阪崎肠杆菌新疆分离株的药敏分析

[目的]对阪崎肠杆菌新疆分离株进行药敏试验,分析其药物敏感性,产超广谱β-内酰胺酶(ESBLs)菌株及耐药性。[方法]采用纸片扩散法对6株阪崎肠杆菌新疆分离株进行了9类共23种抗生素的药敏实验。[结果]所有阪崎肠杆菌对碳青霉烯类抗生素亚胺培南和美洛培南100%耐药,对至少20种抗生素敏感。[结论]阪崎肠杆菌在肠杆菌科属耐药性不显著的细菌。     

深圳市婴幼儿配方粉阪崎肠杆菌检测情况分析

目的了解深圳市婴幼儿配方粉阪崎肠杆菌的污染情况,评估深圳市婴儿感染风险。方法对抽取的144份婴幼儿配方粉进行阪崎肠杆菌荧光定量PCR检测,同时参照GB/T4789.40-2008《阪崎肠杆菌检验》进行分离培养、鉴定。结果共5份样品经荧光定量PCR检测出阪崎肠杆菌阳性;1份进口样品分离出菌株。结论深圳市进口婴幼儿配方粉中存在阪崎肠杆菌污染隐患。需加大抽样检测比例,并加强检验监管力度     

Isolates of the Enterobacter cloacae complex induce apoptosis of human intestinal epithelial cells

Strains of the Enterobacter cloacae complex are becoming increasingly important human pathogen. The aim of the study was to identify, by sequencing the hsp60 gene, the species of clinical isolates phenotypically identified as E. cloacae and to examine them for virulence-associated properties: the ability of adhesion, invasion to HEp-2 cells and the induced apoptosis of infected epithelial cells. The majority of the strains were identified as Enterobacter hormaechei with E. hormaechei subsp. steigerwaltii being the most frequent subspecies. Other strains belonged to E. hormaechei subsp. oharae, E. cloacae cluster III, and E. cloacae cluster IV. The strains were examined for virulence-associated properties: the ability to adhesion and invasion to HEp-2 cells and the apoptosis induction of infected epithelial cells. All strains revealed adherence ability and most of them (71%) were invasive to epithelial cells. Analyses of cellular morphology and DNA fragmentation in the HEp-2 cells exhibited typical features of cells undergoing apoptosis. We observed morphological changes, including condensation of nuclear chromatin, formation of apoptotic bodies and blebbing of cell membrane. The lowest apoptotic index did not exceed 6%, whereas the highest reached 49% at 24 h and 98% at 48 h after infection. Forty strains (73%) induced fragmentation of nuclear DNA and characteristic intranucleosomal pattern with the size of about 180–200 bp in DNA extracted from infected cells at 48 h after infection. The results indicated that the bacteria of the E. cloacae complex may adhere to and penetrate into epithelial cells and induce apoptosis, which could be an important mechanism contributing to the development diseases.     

阪崎肠杆菌新疆分离株侵袭乳鼠肠组织的病变

目的对阪崎肠杆菌新疆分离株侵袭乳鼠肠组织引起病变的特征进行分析。方法阪崎肠杆菌新疆分离株经产毒培养后,灌胃ICR乳鼠,7d后,无菌解剖取肠组织,制做切片,HE染色后镜下观察。结果乳鼠小肠、结肠、直肠发生明显病变。结论阪崎肠杆菌新疆分离株对机体具有潜在危害。     

Investigation of an outbreak of Enterobacter cloacae in a neonatal unit and review of the literature

