嗜麦芽窄食单胞菌临床株的多重耐药外排泵的研究

目的　研究嗜麦芽窄食单胞菌临床株外排泵SmeDEF的表达与耐药的关系及其表达调控。方法　琼脂稀释法检测嗜麦芽窄食单胞菌对抗生素敏感性并检测泵抑制剂的作用 ,提取临床菌的RNA进行smeD的RT PCR扩增。提取DNA进行smeT片段的PCR扩增 ,扩增产物进行序列分析。结果　随机选取的 6株嗜麦芽窄食单胞菌均有扩增产物。SmeT的N端氨基酸序列相当保守 ,smeD smeT间区测序发现耐药且泵抑制阳性株基因序列与敏感株明显不同。推测与耐药有关的突变出现在smeT的 82～ 16 5区间。结论　嗜麦芽窄食单胞菌临床株SmeDEF外排泵的表达强弱与其耐药性有关。smeDEF基因的表达可能与调控基因间区的变化有关。     

207株嗜麦芽窄食单胞菌的临床分布特点及耐药性分析

近年来,由于广谱抗生素和免疫抑制药物的大量应用和介入性医疗操作等,嗜麦芽窄食单胞菌成为了医院感染的重要病原菌之一。在革兰氏阴性非发酵菌中,其临床的检出率仅次于铜绿假单胞菌和不动杆菌而居第三位,作为条件致病菌,它常引起抵抗力低下患者呼吸道感染、心内膜炎、尿路感染、中枢神经系统感染和败血症等,     

42株形成生物被膜的嗜麦芽窄食单胞菌的药物敏感性研究

目的 研究单独及联合使用不同种类抗生素对嗜麦芽窄食单胞菌(Stenotrophomonasmahophilia,SML)体外生物被膜的抗菌活性. 方法 收集从患者分离的非重复SML 42株,分别采用微量接种针和硅胶膜片在水解酪蛋白肉汤中构建细菌生物被膜(bacterial biofilm)的体外模型,经过抗生素(左氧氟沙星、环丙沙星、头孢哌酮/舒巴坦、头孢他啶、哌拉西林、红霉素、磺胺甲噁唑、庆大霉素)作用20 h,超声振荡并测定孵育前后6 h吸光度(A)值的变化,计算相应的细菌生物被膜抑制浓度,进而测定红霉素与左氧氟沙星、头孢哌酮/舒巴坦、哌拉西林对细菌生物被膜的联合作用. 结果 SML对左氧氟沙星、磺胺甲噁唑和哌拉西林敏感率分别为83.33%、66.67%和54.76%,其他抗生素的耐药率均在50%以上.形成生物被膜后,细菌对抗生素的生物被膜抑制浓度大于相应的最小抑菌浓度(MIC)值. 结论 42株SML呈现多重耐药现象,形成生物被膜后耐药性增强.左氧氟沙星的抗菌活性在形成生物被膜前后均优于其他抗生素,联合红霉素与左氧氟沙星有助于增强杀菌效果.     

2014~2016年嗜麦芽窄食单胞菌感染临床分布及耐药性分析

目的 分析我院2014年~2016年所分离嗜麦芽窄食单胞菌在临床标本中的分布和对常用抗菌药物的耐药性。方法 用西门子MicroScan WalkAway96全自动微生物鉴定/药敏测试系统进行细菌鉴定和药物敏感试验,依照CLSI制定的最新判断标准判断药敏试验结果。结果 3年间共检出109株嗜麦芽窄食单胞菌,主要来源于呼吸道痰标本,占83.49%,ICU病区检出最高,占36.70%;其次为急诊科、血液科和神经外科。嗜麦芽窄食单胞菌对复方新诺明和左氧氟沙星敏感性较高,分别为88.99%和79.82%;耐药率较高的是头孢他啶,为74.31%。结论 我院2014年~2016年嗜麦芽窄食单胞菌主要集中在ICU,其次为血液科和神经外科,以呼吸道感染居多。药敏结果显示对复方新诺明和左氧氟沙星敏感性好,替卡西林/棒酸和头孢他啶耐药率较高。     

