携qnrA耐药基因阴沟肠杆菌的分子流行病学研究

目的了解深圳地区临床分离的qnrA基因阳性阴沟肠杆菌的分子流行病学特征。方法采用PCR和产物直接测序法,检测58株临床分离阴沟肠杆菌的qnrA基因,脉冲场电泳进行菌株的DNA分型。结果11株阴沟肠杆菌中检出qnrA基因,其中甲医院6株、乙医院5株;前者可分为A和B 2个克隆系,A系包括3个相同和1个密切相关克隆,B系包括2个相同的克隆;后者5株菌间无相同或密切相关克隆。结论携qnrA基因阴沟肠杆菌的流行不仅存在散发模式,而且存在克隆株医院感染暴发的模式,应加强其医院感染的监控和分子流行病学研究。     

First report of plasmid-mediated quinolone resistance qnrA1 gene in Klebsiella pneumoniae isolate of animal origin

One QnrA1-producing Klebsiella pneumoniae isolate GDKA1 from chicken was detected. The qnrA1 gene on plasmid pGDKA1 was located in a genetic environment similar to that in In36 on plasmid pHSH1 and could be cotransferred to Escherichia coli J53 Az(R) with other resistances by a conjugation experiment. Upstream of the qnrA1 gene, there was a class I integron with the dfrA27 and aadA2 cassettes. Similar genetic environments of qnrA1 in Enterobacteriaceae isolates from both human and animal origin might, to some extent, demonstrate similar mechanisms of qnrA distribution. The presence of qnrA1 in health animal commensal bacteria should be worthy of note. This is the first report of qnrA1 in K. pneumoniae and dfrA27 in an Enterobacteriaceae isolate of animal origin.     

Emerging mechanisms of fluoroquinolone resistance

Broad use of fluoroquinolones has been followed by emergence of resistance, which has been due mainly to chromosomal mutations in genes encoding the subunits of the drugs' target enzymes, DNA gyrase and topoisomerase IV, and in genes that affect the expression of diffusion channels in the outer membrane and multidrug-resistance efflux systems. Resistance emerged first in species in which single mutations were sufficient to cause clinically important levels of resistance (e.g., Staphylococcus aureus and Pseudomonas aeruginosa). Subsequently, however, resistance has emerged in bacteria such as Campylobacter jejuni, Escherichia coli, and Neisseria gonorrhoeae, in which multiple mutations are required to generate clinically important resistance. In these circumstances, the additional epidemiologic factors of drug use in animals and human-to-human spread appear to have contributed. Resistance in Streptococcus pneumoniae, which is currently low, will require close monitoring as fluoroquinolones are used more extensively for treating respiratory tract infections.     

志贺菌对喹诺酮类抗菌药物耐药性及耐药机制研究

目的检测志贺菌对喹诺酮类抗菌药物的耐药情况,探讨染色体介导DNA旋转酶和拓扑异构酶Ⅳ基因突变存在与志贺菌喹诺酮类药物耐药性的相关性。方法用琼脂稀释法对60株志贺菌进行耐药性检测;PCR法检测喹诺酮耐药决定区(QRDR)相关基因gyrA、gyrB、parC、parE,并对其中20株PCR扩增所得的阳性产物进行测序分析;分析志贺菌gyrA、gyrB、parC基因突变与喹诺酮类药物耐药性的关系。结果 60株志贺菌对萘啶酸、诺氟沙星、环丙沙星、左氧氟沙星的耐药率分别为90.0%、35.0%、28.3%和15.0%;测序结果显示gyrA、gyrB、parC基因突变率分别为85%、30%和100%,parE基因未发现突变。结论志贺菌对喹诺酮类耐药严重;靶基因突变是喹诺酮类药物耐药的主要机制之一,以DNA旋转酶GyrA基因突变为主,DNA拓扑异构酶IVparC基因突变次之。     

SOD基因表达与衰老的相关性

目的　探讨SOD活性及SOD基因表达与衰老的相关性。方法　选用快速老化模型鼠 (SAM -P/ 8)进行试验 ,采用生物化学及RT -PCR方法 ,从亚细胞及分子水平上测定衰老过程中丙二醛 (MDA) ,超氧化物歧化酶(SOD)及其基因表达的变化情况。结果　SAM -P/ 8肝组织中SOD活性随着年龄的增加而逐渐降低 ;而MDA含量随年龄的增加逐渐增高 ,有显著性差异 (P <0 0 5 )。不同月龄SAM -P/ 8肝细胞中Cu -ZnSOD基因表达随年龄的增加Cu -ZnSODmRNA逐渐降低 (P <0 0 1)。结论　SOD活性与SOD基因表达的增龄变化有明显的相关性 ,SOD基因转录活性的降低可能是导致SOD活性降低的重要原因 ,表明SOD在衰老过程中扮演着重要角色。     

Acquired fluoroquinolone resistance genes in corneal isolates of Pseudomonas aeruginosa

Fluoroquinolones are widely used as an empirical therapy for pseudomonal ocular infections. Based on increasing reports on acquired fluoroquinolone resistance genes in clinical isolates of Pseudomonas aeruginosa, we investigated 33 strains of P. aeruginosa isolated from the cornea of microbial keratitis patients in India and Australia between 1992 and 2018 to understand the prevalence of acquired fluoroquinolone resistance genes in ocular isolates and to assess whether the possession of those genes was associated with fluoroquinolone susceptibility. Fourteen out of 33 strains were resistant to at least one fluoroquinolone. We obtained the whole genome sequence of 33 isolates using Illumina MiSeq platform and investigated the prevalence of two fluoroquinolone resistance genes crpP and qnrVC1. To examine the associated mobile genetic elements of qnrVC1 positive strains, we obtained long read sequences using Oxford Nanopore MinION and performed hybrid assembly to combine long reads with Illumina short sequence reads. We further assessed mutations in quinolone resistance determining regions (QRDRs) and antibiotic susceptibilities to ciprofloxacin, levofloxacin and moxifloxacin to examine the association between resistance genes and phenotype. Twenty strains possessed crpP in genetic islands characterised by possession of integrative conjugative elements. The qnrVC1 gene was carried by four isolates on class I integrons and Tn3 transposons along with aminoglycoside and beta-lactam resistance genes. We did not observe any evidence of plasmids carrying fluoroquinolone resistance genes. Resistance to fluoroquinolones was observed in those strains which possessed crpP, qnrVC1 and that had QRDRs mutations. The presence of crpP on its own was not associated with increased resistance to fluoroquinolones.     

PTEN启动子甲基化及基因表达与宫颈癌临床指标的关联研究

目的 探讨PTEN启动子甲基化及基因表达与宫颈癌临床指标的相关性.方法 选取2013年1月至2014年1月期间辽阳市中心医院收治的100例宫颈癌患者作为研究对象,分别采用PCR-SSCP、甲基化特异性PCR及免疫组化技术检测组织PTEN启动子甲基化及基因表达情况,并分析其与患者临床病理资料的相关性,PTEN启动子甲基化及基因表达相关性.结果 100例宫颈癌患者中PTEN启动子甲基化阳性例数为62例,PTEN启动子甲基化率为62.0％.PTEN基因表达阳性例数50例,阳性率为50.0％.PCR-SSCP分析发现1例患者出现新的突变,位于第9个外显子.PTEN启动子甲基化与宫颈癌患者FIGO分期、肿瘤分级、肿瘤大小以及淋巴结转移均有显著相关性(x2值分别为4.802、8.440、7.472、8.237,均P＜0.05),与宫颈癌患者年龄以及组织分型均无显著相关性(x2值分别为0.075、0.180,均P＞0.05).PTEN基因表达与宫颈癌患者FIGO分期以及淋巴结转移有显著相关性(x2值分别为2.597、7.250,均P＜0.05),与宫颈癌患者年龄、肿瘤分级、肿瘤大小以及组织分型均无显著相关性(x2值分别为0.041、2.627、2.716、0.219,均P＞0.05).宫颈癌组织中PTEN启动子甲基化及其基因表达呈显著负相关(r=-0.65,P=0.014).结论 PTEN启动子甲基化可以抑制PTEN基因的转录,降低其蛋白表达,PTEN蛋白表达降低可能参与宫颈癌发生、浸润和转移.     

四环素诱导表皮葡萄球菌对氟喹诺酮类耐药性研究

目的　为研究氟喹诺酮类抗菌药物非特异性耐药机制建立细菌筛选方法,并研究其耐药特点及遗传稳定性。方法　使用高浓度四环素作诱导剂,分步诱导敏感表皮葡萄球菌产生高耐突变株,并从中选择对环丙沙星和司帕沙星耐药菌株。结果　经过4 步四环素诱导突变后,获得的突变株对四环素的M IC增加了500 倍,这些菌株中约有1/3 对环丙沙星和司帕沙星中度耐药,MIC比亲代株增加了60 倍。子代菌与亲代菌相比主要生化反应无改变,连续传代培养证明突变株对氟喹诺酮类药物的抗药性可稳定遗传。结论　采用四环素诱导突变的方法可使细菌获得对氟喹诺酮类的耐药性,提示用其它抗菌药物治疗感染失败的患者换用氟喹诺酮类药物时应慎重     

白三烯受体基因mRNA表达水平与儿童哮喘的相关性

目的:检测了白三烯受体基因mRNA在儿童外周血白细胞中的表达;研究轻、中、重度哮喘患者白三烯受体基因mRNA表达水平是否存在不同;探讨性别和年龄因素对哮喘组白三烯受体基因mRNA表达水平产生的影响。方法:应用逆转录聚合酶链式反应(RT-PCR)技术,对比并定量分析CysLT1-Receptor和CysLT2-Receptor基因mRNA在哮喘组和对照组之间的表达差异。结果:哮喘组及对照组中均有CysLT1-Receptor和CysLT2-Receptor基因mRNA的表达;哮喘组白三烯受体基因mRNA的表达显著增高,(P均<0·05);轻、中、重度哮喘患儿CysLT1-Receptor和CysLT2-Receptor基本mRNA表达水平无显著性差异;性别、年龄因素对哮喘组白三烯受体基因mRNA表达无明显影响P>0·05。结论:CysLT1-Receptor和CysLT2-Receptor基因在儿童外周血白细胞中存在表达,其mRNA表达水平在哮喘组显著增高。性别和年龄因素对哮喘组白三烯受体基因mRNA的表达无明显影响。     

多药耐药基因MDR1在大肠癌的表达及意义

目的探讨多药耐药基因（MDR1基因）在大肠癌组织中的表达及其与临床病理的关系。方法应用RT—PCR方法检测了93例手术切除大肠癌组织中的MDR1 mRNA．结果MDR1 mRNA的阳性率为37.63％，MDR1基因的表达与年龄、性别、肿瘤大小、组织学类型、淋巴结转移及Dukes分期等无关。结论化疗前大肠癌组织中MDR1基因即存在较高的表达率，且独立于病理形态学之外。提示化疗前要区别对待，对MDR1基因表达阳性者应合理选择化疗。     

多药耐药基因MDR1在大肠癌的表达及意义

目的探讨多药耐药基因(MDR1基因)在大肠癌组织中的表达及其与临床病理的关系。方法应用RT-PCR方法检测了93例手术切除大肠癌组织中的MDR1 mRNA.结果MDR1mRNA的阳性率为37.63%,MDR1基因的表达与年龄、性别、肿瘤大小、组织学类型、淋巴结转移及Dukes分期等无关。结论化疗前大肠癌组织中MDR1基因即存在较高的表达率,且独立于病理形态学之外。提示化疗前要区别对待,对MDR1基因表达阳性者应合理选择化疗。     

Plasmid-mediated quinolone resistance by genes qnrA1 and qnrB19 in Salmonella strains isolated in Brazil

Considering the importance of the mechanisms involved in quinolone resistance, this study evaluate the presence of PMQR in 126 epidemic and not epidemic strains of Salmonella spp. It was noted that presence of PMQR, by itself, did not generate resistance to ciprofloxacin; but detection of qnr genes in Salmonella spp. and the identification of the qnrB19 variant in a strain of poultry origin alert for the indiscriminate use of quinolones in poultry production, that can result in a pressure for mutant selection of resistant strains with a clinical limitation use of FQs in the near future. And last but not least, is the need to continued study of resistance mechanisms and to monitor the microbial resistance profile of epidemiological strains.     

Chloramphenicol resistance in vancomycin-resistant enterococcal bacteremia: impact of prior fluoroquinolone use?

