Incidence, risk factors and clinical outcome of multidrug-resistant organisms after heart transplantation

BACKGROUND Transplant recipients commonly harbor multidrug-resistant organisms(MDROs),as a result of frequent hospital admissions and increased exposure to antimi-crobials and invasive procedures.AIM To investigate the impact of patient demographic and clinical characteristics on MDRO acquisition,as well as the impact of MDRO acquisition on intensive care unit(ICU)and hospital length of stay,and on ICU mortality and 1-year mortality post heart transplantation.METHODS This retrospective cohort study analyzed 98 consecutive heart transplant patients over a ten-year period(2013-2022)in a single transplantation center.Data was collected regarding MDROs commonly encountered in critical care.RESULTS Among the 98 transplanted patients(70%male),about a third(32%)acquired or already harbored MDROs upon transplantation(MDRO group),while two thirds did not(MDRO-free group).The prevalent MDROs were Acinetobacter baumannii(14%),Pseudomonas aeruginosa(12%)and Klebsiella pneumoniae(11%).Compared to MDRO-free patients,the MDRO group was characterized by higher body mass index(P=0.002),higher rates of renal failure(P=0.017),primary graft dysfunction(10%vs 4.5%,P=0.001),surgical re-exploration(34%vs 14%,P=0.017),mechanical circulatory support(47%vs 26%P=0.037)and renal replacement therapy(28%vs 9%,P=0.014),as well as longer extracorporeal circulation time(median 210 vs 161 min,P=0.003).The median length of stay was longer in the MDRO group,namely ICU stay was 16 vs 9 d in the MDRO-free group(P=0.001),and hospital stay was 38 vs 28 d(P=0.006),while 1-year mortality was higher(28%vs 7.6%,log-rank-χ2:7.34).CONCLUSION Following heart transplantation,a predominance of Gram-negative MDROs was noted.MDRO acquisition was associated with higher complication rates,prolonged ICU and total hospital stay,and higher post-transplantation mortality.

Multidrug resistant organism infections in patients with COVID-19:risk factors and outcomes

Background:Coronavirus disease 2019(COVID-19)has now spread to most countries and regions of the world.Risk factors associated with multi-drug resistant organism(MDRO)infections in patients with COVID-19 have not been well studied yet.In the present study,we aimed to identify the risk factors associated with the MDRO infections and their impact on in-hospital mortality of COVID-19 patients.Methods:This retrospective cohort study was conducted between December 2019 and April 2020 at two tertiary hospitals in Wuhan,China.Data of cases were collected through electronic medical records system.This study was focused on cases with bacterial culture records.Risk factors and outcomes associated with MDRO infections were analyzed using logistic regression model.Results:Of the 2891 patients,370 patients have bacterial culture results,and MDROs were isolated in 38 patients.Respiratory tract infections(67.3%)were the most common hospital acquired infections.Variables independently associated with MDRO infections were dyspnea at admission(odds ratio(OR)4.74;95%confidence interval(CI)2.06-10.88;P<0.001),intensive care unit(ICU)admission(OR 5.02;95%CI 1.99-12.63;P<0.01),and invasive mechanical ventilation(OR 5.13;95%CI 2.15-12.27;P<0.001),adjusted for age and gender.MDROs infection was also a significant risk factor of death for the patients,adjusted for age,gender,severity of illness,ICU admission and mechanical ventilation(OR 1.12,95%CI:0.43-2.96,P=0.817).Conclusion:In our study,dyspnea at admission,ICU admission and invasive mechanical ventilation were associated with the presence of MDRO infections,and clinicians should be alert in MDRO infections in COVID-19 hospitalized patients.

