汕头地区耐亚胺培南铜绿假单胞菌耐药分析

目的：了解汕头地区对亚胺培南耐药的铜绿假单胞菌（PA）的耐药情况及耐药机制。方法：收集临床分离耐亚胺培南的PA共141株，双纸片协同实验检测金属酶表型，PCR法检测外膜孔蛋白OprD2和金属β内酰胺酶（IMP、VIM、SPM）基因。结果：耐亚胺培南的铜绿假单胞菌均为多重耐药茵，对头孢哌酮／舒巴坦的耐药率较低，未发现产金属酶菌株，仅22株菌株扩增出OprD2基因。结论：头孢哌酮／舒巴坦可作为本地区临床治疗耐亚胺培南铜绿假单胞茵所致感染的首选经验用药，OprDa表达减少或不表达可能是临床分离铜绿假单胞茵对亚胺培南耐药的主要机制。     

革兰阴性菌对头孢替坦的耐药性分析

目的了解临床分离革兰阴性菌对头孢替坦的耐药性。方法收集2012年1月至2013年6月从医院各种临床标本中分离的革兰阴性菌,使用VITEK2-compact微生物全自动分析仪进行鉴定和药敏试验,对结果进行回顾性调查。结果分离出革兰阴性菌1 045株,其中肠杆菌科细菌627株,占60.0%;非发酵菌402株,占38.5%。分离前3位的细菌分别为大肠埃希菌（27.7%）、铜绿假单胞菌（20.2%）、肺炎克雷伯菌（14.5%）。肠杆菌科细菌对头孢替坦耐药率低,53.3%的大肠埃希菌和29.6%的肺炎克雷伯菌产超广谱β-内酰胺酶（ESBLs）、产ESBLs大肠埃希菌和肺炎克雷伯菌对头孢替坦耐药率均低于6.0%。非发酵菌中铜绿假单胞菌和鲍曼不动杆菌对头孢替坦的耐药率均高于90.0%。结论头孢替坦可以作为临床治疗产ESBLs细菌感染性疾病的一种经验性治疗方案。     

铜绿假单胞菌对亚胺培南耐药机制的研究

铜绿假单胞菌是引起医院内感染的主要病原菌。亚胺培南(IMP)作为革兰阴性菌的最有效的抗生素，随着青霉烯类抗生素的广泛应用，铜绿假单胞菌的耐药菌株逐渐增多，给临床治疗带来困难。这与铜绿假单胞菌的主动外排机制以及特异性膜蛋白OprD2的缺失有关，能够水解碳青霉烯类抗生素的新β-内酰胺酶一金属酶的产生，对碳青霉烯类抗生素的使用造成了更大威胁。本研究分析耐亚胺培南铜绿假单胞菌产生金属酶合并外膜蛋白OprD2的缺失。     

革兰阴性菌耐药的分子生物学机制及防治对策

近年来 ,革兰阴性菌的耐药性在临床上日渐突出 ,尤其是多重耐药株出现后医院内感染的增多 ,使抗感染治疗面临巨大挑战。探讨革兰阴性菌耐药的分子生物学机制 ,对临床控制耐药菌株感染及研究防治对策具有指导意义。1　细菌耐药机制1 .1　灭活酶或钝化酶　革兰阴性菌产生灭活酶或钝化酶主要包括 :β 内酰胺酶、氨基糖苷类钝化酶、氯霉素钝化酶、大环内酯类 林可霉素类钝化酶等。1 .1 .1　β 内酰胺酶　β 内酰胺酶 (BLA)是革兰阴性菌对 β 内酰胺类抗生素耐药的主要原因之一。根据Bush功能性分类及Ambler分子结构分类 ,将BLA分为 1 4组…     

耐亚胺培南铜绿假单胞菌的分布及耐药性分析

目的:了解耐亚胺培南铜绿假单胞菌的感染情况及其耐药特性,为临床合理使用抗生素及防治耐药菌感染提供参考。方法:收集汕头大学医学院第一附属医院2005年4月到2006年4月间分离的92株耐亚胺培南的铜绿假单胞菌,VITEK-60全自动微生物鉴定仪及其配套试剂(GNS-506、GNS-120、GNS-114)进行细菌鉴定及测定其对多种抗生素的耐药性,肉汤二倍稀释法测定其对亚胺培南的MIC值。结果与结论:耐亚胺培南的铜绿假单胞菌感染主要发生神经外科、外科ICU、呼吸科及ICU和神经内科,对亚胺培南的耐药多为中低度耐药(MIC≤32 mg.L-1),对其它多种抗生素的耐药率均达到100%,仅头孢哌酮/舒巴坦复合制剂保持了较高的敏感率,作为经验性用药可考虑选用。     

