鸟-胞内分枝杆菌复合群鸟和胞内分枝杆菌亚种对20种药物的敏感性特征及亚种间药物敏感性比较

目的 分析鸟-胞内分枝杆菌复合群鸟分枝杆菌亚种和胞内分枝杆菌亚种对20种药物的敏感性特征及比较2个亚种间的药物敏感性差异。方法 用微孔板Alamar blue显色法分别检测97株鸟分枝杆菌和172株胞内分枝杆菌对克拉霉素、卷曲霉素和利福布丁等20种药物的最小抑菌浓度,判断其敏感性,分析2个亚种菌株对20种药物的敏感性特征以及对利福霉素类、氨基糖苷类和大环内酯类内药物的交叉耐药性,并比较2个亚种对20种药物的敏感性差异。结果 对鸟分枝杆菌敏感率高于80%的药物依次是卷曲霉素(100%,97/97)、阿米卡星(97.9%,95/97)、利福布丁(96.9%,94/97)、利福平和卡那霉素(83.5%,81/97)及克拉霉素(82.5%,80/97);对胞内分枝杆菌敏感率高于80%的药物依次是阿米卡星(99.4%,171/172)、卡那霉素(95.9%,165/172)、利福布丁(95.4%,164/172)、克拉霉素(94.2%,162/172)、氯法齐明(87.2%,150/172)、卷曲霉素和罗红霉素(86.1%,148/172)及利福喷丁(82.6%,142/172)。97株鸟分枝杆菌分别有1株、1株和17株而172株胞内分枝杆菌中分别有0株、7株和6株同时对氨基糖苷类、利福霉素类和大环内酯类内各种药物同时耐药或中度敏感。鸟分枝杆菌对利福平和卷曲霉素的敏感率明显高于胞内分枝杆菌。胞内分枝杆菌对利福喷丁、妥布霉素、卡那霉素、乙胺丁醇、莫西沙星、克拉霉素、阿奇霉素和罗红霉素的敏感率均高于鸟分枝杆菌。结论 鸟和胞内分枝杆菌均对卷曲霉素、阿米卡星、利福布丁和克拉霉素敏感性较高,对胞内分枝杆菌敏感的药物多于鸟分枝杆菌,利福喷丁仅对胞内分枝杆菌抗菌性较好,而利福平仅对鸟分枝杆菌抗菌性较好,乙胺丁醇对两个亚种敏感性均较差;对同一种类的药物做药物敏感性试验可为临床医生治疗鸟或胞内分枝杆菌感染选择合适的替代药物做依据。     

tdh+与tdh?副溶血弧菌耐药表型与基因型差异分析

  目的  描述tdh+与tdh?副溶血弧菌表型与基因型耐药差异,分析耐药基因型与耐药表型之间的关系。  方法  采用K-B纸片法检测208株tdh+与73株tdh?副溶血弧菌对临床及水产养殖中常用的7类16种抗生素的敏感性,使用新一代测序技术获得实验菌株的全基因序列,通过序列比对分析基因组中耐药基因及耐药相关基因突变情况。 分析耐药表型与基因型之间的关系。  结果  tdh+菌株和tdh?菌株对亚胺培南均100%敏感。 tdh+菌株对头孢吡肟、阿奇霉素耐药率（0.48%、8.65%）高于tdh?菌株（0.00%、4.11%）;tdh?菌株对氨苄西林、头孢西汀、头孢曲松、环丙沙星、萘啶酸、链霉素、卡那霉素、庆大霉素、磺胺甲恶唑、复方新诺明、四环素、多西环素、氯霉素耐药率均高于tdh+菌株。 tdh?菌株的多重耐药率（34.25%）高于tdh+菌株（19.23%）。 耐药基因共检出5类7种,其中β-内酰胺类bla_CARB基因在所有的tdh+菌株和tdh?菌株均检出;四环素类tet（34）基因在tdh+与tdh?菌株基因携带率分别为99.52%、98.63%;喹诺酮类耐药基因qnrS5 仅在tdh+菌株中检出;tdh?菌株中叶酸代谢抑制类（sul2）、四环素类［tet（35）、tet（59）］、苯丙醇类（floR）耐药基因检出率高于tdh+菌株。 共在14株（tdh+9株,tdh?5株）细菌中检索出6种耐药基因点突变方式,均为编码16S rRNA的rrs基因突变。  结论  tdh?副溶血弧菌耐药现象较tdh+副溶血弧菌更为严重; 16S rRNA的rrs基因突变是除aph（3'）-Ib、aac（3）-Ⅱ、aac（6’） -I、aph（3'）-Id等耐药基因外副溶血弧菌对氨基糖胺类药物耐药的主要机制之一;副溶血弧菌中,可用bla_CARB耐药基因存在情况预测副溶血弧菌氨苄西林耐药表型;除此之外其余抗生素耐药表型与其对应耐药基因之间未见明确的对应的关系。     

