scholarly journals Impaired Parasite Attachment as Fitness Cost of Metronidazole Resistance in Giardia lamblia

2011 ◽  
Vol 55 (10) ◽  
pp. 4643-4651 ◽  
Author(s):  
Noa Tejman-Yarden ◽  
Maya Millman ◽  
Tineke Lauwaet ◽  
Barbara J. Davids ◽  
Frances D. Gillin ◽  
...  
Keyword(s):  
Glucose Metabolism ◽  
Cell Lines ◽  
Giardia Lamblia ◽  
Cross Resistance ◽  
Content Type ◽  
Metronidazole Resistance ◽  
High Level ◽  
Plastic Surfaces

ABSTRACTInfections with the diarrheagenic protozoan pathogenGiardia lambliaare most commonly treated with metronidazole (Mz). Treatment failures with Mz occur in 10 to 20% of cases and Mz resistance develops in the laboratory, yet clinically, Mz-resistant (Mzr)G. lambliahas rarely been isolated from patients. To understand why clinical Mzrisolates are rare, we questioned whether Mz resistance entails fitness costs to the parasite. Our studies employed several newly generated and established isogenic Mzrcell lines with stable, high-level resistance to Mz and significant cross-resistance to tinidazole, nitazoxanide, and furazolidone. Oral infection of suckling mice revealed that three of five Mzrcell lines could not establish infection, while two Mzrcell lines infected pups, albeit with reduced efficiencies. Failure to colonize resulted from a diminished capacity of the parasite to attach to the intestinal mucosain vivoand to epithelial cells and plastic surfacesin vitro. The attachment defect was related to impaired glucose metabolism, since the noninfectious Mzrlines consumed less glucose, and glucose promoted ATP-independent parasite attachment in the parental lines. Thus, resistance ofGiardiato Mz is accompanied by a glucose metabolism-related attachment defect that can interfere with colonization of the host. Because glucose-metabolizing pathways are important for activation of the prodrug Mz, it follows that a fitness trade-off exists between diminished Mz activation and reduced infectivity, which may explain the observed paucity of clinical Mzrisolates ofGiardia. However, the data also caution that some forms of Mz resistance do not markedly interfere within vivoinfectivity.

scholarly journals Evidence for Inhibition of Topoisomerase 1A by Gold(III) Macrocycles and Chelates TargetingMycobacterium tuberculosisandMycobacterium abscessus

2018 ◽  
Vol 62 (5) ◽  
Author(s):  
Rashmi Gupta ◽  
Carolina Rodrigues Felix ◽  
Matthew P. Akerman ◽  
Kate J. Akerman ◽  
Cathryn A. Slabber ◽  
...  
Keyword(s):  
Mycobacterium Abscessus ◽  
Cross Resistance ◽  
Human Pathogens ◽  
Intrinsic Resistance ◽  
Content Type ◽  
Starting Point ◽  
Scalable Synthesis ◽  
High Level ◽  
Novel Drug

ABSTRACTMycobacterium tuberculosisand the fast-growing speciesMycobacterium abscessusare two important human pathogens causing persistent pulmonary infections that are difficult to cure and require long treatment times. The emergence of drug-resistantM. tuberculosisstrains and the high level of intrinsic resistance ofM. abscessuscall for novel drug scaffolds that effectively target both pathogens. In this study, we evaluated the activity of bis(pyrrolide-imine) gold(III) macrocycles and chelates, originally designed as DNA intercalators capable of targeting human topoisomerase types I and II (Topo1 and Topo2), againstM. abscessusandM. tuberculosis. We identified a total of 5 noncytotoxic compounds active against both mycobacterial pathogens under replicatingin vitroconditions. We chose one of these hits, compound 14, for detailed analysis due to its potent bactericidal mode of inhibition and scalable synthesis. The clinical relevance of this compound was demonstrated by its ability to inhibit a panel of diverseM. tuberculosisandM. abscessusclinical isolates. Prompted by previous data suggesting that compound 14 may target topoisomerase/gyrase enzymes, we demonstrated that it lacked cross-resistance with fluoroquinolones, which target theM. tuberculosisgyrase.In vitroenzyme assays confirmed the potent activity of compound 14 against bacterial topoisomerase 1A (Topo1) enzymes but not gyrase. Novel scaffolds like compound 14 with potent, selective bactericidal activity againstM. tuberculosisandM. abscessusthat act on validated but underexploited targets like Topo1 represent a promising starting point for the development of novel therapeutics for infections by pathogenic mycobacteria.

scholarly journals Efficacy of Biocides Used in the Modern Food Industry To Control Salmonella enterica, and Links between Biocide Tolerance and Resistance to Clinically Relevant Antimicrobial Compounds

