Acinetobacter baumannii is a non-fermentative Gram-negative bacterium that can cause nosocomial infections in critically ill patients. Carbapenem-resistant A. baumannii (CRAB) has spread rapidly in clinical settings and has become a key concern. The main objective of this study was to identify the distribution of integrons and biofilm-formation-related virulence genes in CRAB isolates. A total of 269 A. baumannii isolates (219 isolates of CRAB and 50 isolates of carbapenem-sensitive A. baumannii (CSAB)) were collected. Carbapenemase genes (bla KPC, bla VIM, bla IMP, bla NDM, and bla OXA-23-like) and biofilm-formation-related virulence genes (abal, bfms, bap, and cusE) were screened with PCR. Class 1 integron was screened with PCR, and common promoters and gene cassette arrays were determined with restriction pattern analysis combined with primer walking sequencing. Whole-genome sequencing was conducted, and data were analyzed for a bla OXA-23-like-negative isolate. All 219 CRAB isolates were negative for bla KPC, bla VIM, bla IMP, and bla NDM, while bla OXA-23-like was detected in 218 isolates. The detection rates for abal, bfms, bap, and cusE in 219 CRAB were 93.15%, 63.93%, 88.13%, and 77.63%, respectively. Class 1 integron was detected in 75 CRAB (34.25%) and in 3 CSAB. The single gene cassette array aacA4-catB8-aadA1 with relatively strong PcH2 promoter was detected in class 1 integrons. The bla OXA-23-like-negative CRAB isolate was revealed to be a new sequence type (Oxford 3272, Pasteur 2520) carrying bla OXA-72, bla OXA-259, and bla ADC-26. In conclusion, bla OXA-23-like was the main reason for CRAB's resistance to carbapenems. A new (Oxford 3272, Pasteur 2520) CRAB sequence type carrying the bla OXA-72, bla OXA-259, and bla ADC-26 was reported.

By capturing and expressing exogenous resistance gene cassettes through site-specific recombination, integrons play important roles in the horizontal transfer of antimicrobial resistant genes among bacteria. The characteristics of integron integrase make it to be a potential gene editing tool enzyme. In this study, a random mutation library using error-prone PCR was constructed, and amino acid residues mutants that impact on attI2 × attC or attC × attC recombination efficiency were screened and analyzed. Thirteen amino acid mutations were identified to be critical impacted on site-specific recombination of IntI2, including the predicted catalyzed site Y301. Nine of 13 mutated amino acid residues that have critically impacted on IntI2 activity were relative concentrated and near the predicted catalyzed site Y301 in the predicted three-dimensional structure indicated the importance of this area in maintain the activity of IntI2. No mutant with obviously increased recombination activity (more than four-fold as high as that of wild IntI2) was found in library screening, except P95S, R100K slightly increased (within two-fold) the excision activity of IntI2, and S243T slightly increased (within two-fold) both excision and integration activity of IntI2. These findings will provide clues for further specific modification of integron integrase to be a tool enzyme as well as establishing a new gene editing system and applied practically.

Objective:To investigate the distribution of integrons and plasmid-mediated quinolone resistance (PMQR) genes in clinical isolates of Klebsiella aerogenes and to analyze the relationship between integrons and bacterial resistance to antimicrobial agents. Methods:Ninety-one Klebsiella aerogenes strains isolated from clinical samples in the Fengxian District Central Hospital from November 2015 to March 2021 were used in this study. Class 1 and class 2 integron-integrase genes ( intI1 and intI2) and PMQR genes were screened by PCR. The types of promoters and gene cassette arrays of variable regions were determined by sequencing. Besides, the relationship between integrons and antimicrobial resistance was analyzed. Results:The resistance rate of the 91 Klebsiella aerogenes isolates to aztreonam was more than 40.00% and the resistance rates to other commonly used antimicrobial agents were less than 35.00%. Among the 91 isolates, 30 carried the intI1 gene, while none of them carried the intI2 gene. Seven class 1 integron gene cassette arrays of variable regions were detected and the gene cassette array of aac(6′)-11 C- ΔereA2- IS1247- aac3- arr- ΔereA2 was detected in Klebsiella aerogenes. PcH1 with weak activity was the predominant variable region promoter of class 1 integrons. The detection rates of intI1-positive and intI1-negative isolates in ICU, neurosurgery and other clinical departments were statistically different ( P<0.05). The resistance rate of intI1-positive isolates to some commonly used antibiotics was significantly higher than that of intI1-negative isolates ( P<0.05). qnrS gene was the prevalent PMQR gene. The detection rates of integrons and PMQR genes in Klebsiella aerogenes isolates was low except for the strains isolated in 2016. Conclusions:Antimicrobial resistance in Klebsiella aerogenes was closely related to integrons. The distribution of integrons in Klebsiella aerogenes strains isolated from different clinical departments was different, and the monitoring of drug-resistant strains should be strengthened in ICU and neurosurgery. The resistance to quinolones in Klebsiella aerogenes strains in this region was mainly related to qnrS gene.

