Study of the urban-impact on microbial communities and their virulence factors and antibiotic resistance genomes in the Nandu River, Haikou / 中华流行病学杂志

Objective: To explore the changes in bacterial community structure, antibiotic resistance genome, and pathogen virulence genome in river water before and after the river flowing through Haikou City and their transmission and dispersal patterns and to reveal anthropogenic disturbance's effects on microorganisms and resistance genes in the aquatic environment. Methods: The Nandu River was divided into three study areas: the front, middle and rear sections from the upstream before it flowed through Haikou City to the estuary. Three sampling sites were selected in each area, and six copies of the sample were collected in parallel at each site and mixed for 3 L per sample. Microbial community structure, antibiotic resistance, virulence factors, and mobile genetic elements were analyzed through bioinformatic data obtained by metagenomic sequencing and full-length sequencing of 16S rRNA genes. Variations in the distribution of bacterial communities between samples and correlation of transmission patterns were analyzed by principal co-ordinates analysis, procrustes analysis, and Mantel test. Results: As the river flowed through Haikou City, microbes' alpha diversity gradually decreased. Among them, Proteobacteria dominates in the bacterial community in the front, middle, and rear sections, and the relative abundance of Proteobacteria in the middle and rear sections was higher than that in the front segment. The diversity and abundance of antibiotic resistance genes, virulence factors, and mobile genetic elements were all at low levels in the front section and all increased significantly after flow through Haikou City. At the same time, horizontal transmission mediated by mobile genetic elements played a more significant role in the spread of antibiotic-resistance genes and virulence factors. Conclusions: Urbanization significantly impacts river bacteria and the resistance genes, virulence factors, and mobile genetic elements they carry. The Nandu River in Haikou flows through the city, receiving antibiotic-resistant and pathogen-associated bacteria excreted by the population. In contrast, antibiotic-resistant genes and virulence factors are enriched in bacteria, which indicates a threat to environmental health and public health. Comparison of river microbiomes and antibiotic resistance genomes before and after flow through cities is a valuable early warning indicator for monitoring the spread of antibiotic resistance.

Epidemiological characteristics of typhus in China, 1950-2021 / 中华流行病学杂志

Objective: To analyze the epidemiological characteristics of typhus in China from 1950 to 2021, and discuss the challenges in typhus prevention and control in China and suggest future prevention and control strategies. Methods: Based on the reported data of typhus from 1950 to 2021 in China from the Infectious Disease History Database of China Public Health Science Data Center and the National Notifiable Infectious Disease Reporting Information System of Chinese Center for Disease Control and Prevention, we conducted a descriptive statistical analysis. Mann-Kendall test and circular distribution method were used to analyze the incidence, mortality and case fatality of typhus to reveal the temporal, spatial and population distributions and diagnosis of typhus in China. Results: From 1950 to 2021, a total of 452 965 typhus cases and 7 339 typhus deaths were reported in China, with the cases numbers exceeding 10 000 in 14 years of the 1950s, 1960s and 1980s, respectively. Since 1990s, the reported cases and incidence rate of typhus have decreased dramatically and the most cases were sporadic. However, the reported typhus cases in Anhui, Hubei, Hunan Provinces showed significant uptrends. Although typhus could occur all the year round, but the seasonality was observed with the incidence mainly in summer and autumn. For different provinces from the north to the south, the peaks of typhus' monthly incidence tended to shift to earlier dates. The male to female ratio of the cases was 1.01∶1 (18 529∶18 366). However, more cases occurred in women in recent years. The cases aged ≤9 years accounted for the highest proportion (18.9%), but the number of cases aged ≥50 years showed an upward trend. Most cases were farmers with the proportion increasing year by year. Moreover, the cases in students and scattered-living children also accounted for relatively higher proportions. The median of the interval between onset and diagnosis of typhus was 6 days. Most cases were clinically diagnosed, while the proportion of laboratory-confirmed cases was low and most laboratory cases were confirmed by Well-Felix reaction. Conclusions: Although the incidence and mortality of typhus in China has decreased significantly, the risk for local typhus outbreaks still exists. The prevention and control of typhus still face many challenges. It is indispensable to strengthen the pathogen detection and surveillance for typhus in China.

