Investigation and analysis of plague epidemic Yersinia infection in Marmota himalayana, Yugur Autonomous County of Sunan, Gansu Province / 中华地方病学杂志

Objective:To study the epidemic situation of Marmota himalayana plague and Yersinias infection in Yugur Autonomous County of Sunan (Sunan County) of Gansu Province, and to provide new ideas for prevention and control of plague. Methods:From 2014 to 2018, liver and spleen, cecum, throat swabs and blood samples of Marmota himalayana were collected on the spot in Sunan County, where Yersinia strains were isolated and identified, and plague F1 antigen and antibody were detected. Results:A total of 634 liver and spleen samples, 427 cecum samples and 426 throat swabs samples were collected from Marmota himalayana, and 23 strains of Yersinia pestis, 2 strains of Yersinia marcescens, and 1 strain of Yersinia flexneri were detected, with the detection rates of 3.63% (23/634), 0.47% (2/427) and 0.23% (1/426), respectively. The detection rate of Yersinia pestis in different years was statistically significantly different (χ 2 = 13.19, P = 0.010). A total of 1 822 serum samples of Marmota himalayana were detected, and 5 F1 antibody positive samples were detected, with a positive rate of 0.27%, the difference of positive rate between different years was statistically significant (χ 2 = 25.22, P < 0.001); 282 liver and spleen tissue homogenates of Marmota himalayana were detected, 22 F1 antigen positive samples were detected, the positive rate was 7.80%, and there was no statistically significant difference between different years (χ 2 = 7.85, P = 0.097). The 23 strains of Yersinia pestis detected were distributed in Mati Tibetan Township (12 strains), Dahe Township (6 strains) and Qifeng Tibetan Township (5 strains); 1 strain of Yersinia flexneri and 2 strains of Yersinia marcescens were both located in Dahe Township. Conclusion:There is an epidemic of plague among animals in Sunan County from 2014 to 2018, and the areas where Yersinia pestis and non pathogenic Yersinia are detected overlapped.

Effects of daily mean temperature and other meteorological variables on bacillary dysentery in Beijing-Tianjin-Hebei region, China

BACKGROUND@#Although previous studies have shown that meteorological factors such as temperature are related to the incidence of bacillary dysentery (BD), researches about the non-linear and interaction effect among meteorological variables remain limited. The objective of this study was to analyze the effects of temperature and other meteorological variables on BD in Beijing-Tianjin-Hebei region, which is a high-risk area for BD distribution.@*METHODS@#Our study was based on the daily-scale data of BD cases and meteorological variables from 2014 to 2019, using generalized additive model (GAM) to explore the relationship between meteorological variables and BD cases and distributed lag non-linear model (DLNM) to analyze the lag and cumulative effects. The interaction effects and stratified analysis were developed by the GAM.@*RESULTS@#A total of 147,001 cases were reported from 2014 to 2019. The relationship between temperature and BD was approximately liner above 0 °C, but the turning point of total temperature effect was 10 °C. Results of DLNM indicated that the effect of high temperature was significant on lag 5d and lag 6d, and the lag effect showed that each 5 °C rise caused a 3% [Relative risk (RR) = 1.03, 95% Confidence interval (CI): 1.02-1.05] increase in BD cases. The cumulative BD cases delayed by 7 days increased by 31% for each 5 °C rise in temperature above 10 °C (RR = 1.31, 95% CI: 1.30-1.33). The interaction effects and stratified analysis manifested that the incidence of BD was highest in hot and humid climates.@*CONCLUSIONS@#This study suggests that temperature can significantly affect the incidence of BD, and its effect can be enhanced by humidity and precipitation, which means that the hot and humid environment positively increases the incidence of BD.

Interpretation for diagnosis of Yersiniosis / 中华流行病学杂志

Yersiniosis is one of the "other infectious diarrhea" of the notifiable infectious diseases and also an important food-borne disease. However, it lacked the basis or standard for diagnosis. The Chinese Preventive Medicine Association coordinated experienced researchers from National Institute for Communicable Disease Control and Prevention, China CDC and other institutes to produce the group standard entitled "Diagnosis of Yersiniosis" (T/CPMA 005-2019). Based on the principle of "legality, scientificity, advancement, and feasibility" , the standard gives a clear definition for Yerisiniosis, stipulates diagnosis basis, principles and main differential diagnosis and provides two informative appendixes for epidemiological and clinical characteristics and a normative appendix for laboratory detection. The standard provides accurate basis and methods of Yersiniosis diagnosis for hospitals and CDCs at all levels in China. It will solve the problems that Yersiniosis cannot be clearly diagnosed for clinical cases and in the outbreaks.

