtained from children without an identified risk (P=.02). Conclusions.— These findings demonstrate that the prevalence of community-acquired MRSA among children without identified risk factors is increasing.      

Staphylococcus aureus endocarditis: a consequence of medical progress

Context  The global significance of infective endocarditis (IE) caused by Staphylococcus aureus is unknown. Objectives  To document the international emergence of health care–associated S aureus IE and methicillin-resistant S aureus (MRSA) IE and to evaluate regional variation in patients with S aureus IE. Design, Setting, and Participants  Prospective observational cohort study set in 39 medical centers in 16 countries. Participants were a population of 1779 patients with definite IE as defined by Duke criteria who were enrolled in the International Collaboration on Endocarditis-Prospective Cohort Study from June 2000 to December 2003. Main Outcome Measure  In-hospital mortality. Results  S aureus was the most common pathogen among the 1779 cases of definite IE in the International Collaboration on Endocarditis Prospective-Cohort Study (558 patients, 31.4%). Health care–associated infection was the most common form of S aureus IE (218 patients, 39.1%), accounting for 25.9% (Australia/New Zealand) to 54.2% (Brazil) of cases. Most patients with health care–associated S aureus IE (131 patients, 60.1%) acquired the infection outside of the hospital. MRSA IE was more common in the United States (37.2%) and Brazil (37.5%) than in Europe/Middle East (23.7%) and Australia/New Zealand (15.5%, P<.001). Persistent bacteremia was independently associated with MRSA IE (odds ratio, 6.2; 95% confidence interval, 2.9-13.2). Patients in the United States were most likely to be hemodialysis dependent, to have diabetes, to have a presumed intravascular device source, to receive vancomycin, to be infected with MRSA, and to have persistent bacteremia (P<.001 for all comparisons). Conclusions  S aureus is the leading cause of IE in many regions of the world. Characteristics of patients with S aureus IE vary significantly by region. Further studies are required to determine the causes of regional variation.      

Mammalian target of rapamycin inhibitor abrogates abnormal osteoclastogenesis in neurofibromatosis type 1

Background Neurofibromatosis type 1 (NF1) is the most common genetic syndrome predisposing patients to various tumors due to dysregulation of the Ras signaling pathway.Recent research has shown NF1 pat...     

Outcome of in vitro fertilization in endometriosis-associated infertility: a 5-year database cohort study

Background  Endometriosis affects natural fertility through various approaches, and in vitro fertilization (IVF) is a good treatment. But the IVF result of endometriosis patients is still under debate. We investigated the effect of endometriosis on IVF by analyzing the data from a single reproductive center.

Methods  A retrospective, database-searched cohort study was performed. Relevant information was collected from the electronic records of women who underwent IVF/intracytoplasmic sperm injection between January 2006 and December 2010 in the Assisted Reproductive Unit of Sir Run Run Shaw Hospital. Patients with endometriosis were enrolled the study group. The rest of the women formed the control group. The main outcome was the clinical pregnancy rate. Secondary outcomes were oocytes retrieved number, fertilization rate, high-quality embryo rate, number of high-quality embryo for embryo transplantation, and implantation embryo/high-quality embryo ratio (IE/HQE ratio). Comparisons were performed by the  c²-test and independent t-test.

Results  The endometriosis group (n=177) had a markedly lower oocytes retrieved number, fertilization rate, implantation rate, and clinical pregnancy rate (7.6±5.1, 63.6%, 27.7%, and 45.2%, respectively) compared with the non-endometriosis group (n=4267; 11.8±7.3, 68.4%, 36.2%, and 55.2%, respectively).  Stratified analysis showed that this difference was found in the subgroup younger than 35-years old, while only fertilization rate and implantation rate were different in the elder subgroup. The ratio of high-quality embryos transferred is lower in endometriosis group (53.7% vs. 71.8%, P <0.05), but there is no difference in IE/HQE ratio between two groups. There is no significant difference in fertilization rate, implantation rate, and clinical pregnancy rate between mild and severe endometriosis patients.

Conclusions  Endometriosis patients suffer a decreasing IVF pregnancy rates mainly caused by reducing oocytes number and fertilization rate, regardless of the severity of the disease. Appropriate intracytoplasmic sperm injection manipulation might improve the outcomes of IVF.

     

Transduction of mesenchymal stem cells with multidrug resistance gene provides protection for bone marrow toxicity after being transplanted into a nude mice model

Background  Myelosuppression is the main dose-related toxicity of many chemotherapeutic drugs. The human multidrug resistance (mdr1) gene is well-known for its ability to confering drug resistance. In this study, we meant to transplant the placenta mesenchymal stem cells (P-MSCs) moderated by mdr1 gene into a nude mice model radiated by g-Co⁶⁰ and to explore the chemoprotection for bone marrow (BM) toxicity.

