Drugs online research references
Antimicrob Agents Chemother. 1992 May;36(5):1166-9.
Detection of gyrA gene mutations associated with ciprofloxacin resistance in methicillin-resistant Staphylococcus aureus: analysis by polymerase chain reaction and automated direct DNA sequencing.
Goswitz JJ, Willard KE, Fasching CE, Peterson LR.
Microbiology Section, VA Medical Center, Minneapolis, Minnesota.
A portion of the gyrA gene from amino acid codons 67 to 129 was sequenced in 34 methicillin-resistant Staphylococcus aureus strains (14 isolated in Minnesota, 10 isolated in Indiana, and 10 isolated in Tennessee). Twenty-eight of these strains were ciprofloxacin resistant. Sixteen of the strains contained a Ser----Leu mutation at codon 84; 3 contained strains a Ser----Ala mutation at codon 84; 3 strains contained two mutations, Ser----Leu at codon 84 and Ser----Pro at codon 85; and 6 strains contained a Glu----Lys mutation at codon 88. Six strains were wild type and ciprofloxacin susceptible. Several mutations from amino acid codons 84 through 88 can be associated with high-level quinolone resistance.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1510411&dopt=Abstract
Antimicrob Agents Chemother. 1998 Aug;42(8):2103-5.
Identification of novel mutation patterns in the parC gene of ciprofloxacin-resistant isolates of Neisseria gonorrhoeae.
Trees DL, Sandul AL, Whittington WL, Knapp JS.
Division of AIDS, STD, and TB Laboratory Research, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
Of 65 ciprofloxacin-resistant, clinical isolates of Neisseria gonorrhoeae, 5 isolates exhibited ParC mutations previously undescribed in the gonococcus. For isolates containing two ParC mutations (the Ser-87-->Ile and Glu-91-->Gly mutations and the Gly-85-->Cys and Arg116-->Leu mutations) the MICs of ciprofloxacin (8.0 to 64.0 microg/ml) were higher than those for the isolate containing the single ParC mutation (Arg-116-->Leu; MIC, 1.0 microg/ml).
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9687414&dopt=Abstract
Antimicrob Agents Chemother. 1995 Jul;39(7):1554-8.
Analysis of gyrA and grlA mutations in stepwise-selected ciprofloxacin-resistant mutants of Staphylococcus aureus.
Ferrero L, Cameron B, Crouzet J.
Departement des Biotechnologies, Rhone-Poulenc Rorer S.A., Vitry-sur-Seine, France.
Fluoroquinolone-resistant mutants were obtained in vitro from Staphylococcus aureus RN4220 by stepwise selection on increasing concentrations of ciprofloxacin. Results from sequence analysis of the quinolone resistance-determining region of GyrA and of the corresponding region of GrlA, the DNA topoisomerase IV subunit, showed an alteration of Ser-80 to Tyr (corresponding to Ser-83 of Escherichia coli GyrA) or Glu-84 to Lys in GrlA of both low- and high-level quinolone-resistant mutants. Second-step mutants were found to have, in addition to a mutation in grlA, reduced accumulation of norfloxacin or an alteration in GyrA at Ser-84 to Leu or Glu-88 to Lys. Third-step mutants derived from second-step mutants with reduced accumulation were found to have a mutation in gyrA. The results from this study demonstrated that mutations in gyrA or mutations leading to reduced drug accumulation occur after alteration of GrlA, supporting the previous findings (L. Ferrero, B. Cameron, B. Manse, D. Lagneaux, J. Crouzet, A. Famechon, and F. Blanche, Mol. Microbiol. 13:641-653, 1994) that DNA topoisomerase IV is a primary target of fluoroquinolones in S. aureus.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7492103&dopt=Abstract
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