Current Issue : July - September Volume : 2015 Issue Number : 3 Articles : 7 Articles
Overexpression of the ABC transporter genes patA and patB confers efflux-mediated fluoroquinolone resistance in Streptococcus\npneumoniae and is also linked to pneumococcal stress responses. Although upregulation of patAB has been observed in many\nlaboratory mutants and clinical isolates, the regulatory mechanisms controlling expression of these genes are unknown. In this\nstudy, we aimed to identify the cause of high-level constitutive overexpression of patAB in M184, a multidrug-resistant mutant\nof S. pneumoniae R6. Using a whole-genome transformation and sequencing approach, we identified a novel duplication of a\n9.2-kb region of the M184 genome which included the patAB genes. This duplication did not affect growth and was semistable\nwith a low segregation rate. The expression levels of patAB in M184 were much higher than those that could be fully explained by\ndoubling of the gene dosage alone, and inactivation of the first copy of patA had no effect on multidrug resistance. Using a green\nfluorescent protein reporter system, increased patAB expression was ascribed to transcriptional read-through from a tRNA gene\nupstream of the second copy of patAB. This is the first report of a large genomic duplication causing antibiotic resistance in S.\npneumoniae and also of a genomic duplication causing antibiotic resistance by a promoter switching mechanism....
The plant Indigofera macrophylla Schum. and Thonn. is used ethno medicinally in the South-Southern and South-Western parts of Nigeria in the treatment of sores, skin eruptions and wounds. And as such this study aims to investigate the antimicrobial activity of this herb, in order to validate its uses in ethno medicine. The leaves of the plant were extracted in 50% ethanol for 72 hours. The extract was subjected to phytochemical screening to reveal classes of the chemical compounds. Using agar diffusion method, the extract was also subjected to antimicrobial tests such as sensitivity test, minimum inhibitory, minimum bactericidal and minimum fungicidal concentrations. Compounds such as alkaloids, saponins, tannins and cardiac glycosides were detected through phytochemical screening. The leaf extract exhibited varying activities against all the bacteria (Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa) and one of the two fungal (Candida albicans ) strains tested, with zones of inhibition that ranged between 7 and 34 mm. The minimum inhibitory concentration (MIC) for all microorganisms ranged between 12.5 µg/ml and 25 µg/ml. The minimum bactericidal concentration, MBC against the bacterial strains was 50 µg/ml, although there was no effect on Escherichia coli and Candida albicans. The result of this study shows that the leaf extract had both antifungal and antibacterial effects justifying its ethno medicinal use....
Aim of this research was to synthesize, characterize and antimicrobial evaluation of dipeptides. Solid phase peptide synthesis (SPPS) by fluorenyl methyl oxycarbonyl (Fmoc) chemistry protocol method was used. The compounds DP1 and DP2 were found to be extremely powerful inhibition against Bacillus subtillis at 6.25 µg/ml and Escherichia coli and Pseudomonas vulgaris at 12.5 µg/ml than standard (25 µg/ml). The percentage of reduction in the relative light unit (RLU) of the compound DP2 was 53.53% and 60.99% at 100 µg/ml against Mycobacterium tuberculosis H37Rv and clinical isolate of Mycobacterium tuberculosis (streptomycin, isoniazid, rifampicin and ethamputol resistant) as compared with control. Dipeptides were synthesized, characterized and exhibited promising antibacterial, antifungal and antimycobacterial activity....
Multidrug-resistant bacteria pose a major challenge to the clinical management of infections in resource-poor settings. Although\nnontyphoidal Salmonella (NTS) bacteria cause predominantly enteric self-limiting illness in developed countries, NTS is responsible\nfor a huge burden of life-threatening bloodstream infections in sub-Saharan Africa. Here, we characterized nine S. Typhimurium\nisolates from an outbreak involving patients who initially failed to respond to ceftriaxone treatment at a referral hospital\nin Kenya. These Salmonella enterica serotype Typhimurium isolates were resistant to ampicillin, chloramphenicol,\ncefuroxime, ceftriaxone, aztreonam, cefepime, sulfamethoxazole-trimethoprim, and cefpodoxime. Resistance to -lactams, including\nto ceftriaxone, was associated with carriage of a combination of blaCTX-M-15, blaOXA-1, and blaTEM-1 genes. The genes encoding\nresistance to heavy-metal ions were borne on the novel IncHI2 plasmid pKST313, which also carried a pair of class 1 integrons.\nAll nine isolates formed a single clade within S. Typhimurium ST313, the major clone of an ongoing invasive NTS\nepidemic in the region. This emerging ceftriaxone-resistant clone may pose a major challenge in the management of invasive\nNTS in sub-Saharan Africa....