Multidrug-Resistant of Escherichia coli and Salmonella spp. Strains in Chicken Feces Intended for Consumption in Open Spaces of Ouagadougou, Burkina Faso

Resistant bacteria can be transmitted to humans through feces or contaminated meat from local chickens. Bacterial strains were isolated from the intestinal contents of 400 local chicken samples from various sales sites. These strains were then characterized using bacteriological and biochemical methods to identify resistant strains. In a study conducted in Ouagadougou, we systematically collected chicken fecal samples from 20 locations across the city, followed by isolation and identification of Salmonella spp. using specific enrichment and culture methods, as well as Escherichia coli. Bacterial strains were characterized using antibiotic resistance profiles were determined through agar diffusion tests, revealing sensitivity or resistance to a range of antibiotics based on established scientific criteria. The results showed that out of the 400 samples collected, 81.25% and 63.5% were contaminated by Escherichia coli and Salmonella spp., respectively. Among these, 86.15% of identified Escherichia coli and 50.78% of Salmonella spp. displayed resistance to at least one tested antibiotic. Among 280 Escherichia coli isolates identified resistant to at least one antibiotic, 31.07% were resistant to cefotaxime (CTX), 20.35% to ceftazidime (CAZ), 21.07% to ceftriaxone (CTR), 75% to amoxicillin clavulanic acid (AMC), 23.57% aztreoname (ATM) and 27.14% were resistant to imipenem (IMP). In the case of the 129 Salmonella spp. isolates resistant to at least one tested antibiotic, 34.88% were resistant to CTX;41.08% to CAZ;35.65% to CTR, 92% to AMC, 39.53% to ATM and finally 47.28% were resistant to IMP. Our study revealed high prevalence of resistance in bacterial strains isolated from local chickens sold outdoors in Ouagadougou. These findings raise significant public health concerns, due to the possible transmission of these resistant strains to humans through the consumption of contaminated meat, thus complicating the treatment of bacterial infections.

Analysis of Multi-Drug Resistant Organism Surveillance and Antimicrobial Resistance Early Warning in a Hospital in 2022

Objective:To determine the clinical distribution of multi-drug resistant organism(MDRO)in Jiangyan Hospital and the monitoring and warning of drug-resistance bacteria to provide an important basis for guiding the application of broad-spectrum antibiotics in clinical treatment and reducing the occurrence of nosocomial infection.Methods:Retrospective screening and analysis were conducted on the pathogenic strains of hospitalized patients in our hospital in 2022.Results:A total of 2,769 strains of pathogenic bacteria and 390 strains of MDRO were detected and isolated in our hospital in 2022;the detection rate of MDRO was 14.08%.A total of 516 strains(18.64%)Klebsiella pneumoniae(KP)and 62 strains(12.02%)of carbapenem-resistant Klebsiella pneumoniae(CR-KP)were detected;436 strains(15.75%)of Escherichia coli(ECO)were detected,including 8 strains(1.83%)of CR-ECO;342 strains(12.35%)of Pseudomonas aeruginosa(PA)and 116 strains(33.92%)of CR-PA were detected;there were 194 strains(7.01%)of Acinetobacter baumannii(AB),among which 125 strains(64.43%)were CR-AB;there were 291 strains(10.51%)of Staphylococcus aureus,among which 79 strains(27.15%)of methicillin-resistant Staphylococcus aureus(MRSA)were detected;78 strains(2.82%)of Enterococcus faecalis were detected,and vancomycin-resistant enterococcus(VRE)was not detected.The first five MDROs were CR-AB,CR-PA,MRSA,CR-KP,and CR-ECO.The top five departments with the highest MDRO detection rate in 2022 were the ICU(37.44%),the Pulmonology Department(ward 13;31.03%),the Department of Rehabilitation(ward 5;6.67%),the Department of Neurosurgery(ward 11;4.62%),and the Department of General Surgery(ward 10;3.59 The resistance rate of antibacterial drugs is divided into four levels for early warning:30%to 40%,41%to 50%,51%to 75%,and 75%or more.Conclusion:Our hospital should strengthen the monitoring of antimicrobial resistance warning related to MDRO and the abuse of antimicrobial drugs.Based on the results of drug sensitivity and antimicrobial resistance warning,the use of antibiotics should be standardized in clinical practice to reduce nosocomial infection。

Multidrug-resistant organisms in intensive care units and logistic analysis of risk factors

