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Adela G De La Campa - One of the best experts on this subject based on the ideXlab platform.
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Characterization of Recombinant Fluoroquinolone-Resistant Pneumococcus-Like Isolates
Antimicrobial Agents and Chemotherapy, 2012Co-Authors: Luz Balsalobre, Montserrat Ortega, Adela G De La CampaAbstract:Fourteen fluoroquinolone-resistant streptococcal isolates with recombinant DNA topoisomerase genes, preliminarily identified as pneumococci, were further characterized using phenotypic and genotypic approaches. Phenotypic tests classified them as atypical pneumococci. Phylogenetic relationships were analyzed by using the sequences of seven housekeeping alleles from these isolates and from isolates of Streptococcus pneumoniae, Streptococcus mitis, Streptococcus oralis, and Streptococcus pseudopneumoniae. Four isolates grouped with S. pneumoniae, seven grouped with S. pseudopneumoniae, and three grouped with S. mitis. These results generally agreed with those obtained with an Optochin susceptibility test and with the organization of the atp operon chromosomal region, encoding the FoF1 H+-ATPase (the target of Optochin). All seven isolates grouping with S. pseudopneumoniae share the same spr1368-atpC-atpA gene order; all four grouping with S. pneumoniae share the spr1368-IS1239-atpC-atpA order, and two out of the three grouping with S. mitis share the spr1284-atpC-atpA order. In addition, evidence for recombination within the seven housekeeping alleles of the S. pseudopneumoniae population was provided by several methods: the index of association (0.4598, P < 0.001), the pairwise homoplasy index, and the split-decomposition method. This study confirms the existence of pneumococci among the alpha-hemolytic streptococci with DNA topoisomerase genes showing a mosaic structure and reveals a close relationship between atypical pneumococci and S. pseudopneumoniae.
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molecular characterization of disease associated streptococci of the mitis group that are Optochin susceptible
Journal of Clinical Microbiology, 2006Co-Authors: Luz Balsalobre, Asuncion Fenoll, Ernesto Garcia, Antonia Hernandezmadrid, Daniel Llull, Antonio J Martingaliano, Adela G De La CampaAbstract:Eight Optochin-susceptible (Opts) alpha-hemolytic (viridans) streptococcus isolates were characterized at the molecular level. These isolates showed phenotypic characteristics typical of both viridans streptococci and Streptococcus pneumoniae. Comparison of the sequence of housekeeping genes from these isolates with those of S. pneumoniae, Streptococcus mitis, Streptococcus oralis, and Streptococcus pseudopneumoniae suggested that the Opts isolates corresponded to streptococci of the mitis group. Besides, the Opts streptococci were negative by a Gen-Probe AccuProbe pneumococcus test and hybridized with specific pneumococcal probes (lytA and ply) but also with ant, a gene not present in most S. pneumoniae strains. Moreover, the isolates were insoluble in 1% sodium deoxycholate but completely dissolved in 0.1% deoxycholate. Sequence analysis of the lytA gene revealed that the Opts streptococci carried lytA alleles characteristic of those present in nonpneumococcal streptococci of the mitis group. The determination of the partial nucleotide sequence embracing the atp operon encoding the FoF1 H+-ATPase indicated that the Optochin susceptibility of the isolates was due to the acquisition of atpC, atpA, and part of atpB from S. pneumoniae by horizontal gene transfer.
