产超广谱β-内酰胺酶鲍曼不动杆菌耐药机制的研究进展

广谱抗生素的广泛应用使鲍曼不动杆菌的耐药率不断升高，已成为日益严重的医疗事件和公共卫生问题，引起了人们的高度关注。目前在鲍曼不动杆菌已经发现了多种超广谱β-内酰胺酶（ESBL）的基因型，特别是近年来新ESBL基因型不断地在该菌中被发现，如PER型、VEB型，但对其耐药机制仍不明确。因此，对于鲍曼不动杆菌产超广谱β-内酰胺酶的耐药机制深入研究势在必行。     

多重耐药鲍曼不动杆菌blaADC酶耐药基因检测及临床特点分析

目的了解31株多重耐药鲍曼不动杆菌（MI）RAB）中blaADC型β-内酰胺酶基因存在状况。方法对2005年1～6月白求恩国际和平医院临床分离的31株多重耐药鲍曼不动杆菌菌株（耐哌拉西林、第三代头孢菌素、环丙沙星和庆大霉素）应用聚合酶链反应及序列分析方法分析blaADCβ-内酰胺酶基因，应用K-B纸片扩散法检测细菌对药物的敏感性。收集临床资料并作同颐性分析。结果31株MDRAB均对多粘菌素B敏感．3株（9．7％）对受试的其他23种抗菌药物均耐药。31株MDRAB中blaADC全部阳性（100％）。31例MDRAB感染患者，29例（93．5％）为医院内呼吸道感染，1例为菌血症．1例为伤口感染。经抗菌药物治疗后。24例（77．4％）存活，7例（22．6％）死亡。结论MDRAB对8内酰胺类抗菌药物耐药与其产blaADC型β-内酰胺酶密切相关，MDRAB感染患者预后较差。     

肿瘤专科医院临床和环境标本中产超广谱β-内酰胺酶大肠埃希菌流行病学调查北大核心CSCD

目的了解肿瘤专科医院临床和环境标本中产超广谱伊内酰胺酶（ESBL）大肠埃希菌的基因型及同源性。方法检测2012年6月至2013年1月郑卅l大学附属肿瘤医院住院患者的临床标本（St液、尿液、痰液、胸腔积液、腹腔积液、引流液、粪便等）和环境标本（空气、陪护者手、门把手、床扶手、床头柜、医护人员手）中产ESBL大肠埃希菌,经表型确认试验确定ESBL的表型,多重PCR检测blatzEM、blasnv、blaoxn、blaDTX和blarox等基因型,脉冲场凝胶电泳（PFGE）分析临床标本和环境标本中菌株的同源性。结果表型确认试验检测到临床标本和环境标本中共有产ESBL大肠埃希菌41株,其中临床标本中有36株（为28例患者的临床标本）,环境标本中有5株。多重PCR检测ESBL基因,单一型别ESBL菌株以携带TEM-1基因型和CTX14基因型为主;两种型别ESBI．菌株以携带CTX-14、TEM-1基因型为主;三种型别ESBL菌株同时携带CTX-14、TEM-1和SHV—1基因型。PFGE结果显示,28例患者的粪便和其他临床标本中产ESBL大肠埃希菌之间没有同源性,外科一病区3例患者及其中1例患者的床头柜上检出产ESBL大肠埃希菌有同源性。结论郑州大学附属肿瘤医院产ESBL大肠埃希菌主要流行的基因型为TEM-1、CTX-14、CTX-1。同一菌株可具有多种基因型别,以两种型别为主。外源性感染是产ESBL大肠埃希菌感染途径之一。     

