Insertion sequence IS200 fingerprinting of Salmonella typhi: an assessment of epidemiological applicability.

When Pst I-generated digests of genomic DNA from each of the type strains of 49 of the Vi phage types of Salmonella typhi were probed with a PCR-amplified IS200 gene probe, all strains were found to possess at least 11 IS200 elements carried on fragments in the range 24.2-1.2 kb. Fourteen fingerprints were identified but two patterns designated IS200Sty1 and IS200Sty2 predominated. In one strain, a plasmid-mediated IS200 element was identified. When IS200 fingerprinting was applied to epidemiologically-unrelated strains of S. typhi isolated in Ecuador, 3 patterns were identified in 10 strains belonging to 9 different phage types. It is concluded that Vi phage typing remains the method of choice for the primary differentiation of S. typhi but that IS200 fingerprinting may be of limited use in laboratories which do not have access to phage typing.     

Genetic relationships among strains of Salmonella enteritidis in a national epidemic in Switzerland.

A collection of Salmonella enteritidis strains isolated in Switzerland (1965-90) was characterized. The phage type and plasmid profile of isolates were compared with the copy number and insertion loci of the DNA insertion element IS200. Three clonal lines of S. enteritidis were identified by IS200 profile; the various phage types were subtypes reproducibly associated with one of these lines. All human and poultry isolates contained a 38 Mda plasmid which hybridized with a mouse virulence-associated gene probe. In S. enteritidis, the IS200 profile is a race-specific molecular marker of the chromosome, and may be particularly applicable for studying the epidemiology of less common serovars.     

沙门菌毒力岛1缺失山夫登堡沙门菌的特性

目的 研究沙门菌毒力岛1( SPI-1)缺失山夫登堡沙门菌的特性。方法 于2006年从上海10例腹泻患者粪便中分离得到10株山夫登堡沙门菌,运用脉冲场凝胶电泳(PFGE)、PCR、毒力基因测序及细胞侵袭试验对其进行分子分型、侵袭基因及细胞侵袭能力检测,并与2002年深圳分离株( C02013)进行比较。结果 10...     

金黄色葡萄球菌耐药相关基因及SCCmec分型研究

摘要:目的　对郑州地区分离的金黄色葡萄球菌进行耐药性研究,了解其耐药基因携带情况,为临床抗感染治疗提供依据。方法　对2013年7月-2014年7月郑州某三甲医院分离的86株金黄色葡萄球菌,测定25种药物敏感性,应用普通PCR测定10种耐药基因,同时采用多重PCR方法对28株耐甲氧西林金黄色葡萄球菌（Methicillin Resistant S. Aureus,MRSA）进行葡萄球菌染色体mec基因盒（Staphyloccoccal Cassette Chromosome mec,SCCmec）分型。结果　菌株对抗菌药物呈多重耐药,其中青霉素耐药率最高,为95.3%。有11种抗生素的耐药率大于50%;10种耐药相关基因检测结果显示acc（6'）/aph（2"）、aph（3'）-III、ant（4',4"）、ermA、ermB、ermC、msrA、tetM、tetK阳性率分别为100%、72.1%、86.0%、95.3%、79.1%、93.0%、58.1%、97.7%、81.4%,未检测出blaTEM;28株MRSA中14株为SCCmecⅢ型,8株为SCCmecⅠ型,4株为SCCmecⅣE型,2株未能分型。结论　郑州地区分离的金黄色葡萄球菌呈多重耐药,携带较多耐药基因,本地区MRSA以SCCmecⅢ型为主。     

Spread of Staphylococcus aureus strains of phage-type 95 in Denmark 1968-1989.

The spread of Staphylococcus aureus strains of phage-type 95 was traced retrospectively in Denmark by the review of more than 15,000 S. aureus bacteraemia isolates (1957-88) and from data collected by phage-typing of c. 260,000 isolates from all body sites (1977-89). The first two type 95 strains had been isolated from blood in 1968, and after an interval of 3 years there was a steady increase of bacteraemia strains all over Denmark. From 1977 to 1989 the incidence of type 95 strains among isolates from all body sites increased from 3.8 to 18.8%. Different patterns of increase were recorded in 13 major hospitals and in various clinical departments of two hospitals and these were further analysed. Conjunctival swabs gave the highest percentage of type 95 strains and those from abscesses gave the lowest percentage. Of the type 95 bacteraemia strains 90.4% were resistant to penicillin, but neither methicillin nor gentamicin resistance was recorded.     

