Drug Resistance Traits Research Articles

Exosomes derived from imatinib-resistant chronic myeloid leukemia cells mediate a horizontal transfer of drug-resistant trait by delivering miR-365

Chronic myeloid leukemia (CML) is a malignant disorder of hematopoietic stem/progenitor cells. Majority of patients can be effectively treated with tyrosine kinase inhibitors (TKIs) such as imatinib, but a portion of patients will develop drug resistance. Accumulated evidences have identified exosomes in cancer as promoters of tumor progression. Herein, we found that exosomes derived from imatinib resistant CML cells can be internalized into sensitive CML cells and confer drug-resistance traits. We also demonstrated a significant higher level of miR-365 in exosomes derived from drug-resistant CML cells compared with those from sensitive ones using microarray and qRT-PCR. The imatinib sensitive CML cells transfected with pre-miR-365 displayed lower chemosensitivity and apoptosis rate compared with controls. We further confirmed that exosomal transfer of miR-365 induced drug resistance by inhibiting expression of pro-apoptosis protein in sensitive CML cells. In conclusion, our study reveals that exosomes mediate a horizontal transfer of drug-resistant trait in chronic myeloid leukemia cell by delivering miR-365.

Studies on Drug Resistance among Klebsiella and Citrobacter spp Isolated from two Human Groups and Wild Animals

Background: The global threat of antimicrobial resistance is undoubtedly on the increase and most researches in this area have concentrated on effects of drug exposure and usage on resistance. Little attention has been given to natural environments apparently devoid of direct anthropogenic impact as possible reservoirs of drug resistance traits. Objectives: This research was undertaken to determine possible similarities between drug resistance traits in species of Klebsiella and Citrobacter obtained from wild animals and 2 human groups. Methods: Human samples were collected from Humans free from antibiotics (HN) and Human on antibiotics (HA) while samples from wildlife (WL) were taken from rats (Rattus spp), grasscutters (Thryonomys swinderianus), squirrels (Xerus erythropus), antelopes (Tragelephus scriptus), rabbits (Oryctolagus cuniculus), and farm lizards (Agama spp). Samples were analyzed using basic microbiological methods. The Disc diffusion technique was used for drug sensitivity testing while plasmid analysis was based on gel electrophoresis. Results: Members of the genus Klebsiella isolated from HA exhibited more resistance to ampicillin (AMP) and augmentin (AUG) than those isolated from HN. However, Klebsiella isolated from HN displayed higher resistance to ceftriaxone (CTN), clarithromycin (CMN), ofloxacin (OFL), and pefloxacin (PEF) than those from HA. WL isolates were mostly resistant to AMP, CMN, and AUG, and less resistant to PEF, CTN, and ciprofloxacin. Correlation analysis of the antimicrobial resistance pattern on a 2 tailed test P ≤ 0.01 and P ≤ 0.05, revealed a high correlation (ranging from 0.715 to 0.917) among all the microorganisms from both sources. Gel electrophoretic analysis of plasmid DNA extracted from the isolates revealed the presence of a 23.1 kb plasmid DNA in 6 strains of Citrobacter and 3 strains of Klebsiella. Conclusions: These results indicate that wild life may be important reservoirs of drug resistance genes and pathogens that have public health relevance.

The effects of subcurative praziquantel treatment on life-history traits and trade-offs in drug-resistant Schistosoma mansoni.

Natural selection acts on all organisms, including parasites, to maximize reproductive fitness. Drug resistance traits are often associated with life‐history costs in the absence of treatment. Schistosomiasis control programmes rely on mass drug administration to reduce human morbidity and mortality. Although hotspots of reduced drug efficacy have been reported, resistance is not widespread. Using Bayesian state‐space models (SSMs) fitted to data from an in vivo laboratory system, we tested the hypothesis that the spread of resistant Schistosoma mansoni may be limited by life‐history costs not present in susceptible counterparts. S. mansoni parasites from a praziquantel‐susceptible (S), a praziquantel‐resistant (R) or a mixed line of originally resistant and susceptible parasites (RS) were exposed to a range of praziquantel doses. Parasite numbers at each life stage were quantified in their molluscan intermediate and murine definitive hosts across four generations, and SSMs were used to estimate key life‐history parameters for each experimental group over time. Model outputs illustrated that parasite adult survival and fecundity in the murine host decreased across all lines, including R, with increasing drug pressure. Trade‐offs between adult survival and fecundity were observed in all untreated lines, and these remained strong in S with praziquantel pressure. In contrast, trade‐offs between adult survival and fecundity were lost under praziquantel pressure in R. As expected, parasite life‐history traits within the molluscan host were complex, but trade‐offs were demonstrated between parasite establishment and cercarial output. The observed trade‐offs between generations within hosts, which were modified by praziquantel treatment in the R line, could limit the spread of R parasites under praziquantel pressure. Whilst such complex life‐history costs may be difficult to detect using standard empirical methods, we demonstrate that SSMs provide robust estimates of life‐history parameters, aiding our understanding of costs and trade‐offs of resistant parasites within this system and beyond.

