Search

Objectives: To identifyHaemophilus species and characterise the antimicrobial susceptibility of isolates from patients with respiratory tract infections (RTIs) in Cameroon. Methods: Isolates (n = 95) were from patients with RTIs obtained from two hospitals in Yaoundé, Cameroon. Isolates were identified by biochemical assay, a polymerase chain reaction (PCR)-based method, matrix-assisted laser desorption ionization-time of flight (MALDI-TOF), and whole genome sequencing. Antibiotic minimum inhibitory concentrations were determined by E-test. Results: Haemophilus influenzae (H. influenzae) was the most prevalent species, varying from 76.8 to 84.2% according to the different methods. The isolates were mainly non-typeable (n = 70, 96%). Three H. influenzae isolates were capsulated (b, e and f). The isolates were genetically diverse and 40 unique sequence types were identified, including 11 new ones. Resistance to ampicillin was observed among 52 of 94 (55.3%), and 14 of the 52 (26.9%) produced TEM-1 β-lactamase. PBP3 mutations occurred in 40 of 52 (76.9%) ampicillin-resistant isolates. Eleven isolates were chloramphenicol-resistant, with eight of 10 (80%) producing chloramphenicol acetyltransferase. Four Haemophilus isolates were rifampicin-resistant, with two mutations in rpoB gene. Five isolates were ciprofloxacin-resistant and harboured mutations in the quinolone-resistance-determining regions of gyrA and parC genes. Conclusion: TheH. influenzae isolates were highly diverse and showed high levels of antibiotic resistance. H. influenzae serotype b is still circulating in the post-vaccination era.

International audience; Several phenanthrolinic analogs of quinolones have been synthesized and their antibacterial activity tested against Mycobacterium tuberculosis, other mycobacterial species and bacteria from other genera. Some of them show high activity (of the range observed for rifampicin) against M. tuberculosis replicating in vitro and in vivo (infected macrophages) conditions. These derivatives show the same activity with all or several M. tuberculosis complex bacterial mutants resistant to fluoroquinolones (FQ). This opens the way to the construction of new drugs for the treatment of FQ resistant bacterial infections, including tuberculosis. Several compounds showed also activity against Staphylococcus aureus and probably other species. These compounds do not show major toxicity. We conclude that the novel phenanthrolinic derivatives described here are potent hits for further developments of new antibiotics against bacterial infectious diseases including tuberculosis in particular those resistant to FQ.

International audience; OBJECTIVES:Malignant pleural mesothelioma (MPM) is an aggressive tumor with limited therapeutic options, requiring the development of efficient targeted therapies based on molecular phenotype of the tumor and to identify predictive biomarkers of the response.MATERIALS AND METHODS:The effect of inhibitors was investigated by cell viability assessment on primary MPM cell lines established in our laboratory from patient tumors, well characterized at the molecular level. Effects on apoptosis, cell proliferation and viability on MPM growing in multicellular spheroid were also assessed for verteporfin. Gene and protein expression, and gene knockdown by RNA interference were used to define mechanism of inhibition and specific predictive biomarkers.RESULTS:Anti-tumor effect of eight major signaling pathways inhibitors involved in mesothelial carcinogenesis was investigated. Three inhibitors were more efficient than cisplatin, the drug used as first-line chemotherapy in patients with MPM: verteporfin, a putative YAP inhibitor, defactinib, a FAK inhibitor and NSC668394, an Ezrin inhibitor. Verteporfin, the most efficient inhibitor, induced cell proliferation arrest and cell death, and is effective on 3D spheroid multicellular model. Verteporfin sensitivity was YAP-independent and related to molecular classification of the tumors. Biomarkers based on gene expression were identified to predict accurately sensitivity to these three inhibitors.CONCLUSION:Our study shows that drug screening on well-characterized MPM cells allows for the identification of novel potential therapeutic strategies and defining specific biomarkers predictive of the drug response.