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genetic characterization of Optochin susceptible viridans group streptococci
Antimicrobial Agents and Chemotherapy, 2003Co-Authors: Antonio J Martingaliano, Asuncion Fenoll, Luz Balsalobre, Adela G De La CampaAbstract:Two clinical isolates of viridans group streptococci (VS) with different degrees of susceptibility to Optochin (OPT), i.e., fully OPT-susceptible (Opts) VS strain 1162/99 (for which the MIC was equal to that for Streptococcus pneumoniae, 0.75 μg/ml) and intermediate Opts VS strain 1174/97 (MIC, 6 μg/ml) were studied. Besides being OPT susceptible, they showed characteristics typical of VS, such as bile insolubility; lack of reaction with pneumococcal capsular antibodies; and lack of hybridization with rRNA (AccuProbe)-, lytA-, and pnl-specific pneumococcal probes. However, these VS Opts strains and VS type strains hybridized with ant, a gene not present in S. pneumoniae. A detailed characterization of the genes encoding the 16S rRNA and SodA classified isolates 1162/99 and 1174/97 as Streptococcus mitis. Analysis of the atpCAB region, which encodes the c, a, and b subunits of the F0F1 H+-ATPase, the target of Optochin, revealed high degrees of similarity between S. mitis 1162/99 and S. pneumoniae in atpC, atpA, and the N terminus of atpB. Moreover, amino acid identity between S. mitis 1174/97 and S. pneumoniae was found in α helix 5 of the a subunit. The organization of the chromosomal region containing the atp operon of the two Opts VS and VS type strains was spr1284-atpC, with spr1284 being located 296 to 556 bp from atpC, whereas in S. pneumoniae this distance was longer than 68 kb. In addition, the gene order in S. pneumoniae was IS1239-74 bp-atpC. The results suggest that the full OPT susceptibility of S. mitis 1162/99 is due to the acquisition of atpC, atpA, and part of atpB from S. pneumoniae and that the intermediate OPT susceptibility of S. mitis 1174/97 correlates with the amino acid composition of its a subunit.
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molecular bases of three characteristic phenotypes of pneumococcus Optochin sensitivity coumarin sensitivity and quinolone resistance
Microbial Drug Resistance, 1997Co-Authors: Adela G De La Campa, Asuncion Fenoll, Ernesto Garcia, Rosario MunozAbstract:ABSTRACT Streptococcus pneumoniae is uniquely sensitive to amino alcohol antimalarials in the erythro configuration, such as Optochin, quinine, and quinidine. The protein responsible for the Optochin (quinine)-sensitive (Opts, Qins) phenotype of pneumococcus is the proteolipid c subunit of the F0F1 H+-ATPase. OptR/QinR isolates arose by point mutations in the atpC gene and produce different amino acid changes in one of the two transmembrane α-helices of the c subunit. In addition, comparison of the sequence of the atpCAB genes of S. pneumoniae R6 (Opts) and M222 (an OptR strain produced by interspecies recombination between pneumococcus and S. oralis), and S. oralis (OptR) revealed that, in M222, an interchange of atpC and atpA had ocurred. We also demonstrate that Optochin, quinine, and related compounds specifically inhibited the membrane-bound ATPase activity. Equivalent differences between Opts/Qins and OptR/QinR strains, both in growth inhibition and in membrane ATPase resistance, were found. Pneumoc...
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molecular basis of the Optochin sensitive phenotype of pneumococcus characterization of the genes encoding the f0 complex of the streptococcus pneumoniae and streptococcus oralis h atpases
Molecular Microbiology, 1994Co-Authors: Asuncion Fenoll, R Munoz, Ernesto Garcia, Adela G De La CampaAbstract:The gene responsible for the Optochin-sensitive (Opt S ) phenotype of Streptococcus pneumoniae has been characterized. Sequence comparisons indicated that the genes invovled encoded the subunits of the F 0 complex of an H + ATPase. Sequence analysis and transformaton experiments showed that the atpC gene is responsible for the Optochin-sensitive resistant (Opt S /Opf R ) phenotype. Our results also show that natural as well as laboratory Opt R uisolates have arisen by point mutations that produce also show that natural as well as laboratory Opt R isolates have arisen by point mutations that produce different amino acid changes at positions 48, 49 or 50 of the ATPase c subunit
Asuncion Fenoll - One of the best experts on this subject based on the ideXlab platform.
