Objective To investigate the carrying status and drug resistance analysis of pathogenic bacteria in the gut of healthy population in Huadu District,Guangzhou,and provide reference for epidemiological re-search.Methods A total of 337 459 anal swabs were directly isolated and cultured from healthy individuals who underwent physical examinations from 2018 to 2023.600 anal swabs from 2022 were randomly selected for multi pathogen nucleic acid testing,direct isolation and culture,and enrichment culture.Identification of bacteria was conducted by using VITEK 2 Compact and VITEK MS,serological testing was used for determi-nation of type,and drug susceptibility testing of pathogenic bacteria was conducted.Results A total of 128 pathogenic bacteria were isolated from rectal swabs,including 52 strains of Salmonella,71 strains of Aero-monas,3 strains of Vibrio parahaemolyticus,and 2 strains of Shigella flexneri,with a total detection rate of 3.79/10 000.The detection rate of Salmonella in direct isolation and culture of 600 rectal swabs was 0.50％,the detection rate of enrichment culture was 1.00％,and the detection rate of multi-pathogen nucleic acid de-tection was 1.17％.52 strains of Salmonella were divided into 27 serotypes,and Salmonella Ⅰ 4,5,12:i:—was the dominant serotype.Aeromonas sobria was the dominant serotype in Aeromonas.The sensitivity of Salmonella to piperacillin/tazobactam,imipenem,cefepime,levofloxacin,and aztreonam was up to 92.00％or more,however,the phenomenon of multidrug resistance was severe,with a multidrug resistance rate as high as 40.38％.The resistance rate of Aeromonas to ampicillin and ampicillin/sulbactam was up to 85.00％or more,while Aeromonas was relatively sensitive to other antibiotics.Conclusion There are many species and types of intestinal pathogenic bacteria carried by healthy individuals in Huadu District,Guangzhou,with Aero-monas and Salmonella ranking first and second,and levofloxacin treatment could be preferred.The use of bac-terial culture and multi pathogen nucleic acid testing methods could improve the detection rate of intestinal pathogenic bacteria,and attention should be paid to the monitoring of intestinal pathogenic bacteria among rel-evant practitioners.

Objective:To obtain the genome sequences of SARS-CoV-2 in respiratory specimens in Guangdong Province with next-generation sequencing (NGS) and analyze the factors influencing sequencing.Methods:Eight upper and lower respiratory tract specimens were collected from patients with SARS-CoV-2 infection in Guangdong Province in January 2020. RNA library construction was used to obtain the genome sequences of SARS-CoV-2. A bio-informatics software package (CLC Genomics Workbench 12.0) was used to analyze and compare the genomic sequences.Results:Five SARS-CoV-2 genome sequences were obtained from the eight specimens and two were obtained from lower respiratory tract specimens. The nucleotide homology to SARS-CoV-2 was 97.74%-99.90%. The Ct values were lower, while the sequencing depth, coverage, relative abundance and genome integrity were higher in sequencing the SARS-CoV-2 in lower respiratory tract specimens.Conclusions:The low Ct value of SARS-CoV-2 in the samples was good for sequencing.

Objective To quantify the correlations between Elekta XVI cone beam CT dose and various scanning protocols,providing mathematical models to assess the protocol-dependency of imaging dose during imnage guided radiotherapy.Methods Based on standard protocols and various combinations of kVp and mA on an XVI mounted on an Elekta Versa HD accelerator,the air KERMA was measured at various positions in a standard PTW CTDI body phantom using calibrated PTW 30009 kV chamber and UNIDOS webline electrometer.Weighted CT dose index (CTDIw) was computed thereafter.SigmaPlot 10.0 was used to fit the measurements against mA and/or kVp yielding empirical functions.Results Under standard protocols,the CTDIw of Varian OBI was only 11.23％ (chest) and 9.15％ (pelvis) of Elekta XVI.Using the default and other 4 investigated kVp values,the central and peripheral KERMA were both proportional to mA,and vet the slope value a varied dramatically from 0.479 to 6.679.Major affecting factors included kVp settings,measurement locations,and dosimetric mnetrics,etc.None linear regressions were used to fit kVp against KERMA at various locations and CTDIw (R2 ＞ 0.997).The differences between all coefficients were statistically significant (P ＜ 0.05).The impact of changing both mA and kVp on the dose to phantom center can be described as mGy =(5.917-0.197 ×kVp+0.002 × kVp2-5.063 × 10-6 × kVp3) × mA.Conclusions Imaging dose of Elekta XVI is strongly dependent on scanning paraneters.The proposed mathematical models can be used as efficient and robust indicators of such dependency.