Salmonellosis in wild mammals.

One thousand two hundred and sixty-nine freeliving, wild mammals, representative of 16 species from estates in Berkshire, Oxfordshire and Surrey, were examined for the presence of salmonellas. Salmonella typhimurium was isolated from 1 and S. dublin from 7 house mice (Mus musculus). There were no isolations from the other species examined. It was concluded that the house-mice infected with S. dublin acquired the organism from experimentally infected cattle. The wild mammal population does not at present appear to constitute a reservior for infection of domestic animals.     

Salmonella dublin infection of calves: use of small doses to simulate natural infection on the farm.

Small numbers of Salmonella dublin were used to infect calves in an attempt to simulate natural infection on the farm. Twenty calves were exposed to S. dublin by one or more of the following methods: Sucking cows which were excreting S. dublin in their faeces (less than 10(2)-10(5) organisms/g). Housing on S. dublin contaminated bedding. Drinking S. dublin contaminated water (10(2)-10(4) organisms/ml). During this experiment some calves were given therapeutic does of oxytetracycline. After exposure the calves were examined for faecal excretion of S. dublin (in some instances mouth swabs and blood samples were also examined) and for clinical signs of illness. Most of the calves became infected with S. dublin but excretion was usually sporadic and the numbers of salmonellas excreted were small. No clinical signs of salmonellosis were observed by S. dublin was isolated from one calf at post-mortem. Another six calves, dosed orally with either 10(6) or 10(8) S. dublin, showed signs of mild illness and although three calves had diarrhoea excretion of salmonellas was intermittent. S. dublin was isolated from one of these calves at post-mortem.     

Application of ribotyping and IS200 fingerprinting to distinguish the five Salmonella serotype O6,7:c:1,5 groups: Choleraesuis sensu stricto, Choleraesuis var. Kunzendorf, Choleraesuis var. Decatur, Paratyphi C, and Typhisuis.

Sixty-seven strains of the five described Salmonella serotypes having antigens 6,7:c:1,5, that is S. enterica serotype Choleraesuis sensu stricto, Choleraesuis var. Kunzendorf, Choleraesuis var. Decatur, Paratyphi C, and Typhisuis, were examined for 16S rrn profile ribotype, presence of IS200 and phenotypic characters, including rate of change of flagellar-antigen phase and nutritional character. Choleraesuis sensu stricto and its Kunzendorf variant had related but distinct ribotypes. Therefore, ribotyping appears to be a suitable method for differentiating Choleraesuis non-Kunzendorf from Choleraesuis var. Kunzendorf. Some strains of Paratyphi C had 16S profiles that resembled that of Choleraesuis non-Kunzendorf, while others resembled that of Choleraesuis var. Kunzendorf. The Typhisuis profiles were like those of Choleraesuis non-Kunzendorf, while the Choleraesuis var. Decatur profiles were unlike those of any of the other four groups. Furthermore, IS200 fingerprinting discriminated between Choleraesuis var. Decatur and the other strains with antigenic formula O6,7:c:1,5, and comparison of IS200 patterns showed a high degree of genetic divergence within Choleraesuis var. Decatur. Our findings show that ribotyping and IS200 fingerprinting, combined with classical microbiological methods, distinguish the groups Choleraesuis non-Kunzendorf, Choleraesuis var. Kunzendorf, Choleraesuis var. Decatur, Paratyphi C and Typhisuis.     

Salmonellosis in two dairy herds associated with a sewage farm and water reclamation plant.

