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ObjectiveWe conducted a drug resistance and homology analysis of diarrheagenic Escherichia coli （DEC） in Fengxian District of Shanghai in order to provide a basis for clinical rational drug use， risk monitoring and early warning. MethodsDEC were isolated from diarrheal patients in Fengxian District， Shanghai from 2019 to 2022. The minimum inhibitory concentrations （MIC） of 21 drugs to the DEC were determined. Genotyping and homology analysis were conducted with pulsed-field gel electrophoresis （PFGE）. ResultsThe DEC detection rate of diarrhea cases was 18.99% （131/690）， including enteroaggregative E.coli （EAEC） 64.89% （85/131）， enterotoxigenic E.coli （ETEC） 22.14% （29/131）， enteropathogenic E.coli （EPEC） 12.21% （16/131）， and enterohemorrhagic E.coli （EHEC） 0.76%（1/131）. The DEC detection showed obvious seasonal characteristics with a high incidence in summer. The DEC multidrug resistance rate was 66.41% with a total of 65 drug resistance profiles. The five antimicrobial drugs with the highest resistance rate were ampicillin （60.31%）， nalidixic acid （51.91%）， cefazolin （50.38%）， tetracycline （44.27%）， and cotrimoxazole （35.11%）. The rate of DEC resistance to levofloxacin was significantly increased from 2019 to 2022. Cluster analysis showed that the similarity of 85 EAEC cluster was 58.4%‒100.0%， and 69 band patterns were obtained. The similarity of 29 ETEC cluster was 58.5%‒100.0%， and 13 band patterns were obtained， including 2 dominant band types. The similarity of 16 EAEC clusters was 53.9%‒100.0%， and 15 band patterns were obtained. Five groups of homologous strains were found， consistent with the resistance phenotypes. ConclusionAmong the diarrhea cases， the DEC epidemic intensity is high， the drug resistance situation is severe， and the risk of outbreak infection is high in Fengxian District， Shanghai. Therefore， health monitoring and prevention need to be strengthened.
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To perform a comprehensive analysis of the pathogenic causes of a food poisoning case in a district of Wuhan Cit-y,we investigated the molecular epidemiological relationships among pathogenic bacteria,to aid in traceability analysis of food-borne disease outbreaks,as well as clinical diagnosis and treatment.The pathogenic bacteria in this food poisoning case were i-solated and identified according to GB789.4-2016.The isolated strains were subjected to genotyping with pulsed field gel elec-trophoresis(PFGE).Drug resistance gene analysis,multi-locus sequence typing(MLST),and genome-wide single-nucleotide polymorphism analysis(wgSNP)were conducted via whole genome sequencing(WGS).The evolutionary tree for cluster analy-sis was constructed in fasttree software.Drug susceptibility testing was conducted with the broth microdilution method.A total of 12 strains of Salmonella were detected in seven anal swab samples and two fecal samples from the case,as well as three anal swab samples from unaffected individuals.The serotype of the strains was Salmonella typhimurium.The strain exhibited severe multiple drug resistance,including resistance to amikacin,ampi-cillin,cefazolin,gentamicin,piperacillin,and tetracycline,but susceptibility to other antibiotics.The coincidence rate between drug resistance genes and drug resistance phenotypes was high.PFGE revealed that nine strains from this food poisoning case were highly homologous.WGS revealed that the MLST type was ST19,and varying numbers of SNPs(1-6)were present a-mong strains.The phylogenetic tree revealed nine isolated strains forming a distinct cluster,differing from other Salmonella strains in the database and belonging to a novel clonal branch.The single nucleotide site in the strains was highly homologous to that of GCF in Jiangxi_020221795.1.The food poisoning case was caused by Salmonella typhimurium ST19,and all nine iso-lated strains originated from the same source.The chef is closely connected to this food poisoning case.This strain of Salmo-nella typhimurium belongs to a new clonal branch and exhibits multiple drug resistance.