Etiological study of diarrhea in children under 5 years old in Dongcheng district of Beijing / 中华预防医学杂志

Objective@#To analyze the etiological characteristics of infectious diarrhea among people under 5 years old in Dongcheng District, Beijing.@*Methods@#The age, time of infection, clinical symptoms and laboratory test results of the cases who didn't used antibiotics within 3 days in the second maternal and child health care hospital were collected from 2012 to 2015, through the information management system of infectious disease monitoring technology platform. To compare the detection rate of virus and bacteria in children with different sex, time and age,and the difference of clinical characteristics between virus detection group and bacteria detection group by chi square test.@*Results@#1 977 cases of infectious diarrhea were collected, the median of the month age (P25, P75) was 14.19 (8.31, 23.15) months. The virus detection rate was 34.3% (679 cases); the bacterial detection rate was 14.6% (288 cases). The difference of virus detection rate in children with different months was statistically significant (χ2=72.38, P<0.001), the virus detection rate of 24-60 months (40.9% (188/460)) was the hightest, and the detection rate of 0-5 months (15.3% (48/314)) was the lowest. The difference of bacteria detection rate was also statistically significant (χ2=32.67, P<0.001), and the detection rate of 12-17 months (19.0% (81/426)) was the highest, the detection rate of 0-5 months (6.7% (21/314)) was the lowest. The proportion of vomit and water sample in the virus detection group was 22.2% (136 cases) and 73.3% (449 cases), respectively, which were higher than those in bacteria detection group (8.1% (18 cases) and 57.2% (127 cases)), the difference was statistically significant (χ2 values were 125.92 and 19.60; P values were both<0.001); the proportion of mucus stool and fever was 0.8% (5 cases) and 14.0% (86 cases), respectively, which were lower than those in bacterial detection group (4.1% (9 cases) and 18.5% (41 cases)), and the difference was statistically significant (χ2 values were 8.50 and 23.01; P values were 0.004 and <0.001).@*Conclusion@#The virus detection rate of infantile infective diarrhea is higher than that of bacteria in Dongcheng district of Beijing, and the clinical characteristics are significantly different.

The effect of AmpD on the expression of AmpC β-lactamase and the regulation mechanisms of β-N-acetylglucosaminidase in Yersinia enterocolitica / 中华预防医学杂志

Objective@#In this study, we analyze the regulation mechanisms of the expression of ampD in AmpC β-lactamase and the regulation mechanism of β-N-acetylglucosaminidase (NagZ) in Yersinia enterocolitica.@*Methods@#We construct the mutation strains of Yersinia enterocolitica AmpD (AmpD1-3) gene (ampD1-3), Low-Molecular-Mass Penicillin-Binding Proteins (LMM PBPs) gene (pbp4, pbp5a, pbp5b, pbp7), NagZ gene (nagZ), and ampR gene by deleting and complementing genes, and induce them by cefoxitin. We determined the activity of AmpC β-lactamase activity (U) of mutant strains (basal level and induce level) by using cephalothiophene hydrolysis method, the promoter activity of AmpC β-lactamase ((relative light unit (RLU)) was detected by the luxCDABEreporter system, and the activity of β-N-acetylglucosaminidase (nmol/L) was determined by by using 4-nitrophenyl N-acetyl-β-D-glucosaminide as the chromogenic substrate.@*Results@#AmpD1 (Basal level: (3.29±1.58) U; Induced level: (4.08±1.75) U) was the most potent one. The YEΔ5b, YEΔ4Δ5b, YEΔ5aΔ5b and YEΔ5bΔ7 of ampC promoter activity increase significantly, whichYEΔ4Δ5b is the highest one (Basal level: (106 903.16±61 910.61) RLU; Induced level: (205 427.45±45 352.17) RLU). The YEΔ4Δ5bΔ7 of ampC promoter activity is the highest among triple mutant strain (Basal level: (304 108.04±99 274.53) RLU; Induced level: (531 440.21±68 891.02) RLU). Quadruple deletion strain YEΔ4Δ5aΔ5bΔ7 have the highest ampC promoter activity (Basal level: (1 013 810.99±260 955.96) RLU; Induced level: (1 230 214.59±205 526.79) RLU). After the deletion of nagZ gene, there is no significant change in β-lactamase activity of YEΔD1D2D3ΔZ, while β-lactamase activity of YEΔ4Δ5aΔ5bΔ7ΔZ shows a significant decrease (Basal level: (0.30±0.20) U; Induced level: (0.29±0.21) U), which basically drops to the wild strain level.@*Conclusion@#This is the first report of ampC multi-step upregulation mechanism driven by three AmpD homologues in Yersinia enterocolitica. The AmpC regulation mode with the function of single PBP4, PBP5a or PBP7 is relatively low, which work in coordination with PBP5b. Yersinia enterocolitica have both NagZ-depend and NagZ-independent mechanisms for β-lactamase expression.