2012 ◽  
Vol 78 (9) ◽  
pp. 3087-3097 ◽  
Author(s):  
Orla Condell ◽  
Carol Iversen ◽  
Shane Cooney ◽  
Karen A. Power ◽  
Ciara Walsh ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Food Industry ◽  
Multidrug Resistant ◽  
Cross Resistance ◽  
Antimicrobial Compounds ◽  
Cross Tolerance ◽  
Content Type ◽  
Food Grade ◽  
High Level

ABSTRACTBiocides play an essential role in limiting the spread of infectious disease. The food industry is dependent on these agents, and their increasing use is a matter for concern. Specifically, the emergence of bacteria demonstrating increased tolerance to biocides, coupled with the potential for the development of a phenotype of cross-resistance to clinically important antimicrobial compounds, needs to be assessed. In this study, we investigated the tolerance of a collection of susceptible and multidrug-resistant (MDR)Salmonella entericastrains to a panel of seven commercially available food-grade biocide formulations. We explored their abilities to adapt to these formulations and their active biocidal agents, i.e., triclosan, chlorhexidine, hydrogen peroxide, and benzalkonium chloride, after sequential rounds ofin vitroselection. Finally, cross-tolerance of different categories of biocidal formulations, their active agents, and the potential for coselection of resistance to clinically important antibiotics were investigated. Six of seven food-grade biocide formulations were bactericidal at their recommended working concentrations. All showed a reduced activity against both surface-dried and biofilm cultures. A stable phenotype of tolerance to biocide formulations could not be selected. Upon exposure ofSalmonellastrains to an active biocidal compound, a high-level of tolerance was selected for a number ofSalmonellaserotypes. No cross-tolerance to the different biocidal agents or food-grade biocide formulations was observed. Most tolerant isolates displayed changes in their patterns of susceptibility to antimicrobial compounds. Food industry biocides are effective against planktonicSalmonella. When exposed to sublethal concentrations of individual active biocidal agents, tolerant isolates may emerge. This emergence was associated with changes in antimicrobial susceptibilities.

scholarly journals Pattern of pyruvate kinase isozymes in erythroleukemia cell lines and in normal human erythroblasts

Blood ◽  
1984 ◽  
Vol 64 (4) ◽  
pp. 930-936 ◽  
Author(s):  
I Max-Audit ◽  
U Testa ◽  
D Kechemir ◽  
M Titeux ◽  
W Vainchenker ◽  
...  
Keyword(s):  
Pyruvate Kinase ◽  
Cell Lines ◽  
Fetal Liver ◽  
Erythroid Cells ◽  
Low Concentrations ◽  
Erythroleukemia Cell ◽  
Erythroleukemic Cell ◽  
High Level

To further investigate the erythroid nature of the two human erythroleukemia cell lines, K562 and HEL-60, and to define the ontogeny of pyruvate kinase (PK) isozymes (R, M2) in developing human erythroid cells, we have studied the isozymic alterations, if any, during differentiation of these cell lines in vitro and normoblasts isolated from fetal liver in vivo. PK activity of erythroleukemic cell lines was intermediate between that observed in leukocytes and in fetal liver erythroblasts. These cell lines contained a high level of M2-PK, but R- PK was always present, albeit at low concentrations, in all the clones or subclones we studied. Erythroblasts from fetal liver were separated according to density on a Stractan gradient. R-PK levels were nearly constant in the different fractions, whereas M2-PK levels markedly decreased as the erythroblasts became mature and almost completely disappeared in late erythroid cells. Thus, these results clearly demonstrate the erythroid origin of these cell lines.

scholarly journals In VitroandIn VivoActivity of Solithromycin (CEM-101) against Plasmodium Species

2011 ◽  
Vol 56 (2) ◽  
pp. 703-707 ◽  
Author(s):  
Sergio Wittlin ◽  
Eric Ekland ◽  
J Carl Craft ◽  
Julie Lotharius ◽  
Ian Bathurst ◽  
...  
Keyword(s):  
Drug Exposure ◽  
Antimalarial Activity ◽  
Plasmodium Species ◽  
Parasite Clearance ◽  
Response To Treatment ◽  
Cross Resistance ◽  
Asexual Blood Stage ◽  
Content Type