Modeling the chemotherapy-induced selection of drug-resistant traits during tumor growth

The emergence of drug-resistance is a major challenge in chemotherapy. In this paper we develop a mathematical model to study the dynamics of drug-resistance in solid tumors. Our model follows the dynamics of the tumor, assuming that the cancer cell population depends on a phenotype variable that corresponds to the resistance level to a cytotoxic drug. The equation for the tumor density is written as a reaction-diffusion equation with a pressure term that depends on the local cell density. The model incorporates the dynamics of nutrients and two different types of drugs: a cytotoxic drug, which directly impacts the death rate of the cancer cells, and a cytostatic drug that reduces the proliferation rate. This model successfully integrates the phenotype structured drug-resistance approach with an asymmetric tumor growth model in space. Through analysis and simulations we study the impact of spatial and phenotypic heterogeneity on the tumor growth under chemotherapy. We demonstrate that heterogeneous cancer cells may emerge due to the selection dynamics of the environment. Our model predicts that under certain conditions, multiple resistant traits emerge at different locations within the tumor. We show that a higher dosage of the cytotoxic drug may delay a relapse, yet, when this happens, a more resistant trait emerges. Moreover, we estimate the expansion rate of the tumor boundary as well as the time of relapse, in terms of the resistance trait, the level of the nutrient, and the drug concentration. Finally, we propose an efficient drug schedule aiming at minimizing the growth rate of the most resistant trait. By combining the cytotoxic and cytostatic drugs, we demonstrate that the resistant cells can be eliminated.

Pathogenic identification and antibiotic susceptibility of the microorganisms isolated from urine samples of UTI patients

Urinary tract infection (UTI) is the infection that occurs in the urinary tract by the invasion of pathogenic bacteria, fungi, virus etc. under some circumstances only. Some common pathogenic bacteria associated with UTI include Escherichia coli, Proteus spp., Streptococcus spp., Staphylococcus spp., Pseudomonas spp. In the ongoing research work, about 30 UTI patients were selected randomly to detect the pathogen responsible for causing urinary tract infection and also to demonstrate their drug resistant traits. Among the 30 samples, about 14 samples were found to harbor Proteus spp. (1×104 cfu/ml to 1×105 cfu/ml). Escherichia coli was found to be the second predominant agent for UTI and recovered from 13 samples. Among the rest 3 samples, Pseudomonas spp. was found in 2 samples and Klebsiella spp. was found in one sample. Identified isolates showed resistance against different ranges of antibiotics. The study findings revealed the fact that emerging drug resistance of different pathogenic bacteria could become the major difficulties in the treatment of infectious diseases like UTI.Stamford Journal of Microbiology, Vol.6(1) 2016: 34-38

Microbiological analysis for drug resistant pathogenic microorganisms with determination of the antibacterial properties found in Fragaria x ananassa (strawberry) samples

Strawberry is a popular fruit item consumed by people all over the world for its exceptional flavor and aroma. This fruit is being used to prepare a wide range of food items. Strawberries when consumed by people without undergoing any processing, the condition may not be good enough. People may get sick after consuming raw strawberries. Our current study identified several pathogenic bacteria which are very known in causing health related problems. E. coli was found in one sample (1.0×102 cfu/g), Staphylococcus aureus was commonly present in all of the five samples (up to 1.2×106 cfu/g), Klebsiella spp. was found to be present in two samples (within 1.0×103 cfu/g) and Pseudomonas spp. was present in three samples (8.2×104 cfu/g), respectively. All isolated bacteria showed some degree of drug resistant traits against some commonly used antibiotics. The most important and promising part of the study was to successfully find the antimicrobial activity of strawberries against seven types of pathogenic bacteriaStamford Journal of Microbiology, Vol.6(1) 2016: 16-19

Insights into drug resistance mechanisms in Clostridium difficile.

