scholarly journals Alteration in the GyrA Subunit of DNA Gyrase and the ParC Subunit of DNA Topoisomerase IV in Quinolone-Resistant Clinical Isolates ofStaphylococcus epidermidis

1998 ◽  
Vol 42 (12) ◽  
pp. 3293-3295 ◽  
Author(s):  
Zhiyu Li ◽  
Takashi Deguchi ◽  
Mitsuru Yasuda ◽  
Takeshi Kawamura ◽  
Emiko Kanematsu ◽  
...  
Keyword(s):  
Staphylococcus Epidermidis ◽  
Dna Gyrase ◽  
Clinical Isolates ◽  
Fluoroquinolone Resistance ◽  
Simultaneous Presence ◽  
Topoisomerase Iv ◽  
Dna Topoisomerase ◽  
High Level

ABSTRACT We examined 22 clinical isolates of Staphylococcus epidermidis to analyze the association of alterations in GyrA and ParC with fluoroquinolone resistance. The simultaneous presence of GyrA and ParC alterations was associated with a high level of fluoroquinolone resistance in the clinical isolates of S. epidermidis.

scholarly journals Alterations in the GyrA Subunit of DNA Gyrase and the ParC Subunit of DNA Topoisomerase IV Associated with Quinolone Resistance in Enterococcus faecalis

1998 ◽  
Vol 42 (2) ◽  
pp. 433-435 ◽  
Author(s):  
Emiko Kanematsu ◽  
Takashi Deguchi ◽  
Mitsuru Yasuda ◽  
Takeshi Kawamura ◽  
Yoshinori Nishino ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Dna Gyrase ◽  
Quinolone Resistance ◽  
Clinical Isolates ◽  
Fluoroquinolone Resistance ◽  
Primary Target ◽  
Topoisomerase Iv ◽  
Dna Topoisomerase ◽  
High Level

ABSTRACT The gyrA and parC genes of 31 clinical isolates of Enterococcus faecalis, including fluoroquinolone-resistant isolates, were partially sequenced and analyzed for target alterations. Topoisomerase IV may be a primary target in E. faecalis, but high-level fluoroquinolone resistance was associated with simultaneous alterations in both GyrA and ParC.

Topoisomerase Sequences of Coagulase-Negative Staphylococcal Isolates Resistant to Ciprofloxacin or Trovafloxacin

1999 ◽  
Vol 43 (7) ◽  
pp. 1631-1637 ◽  
Author(s):  
Donald T. Dubin ◽  
Joseph E. Fitzgibbon ◽  
Massoumeh D. Nahvi ◽  
Joseph F. John
Keyword(s):  
Dna Gyrase ◽  
Fluoroquinolone Resistance ◽  
Topoisomerase Iv ◽  
Dna Topoisomerase ◽  
Methicillin Resistant ◽  
Intraspecies Variation ◽  
Rrna Sequencing ◽  
Identification Of Species ◽  
Resistant Strains ◽  
Ciprofloxacin Resistance

ABSTRACT Coagulase-negative staphylococcal isolates (n = 188) were screened for susceptibility to oxacillin, ciprofloxacin, and trovafloxacin, a new fluoroquinolone. At an oxacillin concentration of ≥4 μg/ml, 43% were methicillin resistant; of these, 70% were ciprofloxacin resistant (MIC, ≥4 μg/ml). Of the methicillin-resistant, ciprofloxacin-resistant isolates, 46% were susceptible to ≤2 μg of trovafloxacin per ml and 32% were susceptible to ≤1 μg of trovafloxacin per ml. Sixteen isolates, including twelve that expressed fluoroquinolone resistance, were chosen for detailed analysis. Identification of species by rRNA sequencing revealed a preponderance of Staphylococcus haemolyticus andS. hominis among fluoroquinolone-resistant strains. Segments of genes (gyrA and grlA) encoding DNA gyrase and DNA topoisomerase IV were sequenced. Considerable interspecies variation was noted, mainly involving noncoding nucleotide changes. Intraspecies variation consisted of coding changes associated with fluoroquinolone resistance. As for S. aureus, ciprofloxacin resistance (MIC, ≥8 μg/ml) and increased trovafloxacin MICs (0.25 to 2 μg/ml) could be conferred by the combined presence of single mutations in each gyrA and grlA gene. Trovafloxacin MICs of ≥8 μg/ml also occurred, but these required an additional mutation in grlA.

scholarly journals DNA Sequence Analysis of DNA Gyrase and DNA Topoisomerase IV Quinolone Resistance-Determining Regions of Salmonella enterica Serovar Typhi and Serovar Paratyphi A