嗜麦芽窄食单胞菌整合子I和ISCR1研究及ERIC-PCR基因分型

目的了解临床分离嗜麦芽窄食单胞菌的整合子I和ISCR1的分布情况及其基因型。方法分离临床85株嗜麦芽窄食单胞菌,用WHONET5.4分析菌株药敏情况,采用ERIC-PCR方法进行基因分型。采用PCR检测整合酶I、整合子I、ISCR1以及ISCR1携带的耐药基因。结果嗜麦芽窄食单胞菌对亚胺培南、氨曲南、庆大霉素、阿米卡星高度耐药,整合子I阳性菌株和整合子I阴性菌株对复方新诺明耐药性差异有统计学意义。85株嗜麦芽窄食单胞菌12株整合酶阳性,11株整合子I阳性,2株ISCR1和ISCRI携带的耐药基因阳性,ERIC-PCR分为75个基因型。结论整合子I在嗜麦芽窄食假单胞菌中介导复方新诺明耐药性方面有重要作用,ERIC-PCR是研究临床分离嗜麦芽窄食假单胞基因分型的有效方法之一。     

氟喹诺酮类药物对嗜麦芽窄食单胞菌的抗菌活性及CCCP对其的影响

目的 :了解氟喹诺酮类药物 (FQNS)对嗜麦芽窄食单胞菌的抗菌活性及氰氯苯腙 (CCCP)对其抗菌活性的影响。方法 :采用琼脂二倍稀释法测定抗菌药物的最低抑菌浓度 (MIC) ,同时测定CCCP对FQNS的MIC值的影响。结果 :1 4 4株嗜麦芽窄食单胞菌对多种常用抗生素呈现多重耐药 ,但对复方新诺明、替卡西林 /克拉维酸以及FQNS的耐药率较低 ,尤其是新型FQNS具有很高的抗菌活性 ,其中抗菌活性由高到低依次是加替沙星、司帕沙星、左氧氟沙星和环丙沙星。主动外排泵抑制剂CCCP在体外能增强FQNS的抗菌活性 ,主动外排机制不仅存在于FQNS耐药…     

135株嗜麦芽寡养单胞菌的临床分布及耐药性分析

目的了解嗜麦芽寡养单胞菌的临床分布及耐药特征，为临床合理用药提供依据。方法用常规方法对2005—2008年本院临床标本进行细菌的培养、分离，用MicWalK40进行细菌的鉴定，以美国临床实验室标准化研究所推荐的纸片扩散法（K—B法）进行药物敏感性试验，Whonet 5．0进行数据统计。结果135株嗜麦芽寡养单胞菌主要来自痰占76．3％（103／135），分布以重症监护室（ICU）为主占80．0％（108／135）；对6种抗菌药物的敏感率分别为替卡西林／棒酸36．3％、氯霉素57．8％、头孢他啶64．4％、左氧氟沙星75．6％、复方新诺明77．0％及米诺环素100．0％。结论临床分离的嗜麦芽寡养单胞菌主要来自痰标本，分布以ICU为主，米诺环素、复方新诺明、左氧氟沙星、头孢他啶对嗜麦芽寡养单胞菌具有较好的体外抗菌活性。     

88株嗜麦芽窄食单孢菌氨基糖苷类耐药性及其修饰酶基因分析

目的明确2005年8月至2007年7月临床分离的88株嗜麦芽窄食单孢菌对氨基糖苷类抗生素的耐药性及其修饰酶基因的存在状况。方法用Kirby—Bauer（K-B）药敏试验分析88株嗜麦芽窄食单孢菌对3种常用氨基糖苷类抗生素阿米卡星、庆大霉素、妥布霉素的敏感性，再用聚合酶链反应（PeR）法分别扩增常见的8种氨基糖苷修饰酶基因。结果这88株嗜麦芽窄食单孢菌同时对3种氨基糖苷类抗生素都耐药的有19株．占21．6％（19／88）；同时对这3种抗生素都敏感的有12株，占13．6％（12／88）；对阿米卡星，庆大霉素和妥布霉素的耐药率分别为22％，69．3％和58％，敏感率分别为70％，22．7％和23．9％。氨基糖苷修饰酶基因aac（3）-Ⅰ和ant（4′）-Ⅱ未检测到；其余6种基因中，aac（3）-Ⅱ，ant（2′′）-Ⅰ，aae（6′）-I，aae（3）-Ⅲ，aae（3）-Ⅳ和aac（6′）-Ⅱ）的检出率分别是2．3％，5．7％，8％，11．4％，11．4％和12．5％。结论临床分离的嗜麦芽窄食单孢菌对氨基糖苷类修饰酶携带率不是很高，但氨基糖苷类抗生素耐药情况却很严重。     

