Abstract Background: CagA is one of the most important virulence factors of Helicobacter pylori ( H. pylori ). There is a highly polymorphic Glu-Pro-Ile-Tyr-Ala (EPIYA) repeat region in the CagA 3’ variable region. This repeat region is thought to play an important role in the pathogenesis of gastrointestinal diseases. The aim of this study was to investigate the diversity of CagA 3’ variable region and the amino acid polymorphisms in the EPIYA segments, and their association with gastroduodenal diseases. Methods: A total of 515 H. pylori isolates from patients in 14 different geographical regions of China were collected and the genomic DNA was extracted. The 3’ variable region of the cagA was amplified by polymerase chain reaction (PCR) and then followed by DNA sequencing, and the amino acid sequences were analyzed with MEGA 7.0 software. Results: A total of 503 (97.7%) H. pylori isolates were cagA -positive and 1,587 EPIYA motifs were obtained, including 12 types of EPIYA or EPIYA-like sequences. In addition to the four reported major segments, several rare segments (e.g., B’, B’’ and D’) were defined and 20 different sequence types (e.g., ABD, ABC) were found in our study. A total of 481 (95.6%) strains were East Asian type, most of them were ABD subtype (82.1%). Only 22 strains were Western type, including types AC, ABC, ABCC and ABCCCC. The CagA-ABD subtype had statistical difference in different geographic regions (P=0.006). There are seven amino acid polymorphisms in the sequences surrounding the EPIYA motifs, among which amino acid residue 893 and 894 had a statistical difference with gastric cancer (P=0.004). Conclusions: In this study, 503 CagA sequences was studied and analyzed in depth. In Chinese population, most H. pylori isolates are of the CagA-ABD subtype and its presence was associated with gastroduodenal disease. Amino acid polymorphisms at residue 893 and 894 flanking the EPIYA motif had a statistically significant association with gastric cancer.
To determine the genetic structure of ermB-positive Tn1546-like mobile elements in methicillin-resistant Staphylococcus aureus (MRSA) from mainland China.A total of 271 erythromycin-resistant MRSA isolates were isolated from Sir Run Run Shaw Hospital (SRRSH) from 2013 to 2015. Whole-genome sequencing was performed for the ermB-positive strains, and the genetic environment of the ermB genes was analyzed. Southern hybridization analysis and transformation tests were performed to confirm the location of the ermB gene.A total of 64 isolates (64/271, 23.6%) were ermB-positive strains, with 62 strains (62/64, 96.9%) belonging to the CC59 clone. The other two strains, SR130 and SR231, belonging to CC5-ST965, both harbored 14,567 bp ermB-positive Tn1546-like elements and displayed multidrug-resistant profiles. PFGE followed by Southern blot demonstrated that the ermB genes were located on the plasmids of both SR130 and SR231, while two copies of ermB were located on the chromosome of SR231. Further sequencing demonstrated that SR231 carried one Tn1546-ermB elements in the plasmid and two identical copies integrated on the chromosome, which had 99.99% identity to the element in the plasmid of SR130. The Tn1546-ermB elements were highly similar (100% coverage, >99.9% identity) to the element Tn6636 reported in a previous study from Taiwan. The plasmids (pSR130 and pSR231) harboring ermB-positive Tn1546-like elements were also identical to the mosaic plasmid pNTUH_5066148. However, conjugation of ermB-carrying plasmids of SR130 and SR231 were failed after triple repeats.Multiple copies of ermB-positive Tn1546-like mobile elements were found in CC5-ST965 MRSA from mainland China, showing the wide dissemination of these Enterococcus faecium-originated ermB-positive Tn1546-like elements. Molecular epidemiological study of Tn1546-like elements is essential to avoid the spreading of resistant determinants.
