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.

Plant-derived secondary metabolites as the main source of efflux pump inhibitors and methods for identification

The upsurge of multiple drug resistance(MDR)bacteria substantially diminishes the effectiveness of antibiotic arsenal and therefore intensifies the rate of therapeutic failure.The major factor in MDR is efflux pump-mediated resistance.A unique pump can make bacteria withstand a wide range of structurally diverse compounds.Therefore,their inhibition is a promising route to eliminate resistance phenomenon in bacteria.Phytochemicals are excellent alternatives as resistance-modifying agents.They can directly kill bacteria or interact with the crucial events of pathogenicity,thereby decreasing the ability of bacteria to develop resistance.Numerous botanicals display noteworthy efflux pumps inhibitory activities.Edible plants are of growing interest.Likewise,some plant families would be excellent sources of efflux pump inhibitors(EPIs)including Apocynaceae,Berberidaceae,Convolvulaceae,Cucurbitaceae,Fabaceae,Lamiaceae,and Zingiberaceae.Easily applicable methods for screening plant-derived EPIs include checkerboard synergy test,berberine uptake assay and ethidium bromide test.In silico highthroughput virtual detection can be evaluated as a criterion of excluding compounds with efflux substrate-like characteristics,thereby improving the selection process and extending the identification of EPIs.To ascertain the efflux activity inhibition,real-time PCR and quantitative mass spectrometry can be applied.This review emphasizes on efflux pumps and their roles in transmitting bacterial resistance and an update plant-derived EPIs and strategies for identification.

Role of MexA-MexB-OprM Efflux Pump System in Chronic Pseudomonas Aeruginosa Pulmonary Infection in Mice

In order to investigate the role of the MexA-MexB-OprM efflux pump system in the pathogenesis of Pseudomonas aeruginosa(PA)-induced pulmonary infection,pulmonary infection models were established by intratracheal injection of K767(wild type),nalB(MexA-MexB-OprM up-regulated mutant),and △m exB(knockout) strains,separately.All mice were treated with Meropenem(intraperitoneal injection,100 mg/kg body weight,twice every day),and strain-related pathology,bacteria count,cytokine level,myeloperoxidase(MPO,indicator of neutrophil recruitment) activity,and macrophage inflammatory protein-2(MIP-2) expression were evaluated at early(3rd day post-infection) and late(7th and 14th day post-infection) stages of infection.E-test showed that △mexB was more significantly sensitive to panipenan(ETP),meropenem(MP) and imipenem(IP) than K767 and nalB strains.There was no significant difference in sensitivity to cefepime(TM) among the three stains.In contrast to the K767 and nalB groups,the △ mexB group showed decreased bacteria burden over time and less extensive pathological change.Additionally,MPO activity and levels of inflammatory cytokines(IL-1b,IL-12,and TNF-α) were increased at the early stage(day 3) and decreased at the later stage(day 14).Serum MIP-2 expression level was steadily increased in all three groups from early to late stages,but significantly higher in △m exB group than in K767 and nalB groups(P<0.05).In conclusion,the MexA-MexB-OprM efflux pump system might play an important role in PA-induced chronic pulmonary infection.High expression of the MexA-MexB-OprM efflux pump could increase antibacterial resistance and promote infection.

Antibacterial activity and inhibition against Staphylococcus aureus NorA efflux pump by ferulic acid and its esterified derivatives