The incidence of Clostridium difficile infection has been elevated and becoming common in hospitals worldwide. Although antibiotics usually serve as the primary treatment for bacterial infection including C. difficile infection, limitations and failures have been evident due to drug resistance. Antibiotic resistance in C. difficile has been recognized as one of the most important factors to promote the infection and increase the level of severity and the recurrence rate. Several outbreaks in many countries have been linked to the emergence of hypervirulent drug-resistant strains. This pathogen harbours various mechanisms against the actions of antibiotics. The present study highlights three main drug-resistant strategies in C. difficile including drug inactivation, target modification and efflux pump. Other mechanisms that potentially contribute to drug-resistant traits in this organism are also discussed.

Multidrug-Resistant Bacterial Isolates Recovered from Herbal Medicinal Products Sold in Nairobi, Kenya

Background: Medicinal herbs have been reported to be contaminated with microorganisms indigenous to the environment. These microbes become a threat when they harbour drug-resistant traits. Objective: The aim of this study was to evaluate phenotypic and genotypic drug-resistant traits of bacteria isolated from herbal medicinal products in Nairobi, Kenya. Methods: We employed an exploratory as well as laboratory-based experimental design. Herbal products were purchased from markets and transported to Kenya Medical Research Institute laboratories for processing and analysis. Microbial contamination and antibiotic susceptibility were determined following standard methods. Antibiotic-resistant genes were determined using polymerase chain reaction. Data were coded and analysed accordingly. Results: We collected 138 samples of herbal products in the form of liquids, powders, capsules, creams/lotions, and syrups. In total, 117 samples (84.8%) were contaminated with bacteria and 61 (44.2%) were contaminated with fungi. Bacillus, Klebsiella, Proteus, Staphylococcus, Streptomyces, Escherichia, Enterobacter, Serratia, Yersinia, Morganella, Citrobacter, Erwinia, and Shigella were the bacterial genera identified. Most of the isolated bacteria were generally sensitive to the panel of antibiotics tested, although a few (35 [36.5%]) were resistant; more than half of these were resistant to more than 1 of the antibiotic agents we tested. Discussion: We found an association between phenotypic and genotypic drug resistance among the drug-resistant bacteria. This study makes it evident that herbal medicinal products sold in Nairobi are contaminated with drug-resistant bacteria. Conclusions: The results show that herbal medicinal products are a potential source of dissemination of multidrug-resistant bacteria. There is an urgent need for specific education programmes, policies, and regulations that address herbal products' safety to prevent the possibility of these pathogens being involved in deadly invasive infections.

Multidrug-Resistant Bacterial Isolates Recovered from Herbal Medicinal Products Sold in Nairobi, Kenya.

Background:Medicinal herbs have been reported to be contaminated with microorganisms indigenous to the environment. These microbes become a threat when they harbour drug-resistant traits.Objective:The aim of this study was to evaluate phenotypic and genotypic drug-resistant traits of bacteria isolated from herbal medicinal products in Nairobi, Kenya.Methods:We employed an exploratory as well as laboratory-based experimental design. Herbal products were purchased from markets and transported to Kenya Medical Research Institute laboratories for processing and analysis. Microbial contamination and antibiotic susceptibility were determined following standard methods. Antibiotic-resistant genes were determined using polymerase chain reaction. Data were coded and analysed accordingly.Results:We collected 138 samples of herbal products in the form of liquids, powders, capsules, creams/lotions, and syrups. In total, 117 samples (84.8%) were contaminated with bacteria and 61 (44.2%) were contaminated with fungi. Bacillus, Klebsiella, Proteus, Staphylococcus, Streptomyces, Escherichia, Enterobacter, Serratia, Yersinia, Morganella, Citrobacter, Erwinia, and Shigella were the bacterial genera identified. Most of the isolated bacteria were generally sensitive to the panel of antibiotics tested, although a few (35 [36.5%]) were resistant; more than half of these were resistant to more than 1 of the antibiotic agents we tested.Discussion:We found an association between phenotypic and genotypic drug resistance among the drug-resistant bacteria. This study makes it evident that herbal medicinal products sold in Nairobi are contaminated with drug-resistant bacteria.Conclusions:The results show that herbal medicinal products are a potential source of dissemination of multidrug-resistant bacteria. There is an urgent need for specific education programmes, policies, and regulations that address herbal products' safety to prevent the possibility of these pathogens being involved in deadly invasive infections.