OBJECTIVE: The prevalence of vancomycin-resistant enterococci (VRE) has increased markedly during the past decade. Few data exist regarding the epidemiology of resistance of VRE to chloramphenicol, one of the few therapeutic options. DESIGN: Survey and case-control study. SETTING: A 725-bed, tertiary-care academic medical center and a 344-bed urban community hospital. PATIENTS: Hospitalized patients with blood cultures demonstrating VRE. METHODS: We examined the trends in the prevalence of chloramphenicol resistance in VRE blood isolates at our institution from 1991 through 2002 and conducted a case-control study to identify risk factors for chloramphenicol resistance among these isolates. RESULTS: From 1991 through 2002, the annual prevalence of chloramphenicol-resistant VRE increased from 0% to 12% (P < .001, chi-square test for trend). Twenty-two case-patients with chloramphenicol-resistant VRE bloodstream isolates were compared with 79 randomly selected control-patients with chloramphenicol-susceptible VRE. Independent risk factors for chloramphenicol-resistant VRE were prior chloramphenicol use (odds ratio [OR], 10.9; 95% confidence interval [CI95], 1.72-68.91; P = .01) and prior fluoroquinolone use (OR, 4.74; CI95, 1.15-19.42; P = .03). Chloramphenicol-resistant VRE isolates were more likely to be susceptible to beta-lactams and resistant to tetracycline than were chloramphenicol-susceptible VRE isolates. CONCLUSIONS: Significant increases in the prevalence of chloramphenicol-resistant VRE may limit the future utility of chloramphenicol in the treatment of VRE infections, and close monitoring of susceptibility trends should continue. The association between fluoroquinolone use and chloramphenicol-resistant VRE, reflecting possible co-selection of resistance, suggests that recent dramatic increases in fluoroquinolone use may have broader implications than previously recognized.     

Resistin gene expression in visceral adipose tissue of postmenopausal women and its association with insulin resistance

Aim: The present study evaluates resistin mRNA expression in visceral adipose tissue (VAT) and its correlation with insulin resistance (homeostatic model assessment) in postmenopausal obese women. Materials & methods: A total of 68 (nonobese = 34 and obese = 34) age-matched (49-70 years) postmenopausal women were recruited for the study. Fasting blood samples were collected at admission and abdominal VAT were obtained during surgery for gall bladder stones or hysterectomy. Physical parameters (age, height, weight and BMI) were measured. Biochemical parameters (plasma insulin, plasma glucose and serum resistin) were estimated by enzymatic methods. The VAT resistin mRNA expression was evaluated by real-time PCR. Results: The relative mean (± standard deviation) VAT resistin mRNA expression in postmenopausal obese women lowered significantly by 20.4% compared with postmenopausal nonobese women (0.029 ± 0.011 vs 0.023 ± 0.013; p = 0.047). Furthermore, VAT resistin mRNA expression in postmenopausal obese women was downregulated by 0.69-fold when compared with age-matched postmenopausal nonobese women. Furthermore, the relative VAT resistin mRNA expression in postmenopausal obese women showed significant inverse association with insulin resistance (r = -0.48; p < 0.01) and serum resistin (r = -0.84; p < 0.001), while in postmenopausal nonobese women it did not show any association with both insulin resistance (r = 0.03; p > 0.05) and serum resistin (r = -0.03; p > 0.05). Conclusion: The VAT resistin mRNA expression in postmenopausal obese women is associated to insulin resistance.     

A clinical prediction rule for fluoroquinolone resistance in healthcare-acquired gram-negative urinary tract infection

Data from a case-control study were used to derive and internally validate a prediction rule for identifying fluoroquinolone resistance in healthcare-acquired gram-negative urinary tract infection. This prediction rule has an excellent sensitivity and specificity (C-statistic, 0.816). External validation is necessary before implementing this rule to optimize empirical antibiotic use in clinical practice.     

73株志贺菌属细菌对11种抗生素的耐药性分析

目的研究志贺菌属细菌的耐药状况及其特点。方法采用改良Kirby-Bauer纸片法对临床分离的73株志贺菌属细菌进行11种抗生素的药敏试验,并对其耐药特点进行分析。结果志贺菌属细菌对除庆大霉素以外的传统抗生素四环素、链霉素、氯霉素、磺胺甲基异恶唑、氨苄西林的耐药率较高,在68.5%～86.3%之间;对头抱类性抗生素头孢噻吩的耐药率为34.2%;对不同喹诺酮类药物的耐药率在36.9%～79.5%之间,差异有显著性(P值均小于0.05);志贺菌属细菌的多重耐药率为79.5%,存在地区及菌型分布差异(P<0.05)。结论志贺菌属细菌对多种抗生素表现耐药,但存在地区和菌型差异,特别是对庆大霉素耐药率较低,可增加其临床应用;使用喹诺酮类药物治疗菌痢时,应做多种喹诺酮类药物药敏试验。