Drug resistance and genomic characteristics of a strain of O139 Vibrio cholerae isolated from human bloodstream infection / 中华预防医学杂志

Objective: To analyze the drug resistance and genomic characteristics of a strain of serogroup O139 Vibrio cholerae producing cholera toxin isolated from the bloodstream of a person with bacteremia. Methods: The broth dilution method and automatic drug sensitivity analyzer were used to determine the antibiotic sensitivity of the strain. The complete genome sequence of the strain was obtained by using second-generation gene sequencing and nanopore sequencing. BLAST software was used for comparison and analysis with CARD, Resfinder, ISfinder, VFDB, and other databases. The drug-resistant genes, insertion sequences and virulence genes carried by the strain were identified. MEGA 5.1 software was used to construct a genetic phylogenetic tree based on the core genomic single nucleotide polymorphisms. Results: V. cholerae SH400, as the toxigenic strain, carried multiple virulence-related genes and four virulence islands. The strain was resistant to streptomycin, tetracycline and cotrimoxazole, carrying corresponding drug-resistant genes. The strain also carried IncA/C plasmid with the size of 172914 bp and contained 10 drug-resistant genes. Combined with the genomic evolutionary relationship, this study found that the drug-resistant genes and drug-resistant plasmids carried among strains showed certain aggregation. The traditional ST type of strain SH400 was ST69, and the cgMLST type was a new type highly similar to cgST-252. Conclusion: This strain of serogroup O139 V. cholerae carries the ctxAB gene, multiple drug-resistant genes and IncA/C plasmid, and there are multiple drug-resistant islands.

Establishment and evaluation of a method for phages enrichment by ferric trichloride-polyvinylidene fluoride membrane filter / 中华预防医学杂志

Objective: To establish and evaluate a method of enriching bacteriophages in natural water based on ferric trichloride-polyvinylidene fluoride (FeCl3-PVDF)membrane filter. Methods: Based on the principle of flocculation concentration, the method of recovering bacteriophage from water sample was established by using iron ion flocculation combined with membrane filter. The titer of phage was determined by Agar double layer method. The recovery efficiency of phage was detected by phage fluorescence staining and real-time fluorescence PCR reaction. Water samples from different sources were collected for simulation experiment to evaluate the enrichment effect. At the same time, the sewage discharged from hospitals was taken as the actual water sample, and the common clinical drug-resistant bacteria were used as the host indicator bacteria to further analyze the enrichment effect of FeCl3-PVDF membrane filter rapid enrichment method on the bacteriophage in natural water samples. Results: The method of enrichment of bacteriophages in natural water by iron ion concentration 50 mg/L and PVDF membrane filter was established. The recovery rate of this method for bacteriophage was 93%-100%. Under the multi-functional microscope, it was found that the bacteriophage of the enriched water sample increased significantly and the fluorescence value of the enriched water sample determined by the enzyme labeling instrument was about 13 times as high as that before enrichment. After concentration of the actual water samples from the hospital drainage, the positive rate of bacteriophage isolation in the concentrated group and the non-concentrated group was 23% and 4%, and the fluorescence value in the concentrated group was 2-24 times as high as that of the non-concentrated group. Conclusion: The method of FeCl3-PVDF membrane filter is a simple, efficient and rapid method for enriching bacteriophages in different water samples.

Advance on research and application of laboratory pathogen monitoring and early warning technology of bacterial infectious diseases / 中华预防医学杂志

Human beings are still facing the public health challenges from bacterial infectious diseases. Carrying out systematic infectious disease monitoring and early warning is the most direct solution to prevent and control infectious diseases. Etiology is an important part of infectious disease monitoring and early warning. Effective pathogen monitoring can identify pathogens, outbreaks and sources at the first time. In this study, we have reviewed the research and application of etiology monitoring and early warning technology of bacterial infectious diseases and summarized the importance and application scenarios of etiology in infectious disease monitoring and early warning, as well as the research progress of etiology monitoring and early warning technology. Based on the work of existing laboratory monitoring networks, such as Chinese Pathogen Identification Network, the development trend and prospect of infectious disease laboratory network monitoring are put forward to provide a reference for establishing and perfecting the infectious disease monitoring and early warning system.

Application and reflection of laboratory-based monitoring in early warning of infectious diseases / 中华预防医学杂志

Despite the fact that our cognition towards infectious disease prevention, the advanced technology and the economic status of the whole society has made a great progress in the last decade, the outbreak of COVID-19 pneumonia has again enabled the public to acquire more about super-challenges of infectious diseases, epidemics and the relevant preventive measurements. In order to identify the epidemic signals in early stage or even before the onset of epidemic, the data research and utilization of a series of factors related to the occurrence and transmission of infectious diseases have played a significant role in research of prevention and control during the whole period of surveillance and early warning. Laboratory-based monitoring for the etiology has always been an important part of infectious disease warning system due to pathogens as the direct cause of such diseases. China has initially established a laboratory-based monitoring and early warning system for bacterial infectious diseases based on the Chinese Pathogen Identification Network with an aim to identify pathogens, outbreaks and sources. This network has played an essential role in early detection, tracking and precise prevention and control of bacterial infectious diseases, such as plague, cholera, and epidemic cerebrospinal meningitis. This issue focuses on the function of laboratory-based monitoring during the period of early warning, prevention, and control of bacterial infectious diseases, and conducted a wide range of researches based on the analysis of the epidemic and outbreak isolates, together with field epidemiological studies and normal monitoring systems. All of these could illustrate the effect of laboratory surveillance in the infectious disease risk assessment and epidemic investigation. At the same time, we have put forward our review and expectation of scenarios about laboratory-based monitoring and early warning technologies to provide innovative thoughts for promoting a leapfrog development of infectious disease monitoring and early warning system in China.

Development of a luminescence real-time method for monitoring live bacteria during phage lysis / 生物工程学报

The toxin-producing bacterium Vibrio cholerae can cause severe diarrhea and has caused seven global pandemics. Traditional viable cell counts and phage plaques are commonly used to evaluate the efficacy of virulent phage clearance of V. cholerae, but these operations are time-consuming and labor-intensive, and difficult to provide real-time changes. It is desirable to develop a simple and real-time method to monitor V. cholerae during phage lysis. In this study, a luminescence-generating plasmid pBBR-pmdh-luxCDABE was transformed into three O1 serogroup drug-resistant strains of V. cholerae. The results showed that the luminescence value as a monitoring index correlates well with the traditional viable cell count method. Monitoring the number of live cells of V. cholerae by measuring the luminescence allowed real-time analysis of the number of bacteria remaining during phage lysis. This method enables repeated, interference-free, continuous multiple-time-point detection of the same sample without the time delay of re-culture or plaque formation, facilitating real-time monitoring and analysis of the interaction between the phage and the host bacteria.

Comparative Study of the Genetic Diversity, Antimicrobial Resistance, and Pathogenicity of / 生物医学与环境科学（英文）

Objective@#This study was performed to compare the genetic diversity, virulence, and antimicrobial resistance of @*Methods@#A total of 38 clinical strains and 19 strains from healthy individuals were isolated from the samples collected in Ma'anshan City, Anhui Province. Their taxonomy was investigated using concatenated @*Results@#The 57 @*Conclusions@#The taxonomy, virulence properties, and antibiotic resistance of

Transforming bacterial disease surveillance and investigation using whole-genome sequence to probe the trace / 医学前沿

Two decades have passed since the first bacterial whole-genome sequencing, which provides new opportunity for microbial genome. Consequently, considerable genetic diversity encoded by bacterial genomes and among the strains in the same species has been revealed. In recent years, genome sequencing techniques and bioinformatics have developed rapidly, which has resulted in transformation and expedited the application of strategy and methodology for bacterial genome comparison used in dissection of infectious disease epidemics. Bacterial whole-genome sequencing and bioinformatic computing allow genotyping to satisfy the requirements of epidemiological study in disease control. In this review, we outline the significance and summarize the roles of bacterial genome sequencing in the context of bacterial disease control and prevention.We discuss the applications of bacterial genome sequencing in outbreak detection, source tracing, transmission mode discovery, and new epidemic clone identification. Wide applications of genome sequencing and data sharing in infectious disease surveillance networks will considerably promote outbreak detection and early warning to prevent the dissemination of bacterial diseases.