Enterobacter cloacae has emerged as an important pathogen in neonatal units, with several outbreaks of infection being reported. The aim of this study was to investigate an outbreak of sepsis due to E. cloacae in a neonatal unit and to review the literature. A retrospective cohort study was conducted in which cases were compared with all newborns hospitalised for more than 48h in the neonatal intensive care unit (NICU). Cohorting of infected patients and work reorganisation were implemented. Pulsed-field gel electrophoresis was performed. The retrospective cohort included the six cases and 13 control patients that had been in the NICU during April 2006. Univariate analysis showed that the use of dobutamine was significantly associated with infection (P=0.036) and that enteral feeding was a protective factor (P=0.02). Multivariate analysis did not find any independent risk factor. Bed occupancy rate in March 2006 was 109.6%, indicating overcrowding. PFGE identified indistinguishable patterns among isolates from all six newborns. PubMed and OVID was search from 1 January 1983 to 15 January 2008 for papers including the terms 'E. cloacae', 'outbreaks', 'clusters' in combination with 'neonate', 'newborn', and 'infant'.We found 26 reports of outbreaks due to E. cloacae in neonate patients: sixteen (52%) were bloodstream infection outbreaks, of which two (12.5%) were related to multiple-dose medications. The source for our outbreak was not identified. Reinforcement of hygiene practices, restrictions on new admissions and the establishment of single-dose medications helped to control the outbreak.     

婴幼儿配方奶粉中阪崎肠杆菌的3种检测方法比较

[目的]比较和分析3种不同的阪崎肠杆菌定性检测方法的区别。[方法]分别采用美国FDA和ISO推荐阪崎肠杆菌检测方法,同时采用丙酮酸盐修复培养基作为奶粉预增菌液的检测方法,对48份市售婴幼儿配方奶粉进行阪崎肠杆菌定性检测。[结果]运用该3种方法分别检测到2个、3个和5个阳性样品。[结论]mLST-Vm选择性增菌肉汤和DFI显色平板可大大减少工作量,提高工作效率,整体操作简单省时。若同时采用丙酮酸钠修复,可减少漏检率,明显提高阪崎肠杆菌的检出率。     

肠道杆菌耐药性及其耐药相关Ⅰ类整合子可变区结构与进化

目的：了解大肠埃希菌、阴沟肠杆菌和鲍曼不动杆菌临床菌株耐药性,及其Ⅰ类整合子分布、可变区耐药基因盒与分子进化关系。 方法：采用K-B法检测大肠埃希菌、阴沟肠杆菌和鲍曼不动杆菌对12种药物的敏感性。采用PCR及其产物测序检测上述菌株中Ⅰ类整合子携带率及可变区耐药基因盒。采用Clustal X和MEGA软件分析Ⅰ类整合子基因盒中耐药基因分子进化关系。 结果：鲍曼不动杆菌对临床常用青霉素类和头孢菌素类抗生素耐药率为54.2%～100%,大肠埃希菌和阴沟肠杆菌对菌素类抗生素耐药率也高达41.6%～62.5%。62.5%（15/24）大肠埃希菌、67.9%（19/28）阴沟肠杆菌、83.3%（20/24）鲍曼不动杆菌检出Ⅰ类整合子,81.5%（44/54）Ⅰ类整合子呈现为4种单条带谱型,其余为3种双条带谱型。Ⅰ类整合子可变区耐药基因盒中存在aac(6′)、sad(3″)、aad(2″)、cat(4′)和dfr（7、A13和15）耐药基因,可分别介导细菌对氨基糖苷类、氯霉素和磺胺类抗生素耐药。根据二氢叶酸还原酶基因序列差异,上述菌株携带的Ⅰ类整合子可分成4个分子进化组。 结论：上述肠道杆菌耐药情况严重并携带高含多种耐药基因盒的Ⅰ类整合子,Ⅰ类整合子有4条不同的进化途径。     