耐亚胺培南鲍曼不动杆菌耐药性及同源性分析

目的明确我院临床分离亚胺培南耐药鲍曼不动杆菌的耐药谱特点及其同源性。方法采用Vitek-32全自动细菌鉴定药敏系统及纸片扩散法（K-B法）测定鲍曼不动杆菌对16种抗菌药物的敏感性；通过重复序列引物聚合酶链反应（rep-PCR）分析其基因同源性。结果33株亚胺培南耐药株除对头孢哌酮-舒巴坦的耐药率〈10％，对其他抗菌药物的耐药率均在54．5％以上；rep-PCR将鲍曼不动杆菌分为E1、E2、E3三个基因型，其中A型15株，为主要的流行型别。结论我院流行的亚胺培南耐药鲍曼不动杆菌的多重耐药现象严重，且主要是由同一克隆株传播所致。     

部分非鲍曼不动杆菌耐药性及相关基因分析

目的了解目前非鲍曼不动杆菌临床分离株的耐药现状及耐药基因携带情况。方法随机抽取100株不动杆菌临床分离株,采用分子生物学方法筛选非鲍曼不动杆菌,用E-test方法检测非鲍曼不动杆菌对12种抗生素的耐药性,用PCR方法检测16种相关耐药基因的分布。结果共筛选出17株非鲍曼不动杆菌,7株为多重耐药(41.2%),其中对头孢噻肟的耐药率为100%,对氯霉素、哌拉西林、氨苄西林和氨曲南的耐药率分别为76.5%、76.5%、64.7%和52.9%,对多粘菌素B普遍敏感;检出6种耐药基因分别为ampC、blaTEM、blaPER-1、blaOXA-23-like、blaOXA-58和Int1。结论携带超广谱β-内酰胺酶(ESBLs)基因和blaOXA-23-like基因为非鲍曼不动杆菌对β-内酰胺类和碳青霉烯类抗生素耐药的主要原因。非鲍曼不动杆菌的耐药形势严峻,应加强监测。     

老年病房耐亚胺培南鲍曼不动杆菌整合子及分子流行病学研究

目的了解老年病房耐亚胺培南鲍曼不动杆菌携带整合子的情况,分析菌株同源性,为防治院内感染提供依据。方法收集我院老年科2014年3月至2017年3月临床分离的非重复耐亚胺培南鲍曼不动杆菌28株,采用纸片扩散法确定其耐药率,运用聚合酶链式反应(PCR)法检测整合酶基因(intl)Ⅰ、intlⅡ、intlⅢ及可变区,并用多位点序列分型(MLST)法对其进行分子分型。结果耐亚胺培南鲍曼不动杆菌intlⅠ的携带率为35.7%,未扩增出Ⅱ类和Ⅲ类intl。整合子阳性菌扩增出两类可变区,分别含有aac C1-orfx'-aadA1及aac A4-catB8-aad A1基因盒。MLST分型提示ST1415型14株(50.0%)、ST1417型5株(17.9%)、ST195型4株(14.3%)、ST540型3株(10.7%),未分型2株。MLST优势基因型为ST1415。结论耐亚胺培南鲍曼不动杆菌主要携带Ⅰ类整合子,介导对氨基糖苷类、氯霉素耐药。老年病房存在耐亚胺培南鲍曼不动杆菌,尤其是ST1415型的院内感染流行,必须加强感染隔离及控制。     

60株鲍曼不动杆菌喹诺酮类耐药基因分析

目的探究鲍曼不动杆菌喹诺酮类耐药的机制。方法收集2009年1-12月天津市三所三甲医院各类标本分离的鲍曼不动杆菌60株。采用聚合酶链反应（PCR）扩增技术对质粒介导喹诺酮类耐药基因qnrA、qnrB、qnrS、acc（6’）．Ib．cr、qepA及染色体基因gyrA和parC进行基因检测,并对阳性结果进行酶切和测序鉴定。结果60株鲍曼不动杆菌中qnrA、qnrB、qmS和qepA基因均为阴性,acc（6’）-Ib基因12株阳性,经测序证实均未出现变异。37株环丙沙星耐药的鲍曼不动杆菌中30株（81．0％）gyrA基因不被HinfI酶切,26株（70％）parc基因不被Hinf I酶切,证实有基因突变存在。结论天津地区尚未发现鲍曼不动杆菌中存在质粒介导的喹诺酮耐药机制,gyrA和parC基因变异仍为鲍曼不动杆菌喹诺酮耐药的主要原因,但同时亦有其他喹诺酮耐药机制的存在。     

临床分离的醋酸钙鲍曼复合不动杆菌基因分型的研究

目的检测临床分离的醋酸钙鲍曼复合不动杆菌的基因类型。方法收集并分离临床来源的100株醋酸钙鲍曼复合不动杆菌,应用简化的随机扩增多态性DNA（RAPD）技术检测醋酸钙鲍曼复合不动杆菌的基因类型,同时应用模糊聚类人工免疫网络算法（AINFCM）对分型指纹图进行图像分割,提取出图谱亮条信息,为临床分离的醋酸钙鲍曼复合不动杆菌的基因图谱比对提供条件。结果临床分离的100株醋酸钙鲍曼复合不动杆菌中仅2株未得到RAPD指纹图谱,98株共得17种RAPD指纹图谱,以A型和D型为主,分别为37株和22株。结论本文100株醋酸钙鲍曼复合不动杆菌中初步推断为2株醋酸钙不动杆菌,98株为鲍曼不动杆菌。     

16S rRNA甲基化酶基因在鲍曼不动杆菌中的分布

目的调查国内6个省市25家医院临床分离鲍曼不动杆菌中介导高水平氨基糖苷类抗生素耐药的16SrRNA甲基化酶基因armA、rmtA、rmtB的分布情况。方法收集2004年12月-2005年12月国内6省市8家省级医院、浙江省11个地区17家市级医院临床分离的700株鲍曼不动杆菌。琼脂稀释法测定其对妥布霉素、阿米卡星、庆大霉素、异帕米星、奈替米星5种氨基糖苷类抗生素的最低抑菌浓度（MIC）值；PCR筛选三种甲基化酶基因armA、rmtA、rmtB，克隆测序明确基因型；脉冲场凝胶电泳（PFGE）分析菌株的同源性；质粒抽提、接合试验及Southern杂交确定armA基因定位。结果对妥布霉素、阿米卡星、庆大霉素、异帕米星、奈替米星的耐药率分别为67．7％、70．9％、75．7％、63．5％和71．5％。对5种氨基糖苷类抗生素全部耐药的菌株有377株，其中334株检出armA基因；未发现rmtA、rmtB阳性菌株。armA基因阳性菌株PFGE分型以A、B、C为主。碱裂解法反复抽提未得到质粒，多次接合试验未成功；Southern杂交显示，armA基因分别位于克隆A、B、c菌株染色体ApaⅠ酶切PFGE约220、300、220kb大小的PFGE片段上。结论16SrRNA甲基化酶基因armA在鲍曼不动杆菌中广泛存在，armA基因位于鲍曼不动杆菌的染色体上。     

呼吸重症监护病房多重耐药鲍曼不动杆菌耐药基因研究

目的 观察我院呼吸重症监护病房(RICU)临床分离多重耐药鲍曼不动杆菌β-内酰胺酶基因和消毒剂耐药基因qacE△1-sul1存在状况.方法 收集RICU分离多重耐药鲍曼不动杆菌16株,采用PCR方法检测8种β-内酰胺酶基因(TEM、SHV、PER、DHA、IMP、VIM、OXA-23、OXA-24)和消毒剂耐药基因(qacE△1-sul1)共9种基因.采用多基因聚类分析方法进行多重耐药菌株亲缘性分析.结果 16株多重耐药鲍曼不动杆菌中blaOXA-23阳性5株(31.25%),blaTEM阳性2株(12.50%),blaDHA 2株(12.50%),blaOXA-24 1株(6.25%),blaPER 1株(6.25%).blaSHV、blaIMP、blaVIM均未检出,消毒剂耐药基因检测qacE△1-sull阳性16株(100.00%).多基因聚类分析发现存在克隆传播现象.结论 我院RICU多重耐药鲍曼不动杆菌携带多种β-内酰胺酶基因,消毒剂耐药基因携带率高,聚类分析显示存在克隆传播现象,应引起临床重视.     