BACKGROUND Intensive care unit(ICU)patients are critically ill and have low immunity.They will undergo various trauma medical procedures during diagnosis and treatment.The use of high-dose hormones and broad-spectrum antibiotics will increase the incidence of nosocomial infection in ICU patients.Therefore,it is necessary to explore the causes of nosocomial infection in ICU and provide basis for the prevention and control of nosocomial infection in ICU.AIM To explore major pathogens of nosocomial infection in ICUs,methods of detection and drug resistance trends.METHODS Risk factors of multidrug-resistant infection were analyzed to provide a basis for clinical rational use of antimicrobial drugs in the ICU.These findings were used to standardize rational use of antimicrobial agents.BD PhoenixTM100 automatic bacterial identification analyzer was used to for cell identification in specimens collected from the ICU between January 2016 and December 2019.Drug sensitivity tests were carried out and drug resistance trends were analyzed using the optical disc diffusion method.Odds ratios and corresponding 95%CI of independent variables were calculated using a logistic regression model.Backward elimination(trend=0.1)was used as an inclusion criterion for multivariate analysis.All data were analyzed using SPSS version 22.0,and P<0.05 was considered statistically significant.RESULTS We collected 2070 samples from ICU patients between January 2016 and December 2019.Sample types comprised sputum(1139 strains,55.02%),blood(521 strains,25.17%),and drainage fluid(117 strains,5.65%).A total of 1051 strains of major pathogens,including Acinetobacter baumannii,Escherichia coli(E.coli),Pseudomonas aeruginosa(P.aeruginosa),Klebsiella pneumoniae(K.pneumoniae)and Staphylococcus aureus,were detected,with a detection rate of 35.97%(378/1051).Most of these strains were resistant to antibiotics.Detection rate of E.coli was 21.79%(229/1051),and it was generally sensitive to many antimicrobial drugs.Detection rate of P.aeruginosa was 24.74%(260/1051),and showed low sensitivity to most antibiotics.Detection rate of K.pneumoniae was 9.42%(99/1051),which was generally resistant to multiple antimicrobial drugs and resistant forms.K.pneumoniae was resistant to imipenem for approximate 4 years,and showed a 19.9%(19/99)and 20.20%(20/99)rate of meropenem resistance.Logistic analysis showed that mechanical ventilation and ureteral intubation were risk factors for multidrug-resistant bacterial infections.CONCLUSION This study showed a high incidence of ICU infections.Mechanical ventilation and urine tube intubation were risk factors for infection with multidrug-resistant bacteria.

Meta‑analysis of influencing factors associating with treatment outcome of multidrug resistant tuberculosis

Objective:To systematically review the influencing factors of the treatment outcome of multidrug-resistant pulmonary tuberculosis and provide reference for the prevention and treatment of multidrug-resistant pulmonary tuberculosis.Method:Case control studies on the factors influencing the treatment outcome of multidrug-resistant pulmonary tuberculosis in Chinese databases(CNKI,VIP,Wanfang,Sinomed)and English databases(Pubmed,Web of science,Medline,Embase,Scopus)were searched and collected by computer.The search period was from the establishment of the database to January 2023.After screening and quality evaluation,RevMan5.4 was used for meta-analysis.Result:Totally 18 articles were ultimately included,with a sample size of 7328 people.The results showed that retreatment,complications,adverse reactions,and gender were related to the treatment outcome of multidrug-resistant pulmonary tuberculosis.The OR values and 95%CI of each factor were 0.22(0.17-0.29),0.38(0.32-0.46),0.27(0.17-0.44),and 0.43(0.33-0.56),respectively.Conclusion:Complications,retreatment,adverse reactions,and male gender are effective risk factors for the treatment outcome of multidrug-resistant pulmonary tuberculosis.In clinical practice,more targeted measures are needed for different types of patients.Due to the limitations of the number of studies,the above conclusions require more research to support them.

Sensorineural Hearing Loss in Multidrug-Resistant Tuberculosis Patients in Kinshasa (Democratic Republic of Congo): Prospective Cohort Study of Therapeutic Regimen with Aminoglycoside versus Bedaquiline