2002 ◽  
Vol 46 (10) ◽  
pp. 3249-3252 ◽  
Author(s):  
Kenji Hirose ◽  
Ai Hashimoto ◽  
Kazumichi Tamura ◽  
Yoshiaki Kawamura ◽  
Takayuki Ezaki ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
Dna Sequence ◽  
Salmonella Enterica ◽  
Dna Gyrase ◽  
Quinolone Resistance ◽  
Fluoroquinolone Resistance ◽  
Single Mutation ◽  
Topoisomerase Iv ◽  
Dna Topoisomerase ◽  
Salmonella Enterica Serovar Typhi

ABSTRACT The mutations that are responsible for fluoroquinolone resistance in the gyrA, gyrB, parC, and parE genes of Salmonella enterica serovar Typhi and serovar Paratyphi A were investigated. The sequences of the quinolone resistance-determining region of the gyrA gene in clinical isolates which showed decreased susceptibilities to fluoroquinolones had a single mutation at either the Ser-83 or the Asp-87 codon, and no mutations were found in the gyrB, parC, and parE genes.

scholarly journals DNA Gyrase and Topoisomerase IV Mutations Associated with Fluoroquinolone Resistance in Proteus mirabilis

2002 ◽  
Vol 46 (8) ◽  
pp. 2582-2587 ◽  
Author(s):  
L. M. Weigel ◽  
G. J. Anderson ◽  
F. C. Tenover
Keyword(s):  
Proteus Mirabilis ◽  
Bacterial Species ◽  
Clinical Isolates ◽  
Fluoroquinolone Resistance ◽  
Unexpected Result ◽  
Topoisomerase Iv ◽  
Frequent Event ◽  
Nucleotide Insertion ◽  
High Level ◽  
Susceptibility Profiles

ABSTRACT Mutations associated with fluoroquinolone resistance in clinical isolates of Proteus mirabilis were determined by genetic analysis of the quinolone resistance-determining region (QRDR) of gyrA, gyrB, parC, and parE. This study included the P. mirabilis type strain ATCC 29906 and 29 clinical isolates with reduced susceptibility (MIC, 0.5 to 2 μg/ml) or resistance (MIC, ≥4 μg/ml) to ciprofloxacin. Susceptibility profiles for ciprofloxacin, clinafloxacin, gatifloxacin, gemifloxacin, levofloxacin, moxifloxacin, and trovafloxacin were correlated with amino acid changes in the QRDRs. Decreased susceptibility and resistance were associated with double mutations involving both gyrA (S83R or -I) and parC (S80R or -I). Among these double mutants, MICs of ciprofloxacin varied from 1 to 16 μg/ml, indicating that additional factors, such as drug efflux or porin changes, also contribute to the level of resistance. For ParE, a single conservative change of V364I was detected in seven strains. An unexpected result was the association of gyrB mutations with high-level resistance to fluoroquinolones in 12 of 20 ciprofloxacin-resistant isolates. Changes in GyrB included S464Y (six isolates), S464F (three isolates), and E466D (two isolates). A three-nucleotide insertion, resulting in an additional lysine residue between K455 and A456, was detected in gyrB of one strain. Unlike any other bacterial species analyzed to date, mutation of gyrB appears to be a frequent event in the acquisition of fluoroquinolone resistance among clinical isolates of P. mirabilis.

scholarly journals Novel Ser79Leu and Ser81Ile Substitutions in the Quinolone Resistance-Determining Regions of ParC Topoisomerase IV and GyrA DNA Gyrase Subunits from Recent Fluoroquinolone-Resistant Streptococcus pneumoniae Clinical Isolates

2005 ◽  
Vol 49 (6) ◽  
pp. 2479-2486 ◽  
Author(s):  
Nataliya Korzheva ◽  
Todd A. Davies ◽  
Raul Goldschmidt
Keyword(s):  
Streptococcus Pneumoniae ◽  
Amino Acid ◽  
Dna Gyrase ◽  
Quinolone Resistance ◽  
Clinical Isolates ◽  
Fluoroquinolone Resistance ◽  
Amino Acid Substitutions ◽  
Topoisomerase Iv ◽  
Isogenic Strains ◽  
New Mutations

ABSTRACT Resistance of Streptococcus pneumoniae to fluoroquinolones is caused predominantly by amino acid substitutions at positions Ser79 of ParC and Ser81 of GyrA to either Phe or Tyr encoded in the quinolone resistance-determining regions of the parC topoisomerase IV and gyrA DNA gyrase genes. Analysis of highly resistant clinical isolates identified novel second-step substitutions, Ser79Leu (ParC) and Ser81Ile (GyrA). To determine contributions of these new mutations to fluoroquinolone resistance either alone or in combination with other Ser79/81 alleles, the substitutions Ser79Leu/Phe/Tyr in ParC and Ser81Ile/Phe/Tyr in GyrA were introduced into the R6 background, resulting in 15 isogenic strains. Their level of fluoroquinolone resistance was determined by susceptibility testing for ciprofloxacin, levofloxacin, moxifloxacin, gatifloxacin, gemifloxacin, garenoxacin, and norfloxacin. Leu79 and Ile81 alone as well as 79/81Phe/Tyr substitutions did not contribute significantly to resistance, with fluoroquinolone MICs increasing two- to fourfold compared to wild type for all agents tested. Fluoroquinolone MICs for double transformants ParC Ser79Phe/Tyr/Leu-GyrA Ser81Phe/Tyr were uniformly increased by 8- to 64-fold regardless of pairs of amino acid substitutions. However, combinations including Ile81 conferred two- to fourfold-higher levels of resistance than did combinations including any other Ser81 GyrA substitution, thus demonstrating the differential effects of diverse amino acid substitutions at particular hotspots on fluoroquinolone MICs.

scholarly journals Combination of known and unknown mechanisms confers high-level resistance to fluoroquinolones in Enterococcus faecium

2006 ◽  
Vol 55 (6) ◽  
pp. 729-736 ◽  
Author(s):  
Yoshihiro Oyamada ◽  
Hideaki Ito ◽  
Kouichi Fujimoto ◽  
Reiko Asada ◽  
Toshiyuki Niga ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Efflux Pump ◽  
Point Mutations ◽  
Clinical Isolates ◽  
Fluoroquinolone Resistance ◽  
Bacterial Cells ◽  
Topoisomerase Iv ◽  
High Level ◽  
Spontaneous Mutants

In order to elucidate the mechanisms of fluoroquinolone resistance in Enterococcus faecium, spontaneous mutants isolated from Ent. faecium ATCC 19434 by stepwise selection with sparfloxacin (SPX) or norfloxacin (NOR) and 13 clinical isolates of Ent. faecium were characterized by analysing quinolone-resistance-determining regions (QRDRs) of the gyrA, gyrB, parC and parE genes and examining changes in MICs of SPX and NOR in the presence of efflux pump inhibitors. The SPX-selected first-step mutant had a point mutation only in gyrA, and the mutants QR7-18 and QR7-39, and clinical isolates that had point mutations in parC, showed NOR resistance. These results indicate that the primary targets of SPX and NOR are DNA gyrase and topoisomerase IV, respectively, and therefore that the primary target of fluoroquinolones in Ent. faecium differs depending on the structure of the compound used. The characterization of the spontaneous mutants and the clinical isolates demonstrates that in addition to the previously reported alterations in GyrA and ParC, an alteration in GyrB, a NorA-like pump, an unknown efflux pump, which excretes both SPX and NOR from bacterial cells, and probably other unknown mechanism(s) all contribute to fluoroquinolone resistance in Ent. faecium.

scholarly journals Activities of Fluoroquinolones againstStreptococcus pneumoniae Type II Topoisomerases Purified as Recombinant Proteins

1999 ◽  
Vol 43 (11) ◽  
pp. 2579-2585 ◽  
Author(s):  
Ian Morrissey ◽  
John George
Keyword(s):  
Streptococcus Pneumoniae ◽  
Recombinant Proteins ◽  
Dna Gyrase ◽  
Fluoroquinolone Resistance ◽  
Wild Type ◽  
Topoisomerase Iv ◽  
Low Level ◽  
Cloning Method ◽  
High Level ◽  
Level Resistance

ABSTRACT Streptococcus pneumoniae topoisomerase IV and DNA gyrase have been purified from a fluoroquinolone-susceptibleStreptococcus pneumoniae strain, from first-step mutants showing low-level resistance to ciprofloxacin, sparfloxacin, levofloxacin, and ofloxacin, and from two clinical isolates showing intermediate- and high-level fluoroquinolone resistance by a gene cloning method that produces recombinant proteins fromEscherichia coli. The concentrations of ciprofloxacin, sparfloxacin, levofloxacin, or ofloxacin required to inhibit wild-type topoisomerase IV were 8 to 16 times lower than those required to inhibit wild-type DNA gyrase. Furthermore, low-level resistance to these fluoroquinolones was entirely due to the reduced inhibitory activity of fluoroquinolones against topoisomerase IV. For all the laboratory strains, the 50% inhibitory concentration for topoisomerase IV directly correlated with the MIC. We therefore propose that withS. pneumoniae, ciprofloxacin, sparfloxacin, levofloxacin, and ofloxacin target topoisomerase IV in preference to DNA gyrase. Sitafloxacin, on the other hand, was found to be equipotent against either enzyme. This characteristic is unique for a fluoroquinolone. A reduction in the sensitivities of both topoisomerase IV and DNA gyrase are required, however, to achieve intermediate- or high-level fluoroquinolone resistance in S. pneumoniae.

