Etiologic identification and drug susceptibility analysis of a Citrobacter freundii food poisoning event / 中国热带医学

@#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.

Contamination status and molecular typing of Legionella pneumophila in artificial water environment in Shanghai hospitals from 2019 to 2020 / 环境与职业医学

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.

Etiological characteristics of Vibrio parahaemolyticus strains isolated from foodborne outbreaks in Zhongshan in 2019 - 2021 / 公共卫生与预防医学

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.

Etiological characteristics of a foodborne diseases outbreak of Salmonella enteritidis in Suzhou / 上海预防医学

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.

Etiological characteristics of an outbreak of Campylobacter foodborne disease in a middle school / 预防医学

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.

Macrolide resistance, molecular characteristics and PFGE types of Bordetella pertussis strains / 中华微生物学和免疫学杂志

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.

Emergence of optrA-Mediated Linezolid-Nonsusceptible Enterococcus faecalis in a Tertiary Care Hospital

This study investigated resistance mechanisms and epidemiology of emerging linezolid-nonsusceptible Enterococcus faecalis (LNSEF) in a tertiary care hospital. LNSEF isolated from clinical samples were collected from November 2017 to June 2019. The isolates were investigated for linezolid resistance and the associated molecular mechanisms, including mutations of 23S rRNA domain V and acquisition of the cfr or optrA resistance gene. We used pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing for the molecular typing of the isolates. Among 4,318 E. faecalis isolates, 10 (0.23%) were linezolid-nonsusceptible. All LNSEF isolates were optrA-positive and cfr-negative. Of these isolates, five were sequence type (ST) 476, two ST585, one ST16, one ST16-like, and one ST480. Six LNSEF isolates obtained in the first year clustered to three types in the PFGE analysis: two ST476 isolates of type A, two ST585 isolates of type B, and two ST16 or ST16-like isolates of type C. Seven cases were of community-onset and three were hospital acquired, but total of eight were healthcare-associated including five community-onset. None of the patients had a history of linezolid treatment, and in one patient, we detected linezolid-susceptible E. faecalis one month before LNSEF detection. In conclusion, heterogenous clones of optrA-positive LNSEF emerged in the hospital mainly via community-onset.

Molecular typing and distribution characteristics of Legionella pneumophila isolated from cooling water of central air conditioning system in Zhongshan, 2012-2018 / 公共卫生与预防医学

Objective To analyze the genetic characteristics of Legionella pneumophila isolated from cooling water of central air conditioning system in public places in Zhongshan from 2012 to 2018, and to understand the spatiotemporal distribution of homologous strains, in order to provide evidence for the prevention, control and traceability of Legionella pneumophila infection. Methods Eighty-five Legionella pneumophila strains were isolated for serotype identification, and the molecular typing of the 85 isolates was performed using pulsed field gel electrophoresis (PFGE). The strain location data was converted into latitude and longitude coordinates by GIS geocoding technology. The converted location data was overlaid on the map of Zhongshan City, mapping the molecular typing distribution of clusters using Qgis2.18.11 spatial processing software. Results Eighty-five strains of Legionella pneumophila included 9 serotypes, and the highest proportion was LP1, accounting for 61.18% (52/85). According to the similarity of 100%, 85 strains of Legionella pneumophila were divided into 56 patterns of PFGE bands (T1-T56), with 3 types being dominant. Same serotype of Legionella pneumophila strains showed diverse PFGE patterns. Different serotypes of Legionella pneumophila strains were basically identified as different PFGE patterns, while some were identified as same PFGE pattern. According to over 85% similarity, 8 clusters (A-H) were designated, strains of which were distributed in 12 districts. PFGE clustering clusters did not display obvious temporal and regional distribution differences, nor did they have temporal and regional clustering distributions. Conclusion Strains of Legionella pneumophila isolated from cooling water of central air conditioning system in public places in Zhongshan from 2012 to 2018 showed genetic diversity, and the main serotype was LP1. Isolates of clusters did not exist in different years or regions.