Etiology of bacterial diarrhea in large cities, mid-sized/small cities and rural areas of China / 中华流行病学杂志

Objective To understand the etiological characteristics of bacterial diarrhea in different areas,including large cities,mid-sized/small cities and rural area,in China.Methods A cross-sectional surveillance was conducted in 17 provinces of China from 2010 to 2014.The acute diarrhea outpatients were selected from clinics or hospitals in large cities,mid-sized/small cities,including rural-urban fringe zones,and rural areas.The demographical and clinical characteristics of the patients were collected by using questionnaire,and stool samples were taken from them for laboratory detection of 17 kinds of bacteria.The differences in pathogen positive rates (PPR) and pathogen spectrum across the cases from three-type areas were compared.The different infection risk in different cases were analyzed with unconditional logistic regression model.Results In our study,we enrolled 9 253 cases from large cities,5 138 cases from rural areas and 13 683 cases from midsized/small cites.The pathogen with largest differences in infection rate across the three-type areas was Shigella (S.)flexneri (rural area:5.81％,mid-sized/small city:2.78％,large city:0.46％),followed by Aeromonas (A.) hydrophila (rural area:2.14％,mid-sized/small city:0.96％,large city:0.48％).Compared with cases in large cities,the cases in mid-sized/small cities and rural areas had higher infection risks for S.flexneri (mid-sized/small city:OR =6.481,95％CI:4.666-9.002,rural area:OR =11.304,95％ CI:8.018-15.938) and A.hydrophila (mid-sized/small city:OR=1.992,95％ CI:1.401-2.832,rural area:OR=4.083,95％ CI:2.833-5.884).The constituent ratio of diarrheagenic Escherichia coli and Salmonella increased with the urbanization development,while the ratios of Shigella and A.hydrophila had an opposite trend.S.sonnei (60.00％) was the predominant serogroup of Shigella in urban infections,while S.flexneri (77.37％) was the predominant serogroup in rural infections.Conclusion The differences in pathogen spectrum of bacterial diarrhea were obvious across large cities,mid-sized/small cities and rural areas in China,especially the differences in the infection rates of S.flexneri and A.hydrophila.

Etiology of bacterial diarrhea in large cities, mid-sized/small cities and rural areas of China / 中华流行病学杂志

Objective To understand the etiological characteristics of bacterial diarrhea in different areas,including large cities,mid-sized/small cities and rural area,in China.Methods A cross-sectional surveillance was conducted in 17 provinces of China from 2010 to 2014.The acute diarrhea outpatients were selected from clinics or hospitals in large cities,mid-sized/small cities,including rural-urban fringe zones,and rural areas.The demographical and clinical characteristics of the patients were collected by using questionnaire,and stool samples were taken from them for laboratory detection of 17 kinds of bacteria.The differences in pathogen positive rates (PPR) and pathogen spectrum across the cases from three-type areas were compared.The different infection risk in different cases were analyzed with unconditional logistic regression model.Results In our study,we enrolled 9 253 cases from large cities,5 138 cases from rural areas and 13 683 cases from midsized/small cites.The pathogen with largest differences in infection rate across the three-type areas was Shigella (S.)flexneri (rural area:5.81％,mid-sized/small city:2.78％,large city:0.46％),followed by Aeromonas (A.) hydrophila (rural area:2.14％,mid-sized/small city:0.96％,large city:0.48％).Compared with cases in large cities,the cases in mid-sized/small cities and rural areas had higher infection risks for S.flexneri (mid-sized/small city:OR =6.481,95％CI:4.666-9.002,rural area:OR =11.304,95％ CI:8.018-15.938) and A.hydrophila (mid-sized/small city:OR=1.992,95％ CI:1.401-2.832,rural area:OR=4.083,95％ CI:2.833-5.884).The constituent ratio of diarrheagenic Escherichia coli and Salmonella increased with the urbanization development,while the ratios of Shigella and A.hydrophila had an opposite trend.S.sonnei (60.00％) was the predominant serogroup of Shigella in urban infections,while S.flexneri (77.37％) was the predominant serogroup in rural infections.Conclusion The differences in pathogen spectrum of bacterial diarrhea were obvious across large cities,mid-sized/small cities and rural areas in China,especially the differences in the infection rates of S.flexneri and A.hydrophila.