Epidemiological characteristics and molecular typing of typhoid and paratyphoid in China,2009-2013 / 中华流行病学杂志

Objective To understand the epidemiological and molecular characteristics of typhoid and paratyphoid in China from 2009 to 2013,and provide evidence for the prevention and control of typhoid and paratyphoid,the development and improvement of surveillance strategies.Methods Epidemiological analysis was conducted on the incidence data of typhoid and paratyphoid,and related public health emergencies in China during 2009-2013.Pathogen isolation and culture,serologic test were conducted for the typhoid and paratyphoid cases from 13 national surveillance sites.The isolates were subjected to antimicrobial susceptibility testing.Pulsed-field gel electrophoresis (PFGE) was performed for the molecular typing of these isolates.Results The average incidence of typhoid and paratyphoid in China during this period was 1.03/100 000.The reported case number and incidence decreased with year.The provinces reporting high case numbers were Yunnan,Guizhou,Guangxi,Hunan,Zhejiang,Guangdong and Xinjiang.The incidence of age group 0-4 years was highest.The proportion of farmers and children outside child care settings showed an increasing tendency over time.The annual incidence peak was during July-August.Twenty five outbreaks occurred during 2009-2013.The results of pathogen isolation and culture showed that the positive rate was 3.00％ (940/31 322),among the positive isolates,the proportion of Salmonella paratyphi A accounted for higher proportion (68.19％,641/940) compared with Salmonella typhi (31.60％,297/940).The drug resistances of Salmonella typhi and Salmonella paratyphi varied,but their resistances to nalidixic acid were highest (50.22％ and 85.33％) respectively.A certain amount of Salmonella typhi isolates showed the resistance to the 3rd generation cephalosporins.PFGE analysis showed divergent patterns of Salmonella typhi compared with limited patterns of Salmonella paratyphi A.Conclusion The epidemic level of typhoid and paratyphoid in China was relatively low,but the outbreak occurred occasionally.It is necessary to enhance the laboratory-based surveillance,particularly the capability of etiological diagnosis,outbreak investigation,response and antibiotic resistance monitoring,and conduct risk factor investigation in provinces with high incidences in recent years.

Epidemiological characteristics and molecular typing of typhoid and paratyphoid in China,2009-2013 / 中华流行病学杂志

Objective To understand the epidemiological and molecular characteristics of typhoid and paratyphoid in China from 2009 to 2013,and provide evidence for the prevention and control of typhoid and paratyphoid,the development and improvement of surveillance strategies.Methods Epidemiological analysis was conducted on the incidence data of typhoid and paratyphoid,and related public health emergencies in China during 2009-2013.Pathogen isolation and culture,serologic test were conducted for the typhoid and paratyphoid cases from 13 national surveillance sites.The isolates were subjected to antimicrobial susceptibility testing.Pulsed-field gel electrophoresis (PFGE) was performed for the molecular typing of these isolates.Results The average incidence of typhoid and paratyphoid in China during this period was 1.03/100 000.The reported case number and incidence decreased with year.The provinces reporting high case numbers were Yunnan,Guizhou,Guangxi,Hunan,Zhejiang,Guangdong and Xinjiang.The incidence of age group 0-4 years was highest.The proportion of farmers and children outside child care settings showed an increasing tendency over time.The annual incidence peak was during July-August.Twenty five outbreaks occurred during 2009-2013.The results of pathogen isolation and culture showed that the positive rate was 3.00％ (940/31 322),among the positive isolates,the proportion of Salmonella paratyphi A accounted for higher proportion (68.19％,641/940) compared with Salmonella typhi (31.60％,297/940).The drug resistances of Salmonella typhi and Salmonella paratyphi varied,but their resistances to nalidixic acid were highest (50.22％ and 85.33％) respectively.A certain amount of Salmonella typhi isolates showed the resistance to the 3rd generation cephalosporins.PFGE analysis showed divergent patterns of Salmonella typhi compared with limited patterns of Salmonella paratyphi A.Conclusion The epidemic level of typhoid and paratyphoid in China was relatively low,but the outbreak occurred occasionally.It is necessary to enhance the laboratory-based surveillance,particularly the capability of etiological diagnosis,outbreak investigation,response and antibiotic resistance monitoring,and conduct risk factor investigation in provinces with high incidences in recent years.

Study on the mechanism of serotype conversion of historical isolates of Shigella flexneri / 中华预防医学杂志