Staphylococcus aureus in tonsils of patients with recurrent tonsillitis: prevalence, susceptibility profile, and genotypic characterization

ABSTRACT Introduction: Bacterial tonsillitis is an upper respiratory tract infection that occurs primarily in children and adolescents. Staphylococcus aureus is one of the most frequent pathogens in the etiology of tonsillitis and its relevance is due to its antimicrobial resistance and persistence in the internal tissues of the tonsils. Tonsillectomy is indicated in cases of recurrent tonsillitis after several failures of antibiotic therapy. Material and methods: In this study we evaluated 123 surgically removed tonsils from patients who had history of recurrent tonsillitis. The tonsils were submitted to microbiological analysis for detection of S. aureus. The isolates were identified by PCR for femA gene. Antimicrobial susceptibility of the isolates was determined by disk diffusion tests. All isolates were submitted to PCR to detect mecA and Panton-Valentine leucocidin (PVL) genes. The genetic similarity among all isolates was determined by pulsed field gel electrophoresis. Results: Sixty-one S. aureus isolates were obtained from 50 patients (40.7%) with mean age of 11.7 years. The isolates showed high level resistance to penicillin (83.6%), 9.8% had inducible MLSb phenotype, and 18.0% were considered multidrug resistant (MDR). mecA gene was detected in two isolates and the gene coding for PVL was identified in one isolate. The genetic similarity analysis showed high diversity among the isolates. More than one genetically different isolate was identified from the same patient, and identical isolates were obtained from different patients. Conclusions: MDR isolates colonizing tonsils even without infection, demonstrate persistence of the bacterium and possibility of antimicrobial resistance dissemination and recurrence of infection. A specific clone in patients colonized by S. aureus was not demonstrated.

Phage therapy as an approach to control salmonella enterica serotype enteritidis infection in mice

Abstract INTRODUCTION: Salmonella enterica serotype Enteritidis (S. Enteritidis) is a cause of food-borne human illness. Given the prevalence of antibiotic resistance of Salmonella Enteritidis and the lack of antibiotic efficacy in future years, its replacement with other agents is necessary. One of the most useful agents is bacteriophages. METHODS S. Enteritidis was identified using a multiplex polymerase chain reaction assay. The effective bacteriophages were isolated from hospital wastewater samples. The effects of the bacteriophages were evaluated both in vitro and in vivo. RESULTS The phage SE20 belonged to the Podoviridae family, and the genome size was 40 kb. The evaluation of phage SE20 at variable pH ranges showed its susceptibility to pH < 3 and pH > 12. The animal model showed that mice infected with S. Enteritidis developed hepatomegaly and splenomegaly, but did not experience gastrointestinal complications after receiving the bacteriophages. CONCLUSIONS The results of this study suggest that phage SE20 is a promising candidate for controlling salmonellosis caused by Salmonella Enteritidis.

Drug resistance genes and homology of Klebsiella pneumoniae in the pediatric intensive care unit of Guiyang area / 中华实用儿科临床杂志

Objective@#To investigate the genetic characteristics of drug resistance and homology of extended-spectrum β-lactamase (ESBLs)-producing Klebsiella pneumoniae (Kpn) in hospitalized children in the pediatric intensive care unit (PICU) in Guiyang area.@*Methods@#The Kpn strains were collected from hospitalized children at 3 PICU from the Affiliated Hospital of Guizhou Medical University, Guizhou Provincial People′s Hospital and Guiyang Children′s Hospital from September 2014 to December 2016.Automatic bacteria identification instrument and Kirby-Bauer method were used to identify Kpn strains and confirm ESBLs phenotype respectively.The drug resistance genes were detected by using polymerase chain reaction (PCR), and their homology was analyzed by means of pulsed field gel electrophoresis (PFGE) and cluster analysis.@*Results@#(1) A total of 207 non-repetitive Kpn strains were isolated, of which 128 strains produced ESBLs (61.8%). There was no significant difference in the ESBLs detection rates among the different hospitals, years and types of samples(χ2=0.40, 5.19, 4.68, all P>0.05). (2) Among those 128 ESBLs-producing Kpn strains, 123 strains (96.1%) were found to have drug-resistant genes, of which the detection rate of SHV type was the highest, accounting for 87.5%.These 3 drug resistance genotypes were distributed in 7 modes, of which 85.2% were carrying more than 2 genotypes.(3) PFGE genotypic assay showed that there were 109 genotypes and 5 dominant clones.The PICU at 3 hospitals were all prevalent with type A strain, accounting for 14.8%.In 2015, there was a short-term outbreak of type A strain in Guiyang Children′s Hospital.While, the resistance phenotypes of Kpn and the genotype of PFGE could both be consistent or different.@*Conclusions@#The ESBLs-producing Kpn at PICU in Guiyang area has the characteristics of multi-drug resistance, its drug-resistant genotypes have diversified, and there is a small-scale short-term outbreak epidemic, which poses a serious threat to clinical anti-infection treatment.It is necessary to strengthen clinical drug resistance monitoring and adopt effective infection control measures to prevent and control the spread of nosocomial infections.