Enterobacter cloacae complex (ECC) widely exists in the hospital environment and is one of the important conditional pathogens of hospital-acquired infection. To investigate the distribution of integrons and carbapenem-resistant genes in clinical ECC, 70 isolates of ECC from non-sputum specimens were collected. Class 1 and class 2 integron integrase gene intI1 and intI2, as well as common carbapenem-resistant genes, blaKPC, blaVIM, blaIMP, blaNDM, blaGES, and blaOXA-23, were screened. Gene cassette arrays and common promoters of class 1 integron together with subtypes of carbapenem-resistant genes were determined by sequencing. Resistant rates to commonly used antimicrobial agents between class 1 integron-positive and integron-negative ECC isolates were analyzed. The whole-genome of blaNDM-7 harboring Enterobacter hormaechei was sequenced and the sequence around blaNDM-7 was analyzed. Twenty isolates were positive for intI1. Nineteen different antimicrobial-resistant gene cassettes and 11 different gene cassette arrays, including aadA22-lnuF, were detected in this study. Common promoters of class 1 integron PcH1, PcW, PcW-P2, and PcH2 were detected in 12, 4, 3, and 1 isolates, respectively. The rates of antimicrobial resistance of intI1-positive isolates were higher than those of intI1-negative isolates to clinical commonly used antimicrobial agents. Carbapenem-resistant genes blaKPC-2, blaNDM-1, blaNDM-2, and blaNDM-7 were detected in 2, 1, 1, and 1 isolates, respectively. blaNDM-7 was located between bleMBL and IS5. To the best of our knowledge, this study reported for the first time of blaNDM-7 in ECC isolate in China.

Integron can capture and express antimicrobial resistance gene cassettes and plays important roles in horizontal gene transfer. The establishment of a complete in vitro reaction system will help to reveal integron integrase mediated site-specific recombination process and regulation mechanism. As an enzymatic reaction, the concentration of integrase is assumed to have a great influence on the reaction rate. To determine the influence of different concentrations of integrase on the reaction rate and to find the best range of enzyme concentration were essential to optimizing the in vitro reaction system. In this study, plasmids with gradient transcription levels of class 2 integron integrase gene intI2 under different promoters were constructed. Among plasmids pI2W16, pINTI2N, pI2W, and pI2NW, intI2 transcription levels ranged from about 0.61-fold to 49.65-fold of that in pINTI2N. And the frequencies of gene cassette sat2 integration and excision catalyzed by IntI2 were positively correlated with the transcription levels of intI2 within this range. Western blotting results indicated high expression of IntI2 partly existed in the form of an inclusion body. When compared with Pc of class 1 integron, the spacer sequence of P intI2 can increase the strength of PcW but decrease the strength of PcS. In conclusion, the frequencies of gene cassette integration and excision were positively correlated with the concentration of IntI2. intI2 driving by PcW with P intI2 spacer sequence can obtain the optimum IntI2 concentration required to achieve the maximum recombination efficiency in vivo in this study.