ABSTRACTWith the emergence ofPlasmodium falciparuminfections exhibiting increased parasite clearance times in response to treatment with artemisinin-based combination therapies, the need for new therapeutic agents is urgent. Solithromycin, a potent new fluoroketolide currently in development, has been shown to be an effective, broad-spectrum antimicrobial agent. Malarial parasites possess an unusual organelle, termed the apicoplast, which carries a cryptic genome of prokaryotic origin that encodes its own translation and transcription machinery. Given the similarity of apicoplast and bacterial ribosomes, we have examined solithromycin for antimalarial activity. Other antibiotics known to target the apicoplast, such as the macrolide azithromycin, demonstrate a delayed-death effect, whereby treated asexual blood-stage parasites die in the second generation of drug exposure. Solithromycin demonstrated potentin vitroactivity against the NF54 strain ofP. falciparum, as well as against two multidrug-resistant strains, Dd2 and 7G8. The dramatic increase in potency observed after two generations of exposure suggests that it targets the apicoplast. Solithromycin also retained potency against azithromycin-resistant parasites derived from Dd2 and 7G8, although these lines did demonstrate a degree of cross-resistance. In anin vivomodel ofP. bergheiinfection in mice, solithromycin demonstrated a 100% cure rate when administered as a dosage regimen of four doses of 100 mg/kg of body weight, the same dose required for artesunate or chloroquine to achieve 100% cure rates in this rodent malaria model. These promisingin vitroandin vivodata support further investigations into the development of solithromycin as an antimalarial agent.

scholarly journals Genomic and Functional Analysis of Emerging Virulent and Multidrug-Resistant Escherichia coli Lineage Sequence Type 648

2019 ◽  
Vol 63 (6) ◽  
Author(s):  
Katharina Schaufler ◽  
Torsten Semmler ◽  
Lothar H. Wieler ◽  
Darren J. Trott ◽  
Johann Pitout ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
High Risk ◽  
Multidrug Resistant ◽  
Phenotypic Analysis ◽  
Content Type ◽  
Extended Spectrum Beta Lactamase ◽  
Niche Adaptation ◽  
High Level

ABSTRACT The pathogenic extended-spectrum-beta-lactamase (ESBL)-producing Escherichia coli lineage ST648 is increasingly reported from multiple origins. Our study of a large and global ST648 collection from various hosts (87 whole-genome sequences) combining core and accessory genomics with functional analyses and in vivo experiments suggests that ST648 is a nascent and generalist lineage, lacking clear phylogeographic and host association signals. By including large numbers of ST131 (n = 107) and ST10 (n = 96) strains for comparative genomics and phenotypic analysis, we demonstrate that the combination of multidrug resistance and high-level virulence are the hallmarks of ST648, similar to international high-risk clonal lineage ST131. Specifically, our in silico, in vitro, and in vivo results demonstrate that ST648 is well equipped with biofilm-associated features, while ST131 shows sophisticated signatures indicative of adaption to urinary tract infection, potentially conveying individual ecological niche adaptation. In addition, we used a recently developed NFDS (negative frequency-dependent selection) population model suggesting that ST648 will increase significantly in frequency as a cause of bacteremia within the next few years. Also, ESBL plasmids impacting biofilm formation aided in shaping and maintaining ST648 strains to successfully emerge worldwide across different ecologies. Our study contributes to understanding what factors drive the evolution and spread of emerging international high-risk clonal lineages.

Glutathione S-transferases in tracheobronchial epithelium

1995 ◽  
Vol 269 (4) ◽  
pp. L473-L481
Author(s):  
P. M. Reddy ◽  
C. P. Tu ◽  
R. Wu
Keyword(s):  
Cell Differentiation ◽  
Environmental Factors ◽  
Enzymatic Activity ◽  
Cell Lines ◽  
Mucous Cell ◽  
Collagen Gel ◽  
Bronchial Epithelium ◽  
High Level

The purpose of this study is to characterize glutathione S-transferase (GST) gene expression in airway epithelium both in vivo and in vitro. Immunohistochemical staining of nonhuman primate lungs of well-controlled healthy animals reveals the presence of alpha- and pi-class GST isoenzymes in ciliated bronchial epithelium. The stain of mu-GST antibody is either very low or absent in some of these monkey lungs. We observed that primary tracheobronchial epithelial (TBE) cells isolated from human and monkey pulmonary tissues maintain a relatively high level of GST enzymatic activity in culture, compared with various immortalized human TBE cell lines and other nonpulmonary cell lines. Northern blot analysis demonstrated the presence of mu-, pi-, and microsomal-GST messages but not the alpha-class message in cultures of primary TBE cells as well as in various human TBE cell lines. The expression of mu- and pi-class GST genes can be further regulated in culture by various environmental factors; however, most of these regulating factors are associated with TBE cell differentiation in culture. For instance, vitamin A treatment, which was shown to enhance mucous cell differentiation in vitro, stimulated the message levels of mu- and pi-class GST. Furthermore, plating cells on collagen gel substrata, which also enhanced mucous cell differentiation in culture, instead of plastic culture surface, enhanced total GST enzymatic activity by eightfold, and this enhancement is related to an increase in the expression of the pi-class GST gene. These results demonstrated that GST genes are differentially expressed and regulated by various environmental factors in primary TBE cells and various cell lines, and the regulation is correlated to the mucous cell differentiation in culture.