Objective:To evaluate the inhibitory activity of ferulic acid and four of its esterified derivatives(methyl,ethyl,propyl,and butyl)against resistance mechanisms in Staphylococcus aureus strains.Methods:Ferulic acid derivatives were obtained by esterification with methanol,ethanol,propanol,and butanol,and then characterized by hydrogen and carbon-13 nuclear magnetic resonance analysis.The minimum inhibitory concentrations(MIC)of ferulic acid and its esterified derivatives,ethidium bromide,and norfloxacin were obtained using the microdilution test,while the efflux pump inhibition test was conducted by examining reduction in the MICs of norfloxacin and ethidium bromide.Molecular docking was also carried out using the Schrodinger Suite 2015 molecular modeling software.A three-dimensional model of NorA efflux pump was generated using I-TASSER.The best scoring model was used as a receptor for ligand-receptor docking.Results:The methyl and butyl ester derivatives did not demonstrate significant antimicrobial activity.However,a significant synergic effect was evidenced when norfloxacin was combined with the ethyl and propyl esterified derivatives.The docking study demonstrated favorable energy of interaction between ferulate derivatives and NorA,and amino acid residues TYR57,TYR58,and LEU255 were present commonly in stabilizing all complexes.The PCA analysis corroborated the docking hypothesis that the lipophilic character and hydrogen bond interactions were the most relevant characteristics involved with NorA inhibitors.The pharmacokinetic parameters of ferulic acid derivatives showed good ADMET properties,demonstrating that they can be easily absorbed and have no effect or inhibit the cytochrome P450 enzyme complex,revealing their potential as drug candidates.Conclusions:This study provides strong evidence that the molecular basis for this activity is potentially due to the NorA efflux pump.

Detection of oqxA and oqxB efflux pump genes among nosocomial coliform bacilli:An observational cross-sectional study

Objectives:To identify and test the antibiotic susceptibility of nosocomial coliform bacilli and investigate the presence of oqxA and oqxB genes among the multidrug-resistant(MDR)phenotypes.Methods:One hundred and twenty different healthcare-associated infection samples were collected.Coliform bacilli were isolated,identified by conventional methods,and then antibiotic susceptibility tests were done using the VITEK2 system and disk diffusion methods.OqxAB operon was identified using a conventional PCR-based technique.oqxA and oqxB genes were compared between MDR Klebsiella pneumonia(K.pneumonia)phenotypes and MDR Escherichia coli(E.coli)phenotypes.Besides,oqxAB operons were compared between phenotypes of K.pneumonia and E.coli isolates.Results:Seventy coliform bacilli were isolated with the predominance of K.pneumonia and E.coli.Besides,82.1%of K.pneumonia strains and 53.3%of E.coli isolates were MDR phenotypes.Significant more oqxB genes alone were found in MDR E.coli than that in MDR K.pneumoniae phenotypes(χ^(2)=10.160,P=0.003).OqxAB operon was significantly more in MDR phenotypes of E.coli than that in the susceptible phenotypes(P<0.001).There was significantly less of this operon in susceptible E.coli isolates than that in susceptible K.pneumoniae isolates(P<0.001).OqxAB positive isolates that were also resistant to fluoroquinolones,tetracycline,trimethoprim,and chloramphenicol,most probably suggested functional pumps.Conclusions:MDR coliform bacilli are strongly implicated in healthcare-associated infection.Attention should be paid to the presence of oqxAB pump,as an important mechanism in the development of resistance against many antimicrobials because it contributes to co-resistance with other categories;therefore,this pump could be a good target for efflux pump inhibitors.

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.

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.

Drug interactions of dipeptidyl peptidase 4 inhibitors involving CYP enzymes and P-gp efflux pump

Dipeptidyl peptidase 4(DPP4) inhibitors are oral antidiabetic drugs approved to manage type 2 diabetes mellitus. Saxagliptin is a substrate of CYP3A4/5 enzymes while other DPP4 inhibitors such as sitagliptin, linagliptin, gemigliptin and teneligliptin are weak substrates of CYP3A4. DPP4 inhibitors have also been identified as substrates of P-gp. Hence, the drugs inhibiting or inducing CYP3A4/5 enzymes and/or P-gp can alter the pharmacokinetics of DPP4 inhibitors. This review is aimed to identify the drugs interacting with DPP4 inhibitors. The plasma concentrations of saxagliptin have been reported to be increased significantly by the concomitant administration of ketoconazole or diltiazem while no significant interactions between various DPP4 inhibitors and drugs like warfarin, digoxin or cyclosporine have been identified.

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.

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.

