Background: Recently micro-organisms that synthesize extended-spectrum β-lactamase (ESBLs) were increased. The peculiarities of ESBL synthesis of Escherichia coli and Klebsiella pneumoniae strains that cause nosocomi...Background: Recently micro-organisms that synthesize extended-spectrum β-lactamase (ESBLs) were increased. The peculiarities of ESBL synthesis of Escherichia coli and Klebsiella pneumoniae strains that cause nosocomial urinary tract infections, surgical site infections and pneumonia in surgical clinic were studied. ESBL synthesis were observed 38.9% of E. coli strains obtained from urine, 92.3% of strains obtained from surgical site infections, and 50% of strains obtained from sputum. ESBL synthesis were observed 37.5% of K. pneumoniae strains obtained from urine, 85.7% of strains obtained from surgical site infections, and 60% of strains obtained from sputum. Different levels of ESBL synthesize of E. coli and K. pneumoniae strains isolated from different pattern is discussed. Conclusion. ESBL synthesis is common in E. coli and K. pneumoniae strains, which cause nosocomial infections. The frequency of occurrence of ESBL s synthesis among of these strains depends on clinical forms of nosocomial infections.展开更多
Escherichia coli expressing F4 fimbriae is the major pathogenic bacteria that causes diarrhea in piglets before weaning. The adhesion of E. coli to the brush borders of the epithelial cells of piglets is the precondit...Escherichia coli expressing F4 fimbriae is the major pathogenic bacteria that causes diarrhea in piglets before weaning. The adhesion of E. coli to the brush borders of the epithelial cells of piglets is the precondition leading to diarrhea, which in turn is due to the presence of the F4 receptors determined by an autosomal recessive gene on the brush borders of the epithelial cells. In order to clarify the genetic mechanism of the adhesion, an in vitro adhesion experiment was carded out for three variants of E. coli F4 （ab, ac, and ad） in 366 piglets of three pig breeds [Landrace （LR）, Large White （LW）, and Songliao Black （SB）]. The results showed that there existed significant differences （P〈0.001） in the adhesion percentage among the three breeds. Most SB piglets were nonadhesive for all the three variants, whereas most LR piglets were adhesive. Within each breed except for LR, the proportions of the three F4 variants adhering to the brush borders differed significantly. According to the patterns of the adhesion of the three F4 variants in the three breeds, it is very likely that the three F4 variants F4ab, F4ac, and F4ad have different receptors that are controlled by three different loci.展开更多
Objective:To identify the specific integration site of prophage φ297 in the host of E. coli K12 chromosome. Methods:Using molecular techniques such as Siebert PCR for walking from the int gene of prophage 297, which ...Objective:To identify the specific integration site of prophage φ297 in the host of E. coli K12 chromosome. Methods:Using molecular techniques such as Siebert PCR for walking from the int gene of prophage 297, which is similar to that of phage 933W to an unknown region in genomic DNA. A special adaptor is ligated to the ends of DNA fragments generated by digestion of genomic DNA with restriction enzymes that generates blunt ended fragments. Clone and subclone of PCR products, DNA sequencing and data analysis were used in this study. Results:The attL, attR and the core sequences were determined. The bacterial attachment site of phage φ297 was located in the yecE gene of E. coli K12. Conclusion:The phage φ297 integrates into the yecE gene of the E. coli K12 genome.展开更多
The aim of the present study was to investigate minimum inhibitory concentration(MIC)distributions by broth microdilution(BMD)method and to determine the preliminary epidemiological cut-off value(ECV)of colistin by ep...The aim of the present study was to investigate minimum inhibitory concentration(MIC)distributions by broth microdilution(BMD)method and to determine the preliminary epidemiological cut-off value(ECV)of colistin by epidemiological cut-off(ECOFF)finder against E.coli from chickens in China.Anal swabs were collected from chicken farms in China.BMD method was used to measure MIC50 and MIC90 of colistin which were 2 and 4μg•mL^(-1),respectively.MIC frequency distributions for colistin were used to estimate preliminary ECV(8μg•mL^(-1)).High percentages of resistance to ampicillin(94.12%),nalidixic acid(94.12%),enrofloxacin(94.12%),tetracycline(94.12%),ciprofloxacin(88.24%),florfenicol(88.24%),neomycin(64.71%),gentamicin(58.82%),levofloxacin(58.82%),doxycycline(88.24%)and cefalexin(76.47%)were found.In addition,low percentages of resistance to amikacin(5.88%),spectinomycin(17.65%)and fosfomycin(41.18%)were noted.Notably,amoxicillin,sulfisoxazole and trimethoprim resulted in a 100%resistance generation efficacy rate.Prevalence of mcr-1 in E.coli(9/17)in chromosomal DNA was higher than mcr-4(2/17)gene,and mcr-1(5/17)was higher than mcr-4(3/17)in plasmid.展开更多