Two dairy herds, situated on a sewage farm, were monitored for the presence of salmonellas following outbreaks of Salmonella dublin infection. In addition an S. dublin control scheme, which involved examination of adult animals and calf vaccination, was instigated. During the period 1975-84, 12 salmonella serotypes and 10 phage types of S. typhimurium were isolated from the cattle and their environment although their presence was seldom associated with disease. Two adult S. dublin excreters were detected but it was concluded that none of the tests employed to examine the adult animals was sensitive enough. The prevalence of disease in the calves was low and although vaccination may have been beneficial it did not eradicate S. dublin infection. Thus S. dublin persisted in adults and calves during the 8-year period but its presence was seldom associated with disease. The results are discussed with regards the disease risk to animals from the agricultural use of sewage sludge and the public health aspects.     

Stability of genomic DNA fragment patterns in methicillin resistantStaphylococcus aureus (MRSA) during the course of intra- and interhospital spread

The analysis of genomic DNA fragment patterns has revealed as a powerful tool for strain discrimination inStaphylococcus aureus; for use as an epidemiological marker, stability during the course of an outbreak is an essential prerequisite. Genomic DNA fragment patterns (SmaI restriction, pulsed-field electrophoresis) of four different epidemic MRSA strains were compared along with intra- and interhospital and country-wide spread over more than 12 months in Germany. Strain I was isolated from infections in 8 hospitals. In one hospital a subclone arised which differed from the original strain by 4 fragments. Strain II was spread among 4 hospitals, isolates from three of these hospitals exhibited a variability of one to three fragments in the 150–200 kb range. Two hospitals in the Hannover-area were affected by strain III; in 17 isolates of this strain a variability up to three fragments was found in the 170–200 kb range. Strain IV was isolated from 19 cases of infections in 3 hospitals in Berlin. The fragment patterns were completely stable. When S. aureus strains are typed by genomic DNA fragment patterns, a variability in a definite range of molecular masses during the course of an epidemic should be taken into consideration.     

浙江省散发猪链球菌病临床分离株存在89K候选致病岛

目的 对浙江省临床分离猪链球菌血清2型(SS2)菌株进行89K候选致病岛检测.方法 用多种特异性引物进行PCR扩增检测,同时对89K的3个扩增片段进行测序,并结合有关资料进行生物信息学和流行病学分析.结果 8株SS2菌株,均检出89K(1&2)、89K(3&4)、89K(5&6)候选致病岛特异片段和种特异性16S rDNA、cps2J、mrp毒力基因,和1998年江苏省暴发疫情的菌株结果一致.ZJ0501号SS2分离株89K候选致病岛的3个PCR扩增片段序列和1998年江苏省暴发疫情的菌株有99%以上的相似性,其中编码DNA重组蛋白的序列片段和病乳链球菌及无乳链球菌有较高的同源性.结论 近年来在浙江省临床分离Ss2菌株中,存在89K候选致病岛片段.     

Typing of drug resistant isolates of Mycobacterium tuberculosis from India using the IS6110 element reveals substantive polymorphism.

We investigated IS6110 polymorphism in clinical isolates of Mycobacterium tuberculosis from patients attending the outpatient department at various hospitals in northern India. DNA fingerprinting of 126 clinical isolates of M. tuberculosis was carried out using restriction fragment length polymorphism (RFLP) associated with the IS6110 element in M. tuberculosis genomes. A substantive degree of polymorphism was evident in the MDR M. tuberculosis isolates. The number of bands in the fingerprints varied from 0 to 19. However, the lack of common bands made it difficult to cluster the majority of these isolates. We were also unable to associate drug resistance with IS6110 copy number. Specific regions of the gyrA and katG genes from a representative number of these isolates were sequenced to determine the genotype. The majority of the isolates analyzed were found to belong to Group 1, indicating that these strains were evolutionarily older. We find no evidence of the W strain, prevalent in the US, in our study. The epidemiological patterns of the various strains in India seem to be very complex, as reflected by the presence of a large number of different strains (types) within north India.     

Genomic diversity of mec regulator genes in methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis.