Influence of induced ciprofloxacin resistance on efflux pump activity of Klebsiella pneumoniae

Objective:The efflux pump(EP) is one of the major mechanisms of antibiotic resistance in Klebsiella pneumoniae.However,there are few reports on the effect of the abuse of antibiotic use on the activity of EPs.To determine whether the use of low efficacy antibiotics has any effect on the activity of EPs and induces drug resistance in K.pneumoniae,we investigated the effect of ciprofloxacin on the activity of EPs in K.pneumoniae strains.Methods:Sixteen susceptible K.pneumoniae strains were isolated from patients and their minimum inhibitory concentrations(MICs) of ciprofloxacin were measured in the absence and presence of the pump inhibitor carbonyl cyanide m-chlorophenyl hydrazone(CCCP).The strains were then induced with a gradient of ciprofloxacin until the MICs of the strains showed no further increase,to obtain induced resistant strains.The EP activities of the strains before and after induction were compared using EP inhibition and ethidium bromide(EtBr) accumulation assays.Results:The MIC values of the strains were 16 256 times higher after induction than before induction.In the presence of CCCP,the MIC values of 50% of the induced strains were 2 4-fold lower than that in the absence of this inhibitor.The EtBr accumulation assay showed that the fluorescence of EtBr in the induced cells was lower than that in the cells before induction.Conclusions:EPs are widespread in susceptible and drug-resistant K.pneumoniae strains.Induction with ciprofloxacin may increase the activity of EPs in K.pneumoniae.The EtBr accumulation assay is more sensitive than the EP inhibition assay in evaluating the activity of EPs in K.pneumoniae.

Low nutrient levels as drinking water conditions can reduce the fitness cost of efflux pump-mediated ciprofloxacin resistance in Pseudomonas aeruginosa

The long-term persistence of antibiotic resistance in the environment, especially in drinking water, is a public health concern. Expression of an efflux pump, an important mechanism of resistance to antibiotics, usually confers a fitness cost in bacteria. In this study, we aimed to determine why antibiotic resistance conferred by overexpression of an efflux pump persisted in low-nutrient environments(TOC < 10 mg/L) such as drinking and source water in which antibiotic selective pressure might be very low or even absent.Competition experiments between wild-type Pseudomonas aeruginosa and ciprofloxacinresistant mutants revealed that the fitness cost of ciprofloxacin resistance significantly decreased(p < 0.05) under low-nutrient(0.5 mg/L total organic carbon(TOC)) relative to high-nutrient(500 mg/L TOC) conditions. Mechanisms underlying this fitness cost were analyzed. The mexD gene expression in resistant bacteria(cip3 strain) was significantly lower(p < 0.05) in low-nutrient conditions, with 10 mg/L TOC((8.01 ± 0.82)-fold), than in high-nutrient conditions, with 500 mg/L TOC((48.89 ± 4.16)-fold). Moreover, rpoS gene expression in resistant bacteria((1.36 ± 0.13)-fold) was significantly lower(p < 0.05) than that in the wild-type strain((2.78 ± 0.29)-fold) under low-nutrient conditions(10 mg/L TOC),suggesting a growth advantage. Furthermore, the difference in metabolic activity between the two competing strains was significantly smaller(p < 0.05) in low-nutrient conditions(5 and 0.5 mg/L TOC). These results suggest that nutrient levels are a key factor in determining the persistence of antibiotic resistance conferred by efflux pumps in the natural environment with trace amounts or no antibiotics.