Molecular typing and antibiotic resistance of Shigella isolated from 2011 to 2014 in Shandong Province / 中华疾病控制杂志

Objective To study the characteristics and epidemic trend of Shigella in Shandong province through the analysis of serotype, virulence genes, molecular typing and drug sensitivity. Methods The serotype was classified using the method of slide agglutination. Polymerase chain reaction (PCR) was used to amplify the related virulence genes. The molecular typing was carried out by pulsed field gel electrophoresis (PFGE), and the antibiotic sensitivity of the strains was determined by micro-broth dilution method. Results The main serogroups of 44 Shigella strains were Shigella flexneri (54.55%) and Shigella sonnei (43.18%). The carrying rates of ipaH, Set1, Sen and ial were 100%, 43.18%, 56.82% and 50.00%, respectively. By PFGE typing, the strains of Shigella flexneri were divided into 18 patterns with a low similarity. The strains of Shigella sonnei were divided into 14 patterns, and the similarity of 89.47% of the strains was more than 90%. 44 strains of Shigella had different levels of resistance to 14 of the 15 antibiotics. 93.18% of the strains were multidrug resistant. Conclusion The Shigella in Shandong province is dominated by serogroups of Shigella flexneri and Shigella sonnei, with high virulence gene carrying rate, clustering distribution and severe antibiotic resistance. It is necessary to strengthen the monitoring on serotype, traceability and antibiotic resistance of Shigella in Shandong province.

Etiological characteristics and molecular typing of Yersinia enterocolitica in Henan province / 中华微生物学和免疫学杂志

Objective To investigate the distribution and etiological characteristics of Yersinia en-terocolitica in Henan province between 2011 and 2017 and to analyze the homology among pathogenic strains. Methods A total of 12728 samples, including stool specimens from patients with diarrhea and domestic animals, flies, and smear specimens from raw and cooked meat products, were collected. Cold enrichment method was used to isolate Yersinia enterocolitica. The isolated strains were analyzed by biochemical identifi-cation, biotyping, serotyping and virulence gene detection with PCR. Pulsed-field gel electrophoresis ( PFGE) was performed for molecular typing of pathogenic strains. Results There were 390 strains of Yersinia enterocolitica isolated from the 12728 specimens with a detection rate of 3. 06％, including 13 hu-man strains and 377 animal strains. Most of the strains were isolated from pig and chicken feces and both ac-counted for 25. 13％ (98/390). The predominant biotype was 1A and the serotypes of the strains were main-ly O : 5 and O : 8. Results of the virulence gene analysis showed that 21 strains of O : 3 serotype were path-ogenic, including one human strain and 20 pig strains. After NotⅠdigestion, these pathogenic strains were divided into three band types with a band similarity of 94％-100％. Conclusions Yersinia enterocolitica ex-isted in both human population and many kinds of animals in Henan province. Pig was the main host of path-ogenic strains and there was a high homology among these strains.

Antimicrobial Susceptibility and Genetic Analysis of Campylobacter jejuni Isolated from Diarrhea Patients in Busan / 대한임상미생물학회지

BACKGROUND: Campylobacter jejuni is an important food-borne pathogen that causes human gastroenteritis. This study was conducted to investigate the incidence of isolation, antimicrobial susceptibility pattern, and C. jejuni genotype from diarrhea patients in Busan, Korea. METHODS: A total of 97 C. jejuni were isolated from diarrhea patients during five food-borne outbreaks from 2014 to September 2017. Antimicrobial susceptibility tests were carried out by the broth microdilution method for ciprofloxacin (CIP), nalidixic acid (NAL), tetracycline (TET), chloramphenicol, azithromycin (AZI), erythromycin (ERY), streptomycin (STR), gentamicin, and telithromycin. To investigate C. jejuni genotypes, pulsed-field gel electrophoresis (PFGE) profile analysis was performed. RESULTS: The isolation rate of C. jejuni was 2.0% for the last 4 years and increased annually. Antimicrobial resistance rates of C. jejuni were shown to be in the order of NAL (90.9%), CIP (89.4%), TET (13.6%), AZI (3.0%), ERY (3.0%), and STR (1.5%). The proportion of multidrug-resistance was 18.2%, and they commonly contained quinolones (CIP-NAL). Analysis of PFGE patterns of SmaI-restricted DNA of C. jejuni isolates showed 17 clusters; cluster 11 was the major genotype pattern. CONCLUSION: This study will provide useful data for the proper use of antimicrobials and the management of resistant C. jejuni. Also it will help to provide data for the epidemiological investigation of foodborne diseases caused by C. jejuni, which is expected to increase in the future.