Low-affinity penicillin-binding protein PBP-2a encoded by mecA is closely related to methicillin resistance in staphylococci, and expression of PBP-2a is controlled by regulator elements encoded by mecR1 and mecI which are located adjacent to mecA on the chromosome. Deletion or mutation which occurred in mec regulator gene is considered to be associated with constitutive production of PBP-2a. The distribution of the mec regulator genes in 176 strains of Staphylococcus aureus and 33 strains of S. epidermidis isolated from a single hospital was studied by polymerase chain reaction amplification. Most clinical isolates of methicillin-resistant S. aureus (MRSA) (94.3%) and S. epidermidis (MRSE) (83.9%) possessed both mecI and mecR1 genes (type I), whereas no mec regulator genes were detected in mecA-negative isolates. In contrast, 7 MRSA and 5 MRSE isolates were found to have incomplete regulator genes, and they were classified into three groups; strains which lacked only mecI gene (type II), strains which lacked mecI and 3''-end of mecR1 gene (type III), and strains which lacked both regulator genes (type IV). Analysis of mecI gene from all the strains having mecI by restriction fragment length polymorphism after Mse I digestion indicated that three MRSA strains possessed one of the known point mutations identified previously. These findings indicated the predominance of a single type of MRSA possessing both mecI and mecR1 in the study period and also suggested a high genomic diversity in mec regulator region of staphylococci.     

宁波地区2014年麻疹流行情况及病毒基因型分析

目的 了解宁波市2014年麻疹流行情况以及病毒基因型特征.方法 采用描述流行病学方法分析法定传染病报告系统中2014年宁波市麻疹病例相关资料.采用RT-PCR对85份含漱液样本进行麻疹病毒分离,对所得麻疹分离株核蛋白羧基末端450个核苷酸进行扩增和序列测定,并与基因库中麻疹病毒各基因型参考株比对分析.结果 宁波市2014年麻疹确诊病例共176例,0～1岁组发病率最高(58.43/10万);发病主要集中在2-4月份(138例,78.41％).其间象山县发生2起麻疹暴发疫情(第1起20例,第2起16例).85份含漱液样本共分离得到23株麻疹分离株,分为两簇:其中B3基因型11株,均来源于象山县,与当时流行于英国的B3基因型麻疹毒株高度同源;另一簇为H1a亚型12株,来源于其他县市,与中国大陆近年流行株高度同源.B3基因型与中国疫苗株S191之间核苷酸和氨基酸的同源性分别为91.1％～93.2％和86.4％～88.6％,H1基因型与S191同源性分别为89.7％～90.6％和84.8％～87.9％.结论 宁波市2014年麻疹病例主要由本土流行株(H1a亚型)引起,B3基因型仅引起局部流行.我国的麻疹疫苗S191株可能对B3基因型及H1a基因型麻疹病毒感染仍有一定的保护作用.     

A study of the susceptibility of cattle to oral infection by salmonellas contained in raw sewage sludge

Raw sewage sludge, containing up to 10(5) naturally occuring salmonellas/1, was included in the diet of one group of cattle at the rate 1 ]/animal/day and in a second group at the rate of 1 ]/animal/week. Sterilized sludge, to which had been added 10(5) S. dublin/litre, was included in the diet of a third group of animals at the rate of 1 ]/animal/day. Salmonellas were isolated from all samples of raw sewage sludge but were not isolated from the faeces or carcasses of animals fed on the sludge. Salmonellas were isolated from the faeces of one animal and the carcasses of two animals fed on sterilized sludge to which S. dublin had been added.     

浙江省2002-2006年禽流感H5N1病毒基因特性与进化重组分析

目的 对近年来浙江省禽流感病毒H5N1分离株的基因特性与进化重组特征进行分析.方法 通过对2002-2006年浙江省禽与人的H5N1病毒株进行全基因序列测定,采用Mega 3.0生物信息学软件分析病毒株基因特性并与相关基因型标准病毒株进行系统进化分析.结果 2002-2006年浙江省HSNl病毒株HA序列裂解位点序列含多个碱性氨基酸,符合高致病性禽流感病毒特征;与Gs/Guangdong/1/96相比,除Dk/Zhejiang/2/02和Ck/Zhejiang/8/03株外其他病毒株均在NA蛋白茎区缺失20个氨基酸.全基因系统进化分析表明,2002-2003年的分离株遗传基因基本属于当年流行的B、W、X、Y、z等基因型,但部分病毒株不同基因片段属于不同基因型.结论 浙江省禽类中也广泛存在H5N1的基因片段重组现象,2005年后的Ck/Zhejiang/24/05株及人H5N1 Zhejiang/16/06株各遗传基因基本上稳定于近年大陆流行的FJ-like基因型.     

