宁波市耐三代头孢菌素志贺菌携带β-内酰胺酶与基因分型

目的了解本市耐三代头孢菌素志贺菌携带ESBLs及其基因型,为疾病防控提供依据。方法采用直接和增菌培养法,分离患者标本中志贺菌;药敏采用K-B法,ESBLs志贺菌表型确证采用纸片法;CTX-M、OXA、TEM和SHV耐药基因采用PCR法;耐药基因分型采用核苷酸序列法,用BLAST分析比较确定基因型别。结果药敏筛检出69株耐三代头孢菌素志贺菌,占ESBLs志贺菌的74.19%。检出CTX-M(CTX-M-1群和CTX-M-9群)、OXA和TEM耐药基因,检出率分别为79.71%、79.01%和26.09%,未检出CTX-M-2群和SHV耐药基因。DNA序列比对CTX-M-1群以CTX-M-15型为主,还检出7个其它型;CTX-M-9群则以CTX-M-14型多,其它型检出6个;49株OXA和18株TEM耐药基因测序后均为1型(OXA-1型和TEM-1型)。携带2种以上耐药基因的志贺菌21株,占30.43%。结论本市志贺菌对头孢曲松等三代头孢菌素耐药率较高,检出的ESBLs酶型种类多,CTX-M(CTX-M-1群的CTX-M-15型和CTX-M-9群的CTX-M-14型)是主流酶型,且可同时携带多种耐药基因,给疾病防控带来困难。OXA-1型的高携带率,提示我们应加强分析。B群志贺菌无论是表型的耐药性,还是耐药基因检出率均高于D群志贺菌,该发现有助志贺菌的扩散与流行研究。     

沙门氏菌CTX-M型超广谱β-内酰胺酶基因分型及变异研究

目的 通过对不同血清型中沙门氏菌中CTX-M型超广谱β-内酰胺酶分子基因型别、脉冲场凝胶电泳(PFGE)溯源分析及CTX-M氨基酸位点变异情况,研究CTX-M各型别流行特征及在超级耐药克隆中的作用。方法 对来源于江苏及周围地区的61株CTX-M阳性的肠炎沙门氏菌(S. enteritidis)、印第安纳沙门氏菌(S. indiana)、汤卜逊沙门氏菌(S. thompson)等进行CTX-M型别鉴定、PFGE分子分型、全基因测序对不同型别CTX-M氨基酸位点变异分析。 结果 61株菌株分为3个CTX-M群6个型。S. indiana含有6种CTX-M基因型,主要型别是CTX-M- 65和CTX-M- 55; S. enteritidis和S.thompson主要型分别为CTX-M- 55、CTX-M- 65。 PFGE聚类分型有19个型。A2型是携带CTX-M-55型S. enteritidis; B4、B8、B9型是携带CTX-M-55型或CTX-M-65型的S. indiana; D2为携带CTX-M-65型的S.thompson。CTX基因组序列分析显示,在CTX-M-1群、CTX-M-9群、CTX-M-64群易变化氨基酸位点分别是4、3、12个。结论 本地区主要CTX型别为CTX-M-55型或CTX-M-65型,S. indiana是CTX基因主要来源。位于质粒上的CTX-M基因复杂且多变是S. indiana超级耐药克隆形成并广泛流行重要原因之一。     

沙门氏菌CTX-M型超广谱β-内酰胺酶基因分型及变异研究

目的通过对不同血清型中沙门氏菌中CTX-M型超广谱β-内酰胺酶分子基因型别、脉冲场凝胶电泳(PFGE)溯源分析及CTX-M氨基酸位点变异情况,研究CTX-M各型别流行特征及在超级耐药克隆中的作用。方法对来源于江苏及周围地区的61株CTX-M阳性的肠炎沙门氏菌(S.enteritidis)、印第安纳沙门氏菌(S.indiana)、汤卜逊沙门氏菌(S.thompson)等进行CTX-M型别鉴定、PFGE分子分型、全基因测序对不同型别CTX-M氨基酸位点变异分析。结果 61株菌株分为3个CTX-M群6个型。S.indiana含有6种CTX-M基因型,主要型别是CTX-M-65和CTX-M-55;S.enteritidis和S.thompson主要型分别为CTX-M-55、CTX-M-65。PFGE聚类分型有19个型。A2型是携带CTX-M-55型S.enteritidis; B4、B8、B9型是携带CTX-M-55型或CTX-M-65型的S.indiana;D2为携带CTX-M-65型的S.thompson。CTX基因组序列分析显示,在CTX-M-1群、CTX-M-9群、CTX-M-64群易变化氨基酸位点分别是4、3、12个。结论本地区主要CTX型别为CTX-M-55型或CTX-M-65型,S.indiana是CTX基因主要来源。位于质粒上的CTX-M基因复杂且多变是S.indiana超级耐药克隆形成并广泛流行重要原因之一。     

天津地区志贺菌属产超广谱β内酰胺酶及其基因型的检测

目的 了解天津地区志贺菌属产超广谱β内酰胺酶(ESBL)的流行基因型、耐药特征和流行病学特征,探讨产ESBL志贺菌属特性与耐药质粒的关系.方法 136株志贺菌来源于2009年5月至2010年9月在天津市儿童医院、天津医科大学第二医院及天津市第一中心医院门诊就诊的以脓血便为主的腹泻患者粪便标本,纸片扩散法筛选可疑产ESBL志贺菌属;对产ESBL志贺菌进行接合试验,供体菌和接合子进行耐药性测定,以确定耐药性质粒传递;采用TEM、SHV、CTX-M-1组、CTX-M-2组、CTX-M'9组β内酰胺酶通用引物对产ESBL菌株的基因型进行PCR检测.使用肠杆菌科基因间的重复序列PCR(ERIC-PCR)分析产ESBL菌株的分子同源性.采用x2检验.结果 136株志贺菌属中,产ESBL志贺菌20株,检出率为14.7％,未检测出产AmpC酶菌株.其中16株志贺菌基因型为CTX-M-14型,4株为CTX-M-15型;产CTX-M型ESBL菌株对多种抗菌药物耐药,但对亚胺培南的敏感率为100％.18株产ESBL志贺菌接合试验获得成功,其接合子对β内酰胺类抗菌药物耐药.结论 天津地区志贺菌属产ESBL基因型以CTX-M型为主,产ESBL是志贺菌属对β内酰胺类耐药的主要原因,产ESBL菌株的传播机制以质粒介导为主.     

多重耐药HvKP菌株临床感染分布及耐药机制

目的探讨高毒力肺炎克雷伯菌新型变种(Hv KP)临床感染分布和耐药机制。方法肺炎克雷伯菌180株为实验菌株并筛选Hv KP菌株;多位点序列分析和ERIC-PCR检测Hv KP菌株的分子流行病学特征;检测实验菌株对常用抗菌药物的敏感性,梅里埃ETEST药敏纸条检测美罗培南和厄他培南的MIC值;PCR和基因测序检测耐药基因型、血清荚膜分型、毒力基因;黏液丝试验检测菌株高黏液型表型。结果共分离出11株Hv KP菌株,其中医院获得性Hv KP菌株感染率明显高于社区获得性感染率(P<0.05);明确Hv KP菌株感染前碳青霉烯类使用率明显高于其他类抗生素(P<0.05)。11株Hv KP中检出5种ERIC-MLST克隆分型,主要为A/ST23、B/ST263分型。PCR和测序显示,广谱β-内酰胺酶基因中,9株携带bla TEM-1、5株携带bla CTX-M-3、5株携带bla CTX-M-14、3株携带bla SHV-12;质粒介导喹诺酮类耐药基因中,8株携带qnr A1、6株携带qnr B4、6株携带qnr S4、2株携带acc-Ib-cr。荚膜血清型为K1的10株、K2的1株。毒力基因中mag A、rmp A、产气菌素的检出率明显高于其他毒力基因(P<0.05)。结论 A/ST23、B/ST263型分子克隆是引发多重耐药Hv KP菌株的机制之一且存在强毒性血清型和多种毒力基因。     

耐三代头孢菌素阴沟肠杆菌临床株中CTX-M型ESBLs与Ⅰ类整合子的相关性

目的研究CTX-M型超广谱β内酰胺酶（ESBLs）及Ⅰ类整合子在耐三代头孢菌素阴沟肠杆菌中的分布,进一步探讨Ⅰ类整合子与CTX-MM型ESBLs的关系.方法运用K-B法检测阴沟肠杆菌临床株的耐药表型,双纸片协同试验（DDST）初筛产ESBLs的菌株,聚合酶链反应（PCR）扩增确证产CTX-M型ESBLs和含有Ⅰ类整合子的临床菌株,套式PCR及序列测定寻找携带CTX-M型ESBLs基因盒的Ⅰ类整合子.结果37株耐药菌中,21株菌产生CTX-M型ESBLs;20株菌含有Ⅰ类整合子;在13株同时产生Ⅰ类整合子和CTX-M型ESBLs的临床株中,3株菌CH4、CH11和Q1的CTX-M型ESBLs基因盒分布在Ⅰ类整合子上.结论Ⅰ类整合子的存在增加了ESBLs在临床株中水平播散的危险,是造成多重耐药株在院内暴发流行的重要原因.     

陕西省O157出血性大肠杆菌分布研究

目的了解陕西省家禽家畜O157大肠杆菌带菌和致病力情况以及市售食品的污染状况,分析对人群可能造成的威胁。方法根据我省不同地域选择监测点,采集监测点内养殖场或个体养殖户养殖的动物粪便1657份;集贸市场和超市销售的7类食品样品877份进行O157大肠杆菌监测,应用PCR技术对分离菌株进行毒力基因检测和流行病学分析。结果从动物粪便中分离出64株O157大肠杆菌,总带菌率3.86%,其中奶牛带菌率最高,达10.89%。从食品样品中分离出6株,总污染率0.68%。70株分离菌通过PCR检测发现,大多数O157大肠杆菌不携带H7鞭毛素fliCH7基因以及stx1、stx2、eaeA、hlyA4种毒力基因,含有fliCH7基因的9株菌则全部携带有stx2、eaeA、hlyA毒力基因,表现为fliCH7基因与已知毒力基因的相关性及分离菌株毒力基因图谱的一致性。结论陕西省猪、牛、鸡动物存在有O157大肠杆菌,并且食品已受到污染,所显示的毒力基因图谱单一,提示陕西省存在有O157大肠杆菌感染的威胁,有造成O157大肠杆菌流行或局部暴发流行的可能。     

广西宋内志贺菌药敏特性及ESBLs基因检测分析

目的了解广西地区宋内志贺菌的药敏特性及携带超广谱β-内酰胺酶(ESBLs)基因与型别特征,为临床合理用药和控制耐药性的传播提供科学依据。方法采用微量肉汤稀释法对宋内志贺菌分离株进行药物敏感试验;采用PCR方法和毛细管电泳方法检测菌株携带相关ESBLs基因;采用近邻相接法构建系统进化树,分析菌株CTX-M型基因型别;对菌株携带ESBLs基因与特定抗菌药物耐药性的关系进行统计学分析。结果90株宋内志贺菌对环丙沙星敏感率为86.67%,无耐药现象;头孢曲松耐药率为96.67%,阿奇霉素耐药率为96.67%,多重耐药率为98.89%。90株宋内志贺菌中50株检出blaCTX-M-9 group基因,检出率为55.56%,经系统发育分析均为CTX-M-14亚型;1株检出blaTEM基因,检出率为1.11%;未检出blaCTX-M-1 group,blaCTX-M-2 group,blaCTX-M-8 group,blaCTX-M-25 group和blaOXA,blaSHV,blaNDM,blaVIM等β-内酰胺酶基因。blaCTX-M-14基因阳性菌株与blaCTX-M-14基因阴性菌株对头孢噻肟的耐药率差异无统计学意义(χ²=0.000,P>0.05);携带blaTEM基因的菌株对头孢他啶不耐药。结论广西地区的宋内志贺菌对主要治疗药物头孢曲松高度耐药,且多重耐药现象严重;菌株普遍携带ESBLs基因,主要为CTX-M-14亚型;携带单一型别的ESBLs基因与菌株对特定β-内酰胺类抗菌药物耐药无明显关联。     