scholarly journals Pattern of pyruvate kinase isozymes in erythroleukemia cell lines and in normal human erythroblasts

Blood ◽  
1984 ◽  
Vol 64 (4) ◽  
pp. 930-936 ◽  
Author(s):  
I Max-Audit ◽  
U Testa ◽  
D Kechemir ◽  
M Titeux ◽  
W Vainchenker ◽  
...  
Keyword(s):  
Pyruvate Kinase ◽  
Cell Lines ◽  
Fetal Liver ◽  
Erythroid Cells ◽  
Low Concentrations ◽  
Erythroleukemia Cell ◽  
Erythroleukemic Cell ◽  
High Level

Abstract To further investigate the erythroid nature of the two human erythroleukemia cell lines, K562 and HEL-60, and to define the ontogeny of pyruvate kinase (PK) isozymes (R, M2) in developing human erythroid cells, we have studied the isozymic alterations, if any, during differentiation of these cell lines in vitro and normoblasts isolated from fetal liver in vivo. PK activity of erythroleukemic cell lines was intermediate between that observed in leukocytes and in fetal liver erythroblasts. These cell lines contained a high level of M2-PK, but R- PK was always present, albeit at low concentrations, in all the clones or subclones we studied. Erythroblasts from fetal liver were separated according to density on a Stractan gradient. R-PK levels were nearly constant in the different fractions, whereas M2-PK levels markedly decreased as the erythroblasts became mature and almost completely disappeared in late erythroid cells. Thus, these results clearly demonstrate the erythroid origin of these cell lines.

scholarly journals A New NonpolarN-Hydroxy Imidazoline Lead Compound with Improved Activity in a Murine Model of Late-Stage Trypanosoma brucei brucei Infection Is Not Cross-Resistant with Diamidines

2014 ◽  
Vol 59 (2) ◽  
pp. 890-904 ◽  
Author(s):  
Carlos H. Ríos Martínez ◽  
Florence Miller ◽  
Kayathiri Ganeshamoorthy ◽  
Fabienne Glacial ◽  
Marcel Kaiser ◽  
...  
Keyword(s):  
Trypanosoma Brucei ◽  
Late Stage ◽  
Parent Compound ◽  
Central Nervous System Infection ◽  
Sleeping Sickness ◽  
Intrinsic Activity ◽  
Cross Resistance ◽  
Content Type

ABSTRACTTreatment of late-stage sleeping sickness requires drugs that can cross the blood-brain barrier (BBB) to reach the parasites located in the brain. We report here the synthesis and evaluation of four newN-hydroxy and 12 newN-alkoxy derivatives of bisimidazoline leads as potential agents for the treatment of late-stage sleeping sickness. These compounds, which have reduced basicity compared to the parent leads (i.e., are less ionized at physiological pH), were evaluatedin vitroagainstTrypanosoma brucei rhodesienseandin vivoin murine models of first- and second-stage sleeping sickness. Resistance profile, physicochemical parameters,in vitroBBB permeability, and microsomal stability also were determined. TheN-hydroxy imidazoline analogues were the most effectivein vivo, with 4-((1-hydroxy-4,5-dihydro-1H-imidazol-2-yl)amino)-N-(4-((1-hydroxy-4,5-dihydro-1H-imidazol-2-yl)amino)phenyl)benzamide (14d) showing 100% cures in the first-stage disease, while 15d, 16d, and 17d appeared to slightly improve survival. In addition, 14d showed weak activity in the chronic model of central nervous system infection in mice. No evidence of reduction of this compound with hepatic microsomes and mitochondria was foundin vitro, suggesting thatN-hydroxy imidazolines are metabolically stable and have intrinsic activity againstT. brucei. In contrast to its unsubstituted parent compound, the uptake of 14d inT. bruceiwas independent of known drug transporters (i.e.,T. bruceiAT1/P2 and HAPT), indicating a lower predisposition to cross-resistance with other diamidines and arsenical drugs. Hence, theN-hydroxy bisimidazolines (14d in particular) represent a new class of promising antitrypanosomal agents.