Objective To analyze the serotype distribution and antibiotic resistance characteristics of Salmonella strains isolated in Guangdong province for better understanding the condition of Salmonella infection in patients with diarrhea.Methods Fecal samples collected from patients with diarrhea in Guangdong province were used to isolate Salmonella strains.Biochemical analysis was performed to identify these isolated strains.Serotyping and antimicrobial susceptibility testing were carried out for further analysis of the isolated Salmonella strains.Results The rate of Salmonella infection was 7.64％in 2015, and the male to female patient ratio was 1.52∶1.A total of 2 377 patients of all age groups were positive for Salmonella infection and the patients aged 0-6 years accounted for 81.74％.The isolation rate of Salmonella strains in the summer and autumn was higher than that in the winter and spring (10.73％ vs 4.24％;X2=463.77, P<0.01).The Salmonella isolation rates in different areas were as follows: 16.82％ in Zhuhai, 15.85％ in Heyuan, 11.81％ in Yangjiang, 10.68％ in Jiangmen, 8.49％ in Zhongshan, 8.07％ in Maoming, 8.05％ in Jieyang, 7.35％ in Shaoguan, 6.97％ in Foshan, 6.03％ in Dongguan, 5.48％ in Guangzhou and 0.00％ in Zhanjiang.And the differences between different regions were statistically significant (X2=367.67, P<0.01).The 2 377 isolated Salmonella strains were classified into 108 serotypes except for oneSalmonella strain that could not be classified.The top four predominant serotypes were 4,5,12:i:-, Salmonella enteritidis,Salmonella stanley and Salmonella typhimurium.Most Salmonella strains were sensitive to imipenem, azithromycin, ceftazidime, cefotaxime and trimethoprim/sulfamethoxazole, but multidrug resistance was common among those strains.Conclusion Salmonella serotypes of 4,5,12:i:-and Salmonella enteritidis are the predominant pathogens causing human Salmonella infections in Guangdong province.Ceftazidime and cefotaximeare are preferred in the treatment of Salmonella infections.Surveillance for drug resistance in Salmonella should be strengthened as multidrug resistant strains have become a serious problem in Guangdong province.

Objective To understand the antibody levels after the inoculation of measles ,poliomyelitis ,epidemic encephalitis B and hepatitis B vaccines among healthy children aged 7 - < 13 years old in Guangshui City of Hubei province to provide the scientif ‐ic basis for formulating the immune prevention and control strategy and risk assessment in whole city .Methods 4 616 healthy chil‐dren aged 7 - < 13 years old were sampled from the whole city .The enzyme‐linked immunosorbent assays (ELISA) was used to de‐tect the 4‐antibody levels .Results The antibody positive rates of measles ,poliomyelitis ,epidemic encephalitis B and hepatitis B a‐mong healthy children aged 7 - < 13 years old in Guangshui City were 94 .41% ,93 .07% ,93 .78% and 68 .72% respectively .The protection levels of first three kinds of antibody reached more than 85% ;the positive rates had statistical difference among 4 kinds of antibody(χ2 = 1 987 .08 ,P = 0 .000) .The antibody positive rates of epidemic encephalitis B had no statistical difference among different age periods (χ2 = 10 .141 ,P= 0 .071) ;the antibody positive rates of measles ,poliomyelitis and hepatitis B had statistical difference among different age periods(χ2 = 40 .471 ,P = 0 .000 ;χ2 = 25 .174 ,P = 0 .000 ;χ2 = 283 .641 ,P = 0 .000) .The positive rates of 4 kinds of antibody had no statistical difference between different genders (χ2 = 0 .019 ,P= 0 .889 ;χ2 = 1 .017 ,P= 0 .313 ;χ2 = 0 .018 ,P= 0 .892 ;P= 0 .639 ,P= 0 .424) ;the antibody positive rates of measles ,poliomyelitis and epidemic encephalitis B had no statistical differences among 17 villages and towns in the whole city (χ2 = 0 .099 ,P= 1 .000 ;χ2 = 0 .117 ,P= 1 .000 ;χ2 = 0 .134 , P= 1 .000) ,while the antibody positive rate of hepatitis B had statistical difference among these villages and towns (χ2 = 186 .179 , P= 0 .001) .Conclusion The antibody levels of measles ,poliomyelitis and epidemic encephalitis B reach the protection rate ,but the antibody level of hepatitis B needs to be increased .The monitoring work should be continuously strengthened and the seeking missed inoculation and re‐inoculation work should be reinforced .

Objective To prepare simulated stool specimens for proficiency testing ( PT) by mix-ing lentils with Salmonella, Shigella and Escherichia coli strains and to establish an assessment scheme for the detection of Salmonella and Shigella in clinical samples. Methods Salmonella, Shigella and Escherich-ia coli strains were respectively spiked to lentils in Cary-Blair transport medium to create simulated stool specimens. Various ratios of Escherichia coli to Salmonella strains were spiked to lentils to prepare mixed simulated stool specimens. The accuracy and stability of prepared stool samples for PT were tested in-house. Results of sample detection were collected from participating laboratories for further external quality assess-ment. Results The Escherichia coli and Salmonella strains mixed at ratios of 100 ∶ 1 to 106 ∶ 1 could be ef-ficiently isolated from the media. Enrichment was needed in order to effectively isolate Salmonella strains from the media when the ratios of Escherichia coli to Salmonella strains were 104 ∶ 1 to 106 ∶ 1. Of the16 participating laboratories, 14 laboratories (87. 5%) received a grade of“satisfactory” and the other 2 labo-ratories (12. 5%) received a grade of “mainly satisfactory”. Conclusion The simulated stool specimens and the PT procedures designed in this study were suitable for proficiency testing program on the detection of Salmonella, Shigella and other similar microbes.