Drug resistance genes and homology of Klebsiella pneumoniae in the pediatric intensive care unit of Guiyang area / 中华实用儿科临床杂志

Objective To investigate the genetic characteristics of drug resistance and homology of extended-spectrum β-lactamase (ESBLs)-producing Klebsiella pneumoniae (Kpn) in hospitalized children in the pediatric intensive care unit (PICU) in Guiyang area.Methods The Kpn strains were collected from hospitalized children at 3 PICU from the Affiliated Hospital of Guizhou Medical University,Guizhou Provincial People's Hospital and Guiyang Children's Hospital from September 2014 to December 2016.Automatic bacteria identification instrument and Kirby-Bauer method were used to identify Kpn strains and confirm ESBLs phenotype respectively.The drug resistance genes were detected by using polymerase chain reaction (PCR),and their homology was analyzed by means of pulsed field gel electrophoresis (PFGE) and cluster analysis.Results (1) A total of 207 non-repetitive Kpn strains were isolated,of which 128 strains produced ESBLs (61.8％).There was no significant difference in the ESBLs detection rates among the different hospitals,years and types of samples (x2 =0.40,5.19,4.68,all P ＞ 0.05).(2) Among those 128 ESBLs-producing Kpn strains,123 strains (96.1％) were found to have drug-resistant genes,of which the detection rate of SHV type was the highest,accounting for 87.5％.These 3 drug resistance genotypes were distributed in 7 modes,of which 85.2％ were carrying more than 2 genotypes.(3) PFGE genotypic assay showed that there were 109 genotypes and 5 dominant clones.The PICU at 3 hospitals were all prevalent with type A strain,accounting for 14.8％.In 2015,there was a short-term outbreak of type A strain in Guiyang Children's Hospital.While,the resistance phenotypes of Kpn and the genotype of PFGE could both be consistent or different.Conclusions The ESBLs-producing Kpn at PICU in Guiyang area has the characteristics of multi-drug resistance,its drug-resistant genotypes have diversified,and there is a small-scale short-term outbreak epidemic,which poses a serious threat to clinical anti-infection treatment.It is necessary to strengthen clinical drug resistance monitoring and adopt effective infection control measures to prevent and control the spread of nosocomial infections.

Molecular investigation of staphylococcal cassette chromosome mec types and genotypic relations of methicillin-resistant staphylococci isolated from before and after hospital exposed students

Background: Reservoir of methicillin resistance genes called staphylococcal cassette chromosome mec (SCCmec), plasmids and genomic characterisations of isolates have been widely investigated in epidemiologic research. However, the extent to which these organisms are transported by patients or hospital staff is not entirely clear. Aim: This study aims to investigate the molecular relatedness and plasmid profiles of MR staphylococci isolated from nursing students before and after hospital training, to find out the possible source. Materials and Methods: This study examined 39 methicillin-resistant (MR) staphylococci and 2 inducible clindamycin-resistant, methicillin-susceptible Staphylococcus aureus. Specimens were collected before and after 4 months of hospital training from the hands and nares of 75 nursing students. A polymerase chain reaction technique was used to confirm the existence of mecA gene and identify SCCmec types; total DNA was digested by SmaI endonuclease restriction to monitorise clonal relatedness by pulsed-field gel electrophoresis (PFGE); plasmid profiles were monitorised on agarose gel. Results: All 39 isolates tested positive for mecA; SCCmec type III was observed most frequently. Interestingly, in one isolate of Staphylococcus epidermidis, four different types of SCCmec elements were observed. There were 23 different types of plasmids, whose sizes ranged from 1.4 to 46.0 kb. After PFGE dendogram analysis, two strains were classified as indistinguishable; six were closely related. Most of the isolates obtained after hospital training showed clonal similarity and seven had multiple SCCmec elements require further investigation for the possible mechanism. Conclusion: Most of the isolates obtained after hospital training showed clonal similarity and seven had multiple SCCmec elements require further investigation for the possible mechanism.