Review of Restricted Experiment Requests, Division of Select Agents and Toxins, Centers for Disease Control and Prevention, 2006-2013.

The Centers for Disease Control and Prevention (CDC) Division of Select Agents and Toxins (DSAT) regulates laboratories that possess, use, or transfer select agents and toxins in the United States. DSAT also mitigates biosafety risks through the review of "restricted experiments," which under the select agent regulations are experiments that pose heightened biosafety risks. From January 2006 through December 2013, DSAT received 618 requests from 109 entities to perform potentially restricted experiments. Of these requests, 85% were determined not to meet the regulatory definition of a restricted experiment, while 15% of the requests met the definition of a restricted experiment. Of the 91 restricted experiments proposed, DSAT approved 31 (34%) requests because the biosafety conditions proposed were commensurate with the experiments' biosafety risk. All 31 approved restricted experiments were for work with select toxins. DSAT did not approve 60 restricted experiment requests due to potentially serious biosafety risks to public health and safety. All 60 denied restricted experiments proposed inserting drug resistance traits into select agents that could compromise the control of disease. The select agents and toxins associated most frequently with requests that met the regulatory definition of a restricted experiment are Shiga toxin (n = 16), Burkholderia mallei (n = 15), Botulinum neurotoxin (n = 14), and Brucella abortus (n = 14). In general, all restricted experiment decisions are determined on a case-by-case basis. This article describes the trends and characteristics of the data associated with restricted experiment requests among select agents that have an impact on public health and safety (HHS only agents) or both public health and safety and animal health or products (overlap agents). The information presented here, coupled with the information published in the restricted experiment guidance document ( www.selectagents.gov ), is intended to promote awareness among the research community of the type of experiments that meet the regulatory definition of a restricted experiment as well as to provide a greater understanding of the restricted experiment review process.

MALDI-TOF typing highlights geographical and fluconazole resistance clusters in Candida glabrata.

Utilizing matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectra for Candida glabrata typing would be a cost-effective and easy-to-use alternative to classical DNA-based typing methods. This study aimed to use MALDI-TOF for the typing of C. glabrata clinical isolates from various geographical origins and test its capacity to differentiate between fluconazole-sensitive and -resistant strains.Both microsatellite length polymorphism (MLP) and MALDI-TOF mass spectra of 58 C. glabrata isolates originating from Marseilles (France) and Tunis (Tunisia) as well as collection strains from diverse geographic origins were analyzed. The same analysis was conducted on a subset of C. glabrata isolates that were either susceptible (MIC ≤ 8 mg/l) or resistant (MIC ≥ 64 mg/l) to fluconazole.According to the seminal results, both MALDI-TOF and MLP classifications could highlight C. glabrata population structures associated with either geographical dispersal barriers (p < 10(-5)) or the selection of antifungal drug resistance traits (<10(-5)).In conclusion, MALDI-TOF geographical clustering was congruent with MPL genotyping and highlighted a significant population genetic structure according to fluconazole susceptibility in C. glabrata. Furthermore, although MALDI-TOF and MLP resulted in distinct classifications, MALDI-TOF also classified the isolates with respect to their fluconazole susceptibility profile. Further prospective studies are required to evaluate the capacity of MALDI-TOF typing to investigate C. glabrata infection outbreaks and predict the antifungal susceptibility profile of clinical laboratory isolates.

Detection of Salmonella spp. and Microbiological Analysis of Milk and Milk Based Products Available within Dhaka Metropolis, Bangladesh

Aims: With a previous observation of pathogenic drug-resistant microorganisms in raw milk samples, current investigation further endeavored to determine the presence of Salmonella spp. and portrayed a complete map of the overall microbiological feature of milk and milk based products available within Dhaka metropolis, Bangladesh. Methodology: Conventional cultural and biochemical methods were carried out to isolate and enumerate the milk and milk based products accessing microorganisms. Standard agar disc diffusion method was conducted to assess the anti-bacterial resistance pattern of the isolated Salmonella spp. Original Research Article Yasmin et al.; BMRJ, 5(6): 474-480, 2015; Article no.BMRJ.2015.050 475 Results: Out of 35 samples studied, 16 were found to be contaminated with E. coli (~10 6 cfu/ml) and 9 samples were found to be contaminated with Salmonella spp. (~10 5 cfu/ml). Fungal growth was also observed in all samples (~10). The Salmonella isolates were found to be resistant against ampicillin (10 μg), cotrimoxazole (25 μg), chloramphenicol (30 μg), ciprofloxacin (5 μg), cefixime (5 μg) and sensitive against ofloxacin (5 μg). Conclusion: As projected from the current study, the proliferation of Salmonella spp. along with their drug-resistance traits could impart the morbidity and mortality associated risk to the overall public health safety.

