Prevalence and resistance of Helicobacter pylori in a predominantly Hispanic population

BACKGROUND Helicobacter pylori(H.pylori)is the most common chronic bacterial infection in humans.The risk of acquiring H.pylori is related to socioeconomic status and living conditions early in life.Treatment regimens must consider local antibiotic resistance patterns.Adventist Health White Memorial Hospital serves a predominantly indigent population in east Los Angeles with a large number of immigrants from South and Central America.Data regarding the prevalence and resistance of H.pylori in this population is scant.AIM To evaluate the prevalence and resistance of H.pylori and correlate with country of origin.METHODS All gastric biopsies were obtained by a single gastroenterologist at the hospital in a consecutive manner from patients with gastritis from 2017 to 2022 and sent to various labs for evaluation.RESULTS Two hundred and sixty-six patients are born in the United States,450,171,70,and 30 patients are immigrants from Mexico,Central and South America(CSA),Asia,and other countries respectively.Overall,14.65%were found to be infected with H.pylori.Rates of infection in United States-born citizens,immigrants from Mexico,CSA,and Asia are 9.02%,18.67%,13.45%,and 11.43%respectively,with Mexican immigrants having a relative risk of 2.3889[95%confidence interval(CI):1.4789-3.8588,P=0.0004]compared to those born in United States.No correlation seen between infection and length of time immigrants were in United States.Relative risk of infection in patients with no proton pump inhibitor use within the past 30 days found to be 1.9276(95%CI:1.3562-2.7398,P=0.0003).Rates of resistance for clarithromycin and levofloxacin are 21.43%and 31.11%.CONCLUSION H.pylori infection appears to be associated with low socioeconomic status and poor living conditions early in life.Clarithromycin and levofloxacin based treatment regimens should be avoided as first line therapy in this region,particularly in patients of Latin American origin.

Influence of efflux pump inhibitors on the multidrug resistance of Helicobacter pylori

AIM:To evaluate the effect of efflux pump inhibitors (EPIs) on multidrug resistance of Helicobacter pylori (H. pylori).METHODS: H. pylori strains were isolated and cultured on Brucella agar plates with 10% sheep's blood. The multidrug resistant (MDR) H. pylori were obtained with the inducer chloramphenicol by repeated doubling of the concentration until no colony was seen, then the susceptibilities of the MDR strains and their parents to 9 antibiotics were assessed with agar dilution tests. The present study included periods before and after the advent of the EPIs, carbonyl cyanide m-chlorophenyl hydrazone (CCCP), reserpine and pantoprazole), and the minimum inhibitory concentrations (MICs) were determined accordingly. In the same way, the effects of 5 proton pump inhibitors (PPIs), used in treatment of H. pylori infection, on MICs of antibiotics were evaluated.RESULTS: Four strains of MDR H. pylori were induced successfully, and the antibiotic susceptibilities of MDR strains were partly restored by CCCP and pantoprazole, but there was little effect of reserpine. Rabeprazole was the most effective of the 5 PPIs which could decrease the MICs of antibiotics for MDR H. pylori significantly.CONCLUSION: In vitro, some EPIs can strengthen the activities of different antibiotics which are the putative substrates of the efflux pump system in H. pylori.

Efflux pump gene hefA of Helicobacter pylori plays an important role in multidrug resistance

AIM: To determine whether efflux systems contribute to multidrug resistance of H pylori. METHODS: A chloramphenicol-induced multidrug resistance model of six susceptible H pylori strains (5 isolates and H pylori NCTC11637) was developed. Multidrug-resistant (MDR) strains were selected and the minimal inhibitory concentration (MIC) of eryth-romycin, metronidazole, penicillin G, tetracycline, and ciprofloxacin in multidrug resistant strains and their parent strains was determined by agar dilution tests. The level of mRNA expression of hefA was assessed by fluorescence real-time quantitative PCR. A H pylori LZ1026 knockout mutant (ΔH pylori LZ1026) for (puta-tive) efflux protein was constructed by inserting the kanamycin resistance cassette from pEGFP-N2 into hefA, and its susceptibility profiles to 10 antibiotics were evaluated. RESULTS: The MIC of six multidrug-resistant strains (including 5 clinical isolates and H pylori NCTC11637) increased signifi cantly (≥ 4-fold) compared with their parent strains. The expression level of hefA gene was significantly higher in the MDR strains than in their parent strains (P = 0.033). A H pylori LZ1026 mutant was successfully constructed and the ΔH pylori LZ1026 was more susceptible to four of the 10 antibiotics. All the 20 strains displayed transcripts for hefA that con-fi rmed the in vitro expression of these genes.CONCLUSION: The efflux pump gene hefA plays an important role in multidrug resistance of H pylori.