scholarly journals Fluoroquinolone Resistance Mutations in the parC,parE, and gyrA Genes of Clinical Isolates of Viridans Group Streptococci

1998 ◽  
Vol 42 (11) ◽  
pp. 2792-2798 ◽  
Author(s):  
Irene González ◽  
Marios Georgiou ◽  
Fernando Alcaide ◽  
Delia Balas ◽  
Josefina Liñares ◽  
...  
Keyword(s):  
Nucleotide Sequences ◽  
Quinolone Resistance ◽  
Fluoroquinolone Resistance ◽  
Resistance Mutations ◽  
Topoisomerase Iv ◽  
Dna Topoisomerase ◽  
Low Level ◽  
Equivalent Residue ◽  
High Level ◽  
Viridans Group Streptococci

ABSTRACT The nucleotide sequences of the quinolone resistance-determining regions (QRDRs) of the parC and gyrA genes from seven ciprofloxacin-resistant (Cpr) isolates of viridans group streptococci (two high-level Cpr Streptococcus oralis and five low-level Cpr Streptococcus mitis isolates) were determined and compared with those obtained from susceptible isolates. The nucleotide sequences of the QRDRs of the parE and gyrBgenes from the five low-level Cpr S. mitisisolates and from the NCTC 12261 type strain were also analyzed. Four of these low-level Cpr isolates had changes affecting the subunits of DNA topoisomerase IV: three in Ser-79 (to Phe or Ile) of ParC and one in ParE at a position not previously described to be involved in quinolone resistance (Pro-424). One isolate did not show any mutation. The two high-level Cpr S. oralisisolates showed mutations affecting equivalent residue positions of ParC and GyrA, namely, Ser-79 to Phe and Ser-81 to Phe or Tyr, respectively. The parC mutations were able to transformStreptococcus pneumoniae to ciprofloxacin resistance, while the gyrA mutations transformed S. pneumoniaeonly when mutations in parC were present. These results suggest that DNA topoisomerase IV is a primary target of ciprofloxacin in viridans group streptococci, DNA gyrase being a secondary target.

scholarly journals Mutations in the gyrA, parC, and parE Genes Associated with Fluoroquinolone Resistance in Clinical Isolates of Mycoplasma hominis

1999 ◽  
Vol 43 (4) ◽  
pp. 954-956 ◽  
Author(s):  
Cécile M. Bebear ◽  
Joel Renaudin ◽  
Alain Charron ◽  
Hélène Renaudin ◽  
Bertille de Barbeyrac ◽  
...  
Keyword(s):  
Amino Acid ◽  
Mycoplasma Hominis ◽  
Dna Gyrase ◽  
Quinolone Resistance ◽  
Clinical Isolates ◽  
Fluoroquinolone Resistance ◽  
Amino Acid Substitutions ◽  
Topoisomerase Iv

ABSTRACT Five clinical isolates of Mycoplasma hominis from three different patients were examined for resistance to fluoroquinolones; some of these isolates were probably identical. All five isolates harbored amino acid substitutions in the quinolone resistance-determining regions of both DNA gyrase (GyrA) and topoisomerase IV (ParC or ParE). Furthermore, the novobiocin MIC for three isolates showed a significant increase. This is the first characterization of fluoroquinolone-resistant clinical mycoplasma isolates from humans.

scholarly journals Alterations in the GyrA subunit of DNA gyrase and the ParC subunit of topoisomerase IV in quinolone-resistant clinical isolates of Klebsiella pneumoniae.

1997 ◽  
Vol 41 (3) ◽  
pp. 699-701 ◽  
Author(s):  
T Deguchi ◽  
A Fukuoka ◽  
M Yasuda ◽  
M Nakano ◽  
S Ozeki ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Dna Gyrase ◽  
Quinolone Resistance ◽  
Clinical Isolates ◽  
Fluoroquinolone Resistance ◽  
Primary Target ◽  
Gyra Gene ◽  
Topoisomerase Iv ◽  
Complementary Role

We determined a partial sequence of the Klebsiella pneumoniae parC gene, including the region analogous to the quinolone resistance-determining region of the Escherichia coli gyrA gene, and examined 26 clinical strains of K. pneumoniae for an association of alterations in GyrA and ParC with susceptibilities to quinolones. The study suggests that in K. pneumoniae DNA gyrase is a primary target of quinolones and that ParC alterations play a complementary role in the development of higher-level fluoroquinolone resistance.

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