Context: Multidrug-resistant tuberculosis (MDR-TB) remains a major public health problem in developing countries such as the Democratic Republic of Congo (DRC), which continues to face the emergence of MDR-TB cases. Because of the ototoxic effects of AGs, the World Health Organization (WHO) has recommended the introduction of the bedaquiline regimen. However, very few data are available regarding the susceptibility of bedaquiline to induce hearing loss, hence the present study set out to compare the AG-based regimen and the bedaquiline-based regimen in the occurrence of hearing loss in MDR-TB patients. Methods: This is a prospective multicenter cohort study that included 335 MDR-TB patients, performed in Kinshasa (DRC) during the period from January 2020 to January 2021. Sociodemographic, clinical, biological and audiometric data were analyzed using Stata 17. Repeated-measures analysis of variance was used to compare changes in the degree of hearing loss over time between the two groups of patients on AG and bedaquiline regimens. The double-difference method was estimated using regression with fixed-effects. A p value < 0.05 was considered the threshold for statistical significance. Results: The degree of hearing loss was similar between the two groups at the first month [AGs (28 dB) vs BDQ (30 dB);p = 0.298]. At six months, the mean degree of hearing loss was significantly greater in the aminoglycoside regimen group [AGs (60.5 dB) vs BDQ (44 dB);p < 0.001]. The double difference was significant, with a greater increase in hearing loss in the AGs group (diff-in-diff 18.3;p < 0.001). After adjustment for age and serum albumin, the group receiving the AG-based regimen had a 2-point greater worsening than those with bedaquiline at the sixth month (diff-in-diff 19.8;p Conclusion: Hearing loss is frequent with both treatment regimens, but more marked with the Aminoglycoside-based regimen. Thus, bedaquiline should also benefit for audiometric monitoring in future MDR-TB patients.

Determinants of the Sensorineural Hearing Loss in Patients with Multidrug-Resistant Tuberculosis in Kinshasa (Democratic Republic of the Congo): A Prospective Cohort Study

Background: The onset of the hearing loss is a major challenge during the treatment of multidrug-resistant tuberculosis (MDR-TB). Aminoglycoside-based regimens, to a lesser extent based on bedaquiline, induce ototoxic sensorineural hearing loss. Research on risk factors is essential to enable high-risk individuals to benefit from preventive measures in settings with limited resources. Objective: This study aimed to assess the determinants of the hearing loss in patients with MDR-TB. Methods: This prospective multicenter cohort study included 337 patients with MDR-TB. It was performed in Kinshasa (Democratic Republic of the Congo) between January 2020 and January 2021. Sociodemographic, clinical, biological, therapeutic, and audiometric data were exported and analyzed using Stata 17 and MedCalc. The fixed-effect linear regression panel model was used to assess the degree of the hearing loss over time according to the following covariates: therapeutic regimen (aminoglycosides, bedaquiline, or alternate), stage of chronic kidney disease (CKD), age at inclusion, body mass index, serum albumin level, HIV status, alcohol intake, hypertension, and hemoglobin level. The Hausman test was used to select between fixed- and random-effect estimators. The threshold for statistical significance was set at p Result: A total of 236 patients (70%) received an aminoglycoside-based regimen, 61 (18%) received a bedaquiline-based regimen, and 40 (12%) received aminoglycosides relayed by bedaquiline. The frequency of the hearing loss increased from 62% to 96.3% within six months for all therapeutic regimens. The Hearing loss worsened, with moderate (72.4%) and profound (16%) deafness being predominant. An Exposure to the treatment for more than one month (β coeff: 27.695, Se: 0.793, p β coeff: 6.102, Se: 1.779, p β coeff: 5.610, Se: 1.682, p = 0.001), and an eGFR β coeff: 6.730, Se: 2.70, p = 0.013) were the independent risk factors associated with the hearing loss in patients with MDR-TB. Conclusions: The Hearing loss was more prevalent and worsened during the treatment of the patients with MDR-TB. An Exposure for more than one month, AG-based regimens, advanced age, hypoalbuminemia, and CKD have emerged as the main determinants of the worsening of the hearing loss.

Multidrug-resistant bacterial infections after liver transplantation: An ever-growing challenge