Molecular Typing of Enterococcus faecalis from Persistent Endodontic Infections / Tipificación Molecular de Enterococcus faecalis Provenientes de Infecciones Endodónticas Persistentes

ABSTRACT: Molecular techniques that provide valuable information about the epidemiology of oral strains. The purpose of this study was to determine the genetic relatedness of 83 Enterococcus faecalis strains isolated from treated root canals. These strains were obtained from patients who were treated for persistent endodontic infections. E. faecalis isolates were molecular typed by Pulsed Field Gel Electrophoresis using Smal. Ten clonal groups and 13 pulse types with 38.7 % similarity for the less related strains were identified. Genetic heterogeneity among strains from different patients and a high level of genetic homogeneity among intrapatient strains were observed. Therefore, restriction endonuclease fingerprinting of genomic DNA from E. faecalis strains confirmed the polyclonality of the isolates obtained from the root canals of patients diagnosed with persistent endodontic infections, compared with other reports. These results provide additional data for a better understanding of the epidemiological aspects of root canal infections by E. faecalis.

RESUMEN: Las técnicas moleculares proporcionan información valiosa sobre la epidemiología de aislados orales. El propósito de este estudio fue determinar la relación genética de 83 cepas de Enterococcus faecalis aisladas de conductos radiculares tratados. Estas cepas se obtuvieron de pacientes que fueron tratados por infecciones endodónticas persistentes. Los aislados de E. faecalis se tipificaron molecularmente por electroforesis en gel de campo pulsado usando Smal. Se identificaron diez grupos clonales y 13 pulsotipos con un 38,7 % de similitud para las cepas menos relacionadas. Se observó heterogeneidad genética entre las cepas de diferentes pacientes y un alto nivel de homogeneidad genética entre las cepas intrapacientes. Por lo tanto, la toma de huellas dactilares a traves de restricción de ADN genómico de cepas de E. faecalis confirmó la policlonalidad de los aislados obtenidos de los conductos radiculares de pacientes diagnosticados con infecciones endodónticas persistentes, en comparación con otros informes. Estos resultados proporcionan datos adicionales para una mejor comprensión de los aspectos epidemiológicos de las infecciones del conducto radicular por E. faecalis.

Molecular Characterization of Enterotoxigenic Escherichia coli in Foodborne Outbreak

Diarrheagenic Escherichia coli (E. coli) is a main cause of diarrhea worldwide. This study reports the investigation on the occurrence of enterotoxigenic E. coli (ETEC) serotype O27:H7-associated foodborne gastrointestinal disease that occurred at two schools, one middle school and one high school, in Seoul, Korea in June 2015. The immediate government investigation in 1,216 students and 19 food handlers in these two schools revealed that 116 students, 32 students in the middle school and 84 students in the high school, and 2 food handlers, one from middle school and the other from high school, developed gastrointestinal illness symptoms including diarrhea. Following lab investigation identified 29 ETEC serotype O27:H7 strains, 27 from 116 students and 2 from 19 food handlers. Pattern of pulsed-field gel electrophoresis analysis of ETEC isolates suggested that ETEC serotype O27:H7 caused the diarrheal outbreak in June 2015 in Seoul, Korea was a specific clone. In addition, these ETEC serotype O27:H7 isolates were highly resistance to the several antibiotics. The results from the present study provide the evidence that ETEC serotype O27:H7 can be an important cause of domestic foodborne outbreak in Korea.