Occurrence of qacE/qacEDelta1 genes and their correlation with class 1 integrons in salmonella enterica isolates from poultry and swine

In this study, a total of 122 Salmonella enterica isolates from poultry and swine were assessed for susceptibility to clinically important antibiotics and to benzalkonium chloride (BKC). All isolates were examined for the presence of the antiseptic resistance genes qacE and qacEDelta1 and intl1 (class 1 integrase). The intl1-positive strains were further investigated for the presence of the 3' conserved region. The results demonstrated widespread distribution of qacEDelta1 (27%) but no isolate with qacE was observed. The intl1 gene was identified in 23 isolates (70%) with qacEDelta1. All of the intl1-postive strains carried qacEDelta1 in 3' conserved segment, confirming that the qacEDelta1 gene is linked to the integrons. Increased MIC value to BKC was independent of the presence of qacEDelta1, and multiple antibiotic-resistant bacteria were no more tolerant to BKC than the non-multidrugresistant strains, regardless of the presence of qacEDelta1.     

48株鲍曼不动杆菌氨基糖苷类抗生素耐药基因检测

目的了解鲍曼不动杆菌氨基糖苷类抗生素耐药基因分布情况。方法收集蚌埠医学院第一附属医院2015年1月至12月临床分离的48株泛耐药鲍曼不动杆菌,VITEK 2Compact进行鉴定和药敏实验。PCR法检测12个氨基糖苷类修饰酶基因和3个甲基化酶基因以及外排泵基因adeB。结果在实验的16个基因中,共检出4种氨基糖苷类抗生素耐药基因aac(6′)-Ib、armA、adeB和ant(3″)-Ia,其中aac(6′)-Ib检出率为39.6%(19/48),armA基因检出率为89.6%(43/48),adeB检出率89.6%(43/48),ant(3″)-Ia检出率为10.4%(5/48),其余基因均未检出;存在两种以上耐药基因的共39株,检出率为81.3%(38/48)。结论 aac(6′)-Ib、armA基因以及外排泵adeB是介导我院鲍曼不动杆菌氨基糖苷类抗生素耐药的主要基因。     

Pseudomonas aeruginosa bloodstream infections: risk factors and treatment outcome related to expression of the PER-1 extended-spectrum beta-lactamase

Background  

Bloodstream infection (BSI) due to Pseudomonas aeruginosa (Pa) has relevant clinical impact especially in relation to drug resistance determinants. The PER-1 extended-spectrum beta-lactamase (ESBL) is a common enzyme conferring high-level resistance to anti-pseudomonal cephalosporins. Risk factors and treatment outcome of BSI episodes caused by PER-1-positive Pa (PER-1-Pa) strains were compared to those caused by ESBL-negative Pa isolates (ESBL-N-Pa).     

Prevalence of extended-spectrum beta-lactamase and class 1 integron integrase gene intl1 in Escherichia coli from Thai patients and healthy adults

Among 120 Escherichia coli isolates from Thai patients, 37 and 9 isolates were extended-spectrum beta-lactamase (ESBL) and suspected ESBL producers respectively while 5 E. coli isolates from 120 Thai healthy adults were suspected ESBL producers. Integrase (intl1) gene was detected in 99% of the clinical and 87% of the non-clinical isolates. Among 37 ESBL producers, percent recovery of bla(TEM), bla(CTX-M), bla(SHV) and bla(VEB) was 78%, 78%, 8% and 8%, respectively. Twenty-five isolates of ESBL producers carried both bla(TEM) and bla(CTX-M), 2 isolates carried 3 genes (bla(TEM), blac(CTX-M), and bla(SHV)) and 3 showed no detectable bla gene. Among the 14 suspected ESBL producers, intl1 and bla(TEM) were detected in 13 isolates. ESBL producers from clinical samples were resistant to most of the tested antimicrobial agents compared to non-ESBL producers and isolates from healthy adults with about half of the latter susceptible to all tested antimicrobial agents. Only one clinical isolate was resistant to imipenem. Susceptibility to trimethoprim/sulfamethoxazole among the clinical isolates in ESBL producer group (27%) and non-producer group (33%) were comparable, whereas the percent susceptibility of the non-clinical isolates was about twice that of the clinical isolates.     