Molecular characterization of the virulent microorganisms along with their drug-resistance traits associated with the export quality frozen shrimps in Bangladesh.

Current investigation characterized export quality shrimp samples in terms of pathogenic load along with the drug-resistance traits of the isolates, and detected the major virulent genes present in those isolates. Among the 30 such shrimp samples (15 each of Macrobrachium rosenbergi or Golda and Penaeus monodon or Bagda) studied, almost all were found to be contaminated with a huge load of bacteria (106–108 cfu/g) and fungi (104–105 cfu/g). Among the specific pathogens, presence of Escherichia coli, Vibrio spp., Aeromonas spp., Klebsiella spp., Shigella spp., Staphylococcus spp. and Listeria spp. were detected, of which most were likely to be resistant against commonly used antibiotics. Gene specific polymerase chain reaction (PCR) study revealed the presence of eae gene in E. coli, aero specific gene in Aeromonas spp., and sodB gene in Vibrio spp. Together with the huge extent of microbial contamination with a drug-resistance attribute, presence of such virulent genes further projects the probable public health risk upon consumption of the export quality shrimps.

Isolation of pathogenic microorganisms from burn patients admitted in Dhaka Medical College and Hospital and demonstration of their drug-resistance traits

ObjectiveTo isolate and quantify the microflora from the burn patients admitted in the Division of Plastic Surgery and Burns outdoor patients in Dhaka Medical College Hospital, Bangladesh. MethodsThirty wound surface swab samples of first and second degree burn patients were collected and the microbial analysis as well the study of antibacterial susceptibility was conducted. Microbial inhibitory concentration of tobramycin was tested to be applied as effective antimicrobial agent in burn patients. Activity of four disinfectants was also tested against the pathogens. ResutlsAmong all samples, 28 was found to be populated with the total viable bacteria up to 107 CFU/mL. The predominant pathogen was Pseudomonas spp. followed by Staphylococcus aureus and Kebsiella spp. Three of the samples harbored Enterobacter spp. while 2 were found to be proliferated with Escherichia coli. Most of the pathogens were found to be drug-resistant while several isolates were noted to be multi-drug resistant. Dettol partly showed efficacy among the tested disinfectants to prevent pathogenic proliferation. ConclusionsHuge bacterial onset with an alarming threat of multidrug resistance would potentially raise the necessity of proper care and management of burn wound patients in hospital.

Genomic comparative analysis and gene function prediction in infectious diseases: application to the investigation of a meningitis outbreak

BackgroundNext generation sequencing (NGS) is being increasingly used for the detection and characterization of pathogens during outbreaks. This technology allows rapid sequencing of pathogen full genomes, useful not only for accurate genotyping and molecular epidemiology, but also for identification of drug resistance and virulence traits.MethodsIn this study, an approach based on whole genome sequencing by NGS, comparative genomics, and gene function prediction was set up and retrospectively applied for the investigation of two N. meningitidis serogroup C isolates collected from a cluster of meningococcal disease, characterized by a high fatality rate.ResultsAccording to conventional molecular typing methods, all the isolates had the same typing results and were classified as outbreak isolates within the same N. meningitidis sequence type ST-11, while full genome sequencing demonstrated subtle genetic differences between the isolates. Looking for these specific regions by means of 9 PCR and cycle sequencing assays in other 7 isolates allowed distinguishing outbreak cases from unrelated cases. Comparative genomics and gene function prediction analyses between outbreak isolates and a set of reference N. meningitidis genomes led to the identification of differences in gene content that could be relevant for pathogenesis. Most genetic changes occurred in the capsule locus and were consistent with recombination and horizontal acquisition of a set of genes involved in capsule biosynthesis.ConclusionsThis study showed the added value given by whole genome sequencing by NGS over conventional sequence-based typing methods in the investigation of an outbreak. Routine application of this technology in clinical microbiology will significantly improve methods for molecular epidemiology and surveillance of infectious disease and provide a bulk of data useful to improve our understanding of pathogens biology.