Methods  Human P-MSCs were isolated from trypsin-digested term placentas and then transduced by with reconstructed retroviral vector containing mdr1 gene and green fluorescent protein (GFP) reporter gene. The integration and expression of mdr1 gene was observed indirectedly by the expression of GFP. A nude mice model was constructed after irradiation with a sublethal dosage of g-Co⁶⁰. These irradiated mice were transplanted with mdr1-MSCs through the caudal vein and then received paclitaxel (PAC) intraperitoneal chemotherapy. The Peripheral peripheral blood (PB) of the nude mice was collected, and the PB cells counts and values were determined using an automatic analyzer.

Results  After PAC treatment, mdr1-MSCs transplanted mice showed markedly improved survival upon compared to MSCs transplanted mice (85.7% vs. 57.1%). White blood cell (WBC) and red blood cell (RBC) counts as well as the hemoglobin (Hb) values were significantly increased in PAC treated mdr1-MSCs mice compared to PAC treated control mice when PAC chemotherapy had been finished (all P <0.05), but the difference was not found in the plateltes (PLT) count (P >0.05).

Conclusion  Human P-MSCs moderated by mdr1 gene when transplanted into nude mice may provide chemoprotection for hematopoietic toxicity.

     

Effect of angiotensin receptor blockers in the prevention of type 2 diabetes and cardiovascular events: a meta-analysis of randomized trials

Background  As the incidence of type 2 diabetes is rapidly increasing, prevention of the disease should be considered as a crucial objective in the near future. Several studies have shown angiotensin receptor blockers (ARBs) may contribute to the prevention of new-onset type 2 diabetes. This study was conducted to determine if ARBs as monotherapy or combination therapy may experience a decreased incidence of new-onset type 2 diabetes and prevent cardiovascular events.

Methods  Relevant experimental and clinical studies were identified by searching MEDLINE (1969 to May 30, 2011) to extract a consensus of trial data involving the effect of ARBs on prevention of new-onset type 2 diabetes and cardiovascular events. Studies were included if they were randomized controlled trials versus placebo/routine therapy. A random-effects model was utilized. Subgroup and sensitivity analyses were conducted.

Results  Eleven trials were identified, including 82 738 patients. ARBs prevented new-onset type 2 diabetes (odds ratio 0.8 (95% CI 0.76, 0.85)). Regardless of indication for use, essential hypertension (seven trials), impaired glucose tolerance (one trial), cardiocerebrovascular disease (two trials) or heart failure (one trial), reductions in new-onset type 2 diabetes were maintained (0.75 (0.69, 0.82), 0.85 (0.78, 0.92), 0.80 (0.76, 0.85) and 0.80 (0.64, 0.99), respectively). No statistical heterogeneity was observed for any evaluation. However, ARBs did not significantly reduce the odds of all-cause mortality, myocardial infarction and heart failure versus control therapy among all of these studies. But ARBs did reduce the odds of cardiac death and heart failure among the heart failure study versus control therapy.

Conclusion  ARBs have significant ability to reduce risk of developing new-onset type 2 diabetes but does not improve cardiovascular outcomes over the study follow-up periods among all of included studies.

     

Treatment effects of captopril on non-proliferative diabetic retinopathy

Background  Diabetic retinopathy (DR) is one of the most common complications of diabetes. Angiotensin-converting enzyme inhibitor is thought to play an important role in preventing and treating retinal diseases in animal models of DR. The aim of the present study was to investigate the role of angiotensin-converting enzyme inhibitor (ACEI, captopril) in the treatment of patients with non-proliferative DR.

Methods  Three hundred and seventeen type 2 diabetic patients (88.05% of participants) without or with mild to moderate non-proliferative retinopathy were randomly divided into captopril group (n=202) and placebo group (n=115). All subjects received 24-month follow-up. General clinical examinations, including blood pressure and glycated hemoglobin, as well as comprehensive standardized ophthalmic examinations were performed. Color fundus photography and optical coherence tomography (OCT) were used to grade diabetic retinopathy and detect macular edema respectively.

Results  The levels of blood pressure and glycated hemoglobin in the two groups of patients remained within the normal range during the entire follow-up and no significant difference was found between the initial and last visits, suggesting that ACEI drugs play a protective role on the DR patients independent of its anti-blood pressure role. DR classification showed that 169 eyes (83.66%) remained unchanged and the DR grade of 33 eyes (16.34%) increased in captopril group, while 84 eyes (73.04%) remained unchanged and the grade of 31 eyes (26.96%) increased in placebo group (P=0.024). Captopril treatment improved macular edema in 55.45% eyes, which was significantly higher than the 37.39% improvement in placebo group (P=0.002). No significant difference was found in the visual acuity between the two groups (P=0.271).