替加环素治疗高龄老年院内获得性肺炎的疗效及安全性分析

目的观察替加环素治疗高龄老年院内获得性肺炎(HAP)耐药鲍曼不动杆菌感染的临床疗效与安全性。方法筛选2014年6月-2015年8月我院老年病科应用替加环素治疗多重或泛耐药鲍曼不动杆菌感染的高龄HAP病例,收集患者临床相关资料,总结分析其临床、细菌学疗效及药物安全性。结果共30例合格病例被纳入研究,分为两组:替加环素单药治疗组6例,临床有效3例,细菌清除1例。替加环素为基础联合其他抗生素治疗组24例,临床有效15例,死亡1例;细菌清除10例。临床总有效率为60%,细菌清除率36.7%。治疗前后患者肝肾功能无明显变化,治疗过程中出现恶心、欲吐不良反应1例。结论替加环素能有效改善高龄HAP耐药鲍曼不动杆菌感染患者的临床疗效,临床可尝试选用替加环素进行治疗,但同时需密切观察其不良反应。     

Risk factors and clinical outcomes of multidrug-resistant Acinetobacter baumannii bacteremia at a university hospital in Thailand

Multidrug-resistant (MDR) Acinetobacter baumannii has become a major cause of hospital-acquired infection worldwide. There are few papers regarding this particular subject. Our aim was to assess the incidence of bacteremia due to MDR Acinetobacter baumannii, factors associated with the infection, and clinical outcomes. We studied 49 cases of A. baumannii bacteremia in adult patients admitted to a university hospital in Northeast Thailand between 2005 and 2007. The incidence of MDR A. baumannii bacteremia was 3.6 episodes per 10,000 hospital admissions. Significantly independent factors associated with MDR A. baumannii bacteremia were previous: 1) ICU admission [odds ratio (OR) 10.01; 95% confidence interval (CI) 1.39-72.20]; 2) use of beta-lactam/beta-lactamase inhibitor antibiotics (OR 8.06; 95%CI 1.39-46.64); and 3) use of a carbapenem antibiotics (OR 11.40; 95%CI 1.44-89.98). The overall mortality rate was significantly higher in the MDR group than in the susceptible group (91.7% vs 48%, respectively) (p=0.001). The significantly independent factors related to mortality were: 1) APACHE II score (OR 1.25; 95%CI 1.03-1.52) and 2) secondary bacteremia (OR 14.86; 95%CI 1.37-161.90). This study revealed the significantly independent factors associated with MDR A. baumannii bacteremia were prior ICU admission and prior use of broad spectrum antibiotics. This infection has a high mortality rate. Emphasis needs to be on prevention, strict application of infection control and appropriate use of antibiotics.     

Antimicrobial susceptibility profiling and genomic diversity of multidrug-resistant Acinetobacter baumannii isolates from a teaching hospital in Malaysia