猪源大肠杆菌耐药性及超广谱β-内酰胺酶流行性分析

目的对福建地区分离的猪源大场杆菌进行耐药性测定以及对ESBLs流行性进行分析,以期为临床合理用药科学提供依据。方法采用琼脂稀释法测定373株菌大肠杆菌对12种抗菌药物的敏感性,并用PCR方法检测ESBLs耐药基因的携带情况以及分析CTX-M阳性菌的种系发育关系。结果分离株对甲氧苄啶/磺胺甲噁唑、萘啶酸、氟苯尼考及氨苄西林耐药率较高,分别为93.8%、82.8%、73.7%和70.0%;对恩诺沙星、四环素、庆大霉素、多西环素、环丙沙星、卡那霉素、头孢噻呋和头孢噻肟的耐药率依次为54.4%、53.1%、52.0%、46.6%、44.0%、41.0%、35.9%和30.8%。在373株大肠杆菌中,共有122株菌携带有ESBLs耐药基因,检出率为32.7%,其中CTX-M、TEM及OXA的检出率分别是18.0%(67)、12.1%(45)和7.5%(28),其中CTX-M的阳性菌中以CTX-M-14最为流行,其次是CTX-M-65和CTX-M-55;其种系发育显示分离株主要分布在A群。结论福建地区猪大肠杆菌对抗菌药表现出较强的耐药性,ESBLs在猪源大肠杆菌中广泛流行,CTX-M是其主要流行的基因型,并且多数菌以共生型大肠杆菌为主。     

中国肠产毒性大肠杆菌中耶尔森菌强毒力岛的检测

目的　了解耶尔森菌强毒力岛在中国肠产毒性大肠杆菌中的分布及插入位点。方法　使用PCR扩增、DNA打点杂交和DNA测序及分析方法。结果　在 94株分离自中国的肠产毒性大肠杆菌中 ,14株耶尔森菌强毒力岛核心区的 8个基因PCR扩增阳性 ,除 3株菌的整合酶基因外 ,PCR扩增产物长度均与预期一致 ,但天冬酰胺转运RNA(asnTtRNA)位点扩增阴性 ;上述 14株菌进行全菌DNA打点杂交试验 ,均与irp2和 fyuA探针杂交 ;选择上述 3株菌中的 1株 ,对其整合酶基因的PCR产物测序 ,并与鼠疫耶尔森菌强毒力岛的整合酶基因序列比较 ,发现该整合酶基因于 5’端缺失了 347bp的片段。 结论　 14 %肠产毒性大肠杆菌携带的耶尔森菌强毒力岛 ,且均插入在天冬酰胺转运RNA位点处 ;部分菌株所携带的耶尔森菌强毒力岛的整合酶基因发生了缺失。     

Association between antimicrobial resistance and virulence genes in Escherichia coli obtained from blood and faeces

Escherichia coli isolates obtained from faeces (n=85) and blood (n=123) were susceptibility tested against 17 antimicrobial agents and the presence of 9 virulence genes was determined by PCR. Positive associations between several antimicrobial resistances and 2 VF genes (iutA and traT) were found among blood isolates, sometimes among faecal isolates.     

CTX-M-1-Related Extended-Spectrum Beta-Lactamases Producing <Emphasis Type="Italic">Escherichia coli</Emphasis>: so far a Sporadic Event in Western Austria

BACKGROUND: : The present study was aimed to searching for CTX-M-type extended-spectrum beta-lactamases in community- and hospital-acquired Escherichia coli (E. coli) collected in western Austria and to investigate their clonal relatedness and their ability to spread. PATIENTS AND METHODS: : All patients with E. coli positive cultures collected from a catchment population of 186,000 between January and July 2006 were enrolled into the study. CTX-M-producing E. coli were identified by antibiotic susceptibility testing and blaCTX-M multiplex PCR. Clonal relatedness was analyzed by pulsed-field gel electrophoresis (PFGE). RESULTS: : In 2,042 E. coli isolates, 20 isolates (16 from urine, 4 from blood cultures) demonstrated CTX-M-1-related genes and no CTX-M-2- or CTX-M-9-related enzymes or CTX-M-15-producing strains were identified. We did not find clonal relatedness among CTX-M-1 producers isolated from the same referring center. E. coli were investigated for plasmid transfer ability of CTX-M-1-encoding genes. Plasmid digest patterns were not consistent with episomal spread of resistance loci. Transfection of CTX-M-encoding plasmids failed. CONCLUSION: : Our data suggest that the emergence of CTX-M-1-producing E. coli in western Austria may be attributed to multiple independent events.     