Characterization and frequency of antibiotic resistance related to membrane porin and efflux pump genes among Acinetobacter baumannii strains obtained from burn patients in Tehran, Iran

Objective: To explore the characterization and frequency of antibiotic resistance related to membrane porin and efflux pump genes among Acinetobacter baumannii (A. baumannii) strains obtained from burn patients in Tehran, Iran. Methods: In this cross-sectional descriptive study, 100 strains of A. baumannii isolated from burn patients visiting teaching hospitals of Tehran were collected from January 2016 to November 2017. After A. baumannii strains were confirmed, antimicrobial susceptibility testing was done via Kirby-Bauer disc diffusion method according to the Clinical and Laboratory Standards Institute guidelines. PCR amplification was performed for detection of β-lactamase adeR, OprD, adeS genes among A. baumannii strains. Results: All isolates (100%) were resistant to ceftazidime, cefotaxime, cefepime, ciprofloxacin, and piperacillin, and most isolates indicated high resistance (95%-97%) to meropenem, imipenem, gentamicin, ceftriaxone, trimethoprim-sulfamethoxazole, piperacillin-tazobactam, amikacin, and tetracycline. The most effective antibiotic against A. baumannii isolates was colistin (97% sensitivity), followed by tigecycline. The frequency of OprD, adeS, and adeR genes were 98%, 91%, and 77%, respectively. Conclusions: This study shows that the majority of A. baumannii isolates are highly resistant to the antibiotics most commonly used in burn patients. Also, high distribution of OprD and adeRS genes may be responsible for the observed resistances among A. baumannii isolates that demonstrate the possible role of both efflux pumps in simultaneous of carbapenemase production during antibiotic resistance.

Mechanisms Efflux Pumps of <i>Acinetobacter baumannii</i>(MDR): Increasing Resistance to Antibiotics

Acinetobacter baumannii has greatly increased its degree of resistance to become multidrug resistant (MDR) over the past 30 years and is on the red line of the most widely replicated bacteria according to World Health Organization (WHO). The efflux pumps are the main cause for the increasing antibiotic resistance of A. baumannii originated from nosocomial infection. The progressive resistance of A. baumannii even on the recent drugs (tigecycline and fosfomycin) reduces to very effective antibiotic scale. With attention focused on MDR and pan-drug-resistant (PDR) in A. baumannii multiple works on efflux pumps chemical inhibitor (NMP, PAβN, omeprazole, verapamil, reserpine, CCCP) are still in progress. Certain inhibitors from plants (Biricodar and timcodar, Falvone, Mahonia, Dalea versicolor, Lycopus europaeus, and Rosmarinus officinalis) have the capability to have such compounds according to their very significant synergistic effect with antibiotics. In this review we focused on the growth of antibiotic resistance to explain the mechanism of efflux pumps into these different super families and a comprehensive understanding of the extrusion, regulation and physiology role of drug efflux pumps in the essential development of anti-resistivity drugs. We recapitulated the evolution of the work carried out in these fields during the last years and in the course of elaboration, with the aim of increasing the chances of decreasing bacterial resistivity to antibiotics.

