ABSTRACT
Objective:To explore the distribution of integrons in Escherichia coli isolated from community patients with urinary tract infections and their relationship with the phylogenetic groups and antimicrobial resistance. Methods:From November 2015 to December 2018, 152 isolates of E. coli that collected without repetition from the urine samples of outpatients in nephrology of Fengxian District Central Hospital in Shanghai, were studied retrospectively. Bacterial identification and antimicrobial susceptibility analysis was carried out by Phoenix 100 automatic microbiological analyzer. Class 1, 2 integron integrase genes, variable regions of integrons and the phylogenetic groups of isolated E.coli were screened by PCR. The type of promoters and gene cassette arrays of variable regions were determined by sequencing. The relationship of intergon with the phylogenetic groups and antimicrobial resistance was also analyzed. Results:The resistance rate of 152 E. coli to ampicillin was 70.39% (107/152), and the resistance rates to other antibacterial drugs were all less than 40.00%. Among the 152 E. coli isolates, class 1 integron integrase gene intI1 was detected in 65 isolates (42.76%), 8 gene cassette arrays and 14 antimicrobial resistance gene cassettes were detected in 68 class 1 integrons. The most popular gene cassette array was dfrA17-aadA5 (51.47%, 35/68), while the variable regions of class 1 integrons were failed to detected in 12 intI1-positive isolates. Five variable region promoters were detected in 68 class 1 integrons, with the relative weak promoter PcH1 to be the most popular type (77.94%, 53/68). The gene cassette array arr- 2-cmlA5-bla OXA-10-aadA1 was also detected in this study. 65 intI1-positive isolates were mainly belonged to group B2 and D. The class 2 integron integrase gene intI2 was detected in 4 isolates (2.63%,4/152), and their variable region gene cassette arrays were all dfrA1-sat2-aadA1. Conclusions:Class 1 integrons were closely related to antimicrobial resistance in E. coli isolated from community patients with urinary tract infection. Most of the variable region promoters of class 1 integrons were relatively weak promoters. The distribution of each phylogenetic group in the intI1-positive isolates was consistent with the distribution of the overall isolates. The gene cassette array arr-2-cmlA5-bla OXA-10-aadA1 was detected in E. coli.
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Objective To investigate the distribution of integrons in clinical isolates of carbapen-em-resistant Acinetobacter baumannii and their relationships to bacterial resistance to antimicrobial agents.Methods A total of 115 carbapenem-resistant Acinetobacter baumannii strains were isolated from clinical samples of patients from January to October, 2017. Phoenix 100 automatic microbiological analyzer was used for antimicrobial sensitivity analysis. Classes 1 and 2 integrase genes and carbapenemase-encoding genes, bla IMP , blaVIM , blaKPC , blaNDM and blaOXA-23 , were screened by PCR. The variable regions of integrons were amplified by long fragment PCR. The types of promoters and gene cassette arrays of variable regions were de-termined by sequencing and overlap PCR. Relationships between integrons and antimicrobial resistance were analyzed. Results The 115 isolates of carbapenem-resistant Acinetobacter baumannii were resistant to most commonly used antimicrobial agents, but sensitive to polymyxin E. All of the isolates carried blaOXA-23 gene and none of them were positive for blaIMP , blaVIM , blaKPC or blaNDM gene. Class 1 integrase gene intI1 was de-tected in 40 isolates (34. 8％ ), while class 2 integrase gene intI2 was not detected. Two gene cassette ar-rays of variable regions, aacA4-catB8-aadA1 (39 isolates) and aacC1-gacP-gacQ-aadA1a (23 isolates), were detected in intI1-positive isolates. Twenty-two isolates carried both aacA4-catB8-aadA1 and aacC1-gacP-gacQ-aadA1a. The upstream promoters of the variable regions were relatively strong promoters, PcH2 and PcS. The gene cassettes of the variable regions endowed bacteria with resistance to chloramphenicol and aminoglycoside antibiotics. The resistance rate of class 1 integron-positive isolates to compound sulfamethox-azole was higher than that of negative strains. However, their resistance rate to ampicillin/sulbactam was lower than that of negative strains. Conclusions Antimicrobial resistance in carbapenem-resistant Acineto-bacter baumannii was serious. Carbapenem resistance was associated with blaOXA-23 gene. The types of pro-moters of variable regions in class 1 integrons were all relatively strong promoters. Class 1 integrons were closely related to sulfonamides resistance.
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<p><b>OBJECTIVE</b>To investigate the mandibular incisive canal (MIC) with cone-beam computed tomography (CBCT).</p><p><b>METHODS</b>Fifty adults were selected and CBCT was taken. The CBCT data were reconstructed to evaluate the visibility, shape, diameter, length of the MIC and its relationship with mandible.</p><p><b>RESULTS</b>MIC could be identified in 100% (100/100) of CBCT with good clarity in 71% (71/100). The diameters (horizontal diameter versus vertical diameter) of MIC became smaller from origin to end (left origin of MIC was 2.17 mm×2.22 mm, left end was 0.82 mm×0.92 mm; right origin of MIC was 2.14 mm×2.08 mm, right end was 0.87 mm×0.86 mm). The left and right mean length of MIC was 17.84 mm and 17.73 mm respectively. In bucca-lingual direction, MIC was close to buccal cortical border, and in vertical direction, MIC was close to lower margin of mandible. The distance from MIC to apex of root was shortest in canine.</p><p><b>CONCLUSIONS</b>CBCT can identify MIC with high visibility and prominent clarity. In the interforaminal region of mandible, MIC was close to buccal and lower margin of mandible.</p>