河曲马源大肠杆菌耐药相关基因检测及外排泵抑制剂对其生物被膜的影响

[目的]了解河曲马源大肠杆菌的耐药情况,为兽医临床合理使用抗菌药物提供基础理论指导。[方法]采用细菌形态学、革兰染色镜检、16S rDNA序列分析等方法进行细菌分离鉴定。采用微量肉汤稀释法和PCR扩增方法对分离鉴定的大肠杆菌进行抗菌药物敏感性试验及耐药基因、整合酶基因、外排泵基因携带情况检测。同时,采用改良结晶紫半定量方法进行生物被膜形成能力测定。利用棋盘法测定13种外排泵抑制剂与多西环素联用对生物被膜的清除作用。[结果]分离株在伊红-美蓝琼脂培养基上为具有绿色金属光泽的紫黑色菌落,在大肠杆菌/大肠菌群显色培养基上为蓝色菌落,革兰染色镜检可见粉红色短杆状细菌。经16S rDNA测序比对与大肠杆菌高度相似的分离株为64株。64株大肠杆菌分离株对酰氨醇类、磺胺类及利福霉素类药物耐药率相对较高并出现多重耐药菌株,其中20.31%(13/64)表现出对5类抗菌药物耐药;检测到21个耐药基因、1个整合酶基因及6个外排泵基因为阳性;整合酶基因intl 1检出率为89.06%。生物被膜形成能力为强、中、弱及无成膜能力的大肠杆菌分别为8(12.50%)、34(53.13%)、20(31.25%)和2(3.12%)株。外排泵抑制剂与多西环素联合能增强对生物被膜的清除能力。[结论]河曲马源大肠杆菌耐药较为严重,应进一步加强青海省河南蒙古族自治县赛马的用药监管力度,减少或避免多重耐药菌株的出现及耐药性广泛传播。

阿米卡星诱导对大肠埃希氏菌耐药性及生物被膜和外排泵活性的影响

为研究亚抑菌浓度阿米卡星诱导对大肠埃希氏菌敏感菌株耐药性、生物被膜形成能力及外排泵活性的影响,采用微量肉汤稀释法测定阿米卡星对6株菌株的最小抑菌浓度(MIC),并以0.5 MIC作为初始诱导浓度进行诱导,每隔5 d重新测定阿米卡星MIC,并调整诱导浓度,共计30 d,最后将诱导第30天菌株进行无药物压力稳定培养5 d,保存各诱导菌株及无药传代菌株共计210株,测定各诱导菌株药物敏感性、生物被膜形成能力及部分菌株外排泵活性变化。结果发现,随着诱导天数的增加,阿米卡星对6株分离菌株MIC逐渐升高,诱导菌株耐药性不断增强,其对诱导第30天菌株的MIC值为诱导前的8~32倍;经过5 d无药培养后,MIC测定结果与第30天基本保持一致;诱导后的菌株中,强成膜能力菌株占总数的5%,中成膜能力菌株为56.7%;以每5 d的生物被膜形成量平均值与原菌相比,结果发现,所有诱导菌株生物被膜形成量均显著增加(P<0.01),表明亚抑菌浓度阿米卡星诱导可促进大肠埃希氏菌生物被膜的形成;无药稳定培养5 d的菌株与诱导第30天菌株相比,生物被膜形成能力基本保持不变。荧光探针测定外排泵结果显示,诱导菌株外排泵活性显著受到抑制。以上研究结果表明,阿米卡星诱导促进菌株生物被膜的形成,抑制外排泵活性,使菌株的耐药性增强,研究结果可为氨基糖苷类药物用药提供理论依据。

细菌外排泵功能及抑制机制的研究进展

近年来,由于抗生素在临床上的不规范使用,细菌耐药率呈快速增长趋势,显著增加临床的抗感染治疗难度。对于耐药菌而言,外排蛋白基因占所有转运蛋白基因的6%~18%。因此,由外排基因编码的外排泵是细菌产生多重耐药的重要机制之一。最新研究结果表明,外排泵抑制剂是通过抑制外排泵研发针对性抗生素的新治疗靶点,因此,为解决细菌多重耐药性问题,研发外排泵抑制剂势在必行。鉴于此,本研究对细菌外排泵的功能和抑制机制进行综述,以期为临床合理用药及医院感染防控提供帮助与指导。

