Interpretation for the group standards of the Isolation and Identification of Campylobacter jejuni and Campylobacter coli / 中华流行病学杂志

Foodborne Campylobacter is recognized as the leading causes of the bacterial diarrheal illness in both developing and developed countries. C. jejuni and C. coli caused 95% of the human campylobacterisosis. Bacteria culture has been recognized as the "Gold standard" for the diagnosis of the Campylobacter infection. The National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention coordinated the experienced researchers from China National Center for Food Safety Risk Assessment and other local Centers for Disease Control and Prevention to write up the standards for entitled Isolation and Identification of Campylobacter jejuni and Campylobacter coli (T/CPMA 006-2019). The standard is drafted with principles of emphasizing the scientific, normative, applicability and feasible nature. This group standard recommended the procedures and steps for the isolation and identification of C. jejuni and C.coli from variant samples. The standard aims to improve the capacity for Campylobacter identification in China.

Application of NASBA and RPA in detection of pathogenic bacteria / 中华流行病学杂志

Nucleic acid sequence-based amplification and recombinase polymerase amplification are the recently developed thermostatic amplification techniques based on PCR. This paper briefly summarizes the principle of reaction, design principle of primer and probe, advantage of these two techniques (simple, accurate, highly sensitive and rapid) and introduces the application of the techniques in the detection of pathogenic bacteria.

Real-time PCR development for identification of Campylobacter coli from stool specimen / 中国人兽共患病学报

The aim of this study is to develop the real-time PCR assays to detect and qualify C. coli from stool specimen. The primers and probe were designed based on the specific sequence of ceuE gene in C. coli using Primer 5.0 and Vector NTI Suite 6.0 e. The PCR assay was optimized with the reference C. coli strains. The standard curve based on the dilutions of genomic DNA showed a linear relationship between log CFU/mL and threshold cycles. The detectable limitation was 5.62 CFU/mL by using purified DNA from bacteria culture. The reproducibility of this assay was assessed by calculating the variation of the threshold cycle value and the slope from test repeats for the same strains and different strains. Our results indicate that the developed assay has high sensitivity and specificity for identification of C. coli.

Cytotoxic effect of Guillain-Barre syndrome-associated and diarrhea-associated Campylobacter jejuni / 中国人兽共患病学报

In order to assess the cytotoxin effect of Campylobacter jejuni (C.jejuni), the whole cell lysates from 9 strains of Guillan-Barre Syndrome (GBS)- associated C.jejuni and 4 strains of diarrhea-associated C. jejuni were co-cultivated with HeLa cells at the concentration of 0.001-5.00 μg/mL in vitro. The morphologic change of HeLa cells was observed under Olympus BX51 microscope after treatment with different concentration of bacteria lysate in the following 4 days. The morphological changes including swelling, irregularity and lysis of the affected cells over 50% was selected as the cut off for positive change and C.jejuni 81-176 and Helicobacter J99 strains were chosen as the positive and negative control. It was found that the minimum concentration to induce the positive changes in 10 strains(8 GBS associated and 2 strains from diarrhea patients)was 0.1μg/mL and 1 strain with the positive change at the minimum concentration of 1 μg/mL. There was only one GBS-associated strain causing no morphologic change on HeLa cells at the concentration of 5 μg/mL. It was evident that the cytotoxic effect of C.jejuni strains on HeLa cell was strain-specific, and there was no significant difference in the cytotoxic effect on HeLa cell between GBS-associated and diarrhea associated C.jejuni strains.

Dissemination of insertion sequences IS605, IS606 among clinical isolates of Helicobacter pylori in China / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the distribution of IS605, IS606 among clinical isolates of Helicobacter pylori in China.</p><p><b>METHODS</b>A total of 104 H.pylori strains isolated from 5 different geographic regions in China were analyzed by PCR and dot-blot.</p><p><b>RESULTS</b>Forty-two strains out of the 104 isolates from 5 regions in China were found containing IS605 with 19 containing IS606. The frequency (66%) of IS605 positive strains from Yunnan province was higher than that from other areas. The different distribution of IS606 was neither associated with geographical regions nor with the presence of IS605 but IS606 were associated with the different clinical outcomes. However, the two reading frames ORFA and ORFB of IS605 were constantly coexisting.</p><p><b>CONCLUSION</b>In China, IS605 and IS606 of H. pylori were widely existing but the presence of IS605 in H. pylori might be associated with geographic origin.</p>