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ObjectiveTo investigate the pathogenic spectrum and molecular characteristics of infectious diarrhea among children in Putuo District of Shanghai from 2018 to 2023， and to provide scientific basis for the prevention and control of infectious diarrhea in children. MethodsFecal samples from the cases visited sentinel hospitals for children’s diarrheal disease in Putuo District， Shanghai， were collected from January 2018 to December 2023. A total of 11 species of bacteria were isolated and cultured， and 5 species of viruses were detected by real-time fluorescent polymerase chain reaction （PCR）. The molecular typing of some positive strains was analyzed by the standard pulsed-field gel electrophoresis （PFGE） method. The polymerase-capsid protein linkage region of some norovirus-positive samples was amplified by reverse transcription PCR， and was sequenced and analyzed by bioinformatics software. The Chi-square test and Fisher’s exact probability test were used to compare the pathogen-positive rates in 2018‒2019 and 2020‒2023. ResultsOf the 707 cases of children with infectious diarrhea， the total positive rate was 47.67%， with a single bacterial positivity rate of 16.27%， a single viral positivity rate of 22.63%， and a mixed positivity rate of 8.77%， respectively. The dominant pathogens were rotavirus （10.75%）， norovirus （10.33%）， enteropathogenic Escherichia coli （8.06%）， Salmonella （6.36%）， enteroaggregative Escherichia coli （5.52%）， and Campylobacter （5.23%）. Bacterial infections were predominant in summer and fall， and viral infections were predominant in winter and spring. The total positive rate decreased in 2020‒2023 compared with that of 2018‒2019 （χ2=5.753，P<0.05）. Thirty-seven strains of Salmonella， 81 strains of diarrheagenic Escherichia coli， and 19 strains of Campylobacter were completed for the molecular typing analysis by PFGE， which were classified into 28， 80 and 18 banding types， respectively， with a wide range of banding similarity. Nineteen copies of norovirus GⅡ group gene sequences were analyzed and classified into 5 genotypes， which were mainly GⅡ.Pe-GⅡ.4 and GⅡ.P16-GⅡ.2 types. ConclusionRotavirus， norovirus， diarrheagenic Escherichia coli， Salmonella， and Campylobacter are the dominant pathogens of infectious diarrhea in children in Putuo District of Shanghai. The pathogen spectrum shows a trend of seasonal epidemic characteristics， with a diversity of molecular characteristics of some pathogens. Surveillance and monitoring on molecular characteristics of the pathogens of infectious diarrhea in children should be strengthened in different seasons， so as to provide a laboratory basis for the prevention and control of infectious diarrhea.
الملخص
Objective To understand the serotype, drug resistance and pulsed field gel electrophoresis (PFGE) typing of Salmonella isolated from meat products in Hengyang from 2020 to 2022, so as to provide scientific data for the prevention and control of food-borne Salmonella infection in our city. Methods All 101 Salmonella isolated from meat products were serotyped, drug sensitivity tests were performed with micro broth dilution method, molecular typing was performed using PFGE, clustering analysis was performed with BioNumerics software, and statistical analysis was performed using SPSS 18.0 software. Results The total detection rate of Salmonella from meat sources in Hengyang City from 2020 to 2022 was 38.55% (101/262). Totally 23 different serotypes were detected in the 101 strains of Salmonella among which S. London (21.78%, 22/101),was the dominant serotypes. Seventy nine Salmonella strains showed different levels of drug resistance, with a multi drug resistance rate of 42.57% (43/101). Eighty nine different PFGE bands were found in the 101 strains of Salmonella, with a similarity of approximately 55% to 100%. Conclusion Different Salmonella Serotype are widely distributed, and the antibiotic resistance rate is very high. The PFGE map are polymorphic, and the homology of PFGE bands in Salmonella from different sources is relatively low.
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Objective To investigate the etiological characteristics of food poisoning isolates of Vibrio parahaemolyticus (VP) from 2019 to 2021 in Zhongshan City. Methods A total of 37 strains of Vibrio parahaemolyticus isolated from 8 food poisoning incidents in Zhongshan City from 2019 to 2021 were collected, including 1 residual food isolate and 36 human isolates. The genetic correlation of Vibrio parahaemolyticus food poisoning isolates in this region was analyzed by serological typing, virulence gene detection (TLH, TDH, and TRH), drug sensitivity test, pulsed field gel electrophoresis (PFGE) and multipoint sequence typing (MLST). Results The 37 strains of Vibrio parahaemolyticus were divided into 4 serotypes: O3:K6, O10:K4, O4:K8, and O4:KUT. The tdh+ and trh- were the main virulence genotypes, accounting for 97.30% (36/37). The drug resistance rate of cefazolin was 40.54% (15 strains R, 22 strains I), and no multidrug-resistant strains were found. The 37 VP strains were divided into 23 PFGE types and 6 cluster groups, with correlation coefficients ranging from 60.4%-100%. The multipoint sequencing typing showed that the 37 VP strains were divided into 9 ST types and 3 complex groups, of which ST3 type was the main type (23 strains, 62.1%). Conclusion This study has found that the dominant virulence types of Vibrio parahaemolyticus food poisoning isolates in Zhongshan City from 2019 to 2021 are tdh+ and trh-, and 37 representative strains can be divided into 6 PFGE clusters and 9 ST types with MLST type being mainly ST3. This study has identified the rare serotype O10:K4 which has caused an increase in the proportion of food poisoning events, suggesting that we should strengthen detection and be alert to the risk of continued local epidemics of new rare serotype strains.