Comparative proteomics reveals essential mechanisms for osmotolerance in Gluconacetobacter diazotrophicus

Plant growth-promoting bacteria are a promising alternative to improve agricultural sustainability. Gluconacetobacter diazotrophicus is an osmotolerant bacterium able to colonize several plant species, including sugarcane, coffee, and rice. Despite its biotechnological potential, the mechanisms controlling such osmotolerance remain unclear. The present study investigated the key mechanisms of resistance to osmotic stress in G. diazotrophicus. The molecular pathways regulated by the stress were investigated by comparative proteomics, and proteins essential for resistance were identified by knock-out mutagenesis. Proteomics analysis led to identify regulatory pathways for osmotic adjustment, de novo saturated fatty acids biosynthesis, and uptake of nutrients. The mutagenesis analysis showed that the lack of AccC protein, an essential component of de novo fatty acid biosynthesis, severely affected G. diazotrophicus resistance to osmotic stress. Additionally, knock-out mutants for nutrients uptake (Δtbdr and ΔoprB) and compatible solutes synthesis (ΔmtlK and ΔotsA) became more sensitive to osmotic stress. Together, our results identified specific genes and mechanisms regulated by osmotic stress in an osmotolerant bacterium, shedding light on the essential role of cell envelope and extracytoplasmic proteins for osmotolerance.     

云南香格里拉山地自然风景区蚤类多样性的研究

蚤类是传播多种自然疫源性疾病的重要媒介昆虫,人类在自然风景区户外活动时存在被其叮咬而感染虫媒传染病的风险。为了解云南香格里拉县主要山地自然风景区蚤类的多样性状况,2005年秋,我们选择了虎跳峡、哈巴雪山、白水台、千湖山和红山5个不同海拔高度的自然风景区为调查研究的空间范围,应用夹线法捕小型兽类并收集其体表寄生蚤类进行调查取样,对蚤类多样性、群落相似性和蚤类与宿主关系进行了测度和比较研究。结果显示：（1）共捕获蚤类633只,隶属4科19属34种,其中发现云南省1新纪录属及种（喜马狭蚤Stenoponiahimalayana）,当地新纪录蚤类10种（亚种）,显示当地山地自然风景区内蚤种丰富;（2）红山和千湖山景区蚤种丰富度较高（各18种）和物种多样性也较高（分别为2．50和2．18）,而虎跳峡景区捕获的蚤类丰富度（8种）和物种多样性指数（1．79）最低,蚤类物种丰富度和Shannon—Wienor指数均随着景区海拔的升高呈递增趋势;（3）综合分析Jaccard指数和聚类分析的结果,5个风景区被划为虎跳峡-哈巴雪山-白水台、千湖山-红山两个类型,相对植被和水湿条件而言,人为干扰或是导致这一结果更重要的原因;（4）5个自然风景区蚤类群落与宿主群落丰富度的Spearman秩相关系数为0．24,Shannon—Wiener指数的Spearman秩相关系数为0．60,显示5个景区的蚤类多样性与宿主多样性无相关。     