Conclusion  Captopril can improve or delay the development of DR and macular edema, which can be used in the early treatment of DR patients with type 2 diabetic mellitus.

     

Diagnostic value of endometrial thickness determined by transvaginal sonography in infertile women with endometrial polyps

Background  Endometrial polyps (EPs) occur in approximately 34.9% of infertile women. Transvaginal sonography (TVS) is a routine, non-invasive component of fertility evaluation. Most ultrasonographic studies of EPs have focused on abnormal uterine bleeding; few have assessed EPs in infertile women. Furthermore, no studies have explored endometrial thickness and its correlation with EPs in infertile women. This study aimed to assess transvaginal sonographic assessment of endometrial thickness and its value in diagnosis and prediction of EPs in infertile women.

Methods  A retrospective study on 314 infertile women was conducted from June to December 2010. After TVS, endometrial biopsies were obtained by hysteroscopy. Pathologically confirmed EPs were taken as the gold standard.

Results  Based on recognized criteria, TVS had a sensitivity of 37.04%, specificity of 98.71%, positive predictive value of 90.91%, negative predictive value of 81.85%, and accuracy of 82.80% for diagnosing EPs. Mean endometrial thickness was significantly different in patients with and without EPs (P=0.0001). In women in the mid and late-proliferative phase, the endometrial thickness was significantly greater in those with EPs than in those without them (P=0.0001 and 0.024). Receiver operating characteristic analysis showed that endometrial thickness had a sensitivity of 85.2% and specificity of 38% in the diagnosis of EPs, the area under the curve being 0.64. In the mid-proliferative phase, sensitivity was up to 90.9%, the area under the curve being 0.70.

Conclusions  TVS is poor at detecting EPs in infertile women; however, transvaginal sonographic measurement of endometrial thickness is helpful. It is suggested that the diagnostic value of TVS for EPs in infertile women could be improved by adding the measurement of endometrial thickness to the variables that are routinely assessed.

     

Value of frozen section examination in diagnosis and treatment of high-grade cervical intraepithelial neoplasia

Background  Invasive cancer of the cervix is considered a preventable disease because it has a long pre-invasive state, cervical cytology screening programs are currently available, and treatment of pre-invasive lesions is effective. We tested the accuracy of frozen section examination (FSE) of cone specimens to identify the endocervical margin and rule out invasion in patients with high-grade cervical intraepithelial neoplasia (CIN).

Methods  For 320 consecutive patients with a preoperative biopsy result of CIN stage 2/3, cold-knife conization (CKC) was performed followed by FSE. The results from analyses of permanent paraffin sections (PS) were compared with the FSE findings.

Results  The accuracy of FSE was 87% (278/320). For all of the seven patients with an invasive squamous cell carcinoma of the cervix identified by FSE, the diagnosis was confirmed by PS analysis. For one patient, the FSE result was cervicitis, whereas PS ananlysis showed microinvasive carcinoma. Appropriate surgery was performed for all patients based on the FSE and biopsy results. The FSE and PS results were not significantly different (P=0.000). Definitive examination of margin status using PS was concordant with FSE findings in all cases.

Conclusions  FSE is a rapid and reliable method for evaluating CKC specimens. It can identify frank invasion, permit adequate treatment in a one-stage procedure, and reliably detect clear resection margins. Since discrepancies do exist and may result in inappropriate treatment, further research is required to decrease these discrepancies and avoid missing even one case.

     

Genetic characterization of a Chinese family with familial idiopathic pulmonary fibrosis

Background  Idiopathic pulmonary fibrosis (IPF) is a chronic inflammatory interstitial lung disease with an unknown cause. Recent studies have shown that genetic factors play an important role in the pathogenesis of IPF.

Methods  To explore the genetic background of patients with IPF, a candidate gene approach was employed to screen for mutations in seven genes among members with familial IPF in mainland of China.

Results  Within six of the candidate genes, a total of 31 point mutations were identified. Among the missense mutations, the SFTPA1 exon 6 CAG>AAG (Gln238Lys) and SFTPB exon 2 CAC>CCC (His2Pro) mutations caused changes in the physical and chemical properties of amino acids. Each sequence alteration was identified in sporadic IPF patients, control specimens (pneumonia patients and healthy persons). Genotype frequencies and allele frequencies of codon 238 in exon 6 of SFTPA1 were noted significantly higher in patients with IPF than those in other two control subjects. The computational protein structure prediction by protein homology modeling confirmed differences in three-dimensional structure between mutant SFTPA1 and original SFTPA1.     