老年人亚胺培南耐药铜绿假单胞菌耐药性研究

目的 明确我院老年病人临床分离铜绿假单胞菌的耐药性、同源性及耐碳青霉烯菌株的基因型。方法 收集我院2006年5月-2009年5月自临床老年病人分离的262株铜绿假单胞菌,纸片扩散法测定其对16种抗菌药物的耐药性;琼脂稀释法和E test法测定耐碳青霉烯菌株对14种抗菌药物的MIC值,PCR扩增及克隆测序分析金属酶基因型。脉冲场凝胶电泳(PFGE)分析携带金属酶基因型菌株的同源性。结果 262株铜绿假单胞菌中筛选到104株耐碳青霉烯。104株耐碳青霉烯铜绿假单胞菌对氨苄西林/舒巴坦、头孢哌酮/舒巴坦两个含舒巴坦制剂药物耐药率分别为78.9％和35.9％,对多黏菌素E耐药率最低为6.0％,对米诺环素耐药率58.3％,其余抗菌药物耐药率均大于70.0％;104株亚胺培南耐药铜绿假单胞菌中12株携带金属酶基因,10株检测到有携带VIM-2基因的1类整合子。PFGE分型中12株菌株属于5个克隆株。结论 在我院流行的亚胺培南耐药铜绿假单胞菌中,金属酶基因不是最主要的基因型,金属β-内酰胺酶均为VIM-2型金属酶,耐药基因盒分布于不同的1类整合子中,整合子播散是最主要的流行方式。     

噬菌体治疗实验性小鼠耐亚胺培南铜绿假单胞菌感染的研究

目的探讨噬菌体治疗耐药性铜绿假单胞菌感染的疗效.方法以BALB/c小鼠为实验动物,建立耐药性铜绿假单胞菌全身感染模型,应用体外试验所筛选的宽噬噬菌体进行治疗.结果噬菌体在感染复数（multiple of infection,MOI）≥0.01时能有效杀灭铜绿假单胞菌,显著提高小鼠生存率.延迟治疗3 h仍有40%的生存率.结论通过对小鼠生存率、噬菌体在体内分布及机体对噬菌体的免疫反应等指标的观察分析,噬菌体制剂简捷高效,对机体正常组织无毒副作用,从而为临床治疗全身或局部铜绿假单胞菌感染提供了新途径.     

美罗培南等18种β—内酰胺类抗生素对产酶株的抗菌作用

目的 评价美罗培南等18种β-内酰胺类抗生素对产酶株的抗菌作用及β-内酰胺酶稳定性。方法 以琼脂二倍稀释法进行体外抗菌实验，采用紫外分光光度法比较β-内酰胺酶对抗生素的相对水解率，结果 AMOX／SBT2：1联合对质粒介导的标准产酶株作用优于各单药；对产TEM型β-内酰胺酶菌株的抗菌活性强于产SHV型酶菌株；且强于AMP／SBT2：1，与PIP／TAZ8：1相近，第三代头孢菌素对产ESBLs菌株作用明显减弱甚至不敏感，AMOX／SBT等合剂则对产ESBLs菌株有较强抗菌活性，但对产染色体介导的D31、K1等菌株MIC值降低不明显，MRP、IMP对酶高度稳定。结论 将碳烯青霉素美罗培南或AMOX／SBT等β-内酰胺类抗生素—酶抑制剂合剂用于产ESBLs菌株感染的治疗，可能具有良好的抗菌效果。     