Monoclonal antibodies can be seen as valuable tools for many aspects of basic\nas well as applied sciences. In the case of MET/HGFR, they allowed the identification of\ntruncated isoforms of the receptor, as well as the dissection of different epitopes,\nestablishing structureââ?¬â??function relationships. Antibodies directed against MET extracellular\ndomain were found to be full or partial receptor agonists or antagonists. The agonists can\nmimic the effects of the different isoforms of the natural ligand, but with the advantage of\nbeing more stable than the latter. Thus, some agonist antibodies promote all the biological\nresponses triggered by MET activation, including motility, proliferation, morphogenesis,\nand protection from apoptosis, while others can induce only a migratory response. On the\nother hand, antagonists can inhibit MET-driven biological functions either by competing\nwith the ligand or by removing the receptor from the cell surface. Since MET/HGFR is\noften over-expressed and/or aberrantly activated in tumors, monoclonal antibodies can be\nused as probes for MET detection or as ââ?¬Å?bulletsââ?¬Â to target MET-expressing tumor cells,\nthus pointing to their use in diagnosis and therapy....
The present investigation was designed to check antimicrobial activity of leaves Musa sapientum L. and development of suitable dosage form. Leaves of Musa sapientum were collected, air dried, powdered and extracted with ethanol, 50% ethanol and water by maceration method and subjected for phytochemical analysis. Antimicrobial activity of extracts was carried out by the agar well diffusion method and tube dilution method. The extracts were tested on clinical isolates include aerobic, facultative bacteria namely Stapyhlococcus aureus ATCC 25921, Escherichia coli ATCC 25922, Bacillus subtilis and fungus Aspergillus niger. Ethanolic extracts showed greater antimicrobial activity than aqueous and hydroalcoholic extracts. The Minimum inhibitory concentration (MIC) of ethanolic extract varied from species of microorganisms, it was found to be 1.5 to 2.5 mg/ml. Further ethanolic extract was used for preparation of topical formulations such as gel (2.5%) and ointment (2.5%). TLC and HPTLC pattern of extract, gel and ointment was compared which showed no change in Rf and 3D spectrum. Then both the formulations are evaluated for their antimicrobial activity, physical characteristics and stability study....
The emergence of drug-resistant parasites is a serious threat faced by malaria control programs. Understanding the genetic basis\nof resistance is critical to the success of treatment and intervention strategies. A novel locus associated with antimalarial resistance,\nap2-mu (encoding the mu chain of the adaptor protein 2 [AP2] complex), was recently identified in studies on the rodent\nmalaria parasite Plasmodium chabaudi (pcap2-mu). Furthermore, analysis in Kenyan malaria patients of polymorphisms in the\nPlasmodium falciparum ap2-mu homologue, pfap2-mu, found evidence that differences in the amino acid encoded by codon 160\nare associated with enhanced parasite survival in vivo following combination treatments which included artemisinin derivatives.\nHere, we characterize the role of pfap2-mu in mediating the in vitro antimalarial drug response of P. falciparum by generating\ntransgenic parasites constitutively expressing codon 160 encoding either the wild-type Ser (Ser160) or the Asn mutant\n(160Asn) form of pfap2-mu. Transgenic parasites carrying the pfap2-mu 160Asn allele were significantly less sensitive to dihydroartemisinin\nusing a standard 48-h in vitro test, providing direct evidence of an altered parasite response to artemisinin. Our\ndata also provide evidence that pfap2-mu variants can modulate parasite sensitivity to quinine. No evidence was found that\npfap2-mu variants contribute to the slow-clearance phenotype exhibited by P. falciparum in Cambodian patients treated with\nartesunate monotherapy. These findings provide compelling evidence that pfap2-mu can modulate P. falciparum responses to\nmultiple drugs. We propose that this gene should be evaluated further as a potential molecular marker of antimalarial resistance....
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