Diversity and antimicrobial susceptibility of cultivable commensal bacteria from 18 to 22 year-old healthy people's nose and skin / 中华检验医学杂志

Objective To investigate the diversity and antimicrobial susceptibility of cultivable commesal bacteria from 18 to 22 year-old healthy people′s nose and skin. Methods From June to August 2017,18 to 22 year-old healthy people (n=210) were swabbed on skin and nose and cultured with blood plates at Renji Hospital, School of Medicine, Shanghai Jiao Tong University; Species determination was performed using matrix assisted laser desorption Lonization-time of flight-mass spectrometry(MALDI-TOF-MS);Susceptibility testing was performed on the major species by the disc diffusion method; Genomic characteristics of methicillin resistant Staphylococcus epidermidis(MRSE) were determined by pulsed field gel electrophoresis (PFGE) method;SCCmec typing was tested by polymerase chain reaction(PCR);Statistical analysis was performed using SPSS software and association statistics were tested using Chi-Square tests. Results In total, 25 genera were identified of cultivable bacteria from 210 healthy people′s nose (1497 isolates) and skin (941 isolates).Staphylococcus isolates from nose and skin accounted for 82.03% and 80.23% respectively.Eleven species were identified of all Staphylococcus isolates and coagulase-negative Staphylococci(CoNS)from nose and skin accounted for 90.72% and 99.21% respectively.Furthermore, a variety of other species and differences between men and women were observed. Susceptibility testing was done on 631 Staphylococcus isolates, which were sensitive to most antibiotics but show high prevalence of resistance towards penicillin (76.55%), erythromycin (41.20%), clindamycin (10.77%) and trimethoprim/sulfamethoxazole(10.14%). Methicillin Resistant Staphylococcus (MRS) (45 isolates) showed higher prevalence of resistance towards penicillin (χ2=12.17,P<0.001), erythromycin (χ2=10.80,P=0.001), levofloxacin (χ2=20.24, P<0.001) and trimethoprim/sulfamethoxazole (χ2=58.57,P<0.001) compared to methicillin sensitive Staphylococcus (MSS)(586 isolates). Moreover, multidrug resistance (MDR) was observed in 42.16% of 631 isolates and MRS showed a significantly higher proportion than MSS(100.00% vs 37.71%,χ2=66.49,P<0.001).PFGE generated 23 groups out of 33 MRSE isolates. SCCmec genotyping of MRSE showed the most prevalent type was SCCmecⅣ (66.67%). Conclusions Obvious genus and species diversity and genetic diversity were observed on cultivable bacteria from 18 to 22 year-old healthy people′s nose and skin,and CoNS was in the majority. Staphylococcus isolates from healthy people′s nose and skin were sensitive to most antibiotics,but show high prevalence of resistance towards penicillin, erythromycin, clindamycin and trimethoprim/sulfamethoxazole. In addition, MDR was serious especially in MRS. Commensal bacteria may act as reservoir for resistance genes facilitating bacteria infection.

Monitoring of diarrheagenic Escherichia coli infections in patients in Guangdong Province during 2013 to 2016 / 中华微生物学和免疫学杂志

Objective To investigate the infection status, serotype distribution, drug sensitivity and molecular characteristics of diarrheagenic Escherichia coli (DEC) in patients with diarrhea in Guangdong Province. Methods Fecal samples were collected, cultured and isolated by traditional methods. Suspected Escherichia coli isolates were confirmed by multiplex PCR used for detecting specific virulence genes and bio-chemical methods. Positive strains were serotyped, characterized for drug sensitivity and analyzed by pulsed-field gel electrophoresis ( PFGE). Results The total positive rate of DEC in patients with diarrhea was 6.26%. The positive rates of enteropathogenic Escherichia coli (EPEC), enterotoxigenic Escherichia coli (ETEC), enterohemorrhagic Escherichia coli (EHEC), enteroadherent Escherichia coli (EAEC) and en-teroinvasive Escherichia coli (EIEC) were 2. 47% , 1. 54% , 1. 32% , 0. 62% and 0. 09% , respectively, with infections primarily in children aged 0-<7 years. The total seropositive rate was 52. 54% , with EHEC accounting for 15. 00% . DEC showed high sensitivity to imipenem, ciprofloxacin, ceftazidime and cefo-taxime. The multidrug resistance rate of DEC was 58. 45% , with EPEC being the most serious for multidrug resistance. PFGE results showed that ETEC, EHEC, EPEC and EAEC had a high degree of polymorphism. Conclusion EPEC is the predominant type of DEC circulating in Guangdong Province. Third-generation cephalosporins are the first drugs of choice for treating infections in children. Ciprofloxacin can be used to treat adults. The problem of multiple drug resistance of DEC is severe and efforts to monitor DEC infections and drug resistance should be strengthened.