Pathogenic characteristic and distribution of Yersinia enterocolitica in Citellus dauricus plague focuses,Inner Mongolia / 中国人兽共患病学报

In order to investigate the distribution of Yersinia enterocolitica in Citellus dauricus plague focuses in Inner Mongolia,three different ecological environ/ments were chosen as the sampling area.Feces,tongue roots throat swabs,and intestinal contents of rodent,livestock,and poultry were separately collected,and different Y.enterocolitica strains were isolated,and identified.PCR analysis was conducted to detect the toxicity genes of Y.enterocolitica.Statiscal analysis was performed by chisquare test.Of the 3 260 samples,65 Y.enterocolitica strains were isolated and the overall detection rate was 1.99％.To include O ∶ 3/3,O ∶ 5/1A,O ∶ 4/4 serum biological type,the pathogenic strain of serotype O ∶ 3 and biological typt 3 carryinq toxicity genes ail,ystA,VirF yadA and rfbc was isolated from pigs in Citellus dauricus plague focuses,Inner Mongolia are the major carrier of pathogenic Y.enterocolitica distributed in three different ecological environment,and distributed mainly in agricultural area.

Detection of Yersinia Enterocolitica Bacteriophage PhiYe-F10 Lysis Spectrum and Analysis of the Relationship between Lysis Ability and Virulence Gene of Yersinia Enterocolitica / 病毒学报

To determine the lysis spectrum of Yersinia enterocolitica bacteriophage phiYe-F10 and to analyze the relationship between the lysis ability of phiYe-F10 and the virulence gene of Yersinia enterocolitica. To observe the lysis ability of the phage phiYe-F10 to the different Yersinia strains with the double-layer technique. The strains used in this study including 213 of Yersinia enterocolitica and 36 of Yersinia pseudotuberculosis and 1 of Yersinia pestis. The virulence genes of these Yersinia enterocolitica (attachment invasion locus (ail) and enterotoxin (ystA, ystB) and yersinia adhesin A (yadA), virulence factor (virF), specific gene for lipopolysaccharide O-side chain of serotype O : 3 (rfbc) were all detected. Among the 213 Yersinia enterocolitica, 84 strains were O : 3 serotype (78 strains with rfbc gene), 10 were serotype O : 5, 13 were serotype O : 8, 34 were serotype O : 9 and 72 were other serotypes. Of these, 77 were typical pathogenic Yersinia enterocolitica harboring with virulence plasmid (ail+, ystA+, ystB-, yadA+, virF+), and 15 were pathogenic bacterial strains deficiency virulence plasmid (ail+, ystA+, ystB-, yadA-, virF-) and the rest 121 were non pathogenic genotype strains. PhiYe-F10 lysed the 71 serotype O : 3 Yersinia enterocolitica strains which were all carried with rfbc+, including 52 pathogenic Yersinia enterocolitica, 19 nonpathogenic Y. enterocolitica. The phiYe-F10 can not lysed serotype O : 5, O : 9 and other serotype Y. enterocolitica, the lysis rate of serotype O : 3 was as high as 84.5%. The phiYe-F10 can not lysed Yersinia pseudotuberculosis and Yersinia pestis. Yersinia phage phiYe-F10 is highly specific for serotype O : 3 Yersinia enterocolitic at 25 degrees C, which showed a typical narrow lysis spectrum. Phage phiYe-F10 can lysed much more pathogenic Y. enterocolitica than nonpathogenic Y. enterocolitica.