The resistance phenotypes and genomic diversity of 185 Acinetobacter baumannii isolates obtained from the intensive care unit (ICU) of a local teaching hospital in Kuala Lumpur from 2006 to 2009 were determined using antimicrobial susceptibility testing and pulsed-field gel electrophoresis (PFGE). Antibiogram analyses showed that the isolates were fully resistant to β-lactam antimicrobials and had high resistance rates to the other antimicrobial agents tested. However, the isolates were susceptible to polymyxin B. Resistance to cefoperazone/sulbactam was only detected in strains isolated from 2007 to 2009. Some environmental isolates and an isolate from the hands of a healthcare worker (HCW) had identical resistance profiles and PFGE profiles that were closely related to patient isolates. Cluster analyses based on the PFGE profiles showed there was a persistent clone of endemic isolates in the ICU environment. The transmission route from HCWs to fomites to patients, which caused a long-term infection in the ICU of the University Malaya Medical Centre, was observed in this study. These data provide a better understanding of A. baumannii epidemiology within the hospital and the possible transmission routes. Knowledge of changes in the resistance rates of A. baumannii in our local hospital will improve antimicrobial therapy.     

Epidemiology of extended-spectrum beta-lactamase producing gram-negative bacilli at Siriraj Hospital, Thailand, 2003

A cross-sectional study was conducted from August to September, 2003 to determine the prevalence and risk factors in acquiring extended-spectrum beta-lactamase (ESBL) producing gram-negative bacilli (GNB) in patients admitted to Siriraj Hospital and the outcomes of these infections. Of 346 isolates of gram-negative bacteria in 249 patients, 102 isolates from 87 patients were colonization only, but 244 isolates from 162 patients were infections. The common GNB were Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii and Enterobacter cloacae. The overall prevalence of ESBL producers was 30.1%. K. pneumoniae had a very high prevalence of ESBL producers (56.9%). The urinary tract was the most common site for ESBL- producing GNB infections. Nosocomial infections, duration from admission to infection, peripheral line, urinary catheterization, nasogastric tube insertion and previous use of beta-lactams, cephalosporins and fluoroquinolones were associated with acquiring ESBL-producing GNB infections. ESBL-producing GNB were significantly more resistant to antimicrobial agents. More than 80% of ESBL-producing GNB were susceptible to carbapenems. Mortality in patients infected with ESBL-producing GNB (41.3%) was significantly higher than those infected with non- ESBL-producing GNB (19.8%).     

Epidemiology of plasmid-mediated quinolone resistance in salmonella enterica serovar typhimurium isolates from food-producing animals in Japan

A total of 225 isolates of Salmonella enterica serovar Typhimurium from food-producing animals collected between 2003 and 2007 were examined for the prevalence of plasmid-mediated quinolone resistance (PMQR) determinants, namely qnrA, qnrB, qnrC, qnrD, qnrS, qepA and aac(6')Ib-cr, in Japan. Two isolates (0.8%) of S. Typhimurium DT104 from different dairy cows on a single farm in 2006 and 2007 were found to have qnrS1 on a plasmid of approximately 9.6-kbp. None of the S. Typhimurium isolates had qnrA, qnrB, qnrC, qnrD, qepA and acc(6')-Ib-cr. Currently in Japan, the prevalence of the PMQR genes among S. Typhimurium isolates from food animals may remain low or restricted. The PFGE profile of two S. Typhimurium DT104 isolates without qnrS1 on the farm in 2005 had an identical PFGE profile to those of two S. Typhimurium DT104 isolates with qnrS1. The PFGE analysis suggested that the already existing S. Typhimurium DT104 on the farm fortuitously acquired the qnrS1 plasmid.     

Impact of a hospital-wide antimicrobial formulary intervention on the incidence of multidrug-resistant gram-negative bacteria

We examined the impact of an antimicrobial formulary change, based on reduction in third-generation cephalosporin use, on resistant gram-negative pathogens in a tertiary hospital. No significant changes were demonstrated in their incidence per 1000 patient-days. Otherwise, there was a significant decrease in rate of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae (63.1% to 52.5%, P = .04) and third-generation cephalosporin-resistant Enterobacter species (31.4% to 25%, P = .04) between the 2 study periods. On the other hand, there was also a significant increase in rate of ampicillin-sulbactam-resistant Acinetobacter baumannii (8% to 47%, P = .01) after the implementation of the formulary intervention.