嗜麦芽寡养单胞菌所产金属β-内酰胺酶的特性

嗜麦芽寡养单胞菌 (Stenotroph omonasmaltophilia)是一种条件致病菌 ,对临床常用抗菌药物耐药。产金属 β 内酰胺酶 (MBL)使其对卡巴培南类及头孢菌素类耐药。我们采用纸片协同法筛选出产MBL的可疑菌株 ,以等电聚焦确定其等电点 ,并对MBL基因进行克隆、测序 ,从生化及分子水平了解嗜麦芽寡养单胞菌所产金属β 内酰胺酶的特性。收集 1998年 1月～ 2 0 0 2年 10月重庆医科大学第一附属医院从院内感染病人标本分离的嗜麦芽寡养单胞菌共 30株 ,用E试验法筛选产金属 β 内酰胺酶菌株 ,以等电聚焦和酶抑制剂对酶等电点的影响实验确定MBL的…     

嗜麦芽窄食单胞菌对氟喹诺酮类抗菌药的分子耐药机制研究

目的:研究嗜麦芽窄食单胞菌拓谱异构酶II和IV的突变与氟喹诺酮类药物的耐药关系,为新药开发提供实验依据.方法:选择对环丙沙星MIC>2mg/L且主动外排机制阴性的菌株,对其gyrA和parE的喹诺酮决定区域基因分别进行PCR扩增,纯化后直接测序.结果:嗜麦芽窄食单胞菌在DNA解旋酶最常见的83位和87位没有突变,同时在GyrA的整个QRDRs没有氨基酸的改变,并且其83位是Gln而不是其它革兰阴性菌常见的Ser或Thr.5株菌中的parE各有1株菌在402和432突变,但是该突变与FQNS耐药不相关,未观察到Valdezate研究中的1/2菌株的parE突变频率高且主要集中在437,465,477和485位的现象.结论:嗜麦芽窄食单胞菌对FQNS耐药与主动外排泵有关,可能与外膜的通透性降低有关,但与DNA解旋酶和拓谱异构酶IV的靶位点改变关系尚不明确,需进一步研究.     

Stenotrophomonas maltophilia: antimicrobial resistance and molecular typing of an emerging pathogen in a Turkish university hospital

Despite its limited pathogenicity, Stenotrophomonas maltophilia is an emerging nosocomial pathogen. This study investigated the isolation frequency, antimicrobial resistance and genotypic relationships of 205 S. maltophilia isolates from 188 patients in a university hospital between 1998 and 2003. Susceptibility profiles for 11 antimicrobial agents were determined by the NCCLS agar dilution method for non-fermentative bacteria, while enterobacterial repetitive intergenic consensus sequence (ERIC)-PCR and pulsed-field gel electrophoresis (PFGE) were used for genotyping of the isolates. Of the 205 isolates, 56.1% were isolated in the last 2 years of the study. The risk of S. maltophilia isolation was higher in intensive care units, S. maltophilia was isolated mostly (86.8%) after hospitalisation for >or= 48 h, and 90.4% of the patients had underlying diseases. Resistance levels were>60% for all antimicrobial agents tested except co-trimoxazole. High genetic diversity was found among the S. maltophilia isolates, and cross-infection with S. maltophilia was not common. Although ERIC-PCR revealed fewer genotypes than PFGE, it proved to be a rapid and easy method for S. maltophilia genotyping, and was more economical than PFGE.     