Objective@#The serotype screening of Shigella flexneri from 1934 to 1965 preserved by the National Center for Medical Culture Collections was carried out, and the molecular characteristics of the serotype conversion strains were studied.@*Methods@#Serotyping of Shigella flexneri in this study was conducted by slide agglutination and multiplex PCR, respectively. The gtrⅡ gene sequence alignment and pulsed field gel electrophoresis typing were performed on the serotype conversion strains.@*Results@#Among the 255 strains of Shigella flexneri preserved in CMCC (B) from 1934 to 1965, 79 were carrying gtrⅡ gene, of which 19 strains and 1 strain were agglutinated with the Y serotype and X serotype, respectively, and furthermore, the multiplex PCR assays results showed serotypes 2a and 2b, respectively, and the strains were considered to have serotype conversion. The 20 strains carrying the gtrⅡ gene showed multiple nucleotide mutations. Besides 3 strains of 3 amino acid mutations, the amino acid sequences of the other 17 strains showed a stop codon in advance, resulting in functional inactivation of gtrⅡ. PFGE analysis revealed that the similarity between the serotype Y strain carrying the gtrⅡ gene and the serotype 2a strain was 75.8%-100%, and the similarity between the serotype X strain carrying the gtrⅡ gene and the serotype 2b strain was 81.6%-100%.@*Conclusion@#Mutations in the gtrⅡ gene are more complicated in serotype-transforming Shigella flexneri serotype Y or X strains. Molecular typing suggests that the serotype-transforming Shigella flexneri serotype Y or X strains may be derived from the Shigella flexneri serotype 2a or 2b, and advance the serotype conversion to 1949.

Identification of Asymmetry Gait in Parkinson's Disease Based on Kinect / 中国康复理论与实践

@#Objective To develop a non-contact identification method for gait asymmetry in Parkinson's disease based on depth image to assist medical diagnosis and assessment, to avoid the cost, impact on normal life, and complex process of high wear-out sensing equipment. Methods From July to August, 2016, eight patients with Parkinson's disease and ten healthy subjects were collected the gait parameters of walking six meters with Kinect V2.0. The parameters of left and right foot were filtered and clustered. Then similarity matrix algorithm was used to find the difference between healthy subject and patient similarity values. Finally, the recognition effect of this method was verified by Hidden Markov Model. Results The similarity of clustering sequences of left and right foot parameters was less in the patients than in the healthy individuals. There were twelve of 14 data identified in patients, and 35 of 46 in the healthy. Conclusion A non-contact identification method for the asymmetry of gait has been developed based on the parameter clustering results of left and right foot, which is some effective on identifying Parkinson's patients.

Spatial and temporal clustering characteristics of typhoid and paratyphoid fever and its change pattern in 3 provinces in southwestern China, 2001-2012 / 中华流行病学杂志

Objective To analyze the spatial and temporal clustering characteristics of typhoid and paratyphoid fever and its change pattern in Yunnan, Guizhou and Guangxi provinces in southwestern China in recent years. Methods The incidence data of typhoid and paratyphoid fever cases at county level in 3 provinces during 2001-2012 were collected from China Information System for Diseases Control and Prevention and analyzed by the methods of descriptive epidemiology and geographic informatics. And the map showing the spatial and temporal clustering characters of typhoid and paratyphoid fever cases in three provinces was drawn. SaTScan statistics was used to identify the typhoid and paratyphoid fever clustering areas of three provinces in each year from 2001 to 2012. Results During the study period, the reported cases of typhoid and paratyphoid fever declined with year. The reported incidence decreased from 30.15 per 100000 in 2001 to 10.83 per 100000 in 2006 (annual incidence 21.12 per 100000);while during 2007-2012, the incidence became stable, ranging from 4.75 per 100000 to 6.83 per 100000 (annual incidence 5.73 per 100000). The seasonal variation of the incidence was consistent in three provinces, with majority of cases occurred in summer and autumn. The spatial and temporal clustering of typhoid and paratyphoid fever was demonstrated by the incidence map. Most high-incidence counties were located in a zonal area extending from Yuxi ofYunnan to Guiyang of Guizhou, but were concentrated in Guilin in Guangxi. Temporal and spatial scan statistics identified the positional shifting of class Ⅰ clustering area from Guizhou to Yunnan. Class Ⅰ clustering area was located around the central and western areas (Zunyi and Anshun) of Guizhou during 2001-2003, and moved to the central area of Yunnan during 2004-2012. Conclusion Spatial and temporal clustering of typhoid and paratyphoid fever existed in the endemic areas of southwestern China, and the clustering area covered a zone connecting the central areas of Guizhou and Yunnan. From 2004 to 2012, the most important clustering area shifted from Guizhou to Yunnan. Findings from this study provided evidence for the identifying key areas for typhoid and paratyphoid fever control and prevention and allocate health resources.