目的 了解临床中C.freundii的分布和耐药情况,从而为现阶段少见菌种抗菌药物的使用提供针对性的方案.方法 收集97株2016—2021年非重复C.freundii,运用聚合酶链反应(PCR)筛查第1、2、3类整合酶基因(intI1、intI2、intI3),对intI+的C.freundii采用长片段PCR扩增整合子可变区,通过测序确定可变区基因盒种类.结果 97株C.freundii中,21株第1类整合酶阳性,2株第2类整合酶阳性.扩出的可变区中,有8株是dfrA12-aadA2,其中aac(6')-II-ereA2-aac3-arr-ereA2和aac(6')-II-ereA2-tnpA-aac3-arr-ereA2携带的基因盒种类最多.结论 C.freundii菌株整合子携带率低于其他肠杆菌科细菌,其可变区耐药基因盒种类多样,该菌目前临床耐药之所以如此严峻,是与其携带的可变区启动子(Pc)密切相关.碳青霉烯类抗生素(CRE)仍然是对多重耐药菌株具有活性的抗生素,但应限制其使用以避免出现耐药性,而第三代头孢类抗生素依然可作为治疗由C.freundii所引起的感染首选药物.

Integrons can capture and express foreign gene cassettes through site-specific recombination and are important genetic elements in spreading antibiotic resistance genes among bacteria. We have developed a two-dimensional PCR technology (2D-PCR) based on the base quenching probe technology in detecting three major integrons at the same time. The minimum detection limits were evaluated by detecting three plasmids each harboring different types of integron with different concentrations. The specificity of this method was evaluated by screening and typing three major types of integrons in 105 clinical Proteus isolates, and the results were compared with those of traditional PCR. Results indicated that the melting temperature (Tm) difference of the three genes was about 10 °C and was very easy to be distinguished. The minimum detection limits of intI1, intI2 and intI3 were all below 102 copies/μl. The detection results of clinical isolates were consistent with those of traditional PCR. This developed rapid, economic and high-throughput 2D-PCR based method can detect three main classes of integron at the same reaction, and can be applied to clinical isolates in large-scale integron screening and typing.

目的:了解临床分离铜绿假单胞菌Ⅲ型分泌系统毒力基因exoT、exoY、exoS和exoU的携带情况及其与细菌耐药性的关系.方法:收集上海市奉贤区中心医院2016年4月-2018年4月临床样本中非重复分离的157株铜绿假单胞菌,使用Phoenix 100全自动微生物分析仪进行细菌鉴定和药敏试验,PCR检测毒力基因exoS、exoU、exoT和exoY,并分析不同毒力基因型组合与细菌耐药性的关系.结果:157株铜绿假单胞菌中,携带exoT、exoY、exoS和exoU基因的阳性率分别为100.00％(157/157)、95.54％(150/157)、70.06％(110/157)和28.03％(44/157).共检测出6种毒力基因型组合,以exoT+/exoY+/exoS+/exoU-(68.79％,108/157)和exoT+/exoY+/exoS-/exoU+(25.48％,40/157)为主.多重耐药菌株以exoT+/exoY+/exoS+/exoU-型为主,耐碳青霉烯类铜绿假单胞菌以exoT+/exoY+/exoS-/exoU+型为主.exoT+/exoY+/exoS-/exoU+型菌株对亚胺培南、环丙沙星、左氧氟沙星的耐药率高于exoT+/exoY+/exoS+/exoU-型菌株.结论:exoT和exoY基因普遍存在于铜绿假单胞菌中,不同毒力基因型组合与铜绿假单胞对常用抗菌药物的耐药率密切相关.

目的 了解2019年上海市二级医院临床分离菌对抗菌药物的耐药性.方法 对21所二级医院(包括6所三乙医院)临床分离菌采用纸片扩散法或自动化仪器法按上海市细菌真菌耐药监测网统一监测方案进行抗菌药物敏感性试验.按2019年美国临床和实验室标准化协会(CLSI)文件标准判断结果 .结果 收集2019年1-12月上述医院临床分离菌共48650株,其中革兰阳性菌12409株,占25.5％,革兰阴性菌36241株,占74.5％.金黄色葡萄球菌、表皮葡萄球菌和其他凝固酶阴性葡萄球菌中甲氧西林耐药株(MRSA、MRSE和其他MRCNS)的平均检出率分别为49.6％、78.4％和79.9％.MRSA和MRCNS对大多数测试药物的耐药率均显著高于甲氧西林敏感株(MSSA和MSCNS).葡萄球菌属中未见万古霉素耐药株.肠球菌属中粪肠球菌对多数受试抗菌药物的耐药率均显著低于屎肠球菌,粪肠球菌对利奈唑胺耐药率0.4％,屎肠球菌对万古霉素耐药率为0.3％.流感嗜血杆菌、肺炎链球菌和卡他莫拉菌检出率分别为2.5％(1235株)、0.4％(217株)和0.5％(238株),流感嗜血杆菌产β内酰胺酶率为51.3％.肺炎链球菌非脑脊液分离株中以成人分离株为多,占61.7％,成人中青霉素耐药肺炎链球菌(PRSP)检出率为4.5％(6/132),儿童中未发现PRSP菌株.肠杆菌目细菌对碳青霉烯类抗生素较敏感,多数菌属对美罗培南耐药率均低于4％,克雷伯菌属对亚胺培南和美罗培南的耐药率分别为23.6％和23.2％,沙雷菌属对两药耐药率分别为21.4％和16.0％.不动杆菌属细菌对上述两药的耐药率分别为52.1％和53.2％,铜绿假单胞菌对两药的耐药率分别为22.1％和20.5％.结论 2019年上海市二级医院细菌耐药性监测显示:其菌种的分布和耐药性与三级医院大致相仿,临床常见细菌的耐药率和MRSA、碳青霉烯类耐药的肺炎克雷伯菌、铜绿假单胞菌、鲍曼不动杆菌等耐药菌株的检出率较高,面临细菌耐药增加的严重威胁,应引起足够重视;合理使用抗菌药物和规范治疗是当务之急.

[背景]整合子在细菌耐药性的获得及传播中占据重要地位,对于整合反应检测方法的改良及反应机制的研究,可以加深我们对细菌耐药性产生和播散的理解,为遏制耐药菌株的产生和播散提供新的途径.[目的]在细菌染色体上构建第1类整合子反应模型,用于评价整合酶介导的基因盒位点特异性重组.[方法]采用PCR分别扩增含氯霉素耐药基因cat的CM片段、含基因盒aadA5的LacA5片段、含整合子重组位点attI1及强可变区启动子的PcS片段和插入位点两侧的同源臂,重叠延伸聚合酶链反应连接上述5个片段制备整合子模型插入片段,通过同源重组将构建好的整合子模型片段插入大肠埃希菌JM109染色体中.转入高表达第1类整合酶的质粒pHSint,在链霉素平板上筛选发生整合的菌株,并用聚合酶链反应和测序验证.[结果J构建的整合子模型片段经测序与预期一致,整合子模型片段成功插入大肠埃希菌JM109染色体中.转入高表达整合酶的质粒pHSint后,在链霉素平板上成功筛选出基因盒aadA5发生整合的菌株,经聚合酶链反应扩增并测序与预期一致.[结论]在大肠埃希菌染色体上成功构建第1类整合酶介导基因盒位点特异性重组反应模型,为进一步揭示整合子捕获耐药性基因盒的反应机制奠定基础.

A 3,5-didocosyloxybenzyl alcohol tag that was introduced at the anomeric position of the carbohydrate acceptor was applied in the assembly of a pentasaccharide. The intrinsic high solubility in nonpolar solvent and precipitation properties in polar solvent are crucial features of this tag. Thus, rapid and simple precipitation-centrifugation can be conducted throughout the synthetic route at each step to ease work-up and purification processes, and reduce the amount of solvent required. This method provides an efficient, environmental-friendly, and economical approach to synthesize complex oligosaccharides.

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.

A Co(ii)/BOX-catalyzed asymmetric allylation of spiroepoxyoxindoles was developed, which is the first stereoconvergent allylation of epoxides, yielding chiral oxindoles bearing quaternary stereocenters.