耐碳青霉烯类革兰阴性菌对头孢他啶/阿维巴坦的耐药性及产酶表型分析

目的 分析耐碳青霉烯类革兰阴性菌(CRO)对头孢他啶/阿维巴坦(CAZ/AVI)的耐药特点及产酶表型,为临床合理用药及感染防控提供指导。方法 收集2020年1月至2021年9月临床分离的CRO 206株,采用酶抑制剂增强试验和酶免疫层析法检测碳青霉烯酶分型,纸片扩散法(K-B法)检测CAZ/AVI敏感性,并用E-test法对抑菌圈直径为20～22mm的菌株进行复核。结果 206株CRO菌株经鉴定为耐碳青霉烯类肠杆菌131株和铜绿假单胞菌75株,主要来源于神经内科、急诊EICU、神经外科等临床科室。经耐药表型检出,CRO菌株以产A类丝氨酸酶为主。对CAZ/AVI总的耐药率为17.5%(36/206),产丝氨酸酶菌株对CAZ/AVI的耐药率为5.7%(6/106),产金属酶菌株对CAZ/AVI 100%(21/21)耐药。其中肺炎克雷伯菌、铜绿假单胞菌、大肠埃希菌、阴沟肠杆菌对CAZ/AVI的耐药率分别为8.7%(9/104)、13.3%(10/75)、91.7%(11/12)、100%(6/6),产气克雷伯菌、奇异变形杆菌、产酸克雷伯菌对CAZ/AVI均100%敏感。有30株CAZ/AV...     

头孢哌酮/舒巴坦复方制剂的抗菌活性及其对细菌β-内酰胺酶的稳定性

目的 :观察头孢哌酮 (CPZ)和舒巴坦 (SBT)复方制剂 (1∶1 )的体外抗菌活性及其对细菌 β 内酰胺酶的稳定性 ,并检测SBT对 β -内酰胺酶的抑制作用。方法 :用琼脂二倍稀释法测定药物的MIC ,以头孢噻吩为酶解底物 ,用紫外分光光度计测定酶对各种抗生素的水解率。结果 :SBT显著降低CPZ对所试细菌的MIC ;所试细菌的 β 内酰胺酶对头孢噻吩和头孢哌酮的平均水解率分别为 75 .1 %和 49.1 % ,加用等浓度SBT后 ,酶对头孢哌酮的平均水解率降至 8.2 % (P <0 .0 5 )。结论 :SBT增强CPZ抗菌作用可能与抑酶作用有关头孢哌酮/舒巴坦复方制剂…     

Both membrane-bound and soluble forms of CD14 bind to Gram-negative bacteria

Tissue macrophages and their precursors – the blood monocytes – respond rapidly to a bacterial infection with the release of inflammatory mediators. These mediators are involved in the recruitment of phagocytic cells, principally neutrophils, from the blood to the site of infection. To initiate this process macrophages and monocytes must be able to detect the presence of bacteria in a reliable, but nevertheless nonspecific, fashion. It is thought that this is achieved by means of receptors on the cell surface which recognize structures common to many different bacteria. One candidate for such a “pattern recognition element” is the cell surface glycoprotein CD 14. CD 14 has been shown to bind components of the Gram-positive cell wall and it also binds soluble lipopolysaccharide released from Gram-negative bacteria. In both cases the interaction with CD 14 leads to an activation of the cell. Here we show that human peripheral blood monocytes can, in addition, bind intact Gram-negative bacteria in the presence of serum and that this process involves CD14. When CD14 expression is induced on the myelomonocytic cell line U937 by treatment with vitamin D3 the cells concomittently acquire the capacity to bind bacteria. Furthermore, a non-monocytic cell line which does not bind bacteria acquires the capacity to do so when transfected with either the human or mouse CD14 gene. This binding can be inhibited by blocking the CD14 receptor with anti-CD14 antibody or by blocking the ligand on the bacteria with soluble CD14. Finally we demonstrate binding of sCD14 to Escherichia coli. We conclude that in the presence of serum both membrane-bound and soluble forms of CD14 can bind to Gram-negative bacteria. This suggests that CD14 may play a role in the detection and elimination of intact bacteria in vivo.     

High frequency of antibiotic resistance among Gram-negative isolates in intensive care units at 10 Swedish hospitals

Objective: To investigate the resistance rates among Gram-negative isolates in Swedish intensive care units (ICUs).
Method: During 1994–95, members of the Swedish Study Group collected, on clinical indication, 502 consecutive initial isolates of Gram-negative bacteria from patients admitted to ICUs at 10 Swedish hospitals and performed minimal inhibitory concentration (MIC) determinations with the Etest. Breakpoints were defined according to the criteria of the Swedish Reference Group for Antibiotics (SRGA).
Results: The distribution of bacterial species was: Escherichia coli > Klebsiella spp. > Enterobacter spp. > Pseudomonas aeruginosa > Haemophilus spp. > Proteus spp. > Stenotrophomonas maltophilia > Citrobacter spp. > Acinetobacter > Pseudomonas. spp. > Morganella morganii > Serratia spp. Together these constituted 97% of all isolates. The frequencies of resistance for all the initial Gram-negative isolates were: ceftazidime 6.8%, cefotaxime 14.9%, ceftriaxone 18.5%, cefuroxime 44.1%, ciprofloxacin 4.2%, co-trimoxazole 17.8%, gentamicin 5.8%, imipenem 8.6%, piperacillin 20.2%, piperacillin/tazobactam 12.9% and tobramycin 5.8%.
Conclusions: Among Gram-negative isolates in Swedish ICUs, a very high frequency of resistance was seen to cefuroxime, and rather high frequencies of resistance to cefotaxime, ceftriaxone, piperacillin and piperacillin/tazobactam. These drugs cannot be recommended for further use as empirical monotherapy for severe ICU-acquired Gram-negative infections in ICUs in Sweden.     

Antibiotic adjuvants: an alternative approach to overcome multi-drug resistant Gram-negative bacteria

Abstract

Antibiotic resistance in Gram-negative pathogens has emerged and constituted a global crisis, thereby novel antibiotics and other anti-infective strategies are urgently needed. However, the growing gap between clinical need and drug innovation, coupled with the membrane permeability barrier in Gram-negative bacteria restricts the discovery of Gram-negative antibiotics. Antibiotic adjuvants approach provides an alternative and complementary strategy for new antibiotic discovery. These compounds restore or potentiate the activity of commonly used antibiotics against multi-drug resistant (MDR) Gram-negative bacteria by targeting resistance or enhancing action of antibiotics. In this review, we first provide a brief overview of antibiotic resistance mechanism in Gram-negative bacteria, which can be used to guide the development of new antibiotic adjuvants. Additionally, we summarize the recent achievements in the search for antibiotic adjuvants based on their modes of action. Lastly, we discuss our perspectives in developing next-generation adjuvants such as broad-spectrum adjuvants and hybridization approach, which would contribute to enrich our arsenal against MDR Gram-negative bacteria.     

Mediastinitis due to Gram-negative bacteria is associated with increased mortality

The aim of this study was to describe the features of a large cohort of patients with postoperative mediastinitis, with particular regard to Gram-negative bacteria (GNB), and assess their outcome. This bicentric retrospective cohort included all patients who were hospitalized in the Intensive Care Unit with mediastinitis after cardiac surgery during a 9-year period. Three hundred and nine patients developed a mediastinitis with a mean age of 65 years and a mean standard Euroscore of six points. Ninety-one patients (29.4%) developed a GNB mediastinitis (GNBm). Of the 364 pathogens involved, 103 GNB were identified. GNBm were more frequently polymicrobial (44% versus 3.2%; p <0.001). Being female was the sole independent risk factor of GNBm in multivariate analysis. Initial antimicrobial therapy was significantly more frequently inappropriate with GNBm compared with other microorganisms (24.6% versus 1.9%; p <0.001). Independent risk factors for inappropriateness of initial antimicrobial treatment were GNBm (OR = 8.58, 95%CI 2.53–29.02, p 0.0006), and polymicrobial mediastinitis (OR = 4.52, 95%CI 1.68–12.12, p 0.0028). GNBm were associated with more drainage failure, secondary infection, need for prolonged mechanical ventilation and/or use of vasopressors. Thirty-day hospital mortality was significantly higher with GNBm (31.9 % versus 17.0%; p 0.004). GNBm was identified as an independent risk factor of hospital mortality (OR = 2.31, 95%CI 1.16–4.61, p 0.0179).     

Detection of the common resistance genes in Gram-negative bacteria using gene chip technology

Objective: To design a resistance gene detection chip that could, in parallel, detect common clinical drug resistance genes of Gram-negative bacteria. Materials and Methods: Seventy clinically significant Gram-negative bacilli (Klebsiella pneumoniae, Escherichia coli, Enterobacter cloacae, Pseudomonas aeruginosa, Acinetobacter baumannii) were collected. According to the known resistance gene sequences, we designed and synthesized primers and probes, which were used to prepare resistance gene detection chips, and finally we hybridized and scanned the gene detection chips. Results: The results between the gene chip and polymerase chain reaction (PCR) were compared. The rate was consistently 100% in the eight kinds of resistance genes tested (TEM, SHV, CTX-M, DHA, CIT, VIM, KPC, OXA-23). One strain of Pseudomonas aeruginosa had the IMP, but it was not found by gene chip. Conclusion: The design of Gram-negative bacteria-resistant gene detection chip had better application value.     

烧伤中心分离菌变迁趋势及院内感染综合防控的研究

目的了解烧伤病房细菌变迁趋势,为临床抗感染治疗提供依据,制定并实施针对性综合防控措施,减少或避免院内感染的发生。方法收集2001年至2008年间本院烧伤中心不同来源标本细菌培养结果;分析对比实施院感综合防控措施前后各一年,烧伤重症监护病区（BICU）空气及环境采样细菌培养结果;通过部分耐药鲍曼不动杆菌基因分型研究,了解该菌患者间交叉传播情况。结果 8年间列前五位的病原菌分别是金黄色葡萄球菌（31.4%）、铜绿假单胞菌（19.1%）、不动杆菌（12.7%）、大肠埃希菌（6.2%）、阴沟肠杆菌（5.4%）。分年度排名显示,不动杆菌检出率近年来明显上升,2006年后升至第二位,2008年超过金黄色葡萄球菌成为检出率最高的细菌。实施院感综合防控措施前后各一年BICU空气采样合格率分别为80.5%及95.8%（P〈0.01）,环境采样细菌培养合格率分别为82.3%及97.0%（P〈0.01）,差异均有统计学意义。随机引物扩增DNA指纹图谱检测未见相同基因型鲍曼不动杆菌在患者间传播。结论 8年间烧伤病房的检出细菌谱发生明显变化,不动杆菌近年来超过以往最多见的金黄色葡萄球菌和铜绿假单胞菌上升为第一位,且主要为广泛耐药的鲍曼不动杆菌,对危重烧伤患者的救治构成威胁。综合防控措施对减少病区内感染机会,尤其是细菌的交叉传播能起到明显效果。     

壳聚糖抑菌性能的研究进展

壳聚糖是一种天然碱性多糖,因其良好的生物相容性、抗微生物性、可降解性而被广泛应用于食品工程、医药行业、工业降解等领域。而对壳聚糖抑菌性的相关研究一直以来是其特性研究中的热点。本文回顾了从2000年至2018年国内外对壳聚糖抑菌性的研究情况,对其抑菌性影响因素及抑菌机制做了总结,提出了在抑菌性研究方面的问题和观点。以期为壳聚糖抑菌性进一步研究及应用提供理论基础和科学依据。     

Characterization of Antarctic psychrotrophic bacteria with antibacterial activities against terrestrial microorganisms

Five-hundreds and eighty bacterial strains, isolated from various Antarctic marine sources and locations, were screened for antimicrobial activity against terrestrial microorganisms. Twenty-two Antarctic isolates (3.8%), mainly retrieved from the water column at Terra Nova Bay (Ross Sea), expressed antagonistic activity against one to three indicator organisms. Escherichia coli and Proteus mirabilis resulted as the more susceptible, followed by Micrococcus luteus and Bacillus subtilis. None of the isolates inhibited the growth of Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella enterica and the eukaryotic fungus Candida albicans.Active Antarctic isolates, identified by 16S rDNA sequencing and phenotypically characterized by classical methods, were phylogenetically affiliated to the Actinobacteria (16 strains) and the gamma-Proteobacteria (6 strains). Inhibition patterns, as well as phenotypic characteristics, highly vary for different isolates, even though they were affiliated to the same genus or closely related to the identical microorganism retrieved from the database, suggesting that these features were more likely strain-rather than species-specific.Results obtained from the present study confirm previous observations and highlight the potentiality of Antarctic marine bacteria as novel source of antibacterial substances.     

A novel C-type lectin with triple carbohydrate recognition domains has critical roles for the hard tick Haemaphysalis longicornis against Gram-negative bacteria

C-type lectins (CLecs) play an important role in innate immunity against invaders. In this study, a novel CLec was identified from Haemaphysalis longicornis ticks (HlCLec). HlCLec contains a signal peptide and a transmembrane region. Interestingly, HlCLec possesses three dissimilar carbohydrate recognition domains (CRDs). Each CRD contains the mutated motif of Ca²⁺-binding site 2. HlCLec mRNA was up-regulated during blood feeding, and had highest expression in the midgut and ovary. HlCLec localization was also confirmed by immunofluorescent antibody test (IFAT). HlCLec was found on the cell membrane and basal lamina of midgut and ovary. In addition, the recombinant HlCLec and individual CRDs demonstrated direct binding activity to Escherichia coli and Staphylococcus aureus; however, no growth inhibition activity was observed. Furthermore, E. coli injection after silencing of HlCLec caused drastic reduction in survival rate of ticks. These results strongly suggest the key role of HlCLec in tick innate immunity against Gram-negative bacteria.