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Disease Isolates of Streptococcus pseudopneumoniae and Non-Typeable S. pneumoniae Presumptively Identified as Atypical S. pneumoniae in Spain
PLOS ONE, 2013Co-Authors: Dora Rolo, Asuncion Fenoll, Herminia De Lencastre, Alexandra S. Simões, Arnau Domenech, Josefina Liñares, Carmen Ardanuy, Raquel Sá-leãoAbstract:We aimed to obtain insights on the nature of a collection of isolates presumptively identified as atypical Streptococcus pneumoniae recovered from invasive and non-invasive infections in Spain. One-hundred and thirty-two isolates were characterized by: Optochin susceptibility in ambient and CO2-enriched atmosphere; bile solubility; PCR-based assays targeting pneumococcal genes lytA, ply, pspA, cpsA, Spn9802, aliB-like ORF2, and a specific 16S rRNA region; multilocus sequence analysis; and antimicrobial susceptibility. By multilocus sequence analysis, 61 isolates were S. pseudopneumoniae, 34 were pneumococci, 13 were S. mitis, and 24 remained unclassified as non-pneumococci. Among S. pseudopneumoniae isolates, 51 (83.6%) were collected from respiratory tract samples; eight isolates were obtained from sterile sources. High frequency of non-susceptibility to penicillin (60.7%) and erythromycin (42.6%) was found. Only 50.8% of the S. pseudopneumoniae isolates displayed the typical Optochin phenotype originally described for this species. None harbored the cpsA gene or the pneumococcal typical lytA restriction fragment length polymorphism. The Spn9802 and the specific 16S rRNA regions were detected among the majority of the S. pseudopneumoniae isolates (n = 59 and n = 49, respectively). The ply and pspA genes were rarely found. A high genetic diversity was found and 59 profiles were identified. Among the S. pneumoniae, 23 were capsulated and 11 were non-typeable. Three non-typeable isolates, associated to international non-capsulated lineages, were recovered from invasive disease sources. In conclusion, half of the atypical pneumococcal clinical isolates were, in fact, S. pseudopneumoniae and one-fourth were other streptococci. We identified S. pseudopneumoniae and non-typeable pneumococci as cause of disease in Spain including invasive disease.
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molecular characterization of disease associated streptococci of the mitis group that are Optochin susceptible
Journal of Clinical Microbiology, 2006Co-Authors: Luz Balsalobre, Asuncion Fenoll, Ernesto Garcia, Antonia Hernandezmadrid, Daniel Llull, Antonio J Martingaliano, Adela G De La CampaAbstract:Eight Optochin-susceptible (Opts) alpha-hemolytic (viridans) streptococcus isolates were characterized at the molecular level. These isolates showed phenotypic characteristics typical of both viridans streptococci and Streptococcus pneumoniae. Comparison of the sequence of housekeeping genes from these isolates with those of S. pneumoniae, Streptococcus mitis, Streptococcus oralis, and Streptococcus pseudopneumoniae suggested that the Opts isolates corresponded to streptococci of the mitis group. Besides, the Opts streptococci were negative by a Gen-Probe AccuProbe pneumococcus test and hybridized with specific pneumococcal probes (lytA and ply) but also with ant, a gene not present in most S. pneumoniae strains. Moreover, the isolates were insoluble in 1% sodium deoxycholate but completely dissolved in 0.1% deoxycholate. Sequence analysis of the lytA gene revealed that the Opts streptococci carried lytA alleles characteristic of those present in nonpneumococcal streptococci of the mitis group. The determination of the partial nucleotide sequence embracing the atp operon encoding the FoF1 H+-ATPase indicated that the Optochin susceptibility of the isolates was due to the acquisition of atpC, atpA, and part of atpB from S. pneumoniae by horizontal gene transfer.