Objective: To describe the polymorphisms of gene cassette promoters of the class 1 integron in clinical Proteus isolates and their relationship with antibiotic resistance. Methods: Polymorphisms of the gene cassette promoter in 153 strains of Proteus were analyzed by PCR and nucleotide sequencing. Variable regions of atypical class 1 integrons were detected by inverse PCR and nucleotide sequencing. Enterobacterial repetitive intergenic consensus (ERIC)-PCR was used to analyze the phylogenetic relationships of class 1 integron-positive clinical Proteus isolates. Representative beta-lactamase genes (bla), including bla(TEM), bla(SHV), bla(CTX-M-1), bla(CTX-M-2), bla(CTX-M-8), bla(CTX-M-9), bla(CTX-M-25) and bla(OXA-1), and plasmid-mediated quinolone resistance (PMQR) genes including qnrA, qnrB, qnrC, qnrD, qnrS, oqxA, oqxB, qepA, and aac(6')-Ib were also screened using PCR and sequence analysis. Results: Fifteen different gene cassette arrays and 20 different gene cassettes were detected in integron-positive strains. Of them, aadB-aadA2 (37/96) was the most common gene cassette array. Two of these gene cassette arrays (estX-psp-aadA2-cmlA1, estX-psp-aadA2-cmlA1-aadA1a-qacI-tnpA-sul3) have not previously been reported. Three different Pc-P2 variants (PcS, PcWTGN-10, PcH1) were detected among the 96 Proteus strains, with PcH1 being the most common (49/96). Strains carrying the promoters PcS or PcWTGN-10 were more resistant to sulfamethoxazole, gentamicin and tobramycin than those carrying PcH1. Strains with weak promoter (PcH1) harbored significantly more intra-and extra-integron antibiotic resistance genes than isolates with strong promoter (PcWTGN-10). Further, among 153 isolates, representative beta-lactamase genes were detected in 70 isolates (bla(TEM-1), 54; bla(OXA-1), 40; bla(CTX-M-3), 12; bla(CTX-M-14), 12; bla(CTX-M-65), 5; bla(CTX-M-15), 2) and representative PMQR genes were detected in 87 isolates (qnrA, 6; qnrB, 3; qnrC, 5; qnrD, 46; qnrS, 5; oqxA, 7; aac(6')-Ib, 13; aac(6')-Ib-cr, 32). Conclusion: To the best of our knowledge, this study provides the first evidence for polymorphisms of the class 1 integron variable promoter in clinical Proteus isolates, which generally contain relatively strong promoters. Resistance genotypes showed a higher coincidence rate with the drug-resistant phenotype in strong-promoter-containing strains, resulting in an ability to confer strong resistance to antibiotics among host bacteria and a relatively limited ability to capture gene cassettes. Moreover, strains with relatively weak integron promoters can "afford" a heavier "extra-integron antibiotic resistance gene load". Furthermore, the gene cassettes estX, psp and the gene cassette arrays estX-psp-aadA2-cmlA1, estX-psp-aadA2-cmlA1-aadA1a-qacI-tnpA-sul3 have been confirmed for the first time in clinical Proteus isolates. Beta-lactamase genes and PMQR were investigated, and bla(TEM-1) and bla(OXA-1) were the most common, with qnrD and aac (6')-Ib-cr also being dominant.

目的 研究miR-34b调控其靶基因USP22分子机制及其在急性髓细胞白血病细胞HL60中的生物学效应.方法 荧光定量PCR (qPCR)检测miR-34b、USP22转录水平;蛋白免疫印迹(Western blotting)检测USP22、Bax、Bcl-2蛋白表达水平;急性髓细胞白血病HL60细胞中过表达、抑制miR-34b或干扰USP22后,CCK-8及Annexin-V分别检测细胞增殖活性及凋亡变化.双荧光素酶报告基因系统证实miR-34b与USP22的3’非编码区(3’-UTR)相互作用.结果 miR-34b在白血病细胞HL660中表达下调,为外周血健康对照单个核细胞的0.46±0.07倍(P＜0.01).与对照细胞相比,在HL60细胞中过表达miR-34b或抑制miR-34b后,细胞相对活性分别出现减低或增强现象(P＜0.01).miR-34b在HL60中过表达后,凋亡细胞(29.91 ±1.14)％较对照细胞(8.77±0.23)％增加了2.41倍(P＜0.01),Western印迹检测证实了促凋亡分子Bax及抑制凋亡分子Bcl-2在miR-34b过表达后分别出现了上调及下调现象.利用在线预测软件预测USP22可能是miR-34b直接调控基因.在HL60细胞中过表达或抑制miR-34b后,USP22转录水平及蛋白表达水平均不同程度上调及下调(P＜0.01).双荧光素酶报告基因系统证实miR-34b过表达后,USP22野生型的3’-UTR较对照组显著下调(P＜0.01),而突变型无显著改变.进一步敲减USP22后HL60细胞增殖活性减低,并诱导细胞凋亡.结论 miR-34b对白血病细胞HL60的抑癌活性可部分通过抑制USP22得以实现;同时过表达miR-34b或抑制USP22表达有望成为急性髓细胞白血病的诊治靶点.

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.