Bacterial infections are a leading cause of morbidity and mortality among solid organ transplant recipients.Over the last two decades,various multidrug-resistant(MDR)pathogens have emerged as relevant causes of infection in this population.Although this fact reflects the spread of MDR pathogens in health care facilities worldwide,several factors relating to the care of transplant donor candidates and recipients render these patients particularly prone to the acquisition of MDR bacteria and increase the likelihood of MDR infectious outbreaks in transplant units.The awareness of this high vulnerability of transplant recipients to infection leads to the more frequent use of broad-spectrum empiric antibiotic therapy,which further contributes to the selection of drug resistance.This vicious cycle is difficult to avoid and leads to a scenario of increased complexity and narrowed therapeutic options.Infection by MDR pathogens is more frequently associated with a failure to start appropriate empiric antimicrobial ther-apy.The lack of appropriate treatment may contribute to the high mortality occurring in transplant recipients with MDR infections.Furthermore,high therapeutic failure rates have been observed in patients infected with extensively-resistant pathogens,such as carbapenemresistant Enterobacteriaceae,for which optimal treatment remains undefined.In such a context,the careful implementation of preventive strategies is of utmost importance to minimize the negative impact that MDR infections may have on the outcome of liver transplant recipients.This article reviews the current literature regarding the incidence and outcome of MDR infections in liver transplant recipients,and summarizes current preventive and therapeutic recommendations.

Establishment of a human hepatoma multidrug resistant cell line in vitro

AIM:To establish a multidrug-resistant hepatoma cell line(SK-Hep-1),and to investigate its biological characteristics.METHODS:A highly invasive SK-Hep-1 cell line of human hepatocellular carcinoma,also known as malignant hepatoma was incubated with a high concentration of cisplatin(CDDP) to establish a CDDP-resistant cell subline(SK-Hep-1/CDDP).The 50% inhibitory dose(IC50) values and the resistance indexes [(IC50 SK-Hep-1/CDDP)/(IC50 SK-Hep-1)] for other chemotherapeutic agents and the growth curve of cells were all evaluated using cell counting kit-8 assays.The distribution of the cell cycles were detected by flow cytometry.Expression of acquired multidrug resistance P-glycoprotein(MDR1,ABCB1) and multidrug resistance-associated protein 1(MRP1,ABCC1) was compared with that in parent cells by Western blotting and immunofluorescence combined with laser scanning confocal microscopy.RESULTS:The SK-Hep-1/CDDP cells(IC50 = 70.61 ± 1.06 μg/mL) was 13.76 times more resistant to CDDP than the SK-Hep-1 cells(IC50 = 5.13 ± 0.09 μg/mL),and CDDP-resistant cells also demonstrated cross-resistance to many anti-tumor agents such as doxorubicin,5-fluorouracil and vincristine.Similar morphologies were determined in both SK-Hep-1 and SK-Hep-1/CDDP groups.The cell cycle distribution of the SK-Hep-1/CDDP cell line exhibited a significantly increased percentage of cells in S(42.2% ± 2.65% vs 27.91% ± 2.16%,P < 0.01) and G2/M(20.67% ± 5.69% vs 12.14% ± 3.36%,P < 0.01) phases in comparison with SK-Hep-1 cells,while the percentage of cells in the G0/G1 phase decreased(37.5% ± 5.05% vs 59.83% ± 3.28%,P < 0.01).The levels of MDR1 and MRP1 were overexpressed in the SK-Hep-1/CDDP cells exhibiting the MDR phenotype.CONCLUSION:Multiple drug resistance of multiple drugs in the human hepatoma cell line SK-Hep-1/CDDP was closely related to the overexpression of MDR1 and MRP1.

Immune formulation-assisted conventional therapy on anti-infective effectness of multidrug-resistant Mycobacterium tuberculosis infection mice

Objective:To study the effect of immune formulation-assisted conventional therapy on antiinfective ability of multidrug-resistant Mycobacterium tuberculous infection mice.Methods:BALB/c mice were used as experimental animals,multidrug-resistant Mycobacterium tuberculosis infection models were built,randomly divided into model group,moxifloxacin group,thymopentin group and combined treatment group and given corresponding drug intervention,and then colony numbers in the spleen and lung,T lymphocyte subset contents and programmed death-1(PD-1) expression levels in peripheral blood were detected.Results:Colony numbers in lung and spleen of moxifloxacin group and thymopentin group were significantly lower than those of model group and colony numbers in lung and spleen of combined treatment group were significantly lower than those of moxifloxacin group and thymopentin group:contents of CD3^+CD4^+T cells,Thl and Thl7 in peripheral blood of moxifloxacin group and thymopentin group were higher than dtose of model group,and contents of CD3^+CD8^+T cells.Th2 and Treg were lower than those of model group;contents of CD3^+CD4^+T cells.Th 1 and Th 17 in peripheral blood of combined treatment group were higher than those of moxifloxacin group and thymopentin group,and contents of CD3^+CD8^+T cells.Th2 and Treg were lower than those of moxifloxacin group and thymopentin group:PD-I expression levels on T lymphocyte,B lymphocyte and monocyte surface in peripheral blood of moxifloxacin group and thymopentin group were lower than those of model group,and PD-I expression levels on T lymphocyte.B lymphocyte and monocyte surface in peripheral blood of combined treatment group were lower than those of moxifloxacin group and thymopentin group.Conclusions:Immune formulation thymopentin can enhance the anti-infective ability of multidrug-resistant Mycobacterium tuberculosis infection mice,decrease bacterial load in lung and spleen,and enhance immune function.