Resistance to Bensulfuron-Methyl in Water Plantain (Alisma plantago-aquatica) Populations from Chilean Paddy Fields

2008 ◽  
Vol 22 (4) ◽  
pp. 602-608 ◽  
Author(s):  
Rodrigo Figueroa ◽  
Marlene Gebauer ◽  
Albert Fischer ◽  
Marcelo Kogan
Keyword(s):  
Weed Management ◽  
Wide Spectrum ◽  
Acetolactate Synthase ◽  
Rice Fields ◽  
Integrated Weed Management ◽  
Cross Resistance ◽  
Content Type ◽  
Als Inhibitors

Bensulfuron-methyl (BSM) has been one of the most widely used herbicides in Chilean rice fields because it controls a wide spectrum of weeds and does not require field drainage for application. However, failures of BSM to control water plantain in rice fields have been noted since 2002. We assessed BSM effects on suspected resistant (CU1 and CU2) and susceptible (AN1) water plantain accessions collected in Chilean rice fields during 2004 and 2005. BSM rates resulting in 50% growth reduction (GR50) of CU2 and CU1 plants were 12- and 33-fold higher than for AN1 plants, respectively. Acetolactate synthase (ALS) activity assays in vitro suggested resistance in CU1 and CU2 was due to an ALS enzyme with reduced BSM sensitivity compared to the AN1 biotype. Resistance indices (RI), or ratios of the resistant to susceptibleI50values (BSM rate to inhibit ALS-enzyme activity by 50%), were 266 (CU2/AN1) and > 38,462 (CU1/AN1). This agreed with in vivo ALS activity assays whereRIwere 224 (CU2/AN1) and > 8,533 (CU1/AN1). Resistance levels detected in whole-plant or in vivo ALS activity assays were orders of magnitude lower than those detected in in vitro ALS activity studies suggesting nontarget site mechanisms may have mitigated BSM toxicity. However, a consistent ranking of BSM sensitivity levels (AN1 > CU2 > CU1) throughout all three types of assays suggests resistance is primarily endowed by low target site sensitivity. We conclude that susceptible and resistant water plantain biotypes coexist in Chilean paddies, and the use of integrated weed management involving herbicides with a different mode of action would be imperative to prevent further evolution of resistance to BSM and possibly cross-resistance to other ALS inhibitors. In vitro ALS-enzyme assays provided the best discrimination of resistance levels between biotypes.

scholarly journals High-Level Pacidamycin Resistance in Pseudomonas aeruginosa Is Mediated by an Opp Oligopeptide Permease Encoded by theopp-fabIOperon

2013 ◽  
Vol 57 (11) ◽  
pp. 5565-5571 ◽  
Author(s):  
Anita Mistry ◽  
Mark S. Warren ◽  
John K. Cusick ◽  
RoxAnn R. Karkhoff-Schweizer ◽  
Olga Lomovskaya ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
High Frequency ◽  
Cross Resistance ◽  
Peptide Antibiotics ◽  
Content Type ◽  
Resistant Mutants ◽  
High Level ◽  
Level Resistance ◽  
Resistance Mutants

ABSTRACTPacidamycins (or uridyl peptide antibiotics) possess selectivein vivoactivity againstPseudomonas aeruginosa. An important limitation for the therapeutic use of pacidamycins withP. aeruginosais the high frequency (10−6to 10−7) at which resistant mutants emerge. To elucidate the mechanism(s) of this resistance, pacidamycin-resistantP. aeruginosamutants were isolated. Two types of mutants were obtained. Type 1, or high-level resistance mutants with a pacidamycin MIC of 512 μg/ml, were more abundant, with a frequency of ∼2 × 10−6, and did not show cross-resistance with other antibiotics. Type 2, low-level resistance mutants, were isolated with a frequency of ∼10−8and had a pacidamycin MIC of 64 μg/ml (the MIC for the wild-type strain was 4 to 16 μg/ml). These mutants were cross-resistant to levofloxacin, tetracycline, and erythromycin and were shown to overexpress either the MexAB-OprM or MexCD-OprJ multidrug resistance efflux pumps. High-level resistant mutants were isolated by transposon mutagenesis and one insertion was localized tooppB, one of two periplasmic binding protein components of an oligopeptide transport system which is encoded by theopp-fabIoperon. The Opp system is required for uptake of pacidamycin across the inner membrane, since variousopp, but notfabI, mutants were resistant to high levels of pacidamycin. Both of the two putative Opp periplasmic binding proteins, OppA and OppB, were required for pacidamycin uptake. Although both impaired uptake into and efflux from the cell can cause pacidamycin resistance inP. aeruginosa, our data suggest that impaired uptake is the primary reason for the high-frequency and high-level pacidamycin resistance.

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