Analysis of epidemiology characteristics of norovirus among diarrheal outpatients in 27 provinces in China, 2009-2013 / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the epidemiology characteristics of norovirus among diarrheal outpatients in China.</p><p><b>METHODS</b>Diarrhea cases were monitored at emergency/outpatient departments at 173 hospitals in 27 provinces of China, with clinical and epidemiological data, and fecal specimens collected and sent to 58 network-laboratories to detect norovirus by RT-PCR method, and to analyze the positive rate of norovirus in various regions, population and time during 2009-2013.</p><p><b>RESULTS</b>11.6% of the 34 031 diarrheal cases under surveillance were found with norovirus. Age group of 6-23 month-old children and that of people over 45 years old were found with the highest positive percentage, 13.7% and 12.4% respectively. Positive percentage of norovirus peaks in autumn and winter in a year; it peaks in mid-temperate zones (10.7%) and warm-temperate zones (11.6%) in winter. It peaks in sub-tropical zones in autumn (14.3%). The most prevalent genogroups detected were norovirus G II, accounting for 89.9% of identified strains.</p><p><b>CONCLUSION</b>Norovirus affects all ages and was most prevalent in children and the elderly among diarrhea outpatients. Norovirus' positive percentage showed strong seasonal pattern, and peaks at different times of a year in different climate zones of China. Since no effective preventive measures existed, further study on norovirus epidemiology and intervention strategies should be conducted in future.</p>

Analysis of twin-arginine translocation system gene homology and transcription in Vibrio species / 中华预防医学杂志

<p><b>OBJECTIVE</b>To determine the function of twin-arginine translocation system (Tat) and gene cluster in Vibrio strains and to analyze the homology of tat gene cluster among different Vibrio spp. strains based on N16961 and tatABC mutant strains N169-dtat.</p><p><b>METHODS</b>Different serotypes of biotype strains of Vibrio spp. were selected to detect the transcription of 4 genes of Tat transport system and upstream ubi aarF gene and downstream cyt551 gene by the total RNA reverse transcription and homologicity of the gene cluster by sequencing analysis.</p><p><b>RESULTS</b>Our results showed that the 4 genes of tat cluster (tatA, tatB, tatC, and tatE) were intragenic and co-transcribed. We found that ubi aarF gene could be co-transcribed with tatA, tatB, but not with tatC. The electron transport chain and energy metabolism-related genes, cytochrome C551 peroxidase gene, and 4 genes located at upstream of tatABC operon were not transcribed with tatABC. Although the co-transcription between ubi aarF and tatAB was blocked in N169-dtat strain, they were still transcribed separately. Homologous analysis of genes of tat cluster in different types of Vibrio cholerae showed that tat gene cluster was a very conservative.</p><p><b>CONCLUSION</b>The ubi and aarF gene might be co-transcribed with genes of tat cluster in Vibrio cholerae, which and the close relationship showed that they might play a key function in Vibrio cholerae.</p>

Serological investigations on patients with hemolytic uremic syndromes due to enterohemorrhagic Escherichia coli O157:H7 infection / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the etiological agent of patients with diarrhea followed by acute kidney failure symptoms in China, 1999.</p><p><b>METHODS</b>Western blot was used to detect serum specific antibodies of patients against entero-haemorrhagic Escherichia coli hemolysin (EHEC-Hly) and lipo-polysaccharide of E. coli O157.</p><p><b>RESULTS</b>Twenty-one and 16 of 42 patients showed positive reaction of specific IgG or IgM antibodies against EHEC-Hly respectively. Eleven of 42 serum samples were positive for having both IgG and IgM antibodies while 26 of 42 samples were positive for IgG or IgM. For E. coli O157 LPS test, 24 and 24 of 42 samples showed positive for IgG or IgM antibodies respectively. In 42 samples, 20 were positive for IgG and IgM while 29 were positive for IgG or IgM.</p><p><b>CONCLUSIONS</b>Twenty-two of 42 samples were reacted with EHEC-Hly and E. coli O157 LPS, but 34 of 42 samples were positive for EHEC-Hly or E. coli O157. In combination of western blot results, bacterial isolation clinical symptoms and epidemiological investigation findings, it was reasonable to conclude that this cluster of patients with distinguish clinical symptoms was caused by E. coli O157:H7, which had never been reported in China. Hence serological methods with EHEC-Hly and E. coli O157 LPS are valuable for diagnosis of infections of E. coli O157:H7, when bacterial isolation is failed.</p>