Nanotechnology-based combination therapy for overcoming multidrug-resistant cancer

Multidrug resistance(MDR) is a major obstacle to successful cancer treatment and is crucial to cancer metastasis and relapse.Combination therapy is an effective strategy for overcoming MDR. However, the different pharmacokinetic(PK) profiles of combined drugs often undermine the combination effect in vivo, especially when greatly different physicochemical properties(e.g.,those of macromolecules and small drugs) combine. To address this issue, nanotechnology-based codelivery techniques have been actively explored. They possess great advantages for tumor targeting, controlled drug release, and identical drug PK profiles. Thus,a powerful tool for combination therapy is provided, and the translation from in vitro to in vivo is facilitated. In this review, we present a summary of various combination strategies for overcoming MDR and the nanotechnology-based combination therapy.

Synergistic Effect of Hyperthermia and Neferine on Reverse Multidrug Resistance in Adriamycin-resistant SGC7901/ADM Gastric Cancer Cells

Multidrug resistance（MDR） plays a major obstacle to successful gastric cancer chemotherapy.The purpose of this study was to investigate the MDR reversal effect and mechanisms of hyperthermia in combination with neferine（Nef） in adriamycin（ADM） resistant human SGC7901/ADM gastric cancer cells.The MDR cells were heated at 42℃ and 45℃ for 30 min alone or combined with 10 μg/mL Nef.The cytotoxic effect of ADM was evaluated by MTT assay.Cellular plasma membrane lipid fluidity was detected by fluorescence polarization technique.Intracellular accumulation of ADM was monitored with high performance liquid chromatography.Mdr-1 mRNA,P-glycoprotein（P-gp）,γH2AX expression and γH2AX foci formation were determined by real-time PCR,Western blot and immunocytochemical staining respectively.It was found that different heating methods induced different cytotoxic effects.Water submerged hyperthermia had the strongest cytotoxicity of ADM and Nef combined with hyperthermia had a synergistic cytotoxicity of ADM in the MDR cells.The water submerged hyperthermia increased the cell membrane fluidity.Both water submerged hyperthermia and Nef increased the intracellular accumulation of ADM.The water submerged hyperthermia and Nef down-regulated the expression of mdr-1 mRNA and P-gp.The water submerged hyperthermia could damage DNA and increase the γH2AX expression of SGC7901/ADM cells.The higher temperature was,the worse effect was.Our results show that combined treatment of hyperthermia with Nef can synergistically reverse MDR in human SGC7901/ADM gastric cancer cells.

Isolation and identification of multidrug-resistant Staphylococcus haemolyticus from a laboratory-breeding mouse

Objective:To analysis and identify a bacterium strain isolated from laboratory breeding mouse far away from a hospital.Methods:Phenotype of the isolate was investigated by conventional microbiological methods,including Gram-staining,colony morphology,tests for haemolysis, catalase,coagulase,and antimicrobial susceptibility test.The meek and 16S rRNA genes were amplified by the polymerase chain reaction(PCR) and sequenced.The base sequence of the PCR product was compared with known 16S rRNA gene sequences in the CenBank database by phylogenetic analysis and multiple sequence alignment.Results:The isolate in this study was a gram positive,coagulase negative,and catalase positive coccus.The isolate was resistant to oxacillin,methicillin,penicillin,ampicillin,cefazolin,cipr of loxacin erythromycin,et al.PCR results indicated that the isolate was meek gene positive and its 16S rRNA was 1465 bp.Phylogenetic analysis of the resultant 16S rRNA indicated the isolate belonged to genus Saphylococcus,and multiple sequence alignment showed that the isolate was Saphylococcus haemolyticus with only one base difference from the corresponding 16S rRNA deposited in the CenBank.Conclusions: 16S rRNA gene sequencing is a suitable technique for non-specialist researchers.Laboratory animals are possible sources of lethal pathogens,and researchers must adapt protective measures when they manipulate animals.