A survey of β-lactamase-producing Escherichia coli in farm animals and raw retail meat in Shizuoka Prefecture, Japan

We surveyed β-lactamase-producing Escherichia coli from farm animals (chickens, pigs, and cattle) and raw retail meat in Shizuoka Prefecture, Japan. In total 305 E. coli isolates, 15 isolates collected from broilers, beef cattle, chicken meat, and pork meat, were found to have β-lactamase genes encoding CTX-M-2, CTX-M-14, CMY-2, SHV-2, and/or TEM-1, whereas 7 possessed mutations in the ampC promoter region. The findings suggest that broilers are more important than other farm animals with regards to the surveillance of β-lactamase-producing E. coli in this region.     

ESBL genotypes in fluoroquinolone-resistant and fluoroquinolone-susceptible ESBL-producing Escherichia coli urinary isolates in Manitoba

OBJECTIVE: Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli are increasingly common in nosocomial and community settings. Furthermore, fluoroquinolone (FQ) and even multidrug resistance (MDR) appear to be associated with certain ESBL genotypes. The purpose of the present study was to determine which ESBL genotypes are associated with FQ and MDR in E coli urinary isolates in Manitoba. METHODS: The authors determined the antimicrobial susceptibility, genetic similarity and ESBL genotype of 27 FQ-resistant and seven FQ-susceptible, ESBL-producing urinary isolates submitted to the clinical microbiology laboratories of two teaching hospitals between October 2000 and April 2005. Susceptibilities to beta-lactams, FQs, trimethoprim-sulfamethoxazole (SXT), doxycycline (DOX), gentamicin (GM) and tigecycline were determined by microbroth dilution; pulsed-field gel electrophoresis (PFGE) was used to determine genetic relatedness, and ESBL genotype was determined by polymerase chain reaction and sequencing. RESULTS: Of 34 ESBL-producing organisms, 27 (79.4%) were found to be ciprofloxacin (CIP) resistant, 27 (79.4%) were SXT resistant, eight (23.5%) were GM resistant and 29 (85.3%) were DOX resistant. Twenty-three (67.6%) had MDR, with concomitant resistance to CIP and SXT; 16 had concomitant resistance to CIP, SXT and DOX; and seven (20.6%) had MDR, with concomitant resistance to CIP, SXT, DOX and GM. All isolates were susceptible to tigecycline. Of 27 FQ-resistant ESBL-producing organisms, seven (25.9%) were genotype CTX-M-14, 19 (70.4%) were genotype CTX-M-15 and one (3.7%) was genotype CTX-M-24. Among the seven FQ-susceptible strains, three (42.8%) expressed SHV-type enzymes, three (42.8%) expressed TEM-type enzymes and one (14.3%) expressed CTX-M-9. CTX-M-15 was the most common MDR-associated genotype. Of a total of 19 strains, 18 (94.7%) were resistant to FQs and SXT; 15 (78.9%) were resistant to FQs, SXT and DOX; and five (26.3%) were resistant to FQs, SXT, DOX and GM. PFGE analysis revealed genetic similarity within CTX-M-15-producing isolates only. CONCLUSION: CTX-M-15 in E coli is strongly associated with an MDR phenotype compared with other genotypes. CTX-M-14 is associated with FQ resistance only. PFGE suggests clonality of CTX-M-15-producing isolates within and among hospitals.     