The HIV-1 integrase (IN) and reverse transcriptase (RT) are essential enzymes in the virus cycle. RT is crucial for the retrotranscription of the RNA viral genome, while IN is involved in the insertion in host chromosome of the proviral double strand DNA produced by RT. This enzyme has two associated functions: the RNA- and DNA-dependent DNA polymerase (RDDP and DDDP) and the ribonuclease H (RNase H). The RNase H function catalyzes the selective hydrolysis of the RNA strand of the RNA:DNA heteroduplex replication intermediate. Since the discovery that catalytic cores of both HIV-1 RNase H and IN are folded in a very similar way, have very similar active site geometries, and show the same DDE triad absolutely required for catalytic activity, some researches were devoted to study IN and RNase H dual inhibitor. Our decennial interest in design and synthesis of IN inhibitors led us to study the activity of our compounds also on RNase H activity. The results of the activities showed by pyrrolyl and quinolonyl diketo acids are reported and discussed.

Maintaining quinolone concentrations outside the mutant selection window (MSW) between the MIC and mutant prevention concentration (MPC) was suggested by in vitro and in vivo studies to prevent the selection of resistant mutants. However, selection also may depend on the presence of resistant bacterial mutants at the start of treatment, which is highly dependent on the initial inoculum size. In this study, a mouse thigh bacterial infection model was used to test the influence of different exposures to marbofloxacin on the selection of resistant bacteria after infection with a low (10 5 CFU) or high (10 8 CFU) initial inoculum of Escherichia coli . The inoculum size was shown to influence the exposure to marbofloxacin and the values of pharmacokinetic/pharmacodynamic indices. When the abilities of the indices time within the MSW ( T MSW ), area under the concentration-time curve of 0 to 24 h divided by the MIC, and the maximum concentration of drug in plasma divided by the MIC to predict the selection of resistant bacteria were compared, only T MSW appeared to be a good predictor of the prevention of resistance for values less than 30%. When the T MSW was higher than 34%, the selection of resistant bacteria occurred less often in thighs initially infected with the low inoculum (11/24; 46%) than in those infected with the high inoculum (30/36; 80%), suggesting that the selection of resistant mutants depends on both the T MSW and inoculum size. The relevance of these results merits further investigation to test different strategies of antibiotic therapy depending on the expected bacterial burden at the infectious site.

We demonstrate using an in vitro pharmacodynamic model that the likelihood of selection of Escherichia coli mutants resistant to a fluoroquinolone was increased when the initial size of the bacterial population, exposed to fluoroquinolone concentrations within the mutant selection window, was increased.

INTRODUCTION: We have previously shown that FTI-277, a farnesyl transferase inhibitor (FTI), enhances the efficacy of tamoxifen (Tam) in inhibiting the proliferation of the estrogen dependent MCF-7 cell line. As the cellular response to Tam is the result of an inhibition of both estrogen receptor-dependent and -independent pathways, we have used the estrogen receptor selective anti-estrogen ICI182,780 and N-pyrrolidine(-phenylmethyl-phenoxy)-ethanamine-HCl (PBPE), a selective ligand of anti-estrogen binding site (AEBS), to dissect out the mechanism(s) associated with the observed additivity resulting from combination treatment with FTI-277 and Tam. Moreover, for these studies, FTI-277 has been replaced by R115,777, a FTI currently in phase III clinical trials. METHODS: The quantitative sulphorhodamine B (SRB) colorimetric assay was used to determine the growth inhibitory effect of agents on MCF-7 cells. Dose response interactions between R115,777-Tam, R115,777-ICI182,780 and R115,777-PBPE were evaluated, at the IC50 point, using the isobologram method. Apoptotic cell death (DNA fragmentation, nucleus condensation and cytokeratin 18 cleavage) and inhibition of the mevalonate pathway (western blot) were also determined. RESULTS: Combinations of the specific FTI R115,777 with either ICI182,780 or PBPE exhibit a synergistic effect on MCF-7 cell growth inhibition, while its combination with Tam is additive, as previously reported for FTI-277. Apoptosis is detected after treatment with combinations of R115,777 with either Tam or PBPE but not with ICI182,780, suggesting that each combination inhibits cell proliferation by different mechanisms. Even though the ER pathway has not yet been deciphered, it is shown here that the AEBS pathway is able to interfere with the mevalonate pathway at the level of protein farnesylation. CONCLUSION: Overall, this work reveals that combinations of R115,777 with either selective ER ligands or a selective AEBS ligand are able to induce large increases in their anti-proliferative activities on MCF-7 cells. Moreover, these results suggest that it may be of definite interest to evaluate combinations of R115,777 with different anti-estrogens in the treatment of ER positive breast tumours. Based on these experimental data, such combinations may prove beneficial in different clinical scenarios or when used in specific sequences; studying the combination of R115,777 with ICI182,780 for early treatment and reserving combinations with either Tam or a selective AEBS ligand, such as BMS-217380-01, for more resistant disease.

International audience; RATIONALE: Pulmonary arterial hypertension (PAH) is a progressive and fatal disease characterized by pulmonary arterial muscularization due to excessive pulmonary vascular cell proliferation and migration, a phenotype dependent upon growth factors and activation of receptor tyrosine kinases (RTKs). p130(Cas) is an adaptor protein involved in several cellular signaling pathways that control cell migration, proliferation, and survival. OBJECTIVES: We hypothesized that in experimental and human PAH p130(Cas) signaling is overactivated, thereby facilitating the intracellular transmission of signal induced by fibroblast growth factor (FGF)2, epidermal growth factor (EGF), and platelet-derived growth factor (PDGF). MEASUREMENTS AND MAIN RESULTS: In patients with PAH, levels of p130(Cas) protein and/or activity are higher in the serum, in the walls of distal pulmonary arteries, in cultured smooth muscle cells (PA-SMCs), and in pulmonary endothelial cells (P-ECs) than in control subjects. These abnormalities in the p130(Cas) signaling were also found in the chronically hypoxic mice and monocrotaline-injected rats as models of human PAH. We obtained evidence for the convergence and amplification of the growth-stimulating effect of the EGF-, FGF2-, and PDGF-signaling pathways via the p130(Cas) signaling pathway. We found that daily treatment with the EGF-R inhibitor gefitinib, the FGF-R inhibitor dovitinib, and the PDGF-R inhibitor imatinib started 2 weeks after a subcutaneous monocrotaline injection substantially attenuated the abnormal increase in p130(Cas) and ERK1/2 activation and regressed established pulmonary hypertension. CONCLUSIONS: Our findings demonstrate that p130(Cas) signaling plays a critical role in experimental and idiopathic PAH by modulating pulmonary vascular cell migration and proliferation and by acting as an amplifier of RTK downstream signals.

International audience; BACKGROUND: Several small diffusible molecules are involved in bacterial quorum sensing and virulence. The production of autoinducers-1 and -2, quinolone, indole and γ-amino butyrate signaling molecules was investigated in a set of soft-rot bacteria belonging to six Dickeya or Pectobacterium species including recent or emerging potato isolates. METHODOLOGY/PRINCIPAL FINDINGS: Using bacterial biosensors, immunoassay, and chromatographic analysis, we showed that soft-rot bacteria have the common ability to produce transiently during their exponential phase of growth the N-3-oxo-hexanoyl- or the N-3-oxo-octanoyl-l-homoserine lactones and a molecule of the autoinducer-2 family. Dickeya spp. produced in addition the indole-3-acetic acid in tryptophan-rich conditions. All these signaling molecules have been identified for the first time in the novel Dickeya solani species. In contrast, quinolone and γ-amino butyrate signals were not identified and the corresponding synthases are not present in the available genomes of soft-rot bacteria. To determine if the variations of signal production according to growth phase could result from expression modifications of the corresponding synthase gene, the respective mRNA levels were estimated by reverse transcriptase-PCR. While the N-acyl-homoserine lactone production is systematically correlated to the synthase expression, that of the autoinducer-2 follows the expression of an enzyme upstream in the activated methyl cycle and providing its precursor, rather than the expression of its own synthase. CONCLUSIONS/SIGNIFICANCE: Despite sharing the S-adenosylmethionine precursor, no strong link was detected between the production kinetics or metabolic pathways of autoinducers-1 and -2. In contrast, the signaling pathway of autoinducer-2 seems to be switched off by the indole-3-acetic acid pathway under tryptophan control. It therefore appears that the two genera of soft-rot bacteria have similarities but also differences in the mechanisms of communication via the diffusible molecules. Our results designate autoinducer-1 lactones as the main targets for a global biocontrol of soft-rot bacteria communications, including those of emerging isolates.

International audience; RATIONALE: Pulmonary arterial hypertension (PAH) is a progressive and fatal disease characterized by pulmonary arterial muscularization due to excessive pulmonary vascular cell proliferation and migration, a phenotype dependent upon growth factors and activation of receptor tyrosine kinases (RTKs). p130(Cas) is an adaptor protein involved in several cellular signaling pathways that control cell migration, proliferation, and survival. OBJECTIVES: We hypothesized that in experimental and human PAH p130(Cas) signaling is overactivated, thereby facilitating the intracellular transmission of signal induced by fibroblast growth factor (FGF)2, epidermal growth factor (EGF), and platelet-derived growth factor (PDGF). MEASUREMENTS AND MAIN RESULTS: In patients with PAH, levels of p130(Cas) protein and/or activity are higher in the serum, in the walls of distal pulmonary arteries, in cultured smooth muscle cells (PA-SMCs), and in pulmonary endothelial cells (P-ECs) than in control subjects. These abnormalities in the p130(Cas) signaling were also found in the chronically hypoxic mice and monocrotaline-injected rats as models of human PAH. We obtained evidence for the convergence and amplification of the growth-stimulating effect of the EGF-, FGF2-, and PDGF-signaling pathways via the p130(Cas) signaling pathway. We found that daily treatment with the EGF-R inhibitor gefitinib, the FGF-R inhibitor dovitinib, and the PDGF-R inhibitor imatinib started 2 weeks after a subcutaneous monocrotaline injection substantially attenuated the abnormal increase in p130(Cas) and ERK1/2 activation and regressed established pulmonary hypertension. CONCLUSIONS: Our findings demonstrate that p130(Cas) signaling plays a critical role in experimental and idiopathic PAH by modulating pulmonary vascular cell migration and proliferation and by acting as an amplifier of RTK downstream signals.

International audience; We report Salmonella enterica serotype Typhi strains with a nonclassical quinolone resistance phenotype (i.e., decreased susceptibility to ciprofloxacin but with susceptibility to nalidixic acid) associated with a nonsynonymous mutation at codon 464 of the gyrB gene. These strains, not detected by the nalidixic acid disk screening test, can result in fluoroquinolone treatment failure.

OprF is a general outer membrane porin of Pseudomonas aeruginosa , a well-known human opportunistic pathogen associated with severe hospital-acquired sepsis and chronic lung infections of cystic fibrosis patients. A multiphenotypic approach, based on the comparative study of a wild-type strain of P. aeruginosa , its isogenic oprF mutant, and an oprF -complemented strain, showed that OprF is required for P. aeruginosa virulence. The absence of OprF results in impaired adhesion to animal cells, secretion of ExoT and ExoS toxins through the type III secretion system (T3SS), and production of the quorum-sensing-dependent virulence factors pyocyanin, elastase, lectin PA-1L, and exotoxin A. Accordingly, in the oprF mutant, production of the signal molecules N -(3-oxododecanoyl)- l -homoserine lactone and N -butanoyl- l -homoserine lactone was found to be reduced and delayed, respectively. Pseudomonas quinolone signal (PQS) production was decreased, while its precursor, 4-hydroxy-2-heptylquinoline (HHQ), accumulated in the cells. Taken together, these results show the involvement of OprF in P. aeruginosa virulence, at least partly through modulation of the quorum-sensing network. This is the first study showing a link between OprF, PQS synthesis, T3SS, and virulence factor production, providing novel insights into virulence expression.

Introduction : Although independently acquired, plasmid-mediated quinolone resistance appears to be linked with extended-spectrum or AmpC-type beta-lactamases. Since no data are available in African countries, the prevalence of qnr genes at the University Hospital Ibn Rochd, Casablanca, Morocco, was investigated. Methodology: Between October 2006 and March 2007, the following 39 randomly selected non-duplicate Enterobacteriaceae producing an extended-spectrum beta-lactamase (ESBL), representing 20% of ESBL strains with respect to species and ward origin, were collected: Escherichia coli (n = 16); Klebsiella spp (n = 14); Enterobacter cloacae (n = 8); Proteus mirabilis (n = 1). Antibiotic susceptibility testing was performed according to CLSI guidelines. ESBL detection was performed by the double disc diffusion test. A multiplex PCR was conducted to detect qnrA , qnrB and qnrS genes that were confirmed by sequencing of the PCR product. Results: The estimated overall prevalence of qnr reached 36% (n = 14; qnrA , 10.25%; qnrB , 23.07%; qnrS , 2.56%). Genes were identified in E. coli , Klebsiella and Enterobacter with a respective prevalence of 18.7%, 50% and 62.5%. The qnr genes were detected in nine wards and qnrA1 , qnrB1-B2-B4 and qnrS1 variants were identified. Three genes were identified among nalidixic acid susceptible strains (n = 6); three of those were also susceptible to ciprofloxacin. Among nalidixic acid and ciprofloxacin resistant strains, all strains had qnrB . Conclusions: This study highlights the high prevalence of qnr genes among ESBL strains in the Ibn Rochd CHU, Casablanca. Moreover, qnr were present in quinolone-susceptible strains which could lead to in vivo selection of ciprofloxacin-resistant strains.

International audience; BACKGROUND: Our aim was to study the in vivo viral genetic pathways for resistance to raltegravir, in antiretroviral-experienced patients with virological failure (VF) on raltegravir-containing regimens. METHODS: We set up a prospective study including antiretroviral-experienced patients receiving raltegravir-based regimens. Integrase (IN) genotypic resistance analysis was performed at baseline. IN was also sequenced at follow-up points in the case of VF, i.e. plasma HIV-1 RNA>400 copies/mL at month 3 and/or >50 copies/mL at month 6. For phenotyping, the IN region was recombined with an IN-deleted HXB2-based HIV-1 backbone. A titrated amount of IN recombinant viruses was used for antiviral testing against raltegravir and elvitegravir. RESULTS: Among 51 patients, 11 (21.6%) had VF. Four different patterns of IN mutations were observed: (i) emergence of Q148H/R with secondary mutations (n=5 patients); (ii) emergence of N155H, then replaced by a pattern including Y143C/H/R (n=3); (iii) selection of S230N (n=1); and (iv) no evidence of selection of IN mutations (n=2). The median raltegravir and elvitegravir fold changes (FCs) were 244 (154-647) and 793 (339-892), respectively, for the Q148H/R pattern, while the median raltegravir and elvitegravir FCs were 21 (6-52) and 3 (2-3), respectively, with Y143C/H/R. The median plasma raltegravir Cmin was lower in patients with selection of the N155H mutation followed by Y143C/H/R compared with patients with Q148H/R and with patients without emerging mutations or without VF. CONCLUSIONS: Diverse genetic profiles can be associated with VF on raltegravir-containing regimens, including the dynamics of replacement of mutational profiles. Pharmacokinetic parameters could be involved in this genetic evolution.

International audience; We report a duplex real-time PCR assay for the simultaneous screening of mutations involved in fluoroquinolone resistance within gyrA and parC quninolone resistance-determining regions (QRDRs) in Neisseria gonorrhoeae. Our assay clearly detects all mutated QRDRs and allows the identification of common genotypes, whether the QRDRs contain single or double mutations, providing valuable epidemiological tools. When this method is used in conjunction with similar assays and in vitro analyses, essential antibiotic resistance surveillance can be performed for public health purposes.

This phase 3, multicenter, open-label study evaluated the efficacy and safety of tipifarnib compared with best supportive care (BSC), including hydroxyurea, as first-line therapy in elderly patients (≥70 years) with newly diagnosed, de novo, or secondary acute myeloid leukemia. A total of 457 patients were enrolled with 24% 80 years of age or older. Tipifarnib 600 mg orally twice a day was administered for the first 21 consecutive days, in 28-day cycles. The primary endpoint was overall survival. The median survival was 107 days for the tipifarnib arm and 109 days for the BSC arm. The hazard ratio (tipifarnib vs BSC) for overall survival was 1.02 (P value by stratified log-rank test, .843). The complete response rate for tipifarnib in this study (8%) was lower than that observed previously, but with a similar median duration of 8 months. The most frequent grade 3 or 4 adverse events were cytopenias in both arms, slightly more infections (39% vs 33%), and febrile neutropenia (16% vs 10%) seen in the tipifarnib arm. The results of this randomized study showed that tipifarnib treatment did not result in an increased survival compared with BSC, including hydroxyurea. This trial was registered at www.clinicaltrials.gov as #NCT00093990.

Autophagy is a lysosome-dependent degradative pathway frequently activated in tumor cells treated with chemotherapy or radiation. PARP-1 has been implicated in different pathways leading to cell death and its inhibition potentiates chemotherapy-induced cell death. Whether PARP-1 participates in the cell's decision to commit to autophagy following DNA damage is still not known. To address this issue PARP-1 wild-type and deficient cells have been treated with a dose of doxorubicin that induces autophagy. Electron microscopy examination and GFP-LC3 transfection revealed autophagic vesicles and increased expression of genes involved in autophagy (bnip-3, cathepsin b and l and beclin-1) in wild-type cells treated with doxo but not in parp-1(-/-) cells or cells treated with a PARP inhibitor. Mechanistically the lack of autophagic features in PARP-1 deficient/PARP inhibited cells is attributed to prevention of ATP and NAD(+) depletion and to the activation of the key autophagy regulator mTOR. Pharmacological or genetical inhibition of autophagy results in increased cell death, suggesting a protective role of autophagy induced by doxorubicin. These results suggest that autophagy might be cytoprotective during the response to DNA damage and suggest that PARP-1 activation is involved in the cell's decision to undergo autophagy.

International audience; INTRODUCTION: The cytotoxic activity of the farnesyltranseferase inhibitor R115777 was evaluated in cell lines representative of mantle cell lymphoma (MCL). METHODS: Cell growth, proliferation, and apoptosis were analyzed in four human MCL cell lines (Granta, NCEB, REC, and UPN1) in presence of R115777, alone or in combination with vincristin, doxorubicin, bortezomib, cisplatin and cytarabine. Inhibition of farnesylation was determined by the appearance of prelamin A. The antitumor activity of R115777, administered p.o. at 100, 250 and 500 mg/kg, was determined in vivo in nude mice xenografted with UPN1 cells. RESULTS: R115777 inhibited the growth of MCL cell lines in vitro with inhibitory concentrations ranging between 2 and 15 nM. A fifty percent decrease of cell viability was observed at concentrations comprised between 0.08 and 17 microM. Apoptosis, evaluated by annexin V and activated caspase 3 staining, was induced in all cell lines, in 40 to 71% of the cells depending on the cell lines. In addition, R115777 significantly increased the cytotoxic effect of vincristine, doxorubicin, bortezomib, cisplatin and cytarabine (p=0.001, p=0.016, p=0.006, p=0.014 and p=0.007 respectively). Exposure of MCL cell lines to R115777 during 72 hours resulted in inhibition of protein farnesylation. R115777 administered p.o. twice daily for 8 consecutive days to mice bearing established s.c. UPN1 xenograft displayed cytostatic activity at the 500 mg/kg dosage. CONCLUSION: We have demonstrated that inhibition of farnesyltransferase by R115777 was associated with growth inhibition and apoptosis of MCL cell lines in vitro and tumor xenograft stability in vivo.

We used the multilocus sequence typing (MLST) method to study the genetic diversity of Campylobacter coli isolated from chickens in Senegal, and to check the presence of genetic exchange with Campylobacter jejuni. In addition, we assessed the resistance of the isolates to ciprofloxacin and nalidixic acid, and their gyrA sequences. MLST revealed a low level of diversity and the absence of lineages among C. coli isolates. In addition, an exchange of alleles with C. jejuni was found. Twenty percent of the ciprofloxacin-resistant isolates lacked mutations within the quinolone resistance-determining region (QRDR) of GyrA. There was no link between quinolone resistance and sequence type (ST). © 2006 Elsevier Masson SAS All rights reserved.

International audience; Bacteria harbouring the novel qnrA plasmid-mediated mechanism of quinolone resistance have been described in different countries, but the frequency of their occurrence has not been investigated. In total, 1,468 clinical isolates of Enterobacteriaceae with quinolone resistance or extended-spectrum beta-lactamase (ESBL) phenotypes were collected from eight teaching hospitals in France during 2002-2005 and screened for qnrA. Overall, 28 isolates (22 Enterobacter cloacae, three Klebsiella pneumoniae, one Citrobacter freundii, one Klebsiella oxytoca and one Proteus mirabilis) were positive for qnrA, representing 1.9% of all isolates, 3.3% of ESBL-producing isolates (22% of the E. cloacae isolates) and 0% of non-ESBL-producing isolates. The prevalence of qnrA among consecutive ESBL-producing isolates in 2004 from the eight hospitals was 2.8% (18/639). Of the qnrA-positive isolates, 100% were intermediately-resistant or resistant to nalidixic acid, and 75% to ciprofloxacin. Twenty-one of the 22 qnrA-positive E. cloacae isolates were obtained from two hospitals in the Paris area, and molecular typing and plasmid content analysis showed clonal relationships for five, three and two isolates, respectively. The qnrA genetic environment was similar to that of the In36 integron. The remaining two isolates had qnrA variants (30 and 29 nucleotide differences, respectively, compared with the original sequence) and an unknown genetic environment. The ESBL gene associated with qnrA was bla(SHV-12) in most of the isolates, but bla(PER-1) and bla(SHV-2a) were found in two isolates. In France, it appears that qnrA-positive isolates are predominantly E. cloacae isolates producing SHV-12, and may be associated with the dissemination of an In36-like integron.

A qnrB2 determinant was described for a new complex sul1 -type integron from Salmonella enterica serovar Keurmassar. The genetic structure contained two class 1 integrons surrounding two common regions (CRs) separated by a partial 3′ conserved segment. The qnrB2 gene is adjacent to the first CR.

We used the multilocus sequence typing (MLST) method to evaluate the genetic diversity of 46 Campylobacter jejuni isolates from chickens and to determine the link between quinolone resistance and sequence type (ST). There were a total of 16 ST genotypes, and the majority of them belonged to seven clonal complexes previously identified by using isolates from human disease. The ST-353 complex was the most common complex, whereas the ST-21, ST-42, ST-52, and ST-257 complexes were less well represented. The resistance phenotype varied for each ST, and the Thr-86-Ile substitution in the GyrA protein was the predominant mechanism of resistance to quinolone. Nine of the 14 isolates having the Thr-86-Ile substitution belonged to the ST-353 complex. MLST showed that the emergence of quinolone resistance is not related to the diffusion of a unique clone and that there is no link between ST genotype and quinolone resistance. Based on silent mutations, different variants of the gyrA gene were shown to exist for the same ST. These data provide useful information for understanding the epidemiology of C. jejuni in Senegal.

p53 deficiency confers resistance to doxo (doxorubicin), a clinically active and widely used antitumour anthracycline antibiotic. The purpose of the present study was to investigate the reversal mechanism of doxo resistance by the potent PARP [poly(ADP-ribose) polymerase] inhibitor ANI (4-amino-1,8-naphthalimide) in the p53-deficient breast cancer cell lines EVSA-T and MDA-MB-231. The effects of ANI, in comparison with doxo alone, on doxo-induced apoptosis, were investigated in matched pairs of EVSA-T or MDA-MB-231 with or without ANI co-treatment. Doxo elicited PARP activation as determined by Western blotting and immunofluorescence of poly(ADP-ribose), and ANI enhanced the cytotoxic activity of doxo 2.3 times and in a caspase-dependent manner. The long-term cytotoxic effect was studied by a colony-forming assay. Using this assay, ANI also significantly potentiates the long-term cytotoxic effect with respect to treatment with doxo alone. Decrease in mitochondrial potential together with an increase in cytochrome c release, association of Bax with the mitochondria and caspase 3 activation were also observed in the presence of ANI. Therefore PARP inhibition may represent a novel way of selectively targeting p53-deficient breast cancer cells. The underlying mechanism is probably a potentiation of unrepaired DNA damage, shifting from DNA repair to apoptosis due to the effective inhibition of PARP activity.