The mosaic accessory gene structures of the SXT/R391-like integrative and conjugative elements derived from Vibrio spp. isolated from aquatic products and environment in the Yangtze River estuary, China

BackgroundThe emergence, resurgence and spread of human food-borne pathogenic Vibrios are one of the major contributors to disease burden and mortality particularly in developing countries with disputable sanitary conditions. Previous research on pathogenic Vibrio cholerae and Vibrio parahaemolitycus derived from clinical samples has proposed links between acquisition of virulence and multiple drug resistance traits and intercellular transmissibility of mobile genetic elements in the environment. To date, very few information is available on environmental Vibrio isolates. In this study, we characterized eleven Vibrio strains bearing the SXT/R391-like integrative and conjugative elements (ICEs) derived from aquatic products and environment in the Yangtze River Estuary, China.ResultsThe eleven Vibrio strains were isolated in 2010 to 2011, and taxonomically identified, which included six Vibrio cholerae, three Vibrio parahaemolyticus, one Vibrio alginolyticus and one Vibrio natriegens. Most of the strains displayed strong resistance phenotypes to ampicillin, mercury and chromium. The majority of their ICEs, which belong to S and R exclusion system groups, contain ICEs-chromosome junction sequences and highly conserved core-genes required for ICE transfer. However, comparative sequence analysis uncovered interesting diversity in their mosaic accessory gene structures, which carry many novel genes that have not been described in any known ICEs to date. In addition, antibiotic resistance was transmitted by ICEVchChn6 and ICEVpaChn1 from V. cholerae, V. parahaemolyticus to E. coli MG1655 via conjugation, respectively. Our data also revealed that the ICEs characterized in this study are phylogenetically distant from most of the SXT/R391 ICEs reported previously, which may represent a novel cluster likely shaped by the ecological environment in the Yangtze River Estuary, China.ConclusionsThis study constitutes the first investigation of ICEs-positive Vibrio spp. in the Yangze River Estuary, China. The newly identified ICEs were characterized with mosaic accessory gene structures and many novel genes. The results demonstrated self-transmissibility of antibiotic resistance mediated by two of the ICEs from V. cholerae, V. parahaemolyticus to E. coli via conjugation, respectively. Our results also revealed that the ICEs examined in this study may represent a novel cluster in the SXT/R391 family.

Abstract 4888: Axl receptor signaling in required for stem cell traits and metastasis in breast cancer.

Abstract Epithelial-to-mesenchymal transition (EMT) endows carcinoma cells with migratory, survival and stem cell-like attributes that facilitate therapeutic resistance and metastasis. Expression of the Axl receptor tyrosine kinase in aggressive breast cancer correlates with EMT, poor survival and is prevalent in patient metastases. Induction of EMT in immortalized mammary epithelial cells by EMT-transcription factors, TGFbeta or hypoxia upregulates Axl and establishes an autocrine-signaling loop with its ligand, Gas6. Axl receptor signaling is required to maintain EMT-related invasive, drug resistance and cancer stem cell (CSC) traits of malignant breast cancer cells. Targeting Axl signaling with RNAi or pharmacological agents blocks the EMT/CSC gene program and inhibits malignant functions including invasiveness, drug resistance, mammosphere formation, in vivo tumor initiation, and spontaneous metastasis in orthotopic breast cancer models. These results suggest that Axl expression is requisite for the maintenance of EMT and stem cell-like traits during malignant progression. The EMT program is characteristic of normal adult mammary epithelial stem/progenitor cells. Congruently, we show that the Axl receptor expressed on mammary epithelial stem/progenitor cells, and Axl signaling is necessary for mammary epithelial multipotent progenitor activity. Thus Axl receptor signaling represents a novel regulatory pathway linking normal mammary stem/progenitor cells and breast cancer stem cells. Hence, clinical Axl inhibitors represent a novel therapeutic avenue to target EMT/CSC traits of aggressive breast cancer. Citation Format: Crina Tiron, Fanny Pelissier, Katarzyna Wnuk-Lipinska, Ingunn Stefansson, Reeta Virtakoivu, Masaru Miyano, Tone Sandal, David Micklem, James Garbe, Martha Stampfer, Johanna Ivaska, Lars Akslen, Mark LaBarge, James Lorens. Axl receptor signaling in required for stem cell traits and metastasis in breast cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4888. doi:10.1158/1538-7445.AM2013-4888

