ABSTRACT
The aim of study was to determine relationship between cagA and genetic characterization of metronidazole [MTZ] resistant H. pylori strains from a region at high risk of gastric cancer. 172 H. pylori strains were isolated from the patients with dyspeptic symptoms, and antimicrobial susceptibility testing for MTZ was assessed by E-test. rdxA and frxA genes were amplified using PCR among the MTZ resistant isolates. The status of the plasmid and classes 1-3 integrons were investigated in all isolates. MTZ was detected in 88 isolates [51.16%]. Variations in the rdxA gene leading to alterations of amino acids in RdxA proteins were identified in all MTZ resistant strains. FrxA contained missense alterations in 55 MTZ resistant isolates, while the premature truncation of FrxA was caused by frameshift mutations in 9 MTZ resistant strains. Plasmid was found in one MTZ sensitive strain [0.58%], and none of Class 1-3 integrases gene was detected in the studied isolates. The conservative cagA fragment was obtained from all clinical isolates of H. pylori. The sequence of cagA 3' variable region in 164 strains were obtained, including East Asian-type [122, 74.39%] and Western-type [42, 25.61%]. Prevalence of Western-type cagA 3' variable region was significantly higher in MTZ resistant [33.73%, 28/83] than those of MTZ-sensitive strains [17.28%, 14/81] [p=0.02]. A high prevalence of MTZ resistance was found in the region, and bacterial chromosome mutations in the rdxA and frxA gene still contribute to the high-level MTZ resistance. H. pylori strains characterized with West-type cagA 3' variable region tend to acquire MTZ resistance in the region
ABSTRACT
The aim of study was to investigate the distribution of the integrons in Escherichia coli [E. coli] isolates, and analyze the possible relationship between the antimicrobial resistance profiles and the integrons. The antimicrobial profiles of 376 E. coli strains were analysed by disk diffusion test. The integron genes and variable regions were detected by PCR. Some amplicons were sequenced to determine the gene cassettes style. Of 376 isolates, 223 isolates [59.3%] were confirmed as ESBL-EC. Comparison to ESBL-negative E. coli, the high rates of resistance to the third and fourth generation of cephalosporins, penicillins and amikacin were found in ESBL-EC. Only class 1 was integron detected in the isolates, and the prevalence of it was 66.5%. It was commonly found in ESBL-EC [77.6%, 173/223], which was higher than that of ESBLnegative E. coli [50.3%, 77/153] [p < 0.001]. Six different genes cassettes were detected in this study and were classified into three groups: dfr17-aadA5, dfrA12-aadA2 and aacA4-CmlA1. Additionally, more than one gene array harboured in 13.9% isolates of ESBL-EC, while in 9.1% isolates of ESBL-negative E.coli. The high incidence of ESBL-EC with resistance to multiple antibiotics were detected in the isolates from Blood stream infection [BSI]. More resistant gene cassettes in ESBL-EC may partially underlie the high resistance to amikacin, while no relation exists between the high incidence of ESBL-EC and classes 1[tilde] 3 integrons in this region
ABSTRACT
Objective To make biomechanical evaluation on three prosthesis retention schemes for unilateral maxillary defects-clasp retention, one or two zygomatic implants and zygomatic implant and clasp united retention. Methods A three-dimensional (3D) finite element model of normal human skull was constructed based on CT scan data. The maxillary complex stress distributions on three reconstructed models were calculated and analyzed by 3D finite element method to make comprehensive comparison on stress level of the prosthesis, abutment, clasp, implants and zygoma. Results For single clasp retention, peak stress of the abutment was 130.7 MPa, and displacement of the prosthesis was 4.439 mm, while peak stress of the clap was 452.4 MPa, and stress of the contralateral orbital rim was 23.32 MPa. After one zygoma was implanted, the stress of the clap was reduced to 118.1 MPa, while peak stress of the abutment was 31.12 MPa, and stress of the contralateral orbital rim was only 5.387 MPa. For two zygomatic implant retention, zygomatic stress was decreased from 66.11 MPa to 48.12 MPa, and the maximum stress on the zygomatic implants was reduced from 500.2 MPa to 313.8 MPa. Conclusions For zygomatic implant and clasp united retention, the maxillofacial skeleton stress distributions were more consistent with the rules of bite force transduction. The research findings will provide important references for design and optimization of human unilateral maxillary defect reconstruction program.
ABSTRACT
<p><b>BACKGROUND</b>Psoriasis is a common inflammatory skin disease, yet knowledge of the factors that may induce, trigger, or exacerbate psoriasis is not fully delineated. Recent advances have improved our understanding of the link between psoriasis and cell-wall-deficient bacteria (CWDB) infections. In the present study we assessed the prevalence of CWDB infection in patients with psoriasis.</p><p><b>METHODS</b>The carriage rate of CWDB in the tonsil or pharynx of psoriasis patients, chronic tonsillitis patients and controls were investigated using hypertonic medium. Psoriasis patients with CWDB were randomly assigned to two groups and respectively treated with antibiotics or systemic therapy without antibiotic. Human peripheral blood mononuclear cells (PBMC) from psoriasis patients, chronic tonsillitis patients and control subjects were stimulated with bacteria antigens and extra-cellular levels of interferon-gamma (IFN-gamma) and interleukin (IL)-10 were measured in the supernatants using the ELISA technique, in vitro. Meanwhile, the proliferation ability of PBMC to respond to bacteria antigens was detected by MTT assay.</p><p><b>RESULTS</b>CWDB were isolated from 74.2% of psoriasis patients, 23.5% of chronic tonsillitis patients and only 6.3% of controls. Antibiotic therapy was appropriate for approximately 80% of psoriasis patients with CWDB infection, and in only 8.9% psoriasis patients CWDB infection was detected after antibiotic therapy. Meanwhile, our study showed that CWDB and wide-type bacteria did remarkably enhance the production of IFN-gamma, in vitro, and PBMC proliferation.</p><p><b>CONCLUSION</b>CWDB infection may be a virtual triggering factor in psoriasis by regulating T-cell activation.</p>