Conclusions  Although the functions of the mutant candidate genes vary, these genes may ultimately result in damage to alveolar epithelial cells, initiating the progress of pulmonary fibrosis. In particular, while pathophysiological mechanisms need to be illustrated, the Gln238Lys missense variant of exon 6 in the SFTPA1 may have potential susceptibility in the development of IPF, which was shown in patients with sporadic IPF with a statistically higher frequency.

     

Effect of high-dose rosuvastatin loading before percutaneous coronary intervention in female patients with non-ST-segment elevation acute coronary syndrome

Background  Early loading statin therapy before percutaneous coronary intervention (PCI) is associated with reduced mortality and periprocedural myocardial injury. The aim of this study was to study the effect of rosuvastatin loading therapy before PCI in female patients with non-ST-segment elevation acute coronary syndrome (NSTEACS).

Methods  Consecutive 117 female patients with NSTEACS were randomly assigned to either the group of rosuvastatin loading before PCI (20 mg 12 hours before angioplasty procedure, with a further 10 mg dose 2 hours before procedure, the loading dose group, n=59) or the no rosuvastatin treatment group before PCI (control group, n=58). Periprocedural myocardial injury, periprocedural changes of high sensitivity C-reactive protein (hs-CRP), interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF)-a in serum and the incidence of major adverse cardiac events (MACE) 3 months and 6 months later were assessed.

Results  The incidence of periprocedural myocardial injury was higher in control group than loading dose group (CKMB: 10.17% vs. 25.86% , P=0.027; Troponin I: 11.86% vs. 29.31%, P=0.019). MACE occurred in 1.69% of patients in loading dose group and 12.07% of those in control group 3 months after procedure (P=0.026), 3.39% vs. 17.24% at 6 months (P=0.014). The levels of hs-CRP, IL-1, IL-6, and TNF-a in serum were not significantly different between the two groups before PCI, but after PCI they were significantly higher in control group.

Conclusions  High-dose rosuvastatin loading before PCI significantly reduced periprocedural myocardial injury and periprocedural inflammation cytokines release and improved 3-month and 6-month clinical outcomes in female patients with NSTEACS who underwent PCI.     

Effect of in-hospital medical complications on case fatality post-acute ischemic stroke: data from the China National Stroke Registry

Background  In-hospital medical complications are associated with poorer clinical outcomes for stroke patients after disease onset. However, few studies from China have reported the effect of these complications on the mortality of patients with acute ischemic stroke. In this prospective work, the China National Stroke Registry Study, we investigated the effect of medical complications on the case fatality of patients with acute ischemic stroke.   

Methods  From September 2007 to August 2008, we prospectively obtained the data of patients with acute stroke from 132 clinical centers in China. Medical complications, case fatality and other information recorded at baseline, during hospitalisation, and at 3, 6, and 12 months after stroke onset. Multivariable Logistic regression was performed to analyze the effect of medical complications on the case fatality of patients with acute ischemic stroke.

Results  There were 39 741 patients screened, 14 526 patients with acute ischemic stroke recruited, and 11 560 ischemic stroke patients without missing data identified during the 12-month follow-up. Of the 11 560 ischemic patients, 15.8% (1826) had in-hospital medical complications. The most common complication was pneumonia (1373; 11.9% of patients), followed by urinary tract infection and gastrointestinal bleeding. In comparison with patients without complications, stroke patients with complications had a significantly higher risk of death during their hospitalization, and at 3, 6 and 12 months post-stroke. Having any one in-hospital medical complication was an independent risk factor for death in patients with acute ischemic stroke during hospital period (adjusted OR=6.946; 95% CI 5.181 to 9.314), at 3 months (adjusted OR=3.843; 95% CI 3.221 to 4.584), 6 months (adjusted OR=3.492; 95% CI 2.970 to 4.106), and 12 months (adjusted OR= 3.511; 95% CI 3.021 to 4.080). Having multiple complications strongly increased the death risk of patients.

Conclusion  Short-term and long-term outcomes of acute stroke patients are affected by in-hospital medical complications.     