Main coolant pump resistance influence on single phase water reverse flow in the inverted U-tubes under natural circulation

Based on nuclear power plant(NPP) best-estimate transient analysis with RELAP5 / MOD3 code,the reactor point kinetics model in RELAP5 / MOD3 code is replaced by the two-group,3-D space and time dependent neutron kinetic model,and two-fluid model is replaced by drift flux model.A coupled three-dimensional physics and thermal-hydrodynamics model is used to develop its corresponding computing code,thus simulating natural circulation of single-phase flow for the PWR.In this paper,we report the forward and reverse flow distribution in the inverted U-tubes of the steam generator(SG) under some typical operating conditions in the natural circulation case, and analyze the influence of main coolant pump resistance on the forward and reverse flow distribution.The calculation results show that,the pressure drop between SG inlet and outlet plenum decreases,and the SG inlet and outlet mass flow decrease with an increased main coolant pump resistance,but net mass flux of reverse flow in inverted U-tubes,and the ratio of mass flow in all reverse flow tubes to that of main coolant pipeline increase, meanwhile,the secondary steam load is invariable in this process.

Detection of the Mex Efflux Pumps in <i>Pseudomonas</i><i>aeruginosa</i>by Using a Combined Resistance-Phenotypic Markers and Multiplex RT-PCR

The aim of this study was to detect the expression of 4 clinically-important efflux pumps in the Resistance-Nodulation-Cell Division (RND) family including MexAB-OprM, MexXY, MexCD-OprJ and MexEF-OprN in Pseudomonas aeruginosa using a combination of resistance-phenotypic markers and multiplex RT-PCR (mRT-PCR). The antibiotic substrates specific for each Mex systems were used as phenotypic markers including carbenicillin, MexAB-OprM, erythromycin, MexCD-OprJ, norfloxacin and imipenem, MexEF-OprN and gentamicin, MexXY-OprM. The methods were validated with reference strains with known genotypes of the Mex systems and the potential applicability in clinical practice was tested with clinical isolates. The results for the reference strains support that the combination of resistance phenotype and mRT-PCR is a potential-attractive method for diagnosis of efflux-mediated resistance in P. aeruginosa. Further development to make it more practical for clinical use and study in a larger number of clinical isolates is required.

Whole Genome Analysis Reveals New Insights into Macrolide Resistance in Mycoplasma pneumoniae

Objective Mutations in 23 S rRNA gene are known to be associated with macrolide resistance in Mycoplasma pneumoniae（M. pneumoniae）. However, these mutations alone do not fully explain the high resistance rates in Asia. The aim of this study was to investigate other possible mutations involved in macrolide resistance in M. pneumoniae. Methods The whole genomes of 10 clinical isolates of M. pneumoniae with macrolide resistance were sequenced by Illumina Hi Seq2000 platform. The role of the macrolide-specific efflux transporter was assessed by efflux-pump inhibition assays with reserpine and carbonyl cyanide m-chlorophenyl-hydrazone（CCCP）. Results A total of 56 single nucleotide polymorphisms（SNPs） were identified in 10 clinical isolates in comparison to the reference strains M129 and FH. Strikingly, 4 of 30 SNPs causing non-synonymous mutations were clustered in macrolide-specific efflux system gene mac B encoding macrolide-specific efflux pump protein of the ATP-binding cassette transporter family. In assays of the minimal inhibitory concentrations（MIC） of macrolide antibiotics in the presence of the efflux pump inhibitors caused a significant decrease of MICs, even under detectable levels in some strains. Conclusion Our study suggests that macrolide efflux pump may contribute to macrolide resistance in M. pneumoniae in addition to the common point mutations in 23 S r RNA gene.

Advances in Research on Resistance Mechanisms of Bacterial Biofilms

A biofilm refers to a group of organized bacteria attached to the surface of living or inanimate objects and surrounded by some macromolecules. It is rich in organic components such as polysaccharides,peptides and phospholipids,greatly increases the resistance of bacteria to antibacterial drugs,and can cause infections in humans and animals. At present,the measure to prevent the infections is to prevent microbial colonies from adhering to the surface of the objects,which will help to improve the therapeutic effect of clinically serious infectious diseases. In addition,the identification and inhibition of biofilm formation genes is also an important research direction to control such infections. In this paper,molecular mechanisms of bacterial biofilm resistance to drugs that has caused widespread concern were summarized.

Reversal of Tetracycline Resistance by Cepharanthine,Cinchonidine,Ellagic Acid and Propyl Gallate in a Multi-drug Resistant Escherichia coli

Bacterial resistance to antibiotics is an increasing threat to global healthcare systems.We therefore sought compounds with potential to reverse antibiotic resistance in a clinically relevant multi-drug resistant isolate of Escherichia coli(NCTC 13400).200 natural compounds with a history of either safe oral use in man,or as a component of a traditional herb or medicine,were screened.Four compounds;ellagic acid,propyl gallate,cinchonidine and cepharanthine,lowered the minimum inhibi-tory concentrations(MICs)of tetracycline,chloramphenicol and tobramycin by up to fourfold,and when combined up to eightfold.These compounds had no impact on the MICs of ampicillin,erythromycin or trimethoprim.Mechanistic studies revealed that while cepharanthine potently suppressed efflux of the marker Nile red from bacterial cells,the other hit com-pounds slowed cellular accumulation of this marker,and/or slowed bacterial growth in the absence of antibiotic.Although cepharanthine showed some toxicity in a cultured HEK-293 mammalian cell-line model,the other hit compounds exhibited no toxicity at concentrations where they are active against E.coli NCTC 13400.The results suggest that phytochemicals with capacity to reverse antibiotic resistance may be more common in traditional medicines than previously appreciated,and may offer useful scaffolds for the development of antibiotic-sensitising drugs.

AcrAB Efflux Pump in Fluoroquinolone Resistant Salmonella gallinarum Induced by Ciprofloxacin Selective Pressure

Salmonella gallinarum has shown multiple drug resistance(MDR),especially high level fluoroquinolone(FQ)resistance in recent years.To determine whether the active efflux system was responsible for high-level FQ resistance,this research studied AcrAB efflux pump in Salmonella gallinarum on molecular level.The resistant strains were induced by standard strain C79-13 with ciprofloxacin in vitro.With carbonylcyanide-p-chlorophenyl hydrazone(CCCP)as an energy inhibitor,efflux inhibition test initially showed the potential impact of efflux pump on drug resistance.Sequence analysis of acrA gene indicated that gene mutation of AcrAB efflux pump was not definitely associated with MDR and drug resistance level of Salmonella gallinarum.Detected by competitive RT-PCR,the mRNA expression of acrA and acrB genes in the resistant strains significantly increased(p<0.01)compared with that of the control strain C79-13.The mRNA expression level of acrB gene(increased from 1.6-to 2.9-folds)was consistent with that of acrA gene(increased from 1.6-to 2.8-folds),which increased with the drug resistance level.However,gene mutation of acrA gene showed no correlation with its mRNA expression level,indicating that gene mutation did not affect the expression of AcrAB pump itself.The results suggested that the overexpression rather than the gene mutation of AcrAB efflux pump was an important factor causing the high level drug resistance of Salmonella gallinarum.

Mutational and Phylogenetic Analysis of <i>nfxB</i>Gene in Multidrug-Resistant Clinical Isolates of <i>Pseudomonas aeruginosa</i>Hyperexpressing MexCD-OprJ Efflux Pump

The present study focused on MexCD-OprJ efflux pump and its regulatory gene nfxB in multidrug resistant (MDR) clinical isolates of Pseudomonas aeruginosa collected from Kerala, South India. Semi-quantitative reverse transcription-PCR technique was employed to detect hyperexpression of the efflux pump gene, mexD. Amplicons from nfxB gene of isolates hyperexpressing the efflux pump were sequenced for mutational and phylogenetic analysis. Among 29 isolates of MDR P. aeruginosa, increased mexD transcription was detected in 10.3% of the isolates when compared with P. aeruginosa reference strain, PAO (MTCC-3541). Various synonymous and non-synonymous mutations in nfxB regulatory gene sequences were detected. Notably, mutations detected in the strains designate Pa6 and Pa7 have been found to be novel and are hitherto unreported in GenBank data base. The genetic divergence and homogeneity of the nfxB regulatory gene sequences of mexCD-oprJ operon were clearly apparent in the phylogram generated employing similar sequences retrieved from the public database.