Genetic Diversity,Antimicrobial Resistance,and Virulence Genes of Aeromonas Isolates from Clinical Patients,Tap Water Systems,and Food

Objective This study aimed to evaluate the genetic diversity, virulence, and antimicrobial resistance of Aeromonas isolates from clinical patients, tap water systems, and food.Methods Ninety Aeromonas isolates were obtained from Ma'anshan, Anhui province, China, and subjected to multi-locus sequence typing(MLST) with six housekeeping genes. Their taxonomy was investigated using concatenated gyr B-cpn60 sequences, while their resistance to 12 antibiotics was evaluated. Ten putative virulence factors and several resistance genes were identified by PCR and sequencing.Results The 90 Aeromonas isolates were divided into 84 sequence types, 80 of which were novel,indicating high genetic diversity. The Aeromonas isolates were classified into eight different species. PCR assays identified virulence genes in the isolates, with the enterotoxin and hemolysin genes act, aer A, alt,and ast found in 47(52.2%), 13(14.4%), 22(24.4%), and 12(13.3%) of the isolates, respectively. The majority of the isolates(≥ 90%) were susceptible to aztreonam, imipenem, cefepime, chloramphenicol,gentamicin, tetracycline, and ciprofloxacin. However, several resistance genes were detected in the isolates, as well as a new mcr-3 variant.Conclusions Sequence type, virulence properties, and antibiotic resistance vary in Aeromonas isolates from clinical patients, tap water systems, and food.     

Multispacer Typing (MST) of Spotted Fever Group Rickettsiae Isolated from Humans and Rats in Chengmai County,Hainan Province,China

Spotted fever caused by spotted fever group rickettsiae (SFGR) is found throughout China. During 2007–2008, 28 human SFGR isolates and 34 rat SFGR isolates including 15 isolates from Rattus fulvescens, 5 isolates from R. edwardsi, 7 isolates from Callosciurus erythraeus roberti and 7 isolates from Dremomys rufigenis) were obtained from L929 cell culture. Previous research indicated that the 62 strains of SFGR mentioned above shared not only the same serophenotype but also 100% of identity sequences of 16S rRNA, gltA, ompA, groEL and 17KD, which enabled us to apply multispacer typing (MST) to the 62 SFGR isolates in the study. Six primer pairs, which were used for typing of Rickettsia rickettsii and Rickettsia conorii, were chosen, and the results exhibited greater nucleotide polymorphisms among the 62 isolates tested. A total of 48 distinct genotypes were identified. The dominant genotype, represented by h3 isolates, accounted for 21.7% (13/60) of the isolates tested, and the remaining 47 genotypes were all unique. Phylogenetic analysis showed that all the 48 genotypes could be classified in the same clade, while the genetically related strain, R. heilongjiangensis, was close but not the same as the cluster. We concluded that the genetically diverse of spotted fever group rickettsiae strains are endemic in Chengmai County, Hainan Province, China.     

Chromosomal Rearrangement Features of Yersinia pestis Strains from Natural Plague Foci in China

The Yersinia pestis chromosome contains a large variety and number of insert sequences that have resulted in frequent chromosome rearrangement events. To identify the chromosomal rearrangement features of Y. pestis strains from five typical plague foci in China and study spontaneous DNA rearrangements potentially stabilized in certain lineages of Y. pestis genomes, we examined the linking mode of locally collinear blocks (LCBs) in 30 Y. pestis strains by a polymerase chain reaction-based method. Our results suggest most strains have relatively stable chromosomal arrangement patterns, and these rearrangement characteristics also have a very close relationship with the geographical origin. In addition, some LCB linking modes are only present in specific strains. We conclude Y. pestis chromosome rearrangement patterns may reflect the genetic features of specific geographical areas and can be applied to distinguish Y. pestis isolates; furthermore, most of the rearrangement events are stable in certain lineages of Y. pestis genomes.