Study on diarrhea disease caused by enterohemorrhagic Escherichia coli O157:H7 in Xuzhou city, Jiangsu province in 2000 / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the proportion of hemorrhagic colitis (HC) caused by Escherichia coli O157:H7 in bacterial diarrhea in Xuzhou city, Jiangsu province.</p><p><b>METHODS</b>All stool samples from patients with diarrhea were screened for O157 antigen, using Immuno-gold kits. Positive samples were cultured to detect the existence of pathogens. All of the HC patients confirmed by bacterial isolation and identification were investigated for clinical symptoms and laboratory tests.</p><p><b>RESULTS</b>Of the diarrhea patients identified in Feng county in May, and in Tongshan county of Xuzhou city in June 2000, Jiangsu province 0.98% and 5.89% were caused by Escherichia coli O157:H7 respectively, confirmed by bacteriological isolation and identification of stool samples. At the early phase of hemorrhagic colitis, 18.5% patients had at least one abnormal clinical laboratory test results including protein in urea and increased BUN or creatinine that indicating the possibility of kidney damage. In 27 strains of E. coli O157:H7 isolated from those patients, 13 and 14 were identified as Shiga toxin producing and Shiga-toxin negative E. coli O157:H7 (Stx-positive or Stx-negative) respectively. By analysis of the two groups of patients divided by according to the nature of Shiga toxin, four of 13 patients of Stx-positive group showed positive urea protein. However only 1 of the 13 patients of Stx-negative group was urea protein positive. The decreased Platelets counts were observed in 6 of 13 patients with Stx-positive group, but only in 1 of 14 patients with stx-negative group. These differences were statistically significant.</p><p><b>CONCLUSION</b>HC patients caused by E. coli O157:H7 were commonly seen (up to 5.89%) in Xuzhou city, Jiangsu province. Early laboratory tests should be conducted for HC patients as early as possible in order to find early indictor of kidney failure which was critical for prevention of hemolytic uremic syndrome.</p>

Molecular typing of Shiga-toxin producing Escherichia coli O157:H7 isolated in China with pulsed field gel electrophresis / 中华流行病学杂志

<p><b>OBJECTIVE</b>To type and group the Shiga-toxin producing Escherichia coli O157:H7 strains isolated recent years in China to understand the epidemiological features caused by the pathogen.</p><p><b>METHODS</b>Pulsed field gel electrophoresis of large restriction fragments of bacterial chromosomal DNA was used.</p><p><b>RESULTS</b>The 51 isolates of E. coli O157:H7 collected in recent years in China could be divided into 8 Pulsed Field Gel Electrophoresis (PFGE) types based on the size and number of restriction fragments and patterns, that were digested by XbaI. Strains isolated from Ningxia province showed only two types- PFGE1 and PFGE2. Strains isolated in Xuzhou of Jiangsu province had 6 PFGE types. Isolates identified between 1986 - 1988 belonged to PFGE7. Strains isolated from patients in 1999 - 2000 were PFGE5 and PFGE3. Strains isolated from stool samples of domestic animal, food and vegetable were PFGE3 - 6, of which the predominant type was PFGE5. All of the 5 strains isolated from patients with diarrhea and hemolytic uremic syndrome (HUS) belonged to PFGE type 5, which was the dominant type of the isolates from stool samples of domestic animal and samples of food and vegetable contaminated.</p><p><b>CONCLUSION</b>Data suggested that the cluster patients with diarrhea and HUS might have been related to the pathogens from domestic animas and contaminated food or vegetables. The distribution of PFGE types also varied in different provinces of China.</p>

Homologous analysis of E.coli O_(157)∶H_7 by pulsed-field gel electrophoresis and random amplified polimorphic DNA / 中华传染病杂志

Objective To analyze the molecular epidemiological characteristics of E. coli O 157∶H 7 of Xuzhou, Jiangsu. Methods The virulence gene spectrum of E. coli O 157∶H 7 strains were analyzed by PCR and the homology of E. coli O 157∶H 7 strains were detected by PFGE and RAPD. Results In all E. coli O 157∶H 7 strains isolated from epidemic area, 100% possess Hly and eaeA gene, 95.35% possess SLT 2 gene, and 11.63% possess SLT 1 gene. The PFGE spectrum showed that the strains isolated from epidemic area were distinctively different from the strains isolated from Japan, and similar to but not identical with the standard strain 882364. The PFGE spectrum of strains isolated from epidemic area patients were identical with those of strains isolated from excrements of poultries, domestic animals and insect intestine.Conclusions Poultries and domestic animals which carry E.coli O 157∶H 7 could be the source of infection. PFGE could be used to analyze E.coli O 157∶H 7 and played an important role in epidemiology study. The results showed that the method of analysis of E. coli O 157∶H 7 by RAPD was convenient and time saving.