The aim of the study was to investigate the immune effect of fusion protein VP4-STI. 40 mouse were randomly divided into 4 groups of test bacterin group （30 μg VP4-STI ＋0.6 μg LTB）, aluminiumhydroxide vaccine gro...The aim of the study was to investigate the immune effect of fusion protein VP4-STI. 40 mouse were randomly divided into 4 groups of test bacterin group （30 μg VP4-STI ＋0.6 μg LTB）, aluminiumhydroxide vaccine group （30 μg VP4-STI ＋Al（OH）3 gel ） , pure protein VP4- STI vaccine group （30μg VP4-STI ） and PBS control group were immunized by rhinal dripping. And then, the antibody levels of the mouse were determined. The protection effects of mouse in all immune groups were observed after the toxicity test with strong virulent strain C83902 of E. coli. Anti-VP4-STI antibodies were produced in other groups with the highest at the 6th week, except PBS control group. The antibody level in aluminiumhydroxide bactetin group was higher than that in test vaccine group. The antibody level in pure protein VP4-STI bacterin group was lower, being extremely significantly different from that in test vaccine group （ P 〈0. 001 ）. Mouse in test vaccine group and aluminium hydroxide bacterin group had better immuno-protection effect on strong virulent strain C83902 of E. coli, obviously different from that in PBS control group. The research provided basis for further improving the immunogeneticity of STI.展开更多
文摘Background: Recently micro-organisms that synthesize extended-spectrum β-lactamase (ESBLs) were increased. The peculiarities of ESBL synthesis of Escherichia coli and Klebsiella pneumoniae strains that cause nosocomial urinary tract infections, surgical site infections and pneumonia in surgical clinic were studied. ESBL synthesis were observed 38.9% of E. coli strains obtained from urine, 92.3% of strains obtained from surgical site infections, and 50% of strains obtained from sputum. ESBL synthesis were observed 37.5% of K. pneumoniae strains obtained from urine, 85.7% of strains obtained from surgical site infections, and 60% of strains obtained from sputum. Different levels of ESBL synthesize of E. coli and K. pneumoniae strains isolated from different pattern is discussed. Conclusion. ESBL synthesis is common in E. coli and K. pneumoniae strains, which cause nosocomial infections. The frequency of occurrence of ESBL s synthesis among of these strains depends on clinical forms of nosocomial infections.
基金National Basic Research Program of China (No. 2006CB102104)National Natural Sci-ences Foundation of China (No. 30430500).
文摘Escherichia coli expressing F4 fimbriae is the major pathogenic bacteria that causes diarrhea in piglets before weaning. The adhesion of E. coli to the brush borders of the epithelial cells of piglets is the precondition leading to diarrhea, which in turn is due to the presence of the F4 receptors determined by an autosomal recessive gene on the brush borders of the epithelial cells. In order to clarify the genetic mechanism of the adhesion, an in vitro adhesion experiment was carded out for three variants of E. coli F4 （ab, ac, and ad） in 366 piglets of three pig breeds [Landrace （LR）, Large White （LW）, and Songliao Black （SB）]. The results showed that there existed significant differences （P〈0.001） in the adhesion percentage among the three breeds. Most SB piglets were nonadhesive for all the three variants, whereas most LR piglets were adhesive. Within each breed except for LR, the proportions of the three F4 variants adhering to the brush borders differed significantly. According to the patterns of the adhesion of the three F4 variants in the three breeds, it is very likely that the three F4 variants F4ab, F4ac, and F4ad have different receptors that are controlled by three different loci.