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genetic characterization of Optochin susceptible viridans group streptococci
Antimicrobial Agents and Chemotherapy, 2003Co-Authors: Antonio J Martingaliano, Asuncion Fenoll, Luz Balsalobre, Adela G De La CampaAbstract:Two clinical isolates of viridans group streptococci (VS) with different degrees of susceptibility to Optochin (OPT), i.e., fully OPT-susceptible (Opts) VS strain 1162/99 (for which the MIC was equal to that for Streptococcus pneumoniae, 0.75 μg/ml) and intermediate Opts VS strain 1174/97 (MIC, 6 μg/ml) were studied. Besides being OPT susceptible, they showed characteristics typical of VS, such as bile insolubility; lack of reaction with pneumococcal capsular antibodies; and lack of hybridization with rRNA (AccuProbe)-, lytA-, and pnl-specific pneumococcal probes. However, these VS Opts strains and VS type strains hybridized with ant, a gene not present in S. pneumoniae. A detailed characterization of the genes encoding the 16S rRNA and SodA classified isolates 1162/99 and 1174/97 as Streptococcus mitis. Analysis of the atpCAB region, which encodes the c, a, and b subunits of the F0F1 H+-ATPase, the target of Optochin, revealed high degrees of similarity between S. mitis 1162/99 and S. pneumoniae in atpC, atpA, and the N terminus of atpB. Moreover, amino acid identity between S. mitis 1174/97 and S. pneumoniae was found in α helix 5 of the a subunit. The organization of the chromosomal region containing the atp operon of the two Opts VS and VS type strains was spr1284-atpC, with spr1284 being located 296 to 556 bp from atpC, whereas in S. pneumoniae this distance was longer than 68 kb. In addition, the gene order in S. pneumoniae was IS1239-74 bp-atpC. The results suggest that the full OPT susceptibility of S. mitis 1162/99 is due to the acquisition of atpC, atpA, and part of atpB from S. pneumoniae and that the intermediate OPT susceptibility of S. mitis 1174/97 correlates with the amino acid composition of its a subunit.
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molecular bases of three characteristic phenotypes of pneumococcus Optochin sensitivity coumarin sensitivity and quinolone resistance
Microbial Drug Resistance, 1997Co-Authors: Adela G De La Campa, Asuncion Fenoll, Ernesto Garcia, Rosario MunozAbstract:ABSTRACT Streptococcus pneumoniae is uniquely sensitive to amino alcohol antimalarials in the erythro configuration, such as Optochin, quinine, and quinidine. The protein responsible for the Optochin (quinine)-sensitive (Opts, Qins) phenotype of pneumococcus is the proteolipid c subunit of the F0F1 H+-ATPase. OptR/QinR isolates arose by point mutations in the atpC gene and produce different amino acid changes in one of the two transmembrane α-helices of the c subunit. In addition, comparison of the sequence of the atpCAB genes of S. pneumoniae R6 (Opts) and M222 (an OptR strain produced by interspecies recombination between pneumococcus and S. oralis), and S. oralis (OptR) revealed that, in M222, an interchange of atpC and atpA had ocurred. We also demonstrate that Optochin, quinine, and related compounds specifically inhibited the membrane-bound ATPase activity. Equivalent differences between Opts/Qins and OptR/QinR strains, both in growth inhibition and in membrane ATPase resistance, were found. Pneumoc...
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molecular basis of the Optochin sensitive phenotype of pneumococcus characterization of the genes encoding the f0 complex of the streptococcus pneumoniae and streptococcus oralis h atpases
Molecular Microbiology, 1994Co-Authors: Asuncion Fenoll, R Munoz, Ernesto Garcia, Adela G De La CampaAbstract:The gene responsible for the Optochin-sensitive (Opt S ) phenotype of Streptococcus pneumoniae has been characterized. Sequence comparisons indicated that the genes invovled encoded the subunits of the F 0 complex of an H + ATPase. Sequence analysis and transformaton experiments showed that the atpC gene is responsible for the Optochin-sensitive resistant (Opt S /Opf R ) phenotype. Our results also show that natural as well as laboratory Opt R uisolates have arisen by point mutations that produce also show that natural as well as laboratory Opt R isolates have arisen by point mutations that produce different amino acid changes at positions 48, 49 or 50 of the ATPase c subunit
Christian Martin - One of the best experts on this subject based on the ideXlab platform.