Objectives To investigate the expression and clinical significance of BATF2 in the oral tongue squamous cell carcinoma(OTSCC).Methods Expression of BATF2 mRNA and protein in 16 paired OTSCC tissues and adjacent non-tumor mucosa were examined using quantitative PCR,western blotting analysis and immunohistochemistry assays,and the relation between BATF2 expression and clinical pathologic factor and prognosis was analyzed.Results In 16 paired tissues,expression of BATF2 mRNA in 13 OTSCC tissues and expression of BATF2 protein in 14 OTSCC tissues were significantly lower than that in adjacent non-tumor mucosa.In 202 paraffin-embedded OTSCC samples,BATF2 was not expressed in 20 cases(9.9％),low expressed in 104 cases(51.5％) and highly expressed in 78(38.6％).BATF2 expression level was significantly correlated with histological differentiation(P=0.002).Patients with low BATF2 expression had significantly poorer overall survival and disease-free survival than those with high BATF2 expression(P＜0.001).Conclusions BATF2 was low expressed in OTSCC and related to tumor differentiation and prognosis and may serve as a prognostic biomarker and potential therapeutic target for this disease.

To compare and evaluate the discriminatory ability and potential value of pulsed field gel electrophoresis (PF-GE) and multiple locus VNTRs analysis (MLVA) on the genotyping of Brucella ,a total of 60 strains of Brucella and three standards (16M ,544A ,1330S) were genotyped simultaneously by PFGE and MLVA .The result indicated that the similarity coefficient among the 63 isolates was from 72 .1-100 .0% by PFGE ,and could distinguish three species of B .melitensis ,B .su-is and B .abortus at the similarity level of 94 .4% .There were 14 clusters and 29 PFGE types identified by PFGE with discrim-inatory index (DI) of 0 .957 5 at the similarity level of 100% ;the similarity coefficient among the 63 isolates was from 16 .9-100 .0% by MLVA ,and could distinguish three species of Brucella at the similarity level of 52 .3% .There were 8 clusters and 47 MLVA types identified by MLVA with discriminatory index (DI) of 0 .985 2 at the similarity level of 100% .It's suggested that PFGE and MLVA could be used to distinguish three species of Brucella in the similarity coefficient of certain ,but could not effectively distinguish the type in the same species .Both of these two methods could be used for Brucella molecular typing , but MLVA is better than PFGE for its relatively higher discriminating ability .

Objective To investigate the polymorphism of Brucella melitensis biovar 3 ( B.melitensis biovar 3) strains isolated from Guangdong province .Methods PCR assays followed by agar-ose gel electrophoresis and capillary electrophoresis based on the multiple locus variable number of tandem repeats (VNTR) analysis (MLVA) were performed to analyze 43 clinic isolates of B.melitensis biovar 3 strains isolated from clinical patients in Guangdong province .Results MLVA typing showed that the simi-larities of the analyzed locus among 43 strains of Brucella ranged from 68.2%to 100%.32 genotypes identi-fied among the isolates were identical (100%similarity).27 out of 43 strains (62.8%) were single geno-types, while the other 16 strains (37.2%) belonged to 5 other genotypes with 2 to 5 strains in each of them . Conclusion B.melitensis biovar 3 isolates showed polymorphism distribution in Guangdong province as in-dicated by MLVA typing analysis .Single-genotype isolates accounted for 62.8% of all studied strains.No predominant genotype was found among all isolates .

To explore the possibility to type the Brucella strains isolated in Guangdong province with analytical method to detect the fatty acid components and to collect the basic data of fatty acid components of Brucella strains, 29 strains of Brucella were selected for analysis on the bacterial fatty acid components and the cluster analysis on the collected data was performed with Sherlock analysis soft-ware (MIDI). It was demonstrated that the main fatty acid components of Brucella strains isolated in Guangdong province were 19∶0 cycloω8c acid, 16∶0 acid and 18∶0 acid. The content of 19∶0cycloω8c acid was highest in B.abortus, followed by B.melitensis and lowest in B.suis.-In addition, the content differences of 19∶0cycloω8c and 18∶0 acid between B. melitensis and Brucella suis were statistically significant; and that of 19∶0cycloω8c and 18∶0 acid between strains isolated in 1965 and those isolated in recent 3 years was statistically significant. It was also shown that the fatty acid components of Brucella strains were stable, but the contents of fatty acid components were different in different species.-It is evident that at certain euclidean distance, 3 species of Brucella can be differentiated in species level.