Molecular epidemiology of CTX-M producing Enterobacteriaceae isolated from bloodstream infections in Rio de Janeiro,Brazil: emergence of CTX-M-15

ObjectiveThe present study was designed to evaluate the molecular epidemiology of CTX-M producing Klebsiella pneumoniae, Enterobacter cloacae and Escherichia coli isolated from bloodstream infections at tertiary care hospitals in the State of Rio de Janeiro, Brazil.Material and methodsA total of 231 nonduplicate Enterobacteriaceae were isolated from five Brazilian hospitals between September 2007 and September 2008. The antimicrobial susceptibility testing was performed by disk diffusion method according to the Clinical Laboratory Standard Institute. Isolates showing resistance to third-generation cephalosporins were screened for ESBL activity by the double-disk synergy test. The presence of bla_CTX-M, bla_CTX-M-15 and bla_KPC genes was determined by Polymerase Chain Reaction (PCR) amplification and DNA sequencing. The molecular typing of CTX-M producing isolates was performed by pulsed-field gel electrophoresis (PFGE).Results and discussionNinety-three isolates were screened as ESBL positive and 85 (91%) were found to carry CTX-M-type, as follows: K. pneumoniae 59 (49%), E. cloacae 15 (42%), and E. coli 11 (15%). Ten isolates resistant for carbapenems in K. pneumoniae were bla_KPC-2 gene positive. Among CTX-M type isolates, CTX-M-15 was predominant in more than 50% of isolates for K. pneumoniae, E. coli, and E. cloacae. PFGE analysis of CTX-M producing isolates showed the predominance of CTX-M-15 in 10 of 24 pulsotypes in K. pneumoniae, 6 of 13 in E. cloacae and 3 of 6 in E. coli. CTX-M-15 was also predominant among KPC producing isolates. In conclusion, this study showed that CTX-M-15 was circulating in Rio de Janeiro state in 2007–2008. This data reinforce the need for continuing surveillance because this scenario may have changed over the years.     

Molecular epidemiology of 3 putative virulence genes for Escherichia coli urinary tract infection-usp, iha, and iroN(E. coli)

This study describes the epidemiological association of 3 putative genes for virulence of uropathogenic Escherichia coli; uropathogenic specific protein (usp), a Vibrio cholerae zot gene homologue; IrgA homologue adhesin (iha), a nonhemagglutinating adhesin; and iroN(E. coli), a catechole siderophore receptor homologue. We compared the relative frequency in urinary tract infection (UTI) isolates (n=508), compared with non-UTI isolates (n=416). iroN(E. coli) occurred 2.1-3.6 times more frequently in UTI isolates than in rectal isolates (P=1.1x10-18 to P=2.7x10-5) and was associated with several uropathogenic virulence genes found on pathogenicity islands. usp occurred more frequently in isolates from patients with pyelonephritis (P=3.6x10-9), in periurethral isolates (P=.001), and in isolates from patients with UTI who were aged 40-65 years (P=.004), when compared with the rectal isolates; iha was not associated with UTI in this study.     

Ampicillin-resistant Escherichia coli in gestational pyelonephritis: increased occurrence and association with the colonization factor Dr adhesin

The pattern of ampicillin resistance and possible association with virulence factors of 78 Escherichia coli isolates taken from 78 pregnant women with pyelonephritis were evaluated. The current incidence of ampicillin resistance among pyelonephritis isolates (46%) was significantly higher than that reported in 1985 (22%). Resistance was found more frequently during the first (60%) and third (53%) trimesters than during the second trimester (33%). Of all dra(+) E. coli isolates, 75% were ampicillin resistant, whereas dra(+) isolates of O75 serotype E. coli accounted for 87% of ampicillin-resistant strains. The significant increase of ampicillin resistance among gestational pyelonephritis E. coli and the association with the dra gene cluster encoding colonization and invasive capacity may warrant further study involving obstetric and neonate wards, with the latter being at the higher risk for potential problems.     