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a novel mutation in the α helix 1 of the c subunit of the f1 f0 atpase responsible for Optochin resistance of a streptococcus pneumoniae clinical isolate
Diagnostic Microbiology and Infectious Disease, 2000Co-Authors: Nadine Cogne, Jeanpierre Claverys, Francois Denis, Christian MartinAbstract:Abstract Previously reported mutations involved in Optochin resistance of Streptococcus pneumoniae clinical isolates changed residues 48, 49 or 50, in the transmembrane α-helix 2 of the F 1 /F 0 ATPase subunit. We report here an unusual mutation which changes the sequence of the transmembrane α-helix 1 of the AtpC subunit. This mutation involves a Gly to Ser substitution resulting from a G to A transition at codon 14 of the atpC gene.
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A novel mutation in the α-helix 1 of the C subunit of the F1/F0 ATPase responsible for Optochin resistance of a Streptococcus pneumoniae clinical isolate
Diagnostic Microbiology and Infectious Disease, 2000Co-Authors: Nadine Cogne, Jeanpierre Claverys, Francois Denis, Christian MartinAbstract:Abstract Previously reported mutations involved in Optochin resistance of Streptococcus pneumoniae clinical isolates changed residues 48, 49 or 50, in the transmembrane α-helix 2 of the F 1 /F 0 ATPase subunit. We report here an unusual mutation which changes the sequence of the transmembrane α-helix 1 of the AtpC subunit. This mutation involves a Gly to Ser substitution resulting from a G to A transition at codon 14 of the atpC gene.
Herminia De Lencastre - One of the best experts on this subject based on the ideXlab platform.
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Disease Isolates of Streptococcus pseudopneumoniae and Non-Typeable S. pneumoniae Presumptively Identified as Atypical S. pneumoniae in Spain
PLOS ONE, 2013Co-Authors: Dora Rolo, Asuncion Fenoll, Herminia De Lencastre, Alexandra S. Simões, Arnau Domenech, Josefina Liñares, Carmen Ardanuy, Raquel Sá-leãoAbstract:We aimed to obtain insights on the nature of a collection of isolates presumptively identified as atypical Streptococcus pneumoniae recovered from invasive and non-invasive infections in Spain. One-hundred and thirty-two isolates were characterized by: Optochin susceptibility in ambient and CO2-enriched atmosphere; bile solubility; PCR-based assays targeting pneumococcal genes lytA, ply, pspA, cpsA, Spn9802, aliB-like ORF2, and a specific 16S rRNA region; multilocus sequence analysis; and antimicrobial susceptibility. By multilocus sequence analysis, 61 isolates were S. pseudopneumoniae, 34 were pneumococci, 13 were S. mitis, and 24 remained unclassified as non-pneumococci. Among S. pseudopneumoniae isolates, 51 (83.6%) were collected from respiratory tract samples; eight isolates were obtained from sterile sources. High frequency of non-susceptibility to penicillin (60.7%) and erythromycin (42.6%) was found. Only 50.8% of the S. pseudopneumoniae isolates displayed the typical Optochin phenotype originally described for this species. None harbored the cpsA gene or the pneumococcal typical lytA restriction fragment length polymorphism. The Spn9802 and the specific 16S rRNA regions were detected among the majority of the S. pseudopneumoniae isolates (n = 59 and n = 49, respectively). The ply and pspA genes were rarely found. A high genetic diversity was found and 59 profiles were identified. Among the S. pneumoniae, 23 were capsulated and 11 were non-typeable. Three non-typeable isolates, associated to international non-capsulated lineages, were recovered from invasive disease sources. In conclusion, half of the atypical pneumococcal clinical isolates were, in fact, S. pseudopneumoniae and one-fourth were other streptococci. We identified S. pseudopneumoniae and non-typeable pneumococci as cause of disease in Spain including invasive disease.