Study on antibiotic resistance of Escherichia coli and Enterococcus colonized in intestine of neonates from neonatal intensive care unit / 中华流行病学杂志

Objective To understand the antibiotic resistance of bacteria colonized in intestine of the neonates from neonatal intensive care unit (NICU) and provide evidence to guide clinical antibiotic treatment.Methods From May,2014 to May,2015,a total of 572 stool samples were collected from the neonates of NICU in our hospital.Escherichia coli and Enterococcus were detected with VITEK-2 system.Results A total of 328 strains of E.coli and 243 strains of Enterococcus were isolated respectively in this study.The 199 strains of E.coli selected for drug susceptibility test showed lower resistant rate to imipenem,ertapenem,amikacin,nitrofurantoin,ranging from 0.50％ to 3.52％ and showed higher resistant rate to ampicillin,tetracycline,trimethoprim/sulfamethoxazole and cefazolin,ranging from 54.27％ to 84.92％.No meropenem resistant strainsere were found.The percentage of ESBLs production strains was 45％.The multi drug resistance test showed that 34.6％ of the strains were resistant to four antibiotics.Three strains were resistant to seven antibiotics.The 243 strains of Enterococcus showed lower resistant rate to quinupristin/dalfopristin,nitrofurantoin,streptomycin,ranging from 0.41％ to 4.53％ and showed higher resistant rate to ampicillin,benzylpenicillin,ciprofloxacin,tetracycline,gentamicin and erythromycin,ranging from 70.78％ to 91.77％.No strains which were resistant to tigecycline,vancomycin,rina thiazole amine/ketone were found.The multi drug-resistance test showed that 86.5％ of the strains were resistant to five antibiotics.Conclusions According to the analysis of the 199 strains ofE.coli and 243 strains of Enterococcus isolated from the neonates,we found that the resistance of intestinal bacteria in the neonates was very serious,showing multi drug resistance.It is necessary to use antibiotics according to the drug susceptibility test results in clinical treatment.

Spatial and temporal clustering characteristics of typhoid and paratyphoid fever and its change pattern in 3 provinces in southwestern China, 2001-2012 / 中华流行病学杂志

Objective To analyze the spatial and temporal clustering characteristics of typhoid and paratyphoid fever and its change pattern in Yunnan, Guizhou and Guangxi provinces in southwestern China in recent years. Methods The incidence data of typhoid and paratyphoid fever cases at county level in 3 provinces during 2001-2012 were collected from China Information System for Diseases Control and Prevention and analyzed by the methods of descriptive epidemiology and geographic informatics. And the map showing the spatial and temporal clustering characters of typhoid and paratyphoid fever cases in three provinces was drawn. SaTScan statistics was used to identify the typhoid and paratyphoid fever clustering areas of three provinces in each year from 2001 to 2012. Results During the study period, the reported cases of typhoid and paratyphoid fever declined with year. The reported incidence decreased from 30.15 per 100000 in 2001 to 10.83 per 100000 in 2006 (annual incidence 21.12 per 100000);while during 2007-2012, the incidence became stable, ranging from 4.75 per 100000 to 6.83 per 100000 (annual incidence 5.73 per 100000). The seasonal variation of the incidence was consistent in three provinces, with majority of cases occurred in summer and autumn. The spatial and temporal clustering of typhoid and paratyphoid fever was demonstrated by the incidence map. Most high-incidence counties were located in a zonal area extending from Yuxi ofYunnan to Guiyang of Guizhou, but were concentrated in Guilin in Guangxi. Temporal and spatial scan statistics identified the positional shifting of class Ⅰ clustering area from Guizhou to Yunnan. Class Ⅰ clustering area was located around the central and western areas (Zunyi and Anshun) of Guizhou during 2001-2003, and moved to the central area of Yunnan during 2004-2012. Conclusion Spatial and temporal clustering of typhoid and paratyphoid fever existed in the endemic areas of southwestern China, and the clustering area covered a zone connecting the central areas of Guizhou and Yunnan. From 2004 to 2012, the most important clustering area shifted from Guizhou to Yunnan. Findings from this study provided evidence for the identifying key areas for typhoid and paratyphoid fever control and prevention and allocate health resources.