Optimization of Bartonella henselae multilocus sequence typing scheme using single-nucleotide polymorphism analysis of SOLiD sequence data

Background  Multi-locus sequence typing (MLST) is widely used to explore the population structure of numerous bacterial pathogens. However, for genotypically-restricted pathogens, the sensitivity of MLST is limited by a paucity of variation within selected loci. For Bartonella henselae (B. henselae), although the MLST scheme currently used has been proven useful in defining the overall population structure of the species, its reliability for the accurate delineation of closely-related sequence types, between which allelic variation is usually limited to, at most, one or two nucleotide polymorphisms. Exploitation of high-throughput sequencing data allows a more informed selection of MLST loci and thus, potentially, a means of enhancing the sensitivity of the schemes they comprise.

Methods  We carried out SOLiD resequencing on 12 representative B. henselae isolates and explored these data using single nucleotide polymorphism (SNP) analysis. We determined the number and distribution of SNPs in the genes targeted by the established MLST scheme and modified the position of loci within these genes to capture as much genetic variation as possible.

Results  Using genome-wide SNP data, we found the distribution of SNPs within each open reading frame (ORF) of MLST loci, which were not represented by the established B. henselae MLST scheme. We then modified the position of loci in the MLST scheme to better reflect the polymorphism in the ORF as a whole. The use of amended loci in this scheme allowed previously indistinguishable ST1 strains to be differentiated. However, the diversity of B. henselae was still rare in China.

Conclusions  Our study demonstrates the use of SNP analysis to facilitate the selection of MLST loci to augment the currently-described scheme for B. henselae. And the diversity among B. henselae strains in China is markedly less than that observed in B. henselae populations elsewhere in the world.     

贵阳市甲型副伤寒沙门菌脉冲电场凝胶电泳分型分析

目的了解贵阳市甲型副伤寒沙门菌的分子流行病学特征,分析菌株的相似性,为追踪传染来源、查找传播途径提供线索。方法用脉冲电场凝胶电泳(pulsed field gelelectrophoresis,PFGE)方法进行分型。结果根据细菌染色体DNA的SpeI酶切图谱,将贵阳地区146株甲型副伤寒沙门菌分成10个PFGE带型,1型32株占21.9%,2型73株占50.0%,3型13株占8.9%,4型7株占4.8%,5型14株占9.6%,6型、7型、8型和9型各1株,各占0.7%,10型3株占2.7%,各型之间的相似性在98.1%～72.0%。暴发株24株被分为5个PFGE带型,1型占54.2%,带菌者1株为1型。各年菌株的PFGE带型不尽相同,1型和2型为常年流行带型。高流行区县的甲型副伤寒菌株被分为9个PFGE带型。结论贵阳地区甲型副伤寒沙门菌流行复杂以2型和1型为优势流行带型,提示存在同一克隆群的菌株广泛传播。该研究进一步证实PFGE是一种发现或预警暴发的可行服务手段。     

真菌性角膜炎前房积脓的临床分析

Background  Hypopyon is common in eyes with fungal keratitis. The evaluation of the clinical features, culture results and the risk factors for hypopyon and of the possible correlation between hypopyon and the treatment outcome could be helpful for making treatment decisions.   

Methods  The medical records of 1066 inpatients (1069 eyes) with fungal keratitis seen at the Shandong Eye Institute from January 2000 to December 2009 were reviewed retrospectively for demographic features, risk factors, clinical characteristics, laboratory findings and treatment outcomes. The incidence of hypopyon, the fungal culture positivity for hypopyon, risk factors for hypopyon and the effect of hypopyon on the treatment and prognosis were determined. 

Results  We identified 1069 eyes with fungal keratitis. Of the 850 fungal culture-positive eyes, the Fusarium species was the most frequent (73.6%), followed by Alternaria (10.0%) and Aspergillus (9.0%). Upon admission, 562 (52.6%) eyes with hypopyon were identified. The hypopyon of 66 eyes was evaluated via fungal culturing, and 31 eyes (47.0%) were positive. A total of 194 eyes had ocular hypertension, and 172 (88.7%) of these eyes had hypopyon (P <0.001). Risk factors for incident hypopyon included long duration of symptoms (P <0.001), large lesion size (P <0.001) and infection caused by the Fusarium and Aspergillus species (P <0.001). The positivity of fungal culture for hypopyon was associated with duration of symptoms and lesion size. Surgical intervention was more common in cases with hypopyon (P <0.001). Hypopyon was a risk factor for the recurrence of fungal keratitis after corneal transplantation (P=0.002).

Conclusions  Hypopyon is common in patients with severe fungal keratitis and can cause ocular hypertension. About half of the hypopyon cases were positive based on fungal culture. Long duration of symptoms, large lesion size and infection with the Fusarium and Aspergillus species were risk factors for hypopyon. The presence of hypopyon increases the likelihood of surgical intervention.