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@#Abstract: Objective In order to provide reference for emergency treatment of a sudden food poisoning incident, pathogen detection and drug resistance analysis were carried out. Methods Diarrheal stool and surplus food samples were detected by GB 4789 and the isolates were identified by VITEK2 and matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), at the same time, the bacterial drug sensitivity test was carried out by using the method of microbroth dilution, and the isolates from different sources were molecularly classified by pulsed field gel electrophoresis (PFGE), and the correlation between the strains was analyzed by BioNumerics software. Results Totaly 13 leftovers and 3 diarrhea patients were isolated and identified, The total number of colonies and coliforms in 7 leftovers samples all exceeded the standard, and Citrobacter freundii was detected in 5 leftovers and 2 stools. The results of drug sensitivity test showed that seven strains of Citrobacter freundii were sensitive to ciprofloxacin, tetracycline, chloramphenicol, gentamicin, amikacin, cefotaxime and meropenem, but completely resistant to ampicillin, and there was no multiple drug resistance. The results of pulsed field gel electrophoresis (PFGE) showed that 7 strains of Citrobacter freundii had the same PFGE bands and 100% homology, showing the same clone. Conclusions This food poisoning incident was caused by Citrobacter freundii. The pathogen of food poisoning can be quickly and accurately determined by MALDI-TOF MS, which is beneficial to the early diagnosis and treatment of infectious diseases. It is suggested to strengthen the corresponding management, improve food safety awareness and prevent similar incidents.
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Background The incidence of Legionnaires' disease is increasing globally and artificial water environment is becoming a common source of outbreaks. Molecular typing techniques can help prevent and control Legionella. Objective To understand the molecular epidemiological characteristics of Legionella pneumophila in artificial water environment of Shanghai hospitals, and provide a scientific basis for the prevention and control of Legionnaires' disease. Methods Water samples were collected from artificial water environment in 14 hospitals from May to October each year from 2019 to 2020 in Shanghai. A total of 984 water samples were collected from 8 Grade-A tertiary hospitals and 6 non-Grade-A tertiary hospitals, including 312 samples of cooling water, 72 samples of chilled water, and 600 samples of tap water. The water samples were isolated and serotyped for Legionella pneumophila and preserved, and the positive rate of Legionella pneumophila in the samples was used as an indicator of contamination. The preserved strains were resuscitated and 81 surviving strains were obtained for pulsed field gel electrophoresis (PFGE) typing analysis. Results A total of 124 Legionella pneumophila positive water samples were detected, with a positive rate of 12.60%. The positive rate was higher in the Grade-A tertiary hospitals (16.54%, 87/526) than in the non-Grade-A tertiary hospitals (8.08%, 37/458) (χ2=15.91, P<0.001). The positive rate of cooling water (23.40%) was the highest among different types of water samples, and the difference was statistically significant (χ2=61.19, P<0.001). The difference in positive rate of tap water was statistically significant among different hospital departments (χ2=11.37, P<0.05). The positive rate in 2019 (15.06%) was higher than that in 2020 (9.84%) (χ2=6.23, P<0.05). From May to October, August had the highest annual average positive rate (16.46%) and October had the lowest (8.54%), but the difference in positive rates among months was not statistically significant (χ2=5.39, P=0.37). The difference in positive rate among districts was statistically significant (χ2=24.88, P<0.001). A total of 131 strains of Legionella pneumophila were isolated, with serotype 1 (80.15%, 105/131) predominating. Among the 81 surviving strains of Legionella pneumophila subjected to PFGE typing, the band-based similarity coefficients ranged from 41.30% to 100%. Among the 29 PFGE band types (S1-S29) recorded, each band type included 1-10 strains, and S28 was the dominant band type. Four clusters (I-IV) of PFGE band types were identified, accounting for 66.67% (54/81) of all strains and containing 13 band types. Conclusion Legionella pneumophila contamination is present in the artificial water environment of hospitals in Shanghai from 2019 to 2020, and the contamination in tap water deserves attention. The detected serotype of Legionella pneumophila is predominantly type 1, and PFGE typing reveals the presence of genetic polymorphism. Therefore, the monitoring and control of Legionella pneumophila in hospital artificial water environment should be strengthened.
