ABSTRACT
Objective To monitor the constituents and resistant tendency of bacterial pathogens isolated from diarrheal patients in our hospital form 1994 to 2005 to offer the basis for guiding epidemiologic study,vaccination research and clinical treatment. Methods Enteric pathogenic bacteria were cultured and identified to species,group and serotype with biochemical and serologic methods and the susceptibility of bacteria to antimicrobial agents were tested. Results Enteric pathogenic bacteria were isolated predominantly in male patients and mainly in children and youngsters. It reached a peak from July to September every year. Shigella spp.(75.11%) was the most frequendy isolated pathogens and followed by Vibrio spp.(12.7%),Salmonella spp.(6.28%),Aeromonas spp.(4.43%) and Escherichia coli(1.25%).During the period from 1994 to 2005,diarrheal pathogens had a trend of decrease especially Shigella spp.and Salmonella spp.. Of the 6329 isolates of Shigella spp., 75.62% was S. flexneri and S.soanei,S.dysenteriae and S. boydii constituted 23.98%,0.22% and 0.01% respectively.The sensitivity of different species,group or serotype to different antimicrobial agents was not the same.S.flexneri and Aeromonas spp. were highly resistant to most of antibiotics. However, S.sonnei and Vibrio spp.had good susceptibility to antibiotics tested except trimethoprim/sulfamethoxazole and ampicillin. Conclusion There are many species and serotypes of enteric pathogenic bacteria causing infective diarrhea and the distribution changes gradually in Beijing. The resistance rate of enteric pathogenic bacteria to antibiotics is not the same in different species and serotypes.so strict surveillance iS always needed.
ABSTRACT
Objective To amplify the 16S RNA fragments of 7 clinically isolated strains of Brucella spp. by PCR-RFLP technique, so as to provide experimental basis for the studies on diagnostics, genetics and epidemiology of Brucella spp. Methods According to the gene sequence of ATCC 25840 standard strain in GenBank, special primers for the 16S RNA conservative area in the Brucella spp. were designed. DNA extraction and PCR amplification of the 16S RNA fragments were performed with the 7 isolated strains. PCR products were then sequenced and RFLP analysis was conducted with appropriate restricted enzymes to study the homology and the mutation sites in those strains. Meanwhile, the clinical data of infected patients were retrospectively analyzed to evaluate the relationship between the clinical features and genotypes of Brucella infection. Results The amplified target fragments were about 1500bp in length and consistent with what was expected. The sequencing and homology analysis showed a 98.88% homology and 11 mutation sites among the 7 isolated strains. Four genotypes were identified by RFLP. Retrospective analysis of the clinical data indicated that no obvious relationship existed between the genotypes and the clinical features. Conclusions Amplifying 16S RNA fragments by PCR technique is a feasible method to make an early diagnosis of Brucella infection. The 7 clinically isolated strains are different in genotypes and 16S RNA fragment is a highly conservative fragment in bacterial genome with some mutations. The research provides evidence for the genetics and epidemiology of brucellosis.