A simultaneous outbreak of Serratia marcescens and Klebsiella pneumoniae in a neonatal intensive care unit

We describe two concurrent outbreaks of Serratia marcescens and Klebsiella pneumoniae in a neonatal intensive care unit (NICU). Over a 16-month period, a total of 27 infants were either colonized (N=14) or infected (N=13). There were 15 cases of S. marcescens and 11 cases of K. pneumoniae. Both micro-organisms were involved in one fatal case. Seven preterm babies developed septicaemia, two had bacteraemia, three had respiratory infections and one had purulent conjunctivitis. The S. marcescens and K. pneumoniae isolates were investigated by three molecular methods: enterobacterial repetitive intergenic consensus polymerase chain reaction (PCR), arbitrary primed PCR with M13 primer, and random amplification of polymorphic DNA. Different patterns were found in the 16 S. marcescens epidemic isolates from 16 newborn infants. The major epidemic-involved genotype was linked to the first nine cases and this was subsequently replaced by different patterns. Eight different typing profiles were also determined for the 13 K. pneumoniae isolates from 12 newborn infants. Four K. pneumoniae bacteraemic strains proved to be identical. In conclusion, the typing results revealed that two different micro-organisms (S. marcescens and K. pneumoniae) were simultaneously involved in invasive nosocomial infections in preterm newborns. Two simultaneous clusters of cases were documented. Heterogeneous genotypes among both species were also demonstrated to be present in the NICU at the same time. A focal source for both micro-organisms was not identified but cross-transmission through handling was probably an important route in this outbreak. Strict adherence to handwashing policies, cohorting, isolation of colonized and infected patients, and rigorous environmental hygiene were crucial measures in the containment of the epidemic.     

Genotype analysis of Mycobacterium tuberculosis isolates from a sentinel surveillance population

As part of the National Tuberculosis and Genotyping Surveillance Network, isolates obtained from all new cases of tuberculosis occurring in seven geographically separate surveillance sites from 1996 through 2000 were genotyped. A total of 10883 isolates were fingerprinted by the IS6110-restriction fragment length polymorphism method, yielding 6128 distinct patterns. Low-copy isolates (those with six or fewer bands) were also spoligotyped. The distribution of specific genotype clusters was examined. Databases were also examined for families of related genotypes. Analysis of IS6110 patterns showed 497 patterns related to the W-Beijing family; these patterns represent 946 (9%) of all isolates in the study. Six new sets of related fingerprint patterns were also proposed for isolates containing 6-15 copies of IS6110. These fingerprint sets contain up to 251 patterns and 414 isolates; together, they contain 21% of isolates in this copy number range. These sets of fingerprints may represent endemic strains distributed across the United States.     

一起食物中毒事件的金黄色葡萄球菌分子分型研究

目的 运用分子分型方法分析一起在广州发生的由金黄色葡萄球菌所致的重大食物中毒事件,并进行溯源.方法 在常规分离的基础上,采用荧光定量PCR检测所获得的金黄色葡萄球菌特异耐热核酸酶基因(nuc)、耐甲氧西林决定基因(mecA)和其他5种肠毒素基因(sea,seb,sec,sed,see),并对16 S rRNA核苷酸进行序列扩增和使用DNAStar MegAlign 5.0软件分析,同时应用脉冲场凝胶电泳(PFGE)和BioNumerics Version 4.0软件进行聚类分析.结果 10株金黄色葡萄球菌特异性nuc基因均为阳性,其中7株分离菌的肠毒素sea,seb基因为阳性,分离菌可以分为4个16 SrRNA型别和5个PFGE型别.结论 本次食物中毒事件至少由3株以上亲缘关系相近的产毒金黄色葡萄球菌污染食物所致,分子分型方法可以为疫情溯源提供分子流行病学证据和支持.