产新德里金属β-内酰胺酶大肠埃希菌耐碳青霉烯类药物相关机制研究和分子分型

目的 研究某三甲医院临床分离的产新德里金属β-内酰胺酶(NDM)大肠埃希菌的耐药机制和分子流行病学特征。方法 在某三甲医院收集的耐碳青霉烯类大肠埃希菌中利用聚合酶链反应(PCR)筛查是否携带NDM基因,通过测序确定NDM型别并进一步检测其它碳青霉烯酶相关基因和广谱β-内酰胺酶类耐药基因。通过载体构建和表达研究NDM-1、NDM-6及NDM-9对亚胺培南的水解能力。采用多位点序列分型(MLST)对产NDM大肠埃希菌进行分子分型。结果 共筛选出8 株携带NDM大肠埃希菌,其中2株为NDM-9型,6株为NDM-6型。4株大肠埃希菌同时携带NDM-6、TEM和CTX-M-1基因,1 株同时携带NDM-6、TEM和CTX-M-9基因。携带NDM-1、NDM-6与NDM-9重组菌对亚胺培南均耐药,最小抑菌浓度(MIC)分别为32 μg/mL、128 μg/mL和64 μg/mL。产NDM大肠埃希菌MLST分型结果为ST226、ST648和ST1284型各1 株,ST101型5 株,此5 株均来源于神经内科。结论 首次发现同时携带NDM-6、TEM和CTX-M-1基因和携带NDM-6、TEM和CTX-M-9基因的大肠埃希菌,NDM-6、NDM-9对亚胺培南的耐药性比NDM-1强,应引起重视。MLST分型结果提示某三甲医院可能存在耐碳青霉烯类大肠埃希菌的院内局部传播。     

Molecular characterization of diarrheagenic Escherichia coli from Libya

Diarrheagenic Escherichia coli (DEC) are important enteric pathogens that cause a wide variety of gastrointestinal diseases, particularly in children. Escherichia coli isolates cultured from 243 diarrheal stool samples obtained from Libyan children and 50 water samples were screened by polymerase chain reaction (PCR) for genes characteristic of enteroaggregative E. coli (EAEC), enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enterohemorrhagic E. coli (EHEC), and enteroinvasive E. coli (EIEC). The DEC were detected in 21 (8.6%) children with diarrhea; 10 (4.1%) cases were identified as EAEC, 3 (1.2%) as EPEC, and 8 (3.3%) were ETEC; EHEC, and EIEC were not detected. All DEC were grouped phylogenetically by PCR with the majority (> 70%) identified as phylogenetic groups A and B1. The EAEC isolates were also tested for eight genes associated with virulence using PCR. Multi-virulence (≥ 3 virulence factors) was found in 50% of EAEC isolates. Isolated EAEC possessed different virulence traits and belonged to different phylogenetic groups indicating their heterogeneity.     

Role of host and bacterial virulence factors in Escherichia coli spontaneous bacterial peritonitis

OBJECTIVES: Host factors and bacterial virulence determinants may play a role in Escherichia coli (E. coli) spontaneous bacterial peritonitis. We evaluated the importance of these factors in the emergence of fluoroquinolone-resistant strains and outcome in cirrhotic patients with E. coli spontaneous bacterial peritonitis. METHODS: E. coli spontaneous bacterial peritonitis was detected in a 2-year period in three tertiary hospitals. Clinical and bacteriological data were obtained. Phylogenetic group and 15 virulence genes of E. coli strains were analyzed by polymerase gene reaction and compared with 50 isolates from pyelonephritis patients. RESULTS: Forty-seven E. coli spontaneous bacterial peritonitis patients were identified, 18 (38%) were fluoroquinolone-resistant, a 12% increase compared with our earlier series from 1997 to 2002. Fluoroquinolone resistance was associated with norfloxacin prophylaxis, increased resistance to trimethoprim-sulfamethoxazole and cefotaxime, and less bacterial virulence, as demonstrated by a higher prevalence of 'nonpathogenic' phylogenetic groups A+B1 (56 vs. 28%; P=0.04) and lower virulence scores in fluoroquinolone-resistant E. coli compared with fluoroquinolone-susceptible E. coli. E. coli strains from cirrhotic patients belonged more frequently to 'nonpathogenic' phylogenetic groups A+B1, had fewer virulence factors and higher rates of fluoroquinolone resistance than isolates from pyelonephytis patients. Immunosuppression was independently associated with in-hospital and 3-month mortality. Bacterial virulence factors were unrelated to mortality. CONCLUSION: Fluoroquinolone-resistant E. coli spontaneous bacterial peritonitis prevalence is increasing because of norfloxacin prophylaxis. Strains from peritonitis are less virulent than strains from pyelonephritis because of a higher prevalence of A+B1 phylogeny and quinolone resistance. Mortality is related to immunosuppression, but not to bacterial virulence factors.