Simultaneous detection of Salmonella pathogenicity island 2 and its antibiotic resistance genes from seafood

Salmonella enterica serovars are virulent pathogens of humans and animals with many strains possessing multiple drug resistance traits. They have been found to carry resistance to ampicillin, chloramphenicol, florfenicol, streptomycin, sulfonamides, and tetracycline (ACSSuT-resistant). A rapid and sensitive multiplex PCR (mPCR)-based assay was developed for the detection of Salmonella serovars from seafood. Six sets of primers which are one primer pair targeting Salmonella specific gene invA (284bp), two Salmonella pathogenicity island 2 (SPI-2) genes ssaT (780bp) and sseF (888bp) and three antibiotic resistance genes floR (198bp), sul1 (425bp), tetG (550bp) were used for the study. The specificity and sensitivity of the assay were tested by spiking shrimp/fish/clam homogenate with viable cells of Salmonella. This assay allows for the cost effective and reliable detection of pathogenic Salmonella enterica from seafood. The mPCR developed in the present study proved to be a potent analytical tool for the rapid identification of multidrug-resistant Salmonella serovars from seafood.

Detection of copy number variation and single nucleotide polymorphisms in genes involved in drug resistance and other phenotypic traits in P. falciparum clinical isolates collected from Uganda

There is an increasing interest in mapping the genes of pathogens which underlie important phenotypic traits such as virulence and drug resistance. The Plasmodium falciparum genome exhibits sequence variation that contributes to the pathogenic mechanisms of the parasite. Determining the prevalence of resistance markers could provide a prediction about drug efficacy. Copy number polymorphism (CNP) of genes has been shown to influence important parasite phenotypes. In this work, CNPs within genes involved in drug resistance and other phenotypic traits namely P. falciparum multidrug resistance 1 (pfmdr-1), GTP cyclo hydrolase (gch1), Ring infected erythrocyte surface antigen precursor (resa) and a hypothetical protein coding gene were analyzed by quantitative real time-polymerase reaction (qRT-PCR) among clinical isolates collected from Uganda. The pfmdr-1 codons 86 and 1246 and P. falciparum chloroquine resistance (pfcrt) codon 76 were genotyped for single nucleotide polymorphisms (SNPs) by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and the proportion of resistance associated mutations were determined among mild and severe malaria cases using the chi-square test. Forty and 42 P. falciparum isolates collected from children with mild and severe malaria respectively were analyzed for CNPs. Seventy five and 81 P. falciparum isolates from children with mild or severe malaria were analyzed for SNPs. No pfmdr-1, gch1 or novel gene amplifications were identified among the P. falciparum clinical isolates. Although chloroquine was officially withdrawn from policy use since 7 years, all P. falciparum isolates presented the associated pfcrt K76T mutation, whatever the clinical status and no specific mutation in the pfmdr-1 gene was associated with disease type. In conclusion, this study provides baseline measures for continued surveillance for changes in copy number and SNP types among genes implicated in drug resistance and other important phenotypes that may have a potential role in parasite virulence mechanisms or drug treatment outcomes.

Comparison ofEscherichia coliST131 Pulsotypes, by Epidemiologic Traits, 1967–2009

Escherichia coli sequence type 131 (ST131), an emerging disseminated public health threat, causes multidrug-resistant extraintestinal infections. Among 579 diverse E. coli ST131 isolates from 1967-2009, we compared pulsotypes (>94% similar XbaI pulsed-field gel electrophoresis profiles) by collection year, geographic origin, source, and antimicrobial drug-resistance traits. Of 170 pulsotypes, 65 had >2 isolates and accounted for 85% of isolates. Although extensively dispersed geographically, pulsotypes were significantly source specific (e.g., had little commonality between humans vs. foods and food animals). The most prevalent pulsotypes were associated with recent isolation, humans, and antimicrobial drug resistance. Predominant pulsotype 968 was associated specifically with fluoroquinolone resistance but not with extended-spectrum β-lactamase production or bla(CTX-M-15). Thus, several highly successful antimicrobial drug-resistant lineages within E. coli ST131 have recently emerged and diffused extensively among locales while maintaining a comparatively restricted host/source range. Identification of factors contributing to this behavior of ST131 could help protect public health.