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Abstract Staphylococcus capitis , which causes bloodstream infections in neonatal intensive care units, is a common cause of healthcare-associated infections. Thus, a standardized high-resolution typing method to document the transmission and dissemination of multidrug-resistant S. capitis isolates is required. We aimed to establish a core genome multilocus sequence typing (cgMLST) scheme to surveil S. capitis . The cgMLST scheme was defined based on primary and validation genome sets and tested with outbreaks of linezolid-resistant isolates and a validation set. Phylogenetic analysis was performed to investigate the population structure and compare it with the result of cgMLST analysis. The S. capitis population consists of 1 dominant, NRCS-A, and 4 less common clones. In this work, a multidrug-resistant clone (L clone) with linezolid resistance is identified. With the features of type III SCC mec and multiple copies of mutations of G2576T and C2104T in the 23S rRNA, the L clone has been spreading silently across China.
Objective To investigate the relationship between the change of circulating endothelial cell (CEC) level and coronary artery lesion (CAL) of Kawasaki disease (KD),and to further explore the method for early diagnosis of KD.Methods Thirty KD children were recruited for study,including 23 children with complete type of KD and seven children with incomplete KD.According to the results of echocardiography,the KD group was divided into CAL group (9 cases) and non-coronary artery lesion (NCAL)group (21 cases).Ten healthy children were enrolled as control group.Double-blind and controlled trial was conducted,and Hladovec method was applied for CEC counting.Results The CEC level was ( 1.09 ±0.60) × 107/L in KD group,which was higher than that of control group [ (0.38 ±0.14) × 107/L],and the difference was statistically significant ( t =2.85,P ＜ 0.01 ).The CEC level in the CAL group [ ( 1.84 ± 0.24) × 107/L] was higher than that of the NCAL group[ (2.01 ±0.38) × 107/L],and the difference was statistically significant ( t =2.24,P ＜ 0.05 ).The CEC level was ( 1.16 ± 0.63 ) × 107/L in the complete type of KD group and (0.83 ± 0.45 ) × 107/L in the incomplete KD group,which showed no significant difference between the two groups ( t =1.86,P ＞ 0.05 ).Condusion CEC level was elevated significantly in the acute phase of KD.The CEC level in CAL group was higher than that of NCAL group in acute phase.CEC level detection may be helpful for the early diagnosis of KD.
Key words:
Kawasaki disease; Circulating endothelial cells; Coronary artery lesion
Abstract Background The cytotoxin-associated gene A ( cagA ) is one of the most important virulence factors of Helicobacter pylori ( H. pylori ). There is a highly polymorphic Glu-Pro-Ile-Tyr-Ala (EPIYA) repeat region in the C-terminal of CagA protein. This repeat region is thought to play an important role in the pathogenesis of gastrointestinal diseases. The aim of this study was to investigate the diversity of cagA 3′ variable region and the amino acid polymorphisms in the EPIYA segments of the CagA C-terminal region of H. pylori , and their association with gastroduodenal diseases. Methods A total of 515 H. pylori strains from patients in 14 different geographical regions of China were collected. The genomic DNA from each strain was extracted and the cagA 3′ variable region was amplified by polymerase chain reaction (PCR). The PCR products were sequenced and analyzed using MEGA 7.0 software. Results A total of 503 (97.7%) H. pylori strains were cagA -positive and 1,587 EPIYA motifs were identified, including 12 types of EPIYA or EPIYA-like sequences. In addition to the four reported major segments, several rare segments (e.g., B′, B″ and D′) were defined and 20 different sequence types (e.g., ABD, ABC) were found in our study. A total of 481 (95.6%) strains carried the East Asian type CagA, and the ABD subtypes were most prevalent (82.1%). Only 22 strains carried the Western type CagA, which included AC, ABC, ABCC and ABCCCC subtypes. The CagA-ABD subtype had statistical difference in different geographical regions (P = 0.006). There were seven amino acid polymorphisms in the sequences surrounding the EPIYA motifs, among which amino acids 893 and 894 had a statistical difference with gastric cancer (P = 0.004). Conclusions In this study, 503 CagA sequences were studied and analyzed in depth. In Chinese population, most H. pylori strains were of the CagA-ABD subtype and its presence was associated with gastroduodenal diseases. Amino acid polymorphisms at residues 893 and 894 flanking the EPIYA motifs had a statistically significant association with gastric cancer.
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