Study on antibiotic resistance of Escherichia coli and Enterococcus colonized in intestine of neonates from neonatal intensive care unit / 中华流行病学杂志

Objective To understand the antibiotic resistance of bacteria colonized in intestine of the neonates from neonatal intensive care unit (NICU) and provide evidence to guide clinical antibiotic treatment.Methods From May,2014 to May,2015,a total of 572 stool samples were collected from the neonates of NICU in our hospital.Escherichia coli and Enterococcus were detected with VITEK-2 system.Results A total of 328 strains of E.coli and 243 strains of Enterococcus were isolated respectively in this study.The 199 strains of E.coli selected for drug susceptibility test showed lower resistant rate to imipenem,ertapenem,amikacin,nitrofurantoin,ranging from 0.50％ to 3.52％ and showed higher resistant rate to ampicillin,tetracycline,trimethoprim/sulfamethoxazole and cefazolin,ranging from 54.27％ to 84.92％.No meropenem resistant strainsere were found.The percentage of ESBLs production strains was 45％.The multi drug resistance test showed that 34.6％ of the strains were resistant to four antibiotics.Three strains were resistant to seven antibiotics.The 243 strains of Enterococcus showed lower resistant rate to quinupristin/dalfopristin,nitrofurantoin,streptomycin,ranging from 0.41％ to 4.53％ and showed higher resistant rate to ampicillin,benzylpenicillin,ciprofloxacin,tetracycline,gentamicin and erythromycin,ranging from 70.78％ to 91.77％.No strains which were resistant to tigecycline,vancomycin,rina thiazole amine/ketone were found.The multi drug-resistance test showed that 86.5％ of the strains were resistant to five antibiotics.Conclusions According to the analysis of the 199 strains ofE.coli and 243 strains of Enterococcus isolated from the neonates,we found that the resistance of intestinal bacteria in the neonates was very serious,showing multi drug resistance.It is necessary to use antibiotics according to the drug susceptibility test results in clinical treatment.

Comparison of colonization ability of O1 and O139 Vibrio cholerae strains on soft-shelled turtle's surface / 中华预防医学杂志

Objective@#To study the preferred colonization sites of O1 Vibrio cholerae (V.cholerae) and the colonization ability difference for O1 and O139 V. cholerae on soft-shelled turtle's surface.@*Methods@#8 O1 and O139 V. cholerae strains were obtained from branch of diarrheal diseases, Chinese center for disease control and prevention. 63 soft-shelled turtles weighing 150 g and 9 cm in length (diameter of calipash) were selected for use in the study. The preferred colonization sites and proliferation trend were studied by using bioluminescent imaging method. The colonization factors for O1 V. cholerae strains were studied by constructing colonization gene mutant strains (VC1897dmshA, VC1897dgbpA and VC1897dtcpA), performing competition colonization assays and analyzing the competitive indexes. After pairing off O1 and O139 strains respectively to perform 16 competition groups, the colonization difference of these two strains were studied by competition colonization assays.@*Results@#The colonization sites by V. cholerae on soft-shelled turtles surfaces was clustered. More V. cholerae strains colonized on turtle's calipash and carapace on dorsal side and less strain colonized on ventral side. The competition colonization assays showed that colonization ability of O1 serogroup mshA mutant strains were 7.26 times lower than VC1897dlacZ. Besides, the CI value (O139/O1) of 11 out of the 16 competition groups were greater than 2 (between 2.07 and 59.84). Two groups showed values of 1.43 and 0.93 respectively and 3 groups lower than 0.7.@*Conclusion@#The preferred colonization sites for O1 V. cholerae strains on body surface were observed.MSHA was one of the main colonization factors for its colonization. Our study suggested that in general, O139 V. cholerae strains have stronger colonization ability than O1 strains. Besides, strains isolated from soft-shelled turtles tend to have stronger colonization ability than strains isolated from patients.

Study on identification of Cronobacter spp.species in 11 areas in China / 中华流行病学杂志

Objective To compare different methods on the identification of Cronobacter (C.) spp.species and to choose an optimum one.Methods Biochemical test,16S rRNA and fusA sequencing methods were carried out.Results When using the biochemical test,105 strains showed six different conditions but C.turicensis and C.universalis could not be effectively identified.Under the 16S rRNA sequencing analysis,all the strains were divided into 5 groups but C.sakazakii and C.malonaticus were tangled.Finally,all the strains were identified into 58 C.sakazakii,30 C.malonaticus,11 C.dublinensis,5 C.turicensis,1 C.muytjensii,under the fusA sequencing analysis.Conclusion Currently,fusA sequencing analysis seemed an effective method for identifying the species of Cronobacter.Since fusA sequencing analysis method was less intuitive,another method for rapid testing should be developed.