文摘Objective:To identify the specific integration site of prophage φ297 in the host of E. coli K12 chromosome. Methods:Using molecular techniques such as Siebert PCR for walking from the int gene of prophage 297, which is similar to that of phage 933W to an unknown region in genomic DNA. A special adaptor is ligated to the ends of DNA fragments generated by digestion of genomic DNA with restriction enzymes that generates blunt ended fragments. Clone and subclone of PCR products, DNA sequencing and data analysis were used in this study. Results:The attL, attR and the core sequences were determined. The bacterial attachment site of phage φ297 was located in the yecE gene of E. coli K12. Conclusion:The phage φ297 integrates into the yecE gene of the E. coli K12 genome.
基金Supported by the National Key Research and Development Program of China(2016YFD0501302)the National Natural Science Foundation of China(31772801)。
文摘The aim of the present study was to investigate minimum inhibitory concentration(MIC)distributions by broth microdilution(BMD)method and to determine the preliminary epidemiological cut-off value(ECV)of colistin by epidemiological cut-off(ECOFF)finder against E.coli from chickens in China.Anal swabs were collected from chicken farms in China.BMD method was used to measure MIC50 and MIC90 of colistin which were 2 and 4μg•mL^(-1),respectively.MIC frequency distributions for colistin were used to estimate preliminary ECV(8μg•mL^(-1)).High percentages of resistance to ampicillin(94.12%),nalidixic acid(94.12%),enrofloxacin(94.12%),tetracycline(94.12%),ciprofloxacin(88.24%),florfenicol(88.24%),neomycin(64.71%),gentamicin(58.82%),levofloxacin(58.82%),doxycycline(88.24%)and cefalexin(76.47%)were found.In addition,low percentages of resistance to amikacin(5.88%),spectinomycin(17.65%)and fosfomycin(41.18%)were noted.Notably,amoxicillin,sulfisoxazole and trimethoprim resulted in a 100%resistance generation efficacy rate.Prevalence of mcr-1 in E.coli(9/17)in chromosomal DNA was higher than mcr-4(2/17)gene,and mcr-1(5/17)was higher than mcr-4(3/17)in plasmid.
基金Supported by the Doctor Foundation of Xinjiang Production and Con-struction Corps(Bingbo02,NKBOISHZO8)~~
文摘The aim of the study was to investigate the immune effect of fusion protein VP4-STI. 40 mouse were randomly divided into 4 groups of test bacterin group （30 μg VP4-STI ＋0.6 μg LTB）, aluminiumhydroxide vaccine group （30 μg VP4-STI ＋Al（OH）3 gel ） , pure protein VP4- STI vaccine group （30μg VP4-STI ） and PBS control group were immunized by rhinal dripping. And then, the antibody levels of the mouse were determined. The protection effects of mouse in all immune groups were observed after the toxicity test with strong virulent strain C83902 of E. coli. Anti-VP4-STI antibodies were produced in other groups with the highest at the 6th week, except PBS control group. The antibody level in aluminiumhydroxide bactetin group was higher than that in test vaccine group. The antibody level in pure protein VP4-STI bacterin group was lower, being extremely significantly different from that in test vaccine group （ P 〈0. 001 ）. Mouse in test vaccine group and aluminium hydroxide bacterin group had better immuno-protection effect on strong virulent strain C83902 of E. coli, obviously different from that in PBS control group. The research provided basis for further improving the immunogeneticity of STI.
