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Background and Objective: Chronic infection with Hepatitis B virus (HBV) is one of the main causes of cirrhosis and hepatocellular carcinoma (HCC). The pathogenicity of the virus is determined by the multi-functional protein x (HBx). Changing the sequence of the gene encoding this protein causes the regulation of transcription and pathogenicity factors. This study was done to analyze the genetic dynamics of the HBx coding gene in a person with chronic HBV.
Methods: In this descriptive laboratory study, an infected person with chronic hepatitis B virus infection was first amplified and cloned into complete sequence of HBx encoder. Then, the reference sequences of genotypes, serotypes and different virus subtypes of the GenBank database were matched by CLC Sequence Viewer software. The comparative result was used to plot the phylogenic tree by T-rex server and population genetic analysis using DnaSP software. Natural selection at the nucleotide and protein level was performed by the Tajima's D test.
Results: No known mutation at the level of the protein was found in the chronic sequence of the HBx encoder. The results of natural selection indicated neutral mutations in the HBx gene. The phylogenetic results showed that the HBx encoding sequences in the chronic infected individual had a genetic affinity with genotype D and ayw2 subtype.
Conclusion: Neutrality polymorphism takes place in HBx coding region. Also, the phylogenetic results of the present study are consistent with the previous findings of Golestan province and Iran which have reported the prevalence of genotype D and subspecies ayw2.

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Background and Objective: Production of beta-lactamase enzymes is the most common mechanism of bacterial resistance against beta-lactam antibiotics. The aim of this study was to determine the antibiotic resistance pattern and the frequency of AmpC genes in Escherichia coli (E.coli) isolated in outpatients.
Methods: In this descriptive-analytical study, 67 isolates of E.coli were investigated from urinary tract infection of outpatients of the largest medical center in Kermanshah, west of Iran. Their susceptibility to ceftriaxone, cefotaxime, ceftazidime, cefoxitin and imipenem antibiotics was determined using disk diffusion. AmpC phenotypic screening was performed using combination disk method (cefoxitin with and without boronic acid). After extraction the bacterial genome, the presence of MOX, CIT, DHA, ACC, EBC and FOX genes were tested by multiplex PCR.
Results: The resistance of 67 E.coli isolated to ceftriaxone, cefotaxime, ceftazidime and cefoxitin was 49.2%, 49.2%, 37.3% and 25.3%, respectively. The 100% of the isolates were sensitive to imipenem. Seventeen (25.3%) and 9 isolates (13.4%) were phenotypically and genotypically positive for AmpC, respectively. The prevalence of CIT, MOX, FOX, DHA and EBC genes was 7.4%, 5.9%, 4.4%, 4.4% and 2.9%, respectively. However, the ACC gene was not found in isolates. Except for significant correlation between AmpC phenotype and MOX gene (P<0.05), no significant statistical relationship was found between phenotype and AmpC genotype. There was a significant correlation between AmpC phenotype and ceftazidime antibiotic (P<0.05). There was a significant correlation between CIT gene and EBC and FOX (P<0.05).
Conclusion: AmpC-producing E.coli isolates cause significant resistance to cephalosporins. One of the current therapeutic options is using of carbapenems. However, the relatively high prevalence and synergistic genes of AmpC in outpatients are a big concern and unfortunately it reflects the fact that these isolates are prevalent in the society.