scholarly journals A novel, double mutation in DNA gyrase A of Escherichia coli conferring resistance to quinolone antibiotics.

1997 ◽  
Vol 41 (1) ◽  
pp. 85-90 ◽  
Author(s):  
Q C Truong ◽  
J C Nguyen Van ◽  
D Shlaes ◽  
L Gutmann ◽  
N J Moreau
Keyword(s):  
Escherichia Coli ◽  
Nalidixic Acid ◽  
Acid Resistance ◽  
Gyra Gene ◽  
Double Mutation ◽  
E Coli ◽  
Quinolone Antibiotics ◽  
Gyrase A ◽  
Level Resistance ◽  
Nalidixic Acid Resistance

A spontaneous Escherichia coli mutant, named Q3, resistant to nalidixic acid was obtained from a previously described clinical isolate of E. coli, Q2, resistant to fluoroquinolones but susceptible to nalidixic acid (E. Cambau, F. Bordon, E. Collatz, and L. Gutmann, Antimicrob. Agents Chemother. 37:1247-1252, 1993). Q3 harbored the mutation Asp82Gly in addition to the Gly81Asp mutation of Q2. The different mutations leading to Gly81Asp, Asp82Gly, and Gly81AspAsp82Gly were introduced into the gyrA gene harbored on plasmid pJSW102, and the resulting plasmids were introduced into E. coli KNK453 (gyrAts) by transformation. The presence of Asp82Gly or Gly81Asp alone led to a low-level resistance to fluoroquinolones but not to nalidixic acid resistance. When both mutations were present, resistance to both nalidixic acid and fluoroquinolones was expressed. Purified gyrases of the different mutants showed similar rates of supercoiling. Dominance of the various gyrA mutant alleles harbored on plasmids was examined. The susceptibility to quinolones associated with wild-type gyrA was always dominant. The susceptibility to nalidixