大肠埃希菌宽宿主谱噬菌体生物学特性的比较研究

目的比较研究1株宿主谱发生突变的宽宿主范围噬菌体与其原始野生型单一宿主谱噬菌体株的生物学特性改变,探讨噬菌体识别特异性机制和将噬菌体作为生物消毒剂,应用于环境污水净化的可行性。方法利用大肠埃希菌285菌株自环境污水中筛选到1株具有宽宿主范围的噬菌体,与野生型噬菌体f2比较观察,分析宿主谱改变对噬菌体的生物学特性的影响。结果两噬菌体电镜下形态均为微球形且棱角不明显,但(噬菌体XY)颗粒偶见短尾,大小形态不均一;噬菌体f2和噬菌体XY的抗血清K值分别为30.1和41.5;噬菌体XY与噬菌体f2的相关度较低(K值比<0.45);结果显示,噬菌体XY较噬菌体f2具有吸附速率高、潜伏期短、裂解量大的特点;两噬菌体均为约6 000 bp的单链RNA噬菌体,但宿主谱改变前后它们的RAPD-PCR及RT-PCR差异有统计学意义;噬菌体XY对环境水样本中的大肠埃希菌杀灭率可达到36.75%~56.28%,而噬菌体f2则为19.19%~35.06%(P<0.01)。结论宽宿主谱噬菌体较噬菌体f2在超微形态、一步生长曲线、抗原性等方面差异均有统计学意义;微生物杀灭效果也明显高于噬菌体f2(P<0.01);核酸分析证实其宿主特异性裂解效应已从基因水平发生了变化。     

外环境与医院感染大肠杆菌耐药相关性研究

目的 研究医院感染(NI)大肠杆菌(E．coli)与医院环境E．coli之间的相关性，以了解NI病原菌来源。方法 比较E．coli医院感染株(院感株)、社区感染株、环境株的耐药谱以及随机引物扩增多态性基因分型(RAPD)型别之间的差异，判断三者之间的相关性。结果 收集到E．coli院感株5株，社区感染株17株；1190份环境样中共分离到E．coli 72株，环境分离率为6．05％。耐药率、耐药谱与RAPD分型综合研究表明：在外科院感株和环境株之间有相关性，E．coli NI主要是外源性感染；其它科室，从时间和空间上来看，院感株、社区感染株和环境株之间无相关性，E．coli NI以内源性感染为主。结论 在E．coli NI中外源性和内源性途径均存在。     

O157大肠杆菌溶原性噬菌体的初步探讨

[目的]探讨E．coli O157携带噬菌体的情况及噬菌体特性。[方法]从3种血清型E．coli O157菌株中分离筛选噬菌体，并分别从O157：H7和O157：NM检出的噬菌体中各筛选出5株对同源菌进行裂解试验。[结果]3种不同血清型的E．coli O157携带噬菌体的检出率O157：H7为29．9％，对同源菌的裂解率为75．0％；O157：NM检出率为17．3％，对同源菌的裂解率为23．1％；O157：H7为8．1％。[结论]3种不同血清型的E．coli O157均携带温和噬菌体，裂解力较差，噬菌斑均为磨玻璃状，符合前噬菌体的特性。     

转导（Transduction）

由噬菌体介导的细菌间基因的转移叫转导。携带来自宿主菌和自身基因的噬菌体叫转导噬菌体。由逆转录病毒获得并转移真核细胞核酸序列的过程也可叫转导。噬菌体携带宿主细胞随机DNA片段所进行的转导叫一般性转导，噬菌体携带宿主细胞特异性基因或基因群所进行的转导叫特异性转导。总之，一切通过病毒转送遗传信息的过程均称为转导。     

铜绿假单胞菌医院感染与外环境关系的研究

目的 分析比较铜绿假单胞菌(PA)医院感染与外环境中PA的相关性，以了解医院感染病原菌来源。方法 比较PA医院感染株、社区感染株、环境株的耐药谱以及随机引物扩增多态性基因分型(RAPD)型别之间的差异，判断三者之间的相关性。结果 收集PA医院感染株18株，社区感染株17株；1190份环境样中共分离到PA21株，环境分离率为1．76％。耐药谱与RAPD分型表明医院感染株与社区感染株、环境株之间无明显相关性。结论 铜绿假单胞菌医院感染可能以内源性途径为主。     

随机扩增DNA多态性技术在粘质沙雷菌分型研究中的应用

目的应用随机扩增DNA多态性(RAPD)技术对医院感染的粘质沙雷菌进行基因分型。方法对心外科ICU病房5例术后发热患者血液中分离出的粘质沙雷菌，用VITEK细菌全自动分析仪进行系统生化鉴定，K-B纸片扩散法进行药敏试验，用2条不同的随机引物进行RAPD基因分型。结果5株粘质沙雷菌药敏谱全部一致，2条随机引物中一条引物未能分型，另一条引物可分为2个基因型。其中，4株菌扩增出相同带谱，为同基因型；1株菌有独特的带谱为另一种基因型。结论本次调查的5株粘质沙雷菌有2种RAPD基因型，其中4株为相同基因型，证实存在感染流行。     

江苏省2001年～2003年伤寒副伤寒监测及流行病学分析

目的：了解江苏省2001年～2003年伤寒副伤寒疫情特点及菌株的分型耐药情况，为防治工作提供依据。方法：对江苏省2001年～2003年的疫情进行流行病学分析，对181株伤寒副伤寒菌株进行耐药性检测，对其中的136株伤寒菌株进行噬菌体分型。结果：江苏省2001年～2003年的年平均发病率为2．24／10万，发病以5～10月份为多，苏州、南通、盐城和扬州4市是高发地区，人群分布以农民和学生为主，男女发病没有明显差异。136株伤寒菌株可分为14个型，分型率73．21％，噬菌体菌型主要为J1、M1和D2，分别占可分型菌总数的14．29％、13．39％和10．71％。不同年份伤寒菌株的分型率不同。伤寒、副伤寒菌株均对磺胺、红霉素、复方新诺明和氨苄青霉素具有不同程度的耐药性，副伤寒菌株的耐药谱较伤寒菌株宽。结论：江苏省2001～2003年伤寒疫情呈逐年下降趋势，高发季节、高发地区和人群职业分布无明显变化，但男性发病年轻化。噬菌体分型结果显示江苏省的主要流行菌型变化不大，除以往耐药的M1型菌株外，J1型菌株的耐药性也普遍较高，且有多重耐药现象；副伤寒甲出现的比例逐年增高，且其耐药率及耐药谱均较伤寒菌株高或宽。     

噬菌体裂解系统及其相关蛋白的研究进展

1896年,Hankin描述了一种可以限制霍乱流行、传播并有抗菌活性的物质-抗霍乱弧菌素,随后Gamaleya在枯草杆菌中发现了类似现象[1].噬菌体分别由Twort于1915年和Felix d'Herelle于1917年独立发现[2].噬菌体是感染细菌、真菌、放线菌或螺旋体等微生物的特异性病毒,即具有不同特性的、显示出长时期多种变异、适应和分化特征的超微生物.其中95%是双链DNA有尾噬菌体;其他少数噬菌体的颗粒大小、蛋白外壳和生活周期等差别很大.大多数噬菌体导致宿主细胞裂解,丝状噬菌体f1和M13等并不裂菌.噬菌体对其宿主的破坏作用很早就用于杀灭致病菌的研究.随着细菌耐药性的出现,对多种耐药性病原菌进行了很多探索性噬菌体治疗研究,现已有数百例关于噬菌体成功治疗人体感染的文献报道[3].噬菌体活体治疗存在很大的局限性,为寻找安全可靠的替代治疗方案,噬菌体裂解机制的研究越来越受到关注.     

辽宁省鼠伤寒沙门氏菌噬菌体分型及耐药谱监测

辽宁省自１９８８年以来从不同地区、不同来源标本中分离到１５１株鼠伤寒 沙门氏菌,可分为１４个菌体型,分型率为９７．３５％,其中４７７４为我省优势噬菌体型,占暴发株的５７．８０％。１５１株鼠伤寒沙门菌耐药谱复杂,所有菌株匀呈三耐以上。     

耐青霉素大肠杆菌噬菌体的筛选及其特性研究

为了筛选耐青霉素大肠杆菌的相应噬菌体,并对其进行基本特性研究,从生活污水和河水中筛选出能裂解耐50μg/ml青霉素大肠杆菌的噬菌体,其噬菌斑直径为9~10 mm。环境扫描电子显微镜显示其为蝌蚪状,头部为二十面体,直径约为244 nm,尾部约长183 nm,尾宽约61 nm。电泳结果表明其核酸为DNA,总量约10 kb左右。对该噬菌体对实验室污水处理效果进行了初步研究,显示1 h内188个噬菌体可以裂解一个大肠杆菌,大肠杆菌杀灭率达85.6%。     

饮水试验中二氧化氯对大肠杆菌F2噬菌体消毒效果的实验研究

[目的]研究二氧化氯对大肠杆菌F2噬菌体消毒效果及将大肠杆菌F2噬菌体作为评价消毒效果的指示微生物的可行性进行评价,同时观察残留二氧化氯浓度衰减速度。[方法]采用悬液定量杀菌试验,观察大肠杆菌F2噬菌体对常用化学消毒剂二氧化氯的抵抗力。[结果]二氧化氯投加量为1 mg/L时,作用10 min,对大肠杆菌F2噬菌体的杀灭对数值4.0;作用30 min,染菌水样中残留二氧化氯浓度分别降解为0.35 mg/L;二氧化氯投加量为2 mg/L时,作用3 min,对大肠杆菌F2噬菌体的杀灭对数值4.0;作用30 min,染菌水样中残留二氧化氯浓度分别降解为0.68 mg/L。[结论]大肠杆菌F2噬菌体对二氧化氯消毒剂,在常规剂量作用下,可有效灭活大肠杆菌F2噬菌体。因此选择大肠杆菌F2噬菌体作为病毒消毒试验的指示微生物,可明显缩短病毒灭活效果评价周期。二氧化氯衰减速度随浓度和时间的变化而加快。     

Reduction of microorganisms in sewage effluent using hypochlorite and peracetic acid as disinfectants.

A comparative study on peracetic acid and sodium hypochlorite in inactivating bacteria and viruses was carried out. Therefore the disinfection actions of peracetic acid, in comparison with sodium hypochlorite, was evaluated against the usual indicators of faecal contamination, the pathogen Salmonella, Pseudomonas spp., bacteriophages anti-Escherichia coli, F+/phage and the phage of Bactericides fragilis B40-8 and enteroviruses. Under the experimental conditions, no representative results were obtained for enteroviruses and phages because of their low concentration in the sewage effluent. On the other hand, the indicator organisms were reduced substantially by the sodium hypochlorite and peracetic acid concentrations, while more variable results were obtained against Pseudomonas and bacteriophages anti-Escherichia coli.     

Bacteriophage isolated from feedlot cattle can reduce Escherichia coli O157:H7 populations in ruminant gastrointestinal tracts

Escherichia coli O157:H7 can live undetected in the gut of food animals and be spread to humans directly and indirectly. Bacteriophages are viruses that prey on bacteria, offering a natural, nonantibiotic method to reduce pathogens from the food supply. Here we show that a cocktail of phages isolated from commercial cattle feces reduced E. coli O157:H7 populations in the gut of experimentally inoculated sheep. A cocktail of phages was used in order to prevent the development of resistance to the phages. In our first in vivo study we found that our cocktail of phages reduced E. coli O157:H7 populations in the feces of sheep (p < 0.05) by 24 hours after phage treatment. Upon necropsy, populations of inoculated E. coli O157:H7 were reduced by phage treatment in both the cecum (p < 0.05) and rectum (p < 0.1). In our second in vivo study, several ratios of phage plaque-forming units (PFU) to E. coli O157:H7 colony-forming units (CFU) were used (0:1, 1:1, 10:1, and 100:1 PFU/CFU) to determine the most efficacious phage dose. A 1:1 ratio of phage to bacteria was found to be more effective (p < 0.05) than either of the higher ratios used (10:1 or 100:1). Ruminal levels of E. coli O157:H7 were not significantly reduced (p > 0.10) in any of the studies due to relatively low inoculated E. coli O157:H7 ruminal populations. Our results demonstrate that phage can be used as a preharvest intervention as part of an integrated pathogen reduction scheme.     

The effect of wetland vegetation on the survival of Escherichia coli, Salmonella typhimurium, bacteriophage MS-2 and polio virus

A study was conducted to examine the role of aquatic plants used in constructed wetlands on the survival of enteric bacteria and viruses. Four small-scale wetland systems, receiving fresh water and two other wetland systems, receiving secondary unchlorinated sewage were used in this study. Fresh water and secondary sewage without the presence of any aquatic plants were used as controls. Escherichia coli, Salmonella typhimurium, bacteriophage MS-2 and poliovirus were added to the waters collected from the wetlands and controls. The presence of aquatic plants significantly increased the die-off of both bacteria in fresh water and secondary sewage. No significant difference in the die-off of E. coli and S. typhimurium was observed in water from wetlands with different types of plants in freshwater. However, there was a significant difference in the die-off of E. coli in water with aquatic plants when sewage was used. The presence of the plants significantly increased the inactivation of MS-2 and poliovirus. Additional work on the survival of E. coli indicated that the plausible mechanism of bacterial die-off in constructed wetlands is through increased microbial competition or predation.     

The effect of wetland vegetation on the survival of Escherichia coli, Salmonella typhimurium, bacteriophage MS-2 and polio virus

A study was conducted to examine the role of aquatic plants used in constructed wetlands on the survival of enteric bacteria and viruses. Four small-scale wetland systems, receiving fresh water and two other wetland systems, receiving secondary unchlorinated sewage were used in this study. Fresh water and secondary sewage without the presence of any aquatic plants were used as controls. Escherichia coli, Salmonella typhimurium, bacteriophage MS-2 and poliovirus were added to the waters collected from the wetlands and controls. The presence of aquatic plants significantly increased the die-off of both bacteria in fresh water and secondary sewage. No significant difference in the die-off of E. coli and S. typhimurium was observed in water from wetlands with different types of plants in freshwater. However, there was a significant difference in the die-off of E. coli in water with aquatic plants when sewage was used. The presence of the plants significantly increased the inactivation of MS-2 and poliovirus. Additional work on the survival of E. coli indicated that the plausible mechanism of bacterial die-off in constructed wetlands is through increased microbial competition or predation.     

两种方法检测壁挂式食具消毒柜对微生物杀灭效果观察及研究

〔目的〕用两种方法检测壁挂式食具消毒柜对微生物的杀灭效果。〔方法〕按照《食具消毒柜安全与卫生要求》(GB 17988-2 0 0 0 )的载体定量杀菌试验[1 ] 和《消毒技术规范》(2 0 0 2版 )载体定量杀菌试验[2 ] 的方法 ,观察了消毒柜工作不同时间对大肠杆菌、金黄色葡萄球菌、现场试验 (模拟现场试验 )的杀灭效果。〔结果〕用前种方法检测消毒柜满载时工作 60min(消毒 3 0min、烘干 3 0min ,下同 ) ,对染于玻片上大肠杆菌、金黄色葡萄球菌的杀灭率均达到 10 0 %;工作 60min ,对餐具表面自然菌的杀灭率均为 10 0 %,均未检出金黄色葡萄球菌、志贺菌、沙门菌、乙型溶血性链球菌。〔结论〕用后种方法检测消毒柜工作 60min ,对染于玻片上的大肠杆菌的杀灭对数值均 >5 .0 0 ;工作 75min(消毒 45min、烘干 3 0min ,下同 )对染于玻片上的金黄色葡萄球菌的杀灭对数值分别为 1.5 2 -1.77,对染于餐具表面大肠杆菌的杀灭对数值分别为 1.99-3 .64、1.83 -3 .80、1.79-3 .5 2。     

Roles for non-human primate-associated phage diversity in improving medicine and public health

Mammals harbor trillions of microorganisms and understanding the ecological and evolutionary processes structuring these ecosystems may provide insights relevant to public health and medicine. Comparative studies with our closest living relatives, non-human primates, have provided first insights into their rich bacteriophage communities. Here, I discuss how this phage diversity can be useful for combatting antibiotic-resistant infections and understanding disease emergence risk. For example, some primate-associated phages show a pattern suggesting a long-term co-divergence with their primate superhosts—co-diverging phages may be more likely to exhibit a narrow host range and thus less useful for phage therapy. Captive primates lose their natural phageome, which is replaced by human-associated phages making phages an exciting tool for studying rates of microorganism transmission at human–wildlife interfaces. This commentary tackles avenues for selecting phages for therapeutic interventions based on their ecological and evolutionary history, while discussing frameworks to allow primate-associated phages to be incorporated into the arsenal of clinicians.     

抗菌洗液杀菌效果及毒性实验研究

目的研究以有效碘为主要成分的抗菌洗液的杀菌效果和毒性。方法采用悬液定量杀菌实验及动物毒性实验,对该抗菌洗液杀菌效果及毒性进行实验观察。结果以含500 mg/L有效碘的抗菌洗液作用1.5 min,对悬液内的大肠埃希菌、金黄色葡萄球菌、铜绿假单胞菌的平均杀灭率均>99.99%;对白色假丝酵母菌作用1.5 min,平均杀灭对数值均>99.99%;将抗菌洗液于37℃存放90 d,有效碘的下降率为4.15%;小鼠急性经口LD50值>5000 mg/kg,抗菌洗液原液对家兔皮肤刺激实验指数为0,属于无刺激性。结论该抗菌洗液性能稳定,对细菌繁殖体有良好的杀菌效果,属无毒无刺激性洗液。     

臭氧灭活水中f_2噬菌体的效果研究

目的 研究臭氧灭活水中f_2噬菌体的效果.方法 分别向不同pH值(6.5～8.5)、不同色度(O-30度)的臭氧水(通气5～30min)中加入f_2噬菌体悬液原液(终浓度为10~4～10~5pfu/ml),作用5、15、30min后进行f_2噬菌体计数,并计算灭活率.结果 在相同的通气条件下,pH值对臭氧灭活f_2噬菌体效果的影响并不明显;随着色度的提高,臭氧对f_2噬菌体的灭活效果有所降低.结论 高色度的水质条件不利于臭氧灭活水中f_2噬菌体.

Abstract：

Objective To observe the efficacy of ozone in the inactivation of f_2 phage in water. Methods The concentration of ozone in water was measured by iodometry. During the experiment, the suspension of f_2 phage was added in the ozonized water, at 5,15,30 min, the f_2 phage inactivation rate was calculated. Results Under the same condition of ventilation,in the range of pH regulated in the drinking water sanitary standard,the effect of pH on the inactivation of f_2 phage was not obvious, while the chromaticity of water could remarkably influence the inactivation of f_2 phage. Conclusion The higher chromaticity of water can interfere the inactivation of f_2 phage in water by ozone.     

Impact of bile salts on coevolutionary dynamics between the gut bacterium Escherichia coli and its lytic phage PP01

Although host and parasites are typically embedded in complex abiotic and biotic environments our understanding of how environmental variation impacts on host-parasite interactions, including antagonistic coevolution (AC) is poorly understood. Nonetheless, previous studies using bacteria and bacteriophages have shown that variation in just one abiotic parameter can have profound effects not only on the type of AC dynamics observed but also the time-frames over which AC interactions can persist. Here, we investigated the effect of an important component of the abiotic human gut environment, bile salts, on AC dynamics between the bacterium Escherichia coli and the lytic phage PP01 in an in vitro model system. In the absence of bile salts E.coli and PP01 coevolved in a manner that is consistent with a directional arms race dynamic (ARD), with bacteria and phages evolving increasing resistance and infectivity ranges through time. However, in the presence of bile salts, evidence of directional coevolution was weaker and more variable across replicate communities. These effects may be explained, in part, by the negative effect of bile salts on both host and parasite population sizes; lower population sizes for both bacteria and phages will reduce encounter rates which in turn could mitigate the benefits of generalism in both host and parasite resistance and infectivity ranges that are observed for ARDs. The negative effect of bile salts on phage population size may also be partially independent of host population size as bile salts was found to negatively impact phage viability in the absence of bacteria, as well as reducing phage adsorption efficiency. Differences in bacterial morphological diversity between treatments were also noted, with the emergence of mucoid colonies in both bile salts and non-bile salts treatments but only in the presence of phages. These data contribute to the growing body of knowledge on how environmental variation can impact on interactions between hosts and parasites. More specifically, these results are particularly relevant to our understanding of how bacteria-phage interactions may be affected by different abiotic factors relevant to the complex environment of the human gut and have clear implications for the development of phage as therapeutics to target members of the gut microbiota and/or intestinal pathogens.