Cardiovascular Function during First 24 Hours after Off-Pump and On-Pump CABG—A Prospective Observational Comparative Study

Purpose: Myocardial revascularization by coronary artery bypass grafting (CABG) in ischemic heart disease patients has direct impact on hemodynamic parameters in the immediate post-operative period. The peri-operative cardiovascular functioning is an important determinant for outcome of surgery. In On-Pump CABG (ONCAB), the cardiopulmonary bypass has a negative effect on myocardium. Off-Pump CABG (OPCAB) avoids the effect of CPB but complete revascularization with difficult positioning of heart is technically demanding. This study is aimed to compare the cardiovascular functioning in the immediate post-operative period after OPCAB and ONCAB. Methods: Total 106 patients were operated for CABG from January 2015 to June 2016, of which 75 patients were operated for OPCAB and 31 patients were operated for ONCAB. For the comparison, hemodynamic parameters were measured during anesthesia before surgery, postoperatively after 1 and 4 hours (h) in the ICU, and in the morning after surgery, approximately after 20 h. Results: The time-dependent rise of hemodynamic parameters like Cardiac Output (CO), Cardiac Index (CI), Stroke volume (SV) and Left Ventricular Stroke Work Index (LVSWI) in the immediate post-operative hours (1 h and 4 h) are more predominant in OPCAB group than ONCAB group although the difference is eliminated mostly at 20 h. The better peripheral vasodilation after OPCAB causes immediate fall of Systemic Vascular Resistance Index (SVRI) after OPCAB. Conclusion: Better cardiovascular functioning immediately after OPCAB than ONCAB may be important for better hemodynamic stability. The difference is however eliminated after 24 hours indicating little significance in long term outcome.

中深层地埋管热泵供热系统运行特性实测研究

通过大量工程实测研究,总结了中深层地埋管热泵供热技术的运行特性。中深层地埋管具有出水温度高、取热功率大、长期运行稳定的特点,为热泵系统提供了高品位的低温热源,以提升其运行性能;同时中深层地埋管自身存在间歇蓄热特性,能很好地满足建筑供热需求变化与柔性用能;无级变频热泵机组更适合与中深层地埋管匹配运行,节能减排效果显著;热源侧水系统具有小流量、大扬程,且阻力随着流量变化而大幅度变化的特性。研究结果可为提升该技术的供热性能提供关键指导。

地浸采铀用潜水电泵泵轴结构与材料优选

泵轴断裂、泵体腐蚀导致潜水电泵损毁率高。通过理论计算和ANSYS数值模拟,对六棱轴和圆柱轴结构的强度、刚度等力学特性进行了对比,并开展了304、316L、904不锈钢材料的耐腐蚀现场对比试验。结果表明:在同等载荷和等效直径条件下,圆柱轴的圆截面所受剪切应力为六棱轴的64.95%,且扭转角度仅为六棱轴的56.25%;模拟结果显示圆柱轴联轴器最大环向形变为六棱柱轴最大环向形变的68.4%,圆柱轴结构的抗扭性能更优;904不锈钢抗腐蚀性能最佳,但304和316L不锈钢对酸性介质具有类似抗腐蚀性能。综合考虑耐腐蚀余量和制造成本,建议在地浸采铀专用潜水电泵研发过程中选用圆柱泵轴结构,沿用现有316L不锈钢作为主材的选材方案。

选矿粗磨工艺中TZJK-350耐磨渣浆泵过流件开发与应用

本文针对钼选矿厂一段磨矿粗磨工艺中TZJK-350金属渣浆泵过流件磨损快的问题,研究了耐磨耐腐蚀陶瓷材料特性、制作工艺和工程适应性等,通过工业试验将TZJK-350金属泵替换为陶瓷泵,大幅提升了粗磨工艺中渣浆泵的使用寿命和可靠性。应用实践表明,陶瓷泵使用寿命是金属泵的4倍,降低了检修维护成本,稳定了生产工艺,该设备具有非常高的推广应用价值。