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Optochin resistance among streptococcus pneumoniae strains colonizing healthy children in portugal
Journal of Clinical Microbiology, 2008Co-Authors: Sonia Nunes, Raquel Saleao, Herminia De LencastreAbstract:Two percent of 1,973 pneumococcus strains isolated from carriers since 2001 in Portugal were found to be Optochin resistant. These strains belonged to eight serotypes (and some were nontypeable), and they had diverse genetic backgrounds. Novel Optochin-resistant lineages were detected over time, suggesting that there was a continuous, although sporadic, emergence of Optochin resistance.
Jose Echenique - One of the best experts on this subject based on the ideXlab platform.
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subinhibitory concentrations of penicillin increase the mutation rate to Optochin resistance in streptococcus pneumoniae
Journal of Antimicrobial Chemotherapy, 2008Co-Authors: Paulo R Cortes, German E Pinas, Andrea Albarracin G Orio, Jose EcheniqueAbstract:Objectives: The aim of this work was to study the effect of subinhibitory concentrations of penicillin, chloramphenicol and erythromycin on the mutation rate of Streptococcus pneumoniae. Methods: The mutation rate to rifampicin and Optochin resistance was estimated using fluctuation analysis in three capsulated S. pneumoniae strains, cultured both with and without different subinhibitory antibiotic concentrations. The atpAC and rpoB mutations that conferred Optochin and rifampicin resistance, respectively, were identified by DNA sequencing. Results: The exposure to subinhibitory concentrations of penicillin increased the mutation rate (expressed as mutation per cell division) to Optochin resistance between 2.1- and 3.1-fold for all three strains studied. In contrast, the rifampicin resistance assay showed no significant variations. To analyse the putative cause of the different responses between the Optochin and rifampicin tests, mutations that conferred resistance in both cases were analysed. The difference may be explained by the genetic nature of the atpAC mutations, mostly transversions, which are not efficiently repaired by the HexAB mismatch repair system. Conclusions: We demonstrated that subinhibitory concentrations of penicillin significantly increased the mutation rate of S. pneumoniae, suggesting that exposure to this antibiotic could help this pathogen to acquire mutations that confer resistance to other antibiotics. The Optochin test was useful to detect this phenomenon and it should be considered for further mutability analysis in S. pneumoniae.
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characterization of in vitro generated and clinical Optochin resistant strains of streptococcus pneumoniae isolated from argentina
Journal of Clinical Microbiology, 2008Co-Authors: Paulo R Cortes, German E Pinas, Andrea Albarracin G Orio, Mabel Regueira, Jose EcheniqueAbstract:Optochin susceptibility is a key test used for pneumococcal diagnosis, but Optochin-resistant (Optr) pneumococci have been reported in the last 2 decades. In this work, we characterized eight Optr clinical strains which presented a new mutation, G47V, a predominant A49S mutation (recently reported in Brazil) and A49T. These mutations were found in the c subunit of the F0F1 ATPase encoded by the atpC gene, and W206C was found in the a subunit encoded by the atpA gene. The Optr clinical isolates were analyzed by BOX PCR, multilocus sequence typing, and serotype and antimicrobial resistance profiles, and they showed no epidemiological relationship. To characterize the Optr mutations that could emerge among clinical strains, we studied a pool of spontaneous Optr colonies obtained in vitro from the virulent D39 strain. We compared the atpAC mutations of these Optr pneumococci (with or without passage through C57BL/6 mice) with those described in the clinical isolates. This analysis revealed three new mutations, G47V and L26M in the c subunit and L184S in the a subunit. Most of the mutations identified in the laboratory-generated Optr strains were also found in clinical strains, with the exception of the L26M and L184S mutations, and we suppose that both mutations could emerge among invasive strains in the future. Considering that atpAC are essential genes, we propose that all spontaneous mutations that confer in vitro Optochin resistance would not present severe physiological alterations in S. pneumoniae and may be carried by circulating pneumococcal strains.