GENE EXPRESSION PROFILING IN MULTIDRUG RESISTANT KB CELLS USING cDNA MICROARRAYS

Objective: A single mechanistic pathway cannot explain the genesis of drug resistance in cancer. Drug resistance in cancer is a major obstacle to successful chemotherapy. KB cells provide a useful starting point for selection of the multidrug resistant (MDR) cell lines. Methods: We used cDNA microarrays containing 12,720 sequences of known genes, expressed sequence tags and unknown clones to monitor gene expression profiles in MDR KB cells. Results: Preliminary data analysis showed that 18 genes were up-regulated and 18 genes were down-regulated by comparison of expression patterns between KB 3-1 and MDR KB-V1 cells. Furthermore, the highly over-expressed CGA, CLU genes in MDR KB-V1 cell were verified with conventional Northern blot analysis. These genes contain information predictive of drug resistance of cancer cells. Conclusion: Our study demonstrates that genome-wide gene expression profiling by using cDNA microarray technique is a valuable approach in obtaining molecular mechanism of drug resistance in cancer cells.

Severe infection with multidrug-resistant Salmonella choleraesuis in a young patient with primary sclerosing cholangitis

Massive global spread of multidrug-resistant(MDR) Salmonella spp. expressing extended-spectrum beta-lactamase(ESBL) and additional resistance to fluoroquinolones has often been attributed to high international mobility as well as excessive use of oral antibiotics in livestock farming. However, MDR Salmonella spp. have not been mentioned as a widespread pathogen in clinical settings so far. We demonstrate the case of a 25-year-old male with primary sclerosing cholangitis who tested positive for MDR Salmonella enterica serotype Choleraesuis expressing ESBL and fluoroquinolone resistance. The pathogen was supposedly acquired during a trip to Thailand, causing severe fever, cholangitis andpancreatitis. To our knowledge, this is the first report of Salmonella enterica serotype Choleraesuis in Europe expressing such a multidrug resistance pattern. ESBL resistance of Salmonella enterica spp. should be considered in patients with obstructive biliary tract pathology and travel history in endemic countries.

Genotyping Characteristics of Human Fecal Escherichia coli and Their Association with Multidrug Resistance in Miyun District, Beijing

Objective To explore the genotyping characteristics of human fecal Escherichia coli(E. coli) and the relationships between antibiotic resistance genes(ARGs) and multidrug resistance(MDR) of E. coli in Miyun District, Beijing, an area with high incidence of infectious diarrheal cases but no related data.Methods Over a period of 3 years, 94 E. coli strains were isolated from fecal samples collected from Miyun District Hospital, a surveillance hospital of the National Pathogen Identification Network. The antibiotic susceptibility of the isolates was determined by the broth microdilution method. ARGs,multilocus sequence typing(MLST), and polymorphism trees were analyzed using whole-genome sequencing data(WGS).Results This study revealed that 68.09% of the isolates had MDR, prevalent and distributed in different clades, with a relatively high rate and low pathogenicity. There was no difference in MDR between the diarrheal(49/70) and healthy groups(15/24).Conclusion We developed a random forest(RF) prediction model of TEM.1 + baeR + mphA + mphB +QnrS1 + AAC.3-IId to identify MDR status, highlighting its potential for early resistance identification. The causes of MDR are likely mobile units transmitting the ARGs. In the future, we will continue to strengthen the monitoring of ARGs and MDR, and increase the number of strains to further verify the accuracy of the MDR markers.