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Objective@#To analyze the etiological characteristics of an outbreak of Campylobacter foodborne disease in a middle school in Suzhou City, so as to provide insights into the identification of pathogenic factors of Campylobacter foodborne disease outbreaks.@*Methods@#Eighteen anal swabs from patients, 10 anal swabs from canteen workers, 43 food samples, 2 drinking water samples, 2 food original material samples and 31 environmental samples were collected, and the pathogens were rapidly screened using the gastrointestinal infection detection strip. The pathogens were isolated and cultured using the double-pore filtration membrane method, and cluster analysis of bacterial isolates was performed using pulsed field gel electrophoresis ( PFGE ). In addition, the susceptibility of Campylobacter isolates to antibiotics was tested using the Campylobacter agar dilution method.@*Results@#A total of 63 cases with Campylobacter infections were reported, and the major clinical symptoms included diarrhea ( 51 cases, 80.95% ) and fever ( 39 cases, 61.90% ), while no inpatients or deaths were found. Twelve Campylobacter-positive samples were detected, including 11 anal swabs sampled from patients and one food original material sample. Among the 11 positive anal swabs, there were 10 samples positive for Campylobacter jejuni and one sample positive for C. coli, and of the one positive food original material, C. coli was identified. PFGE analysis showed that 10 C. jejuni isolates of had 100.0% homology, and these 10 isolates were 100.0% resistant to naphthyridic acid, ciprofloxacin and tetracycline, appearing multidrug resistance.@*Conclusions@#This is an outbreak of foodborne disease caused by C. jejuni infections. Gastrointestinal infection detection strips, double-pore filtration membrane and PFGE typing are rapid and accurate to identify pathogenic factors.
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ObjectiveTo determine the pathogenic cause in a foodborne diseases outbreak of Salmonella enteritidis in a company in Suzhou City， and provide evidence for epidemiological investigation and guidance for clinical treatment. MethodsRelevant specimens were examined for Salmonella， Shigella， Staphylococcus aureus and Vibrio parahaemolyticus. Furthermore， for the isolated Salmonella enteritidis， a micro broth dilution method was used for antimicrobial susceptibility testing， and pulsed field gel electrophoresis （PFGE） was used for molecular typing. ResultsA total of 44 strains of Salmonella enteritidis were detected from 43 anal swabs of the patients in the outbreak， 7 anal swabs of canteen employees， 31 retained food specimens and 6 environmental specimens. A total of 15 antimicrobial susceptibility testings showed that the 44 strains had the same antimicrobial resistance spectrum， which was 100% resistant to cefazolin， ampicillin， ampicillin/sulbactam， polymyxin E and nalidixic acid， suggesting a multi-drug resistance to more than three antibiotics. PFGE cluster analysis showed that the 44 strains had a 100% of genetic similarity. ConclusionThe outbreak is caused by the consumption of food contaminated with Salmonella enteritidis. The isolated strains have multi-drug resistance， which could guide appropriate antimicrobial treatment based on the antimicrobial susceptibility testing.
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Objective:To analysis the macrolide resistance, molecular characteristics and plused-field gel electrophoresis(PFGE) type of Bordetella pertussis ( Bp), explore the possible resistance mechanism and the relationship between PFGE types and macrolide resistance profiles. Methods:Erythromycin, azithromycin and clarithromycin susceptibility of clinical isolates during 2016 to 2018 was determined by E-test. PCR was used to detect the drug-resistant genes and mutation sites. PFGE were employed to do molecular typing for the strains.Results:Thirty-five strains were isolated, of which 27 strains were resistant to all three antibiotics, two strains were resistant to erythromycin and azithromycin, and six strains were sensitive to all three antibiotics. Partial macrolide resistant strains carried the methylase gene ermA (27.6%, 8/29) and ermB (31.0%, 9/29); A2047G site mutation was detected in macrolide-resistant strains, while no drug-resistant genes or mutation sites were found in sensitive strains. Resistant strains were classified into BPSR23 and BPFINR9 types, while sensitive strains were other profiles. Conclusions:The clinical isolated Bp were seriously resistant to erythromy and showed signs of resistance to other macrolides. The acquisition of methylase gene and mutation of A2047G site might be the main mechanism of resistance. The macrolide resistance might have has a certain correlation with PFGE profile.