阪崎克罗诺杆菌TaqMan-MGB探针实时荧光PCR快速检测技术研究

[目的]建立阪崎克罗诺杆菌TaqMan—MGB探针实时荧光定量聚合酶链反应（RT．PCR）快速检测方法。[方法]在阪崎克罗诺杆菌保守序列设计一对特异性引物和TaqMan—MGB探针,通过对PCR反应条件和扩增体系的优化,建立阪崎克罗诺杆菌TaqMan—MGB探针实时荧光PCR检测方法;用已知浓度的阪崎克罗诺杆菌验证其敏感性;用阪崎克罗诺杆菌、大肠埃希菌、鸭沙门菌株、柠檬酸杆菌等菌株验证其特异性;用婴幼儿配方粉等食品开展TaqMan—MGB探针实时荧光PCR技术与常规检测方法符合性比较。[结果]本研究建立的阪崎克罗诺杆菌实时荧光PCR检测技术,反应循环（cyclethreshold,CT）值-9模板浓度的对数值具有良好的对应关系[Y=-3．06×log（X）＋36．63,R^2=0．999],最低检测浓度为100CFU／mL,经36℃增菌8h最低检测限可达1CFU／mL,敏感性较普通TaqMan探针高10倍;11株阪崎克罗诺杆菌CT值均小于30,而大肠埃希菌、鲍曼不动杆菌、柠檬酸杆菌等30株菌株CT值大于30或扩增曲线成一平滑直线;隔天连续5次反应CT值变异系数小于5％;140件不同批次不同婴幼儿配方粉、192件婴幼儿谷物辅助食品检测结果与常规分离培养比较,差异无统计学意义（X^2=0．624,P〉0．05）。[结论]阪崎克罗诺杆菌TaqMan—MGB探针实时荧光PCR快速检测技术具有特异性强、敏感性高、易操作等优点,适用于婴儿配方粉等食品开展阪崎克罗诺杆菌快速检测与监测工作。     

2012年广东省婴幼儿食品中3种食源性致病菌污染状况调查

目的了解广东地区市场上销售的婴幼儿食品中3种食源性致病菌的污染状况。方法根据广东省人口分布情况、食品生产特点和地域分布特点选择广东省13个地区的市及县、乡镇的超市、百货、便利店和农贸市场进行采样,参照2012全国食源性致病菌监测工作手册,对婴幼儿食品（包括婴幼儿配方食品和婴幼儿谷基辅助食品）分别进行阪崎肠杆菌、蜡样芽孢杆菌和金黄色葡萄球菌的定性和定量检测。结果共采集到64个生产厂家的婴幼儿食品314份,其中婴幼儿配方奶粉92份、婴幼儿谷基辅助食品222份。314份样品中检出阪崎肠杆菌10份,检出率为3.18%,其中婴幼儿配方奶粉阳性检出率为2.17%（2/92）,谷基辅助食品阳性检出率为3.60%（8/222）;检出蜡样芽孢杆菌90份,检出率为28.67%,其中婴幼儿配方奶粉阳性检出率为30.43%（28/92）,谷基辅助食品阳性检出率为27.93%（62/222）;未检出金黄色葡萄球菌。10份阪崎肠杆菌阳性样品定量检测结果：9份〈5 MPN/100g,1份〉110 MPN/100g;90份蜡样芽孢杆菌阳性样品中66份采用MPN法检测,结果显示3份〉103MPN/100g,41份〈102MPN/100g,22份未检出,另外24份采用平板法检测,结果显示14份〈102cfu/g,10份未检出。结论广东省婴幼儿食品中阪崎肠杆菌和蜡样芽孢杆菌的污染状况不容忽视,对婴幼儿的健康可能存在风险,今后应加强婴幼儿食品的监管,预防和控制婴幼儿食源性疾病的发生。     

Isolation of silver- and antibiotic-resistant Enterobacter cloacae from teeth

Antibiotic-resistant bacteria pose a serious threat to human health; hence the mechanisms that lead to their selection need to be investigated. One possible mechanism is that the silver and mercury in amalgam dental restorations may select for bacteria that contain heavy metal and antibiotic-resistance determinants, leading to the spread of these resistances, particularly if they are contained on the same mobile genetic element. The incidence of silver-resistant bacteria on teeth is investigated in this work. Two silver-resistant Enterobacter cloacae isolates were isolated from infected teeth containing dental restorations. Both isolates were also resistant to ampicillin, erythromycin, and clindamycin. The silE gene, which is encoded on the silver resistance operon, has been sequenced from both isolates. Results suggest that the silver resistance operon is encoded on plasmid DNA.