Folic acid-conjugated liposomal vincristine for multidrug resistant cancer therapy

We encapsulated vincristine into folic acid-conjugated PEGylated liposomes to improve the anti-tumor efficacy on multidrug resistant cancers.It was observed that the drug delivery system we constructed exhibited maximum cytotoxicity on KBv200 cells(multidrug resistant variant)compared with any other formulations.The semi-quantitative analysis of region of interest revealed that there was a great increase in area under curve(AUC)of a near-infrared fluorescein in solid tumors due to folic acid-mediated accumulation.Folic acid-conjugated PEGylated liposomes showed a significant tumor growth inhibiting effect in vitro and in vivo.TUNEL assay revealed that folic acid-conjugated PEGylated liposomes could induce cell apoptosis much more greatly than others.This study demonstrated that it had potential application prospective for the treatment of multidrug resistant cancer.

Down-regulation of extracellular signal-regulated kinase 1/2 activity in P-glycoprotein-mediated multidrug resistant hepatocellular carcinoma cells

AIM:To study the expression and phosphorylation of extracellular signal-regulated kinase(ERK)1 and ERK2 in multidrug resistant(MDR)hepatocellular carcinoma(HCC)cells.METHODS:MDR HCC cell lines,HepG2/adriamycin(ADM)and SMMC7721/ADM,were developed by exposing parental cells to stepwise increasing concentrations of ADM.MTT assay was used to determine drug sensitivity.Flow cytometry was employed to analyze cell cycle distribution and measure cell P-glycoprotein(P-gp)and multidrug resistant protein 1(MRP1)expression levels.ERK1 and ERK2 mRNA expression levels were measured by quantitative real-time PCR(QRTPCR).Expression and phosphorylation of ERK1 and ERK2 were analyzed by Western blot.SMMC7721/ADM were resistant not only to ADM,but also to multiple anticancer drugs.The P-gp expression was over 10-fold higher in HepG2/ADM cells than in HepG2 cells(8.92%±0.22%vs 0.88%±0.05%,P<0.001)and over 4-fold higher in SMMC7721/ADM cells than in SMMC7721 cells(7.37%±0.26%vs 1.74%±0.25%,P<0.001).However,the MRP1 expression was not significantly higher in HepG2/ADM and SMMC7721/ADM cells than in parental cells.In addition,the percentage of MDR HepG2/ADM and SMMC7721/ADM cells was significantly decreased in the G0/G1 phase and increased in the the S phase or G2/M phase.QRT-PCR analysis demonstrated that the ERK1 and ERK2 mRNA expression increased apparently in HepG2/ADM cells and decreased significantly in SMMC7721/ADM cells.Compared with the expression of parental cells,ERK1 and ERK2 protein expressions were markedly decreased in SMMC7721/ADM cells.However,ERK2 protein expression was markedly increased while ERK1 protein expression had no significant change in HepG2/ADM cells.Phosphorylation of ERK1 and ERK2 was markedly decreased in both HepG2/ADM and SMMC7721/ADM MDR cells.CONCLUSION:ERK1 and ERK2 activities are downregulated in P-gp-mediated MDR HCC cells.ERK1 or ERK2 might be a potential drug target for circumventing MDR HCC cells.

Production systems and important antimicrobial resistant-pathogenic bacteria in poultry:a review

Economic losses and market constraints caused by bacterial diseases such as colibacillosis due to avian pathogenic Escherichia coli and necrotic enteritis due to Clostridium perfringens remain major problems for poultry producers,despite substantial efforts in prevention and control.Antibiotics have been used not only for the treatment and prevention of such diseases,but also for growth promotion.Consequently,these practices have been linked to the selection and spread of antimicrobial resistant bacteria which constitute a significant global threat to humans,ani-mals,and the environment.To break down the antimicrobial resistance(AMR),poultry producers are restricting the antimicrobial use(AMU)while adopting the antibiotic-free(ABF)and organic production practices to satisfy consum-ers’demands.However,it is not well understood how ABF and organic poultry production practices influence AMR profiles in the poultry gut microbiome.Various Gram-negative(Salmonella enterica serovars,Campylobacter jejuni/coli,E.coli)and Gram-positive(Enterococcus spp.,Staphylococcus spp.and C.perfringens)bacteria harboring multiple AMR determinants have been reported in poultry including organically-and ABF-raised chickens.In this review,we discussed major poultry production systems(conventional,ABF and organic)and their impacts on AMR in some potential pathogenic Gram-negative and Gram-positive bacteria which could allow identifying issues and opportuni-ties to develop efficient and safe production practices in controlling pathogens.