An evaluation of six-year Stenotrophomonas maltophilia infections in a university hospital

BackgroundStenotrophomonas maltophilia is a Gram-negative bacillus and opportunistic emergent pathogen causing hospital-acquired infections (HAIs). Due to risk factors such as prolonged intensive care unit stay and invasive procedures, it has become one of the leading causes of HAIs.ObjectiveThe aim of this study was to evaluate the epidemiology of S.maltophilia infections over a six-year period at Düzce University Hospital, Turkey.MethodsThe incidence, clinical characteristics, antimicrobial susceptibility and outcomes of nosocomial S. maltophilia infections during this period were retrospectively analyzed.ResultsDuring the study period, 67 samples obtained from 61 patients were identified. Pneumonias (82%) were the most common HAIs, followed by bloodstream infections (10.5%), urinary tract infections (3%), skin and soft tissue infections (3%) and surgical site infection (1.5%). Admission to intensive care, hospitalization exceeding 30 days, and previous use of broad-spectrum antibiotics constituted risk factors. Resistance to cotrimoxazole (6%) was lower than that to levofloxacin (18%).ConclusionThe most important risk factors for S.maltophilia infection in patients are previous exposure to antibiotics, prolonged hospitalization and invasive procedures such as mechanic ventilation. Discharging patients as early as possible with the rational use of antibiotics may be effective in reducing S. maltophilia infections and resistance rates.     

Stenotrophomonas isolates in a tertiary care centre in South India

PurposeStenotrophomonas maltophilia is an emerging multi-drug resistant pathogen increasingly isolated in India. This study aimed to identify patients from whom Stenotrophomonas maltophilia had been isolated and assess predictors of mortality in this population.MethodsThis was a retrospective cohort study of hospitalized patients with a positive culture for S. maltophilia over a 3-year period. Clinical details and laboratory results were assessed from hospital records. Bivariate and multivariate analysis was used to identify risk factors for mortality.ResultsOne hundred and nineteen patients (mean age 48.6 years) were included in the study. Of these, 111 patients were hospitalized for at least 48 ?hours prior to culture and 98 were admitted in the intensive care unit. Bivariate analysis revealed multiple associations with mortality, including a background of renal, cardiac, autoimmune disease, recent carbapenam use and COVID-19 infection and increasing ventilatory requirement, lower PaO₂/FiO₂ (P/F) ratio, vasopressor use, thrombocytopenia, and hypoalbuminemia at the time of positive isolate. Multivariate analysis showed that autoimmune disease [OR 27.38; 95% CI (1.39–540)], a P/F ratio of less than 300 [OR 7.58; 95% CI (1.52–37.9)], vasopressor requirement [OR 39.50; 95% CI (5.49–284)] and thrombocytopenia [OR 11.5; 95% CI (2.04–65.0)] were statistically significantly associated with increased mortality, while recent surgery and receipt of antibiotics [OR 0.16; 95% CI (0.03–0.8)] targeted against S. maltophilia were associated with decreased mortality.ConclusionStenotrophomonas maltophilia is primarily isolated in patients in the intensive care unit. In our study the need for vasopressors, autoimmune disease, lower P/F ratios and thrombocytopenia were associated with higher mortality. The association of targeted antibiotics with reduced mortality suggests that the pathogenic role of S. maltophilia should not be underestimated. This finding needs to be confirmed with larger, prospective studies.     

Spread of Stenotrophomonas maltophilia colonization in a pediatric intensive care unit detected by monitoring tracheal bacterial carriage and molecular typing

In our pediatric intensive care unit in Tours (France), intubated and ventilated inpatients are systematically monitored for tracheal bacterial colonization twice a week. This led us to detect five patients colonized with Stenotrophomonas maltophilia over a 4-month period. Molecular typing of the isolates using random amplified polymorphism DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) confirmed that four of the five isolates were genetically related. The strict isolation of carriers and improvements in hygiene measures stopped the spread. This systematic strategy prevented pulmonary nosocomial infections or allowed their early detection. Moreover, it has made it possible to assess the efficiency of care practices continuously.