穿心莲内酯对金黄色葡萄球菌外排系统的抑制作用

为探究穿心莲内酯(AP)对金黄色葡萄球菌(S.aureus)外排系统的抑制作用,本试验采用微量肉汤稀释法和棋盘法检测AP与抗菌药物的联合抑菌作用,荧光分光光度法检测AP对S.aureus体内环丙沙星蓄积量的影响,PCR和实时荧光定量PCR方法检测S.aureus外排泵基因的携带情况和AP对S.aureus外排泵基因转录水平的影响。结果显示,AP与环丙沙星具有协同作用;AP与S.aureus作用12 min时,能极显著提高菌体内环丙沙星的蓄积量(P<0.000 1);外排泵基因norA、norB、norC、sepA、mepA和mdeA同时携带的比例为24.1%,norB基因的检出率最高,为87.4%;AP作用后,S.aureus外排泵基因转录水平均极显著下降(P<0.001或P<0.000 1),其中norB在AP浓度达到256和512μg/mL时下降幅度最大,较空白对照降低91%(P<0.001),提示AP可通过抑制外排泵基因的表达来增强S.aureus对药物的敏感性。本试验从耐药表型和基因表达水平来确认AP是否可成为一种潜在的外排泵抑制剂,为解决S.aureus耐药问题提供新的思路。

耐碳青霉烯类鲍曼不动杆菌生物膜形成与外排泵基因AdeABC表达的相关性研究

目的 研究鲍曼不动杆菌的生物膜形成,以及浮游态和生物膜状态下对外排泵基因AdeABC的相对表达量作用于碳青霉烯类抗生素耐药机制的影响。方法 将菌株经药物敏感性试验分为碳青霉烯类耐药鲍曼不动杆菌(CRAB)组和碳青霉烯类敏感鲍曼不动杆菌(CSAB)组,采用结晶紫染色法检测两组生物膜形成能力;通过微量肉汤稀释法分别测定两组对亚胺培南的MIC、MBIC值,并计算MBIC/MIC的比值进一步比较分析生物膜菌和浮游菌的耐药性;同时提取CRAB组浮游态和生物膜态的RNA,通过RT-qPCR检测外排泵基因AdeABC相对表达量。结果 35株标本的生物膜阳性率为91.43%,其中CRAB组生物膜的阳性检出率为92%,生物膜阴性、弱阳性、阳性和强阳性分别占8%、48%、36%和8%。MBIC/MIC比值显示,形成生物膜后,鲍曼不动杆菌的耐药能力呈现不同程度的增加,CSAB组的耐药增加幅度以2倍的菌株最多;CRAB组的增加幅度以4倍的菌株最多。同时CRAB组RT-qPCR结果显示,生物膜较浮游态相比,外排泵基因adeA和adeB的相对表达量明显增高(P<0.01),外排泵基因adeC相对表达量则无差异(P>0.05)。结论 鲍曼不动杆菌碳青霉烯类耐药与生物膜密切相关,且生物膜态的鲍曼不动杆菌较浮游态可促进外排泵基因AdeABC的表达从而增强碳青霉烯类抗生素的耐药性。

氯己定与抗生素耐药性相关性的研究进展

抗生素耐药性是全球人类公共健康领域的巨大危机,影响生命安全并给社会带来巨大的经济负担。氯己定(chlorhexidine,CHX)是临床最为常用的消毒剂之一。目前已有大量研究发现,CHX应用与抗生素耐药性密切相关。一方面,已有研究证实CHX可诱导多种重要的院内感染病原菌发生抗生素交叉耐药,甚至出现对最后一线抗生素的耐药性;另一方面,CHX与抗生素可能存在共耐药。主动外排泵的过度表达及细胞膜的相关改变是CHX与抗生素耐药性相关性中的重要机制。然而,CHX被广泛无限制地应用于临床领域,其潜在风险被严重低估。因此,本文将回顾CHX与抗生素耐药性的相关性及其相关机制,以提高CHX临床应用的警示。

氯己定在口腔细菌中敏感性下降及其相关机制的研究进展

氯己定(chlorhexidine,CHX)被广泛应用于医疗领域的表面消毒,然而其应用缺乏临床限制。其长期广泛应用已导致多种重要的院内感染病原体临床分离菌株出现CHX敏感性下降,并可产生对一系列关键抗生素的交叉耐药。然而,CHX已在口腔领域作为金标准应用超过50年,其在口腔细菌中的耐药风险却未被重视。因此,本文旨在回顾CHX在口腔细菌中敏感性下降的研究进展并对其相关机制进行阐述,引发口腔领域对于CHX应用潜在风险的关注。