采油螺杆泵定子橡胶研究综述

采油螺杆泵在高黏度、高含砂量原油开采中具有突出优势,螺杆泵工作原理和工作环境决定了其核心部件橡胶定子的使役寿命,提升螺杆泵定子橡胶材料的耐磨、耐溶胀等性能具有重要意义。介绍了采油螺杆泵的核心部件组成和采油工作原理,面向螺杆泵定子橡胶的实际需求,梳理了国内外学者在定子橡胶材料老化、溶胀、摩擦等关键性能方面的主要研究成果,并针对近年来新兴的材料多尺度研究手段,从概念、原理、方法及其在定子橡胶力学与摩擦学性能等方面进行了综述,对未来持续提升采油螺杆泵定子橡胶耐磨、耐溶胀等性能的方法与研究手段进行了展望。

利拉鲁肽序贯联合胰岛素泵强化治疗对初诊肥胖T2DM疗效及对患者相关指标的影响

目的探讨利拉鲁肽序贯联合胰岛素泵强化(CSⅡ)治疗初诊肥胖2型糖尿病(T2DM)疗效及对患者糖脂代谢、胰岛功能及体重相关指标的影响。方法选取我院内分泌科于2018年4月-2022年4月收治的合并肥胖[体重质量指数(BMI)≥28 kg/m 2]的T2DM患者104例,均空腹血糖(FPG)≥11.1 mmol/L和(或)糖化血红蛋白(HbA1c)≥9%,将患者分为常规组与GLP-1组,每组52例。两组均给予胰岛素泵强化治疗1周,血糖控制达标,撤泵后常规组给予二甲双胍,GLP-1组给予利拉鲁肽注射治疗,两组患者治疗10周。比较两组患者治疗前后体重相关指标(BMI、腰围)、糖代谢[FPG、餐后2 h血糖(2 hPG)及HbA1c]、脂代谢[载脂蛋白A1(ApoA1)、载脂蛋白B(ApoB)、总胆固醇(TC)及三酰甘油(TG)]、胰岛素抵抗情况[胰岛β细胞指数(HOMA-β)、胰岛素抵抗指数(HOMA-IR)]并统计药物不良反应。结果治疗后,两组患者BMI、腰围、FPG、2 hPG及HbA1c、ApoB、TC、TG及HOMA-IR均显著下降(P<0.05),且GLP-1组显著低于常规组(P<0.05);治疗后,两组患者ApoA1、HOMA-β均显著上升(P<0.05);GLP-1组与常规组总药物不良反应发生率差异无统计学意义(P>0.05)。结论利拉鲁肽序贯联合CSⅡ治疗可显著改善肥胖T2DM患者体脂情况、糖脂代谢以及胰岛素抵抗等情况,不良反应较小,安全有效,值得推广应用。

电学计量中的量子标准与自然常数

介绍了库仑定律和安培定律在电学单位制中发挥的作用,依据机械功率与电功率等效的原理,选择电流单位安培(A)作为基本物理单位,并介绍了实用单位制和电学实物计量标准。阐述了三种电学计量的量子标准原理和溯源到自然常数的途径,分析了真空磁导率在安培定律公式中发挥的作用,探讨了电学量子三角形与欧姆定律兼容的问题。指出基本电荷量常数不是简单地从约瑟夫森常数K_(J-90)和冯·克里青常数R_(H-90)推导而来,而是由精细结构常数公式计算出来的,能量守恒原理是单位制中的第一性原理,是力学和电学计量单位的纽带。提出量子点之间的位移电流对单电子隧道泵有一定的影响,真空磁导率不再是理想的常数,真空磁导率的变化将成为后来理论界研究的重点。

竖直单U型地埋管换热器埋管间负热阻现象的参数化研究与分析

基于Mutipole方法对竖直单U型地埋管换热器钻孔内外的耦合传热过程进行求解,在钻孔内三热阻和四热阻简化传热模型基础上,详细地分析钻孔内的复杂稳态传热过程,参数化研究埋管布置结构、回填料与岩土热物性等因素对钻孔内埋管间直接传热热阻的影响规律,揭示导致钻孔内埋管间负热阻现象的本质原因,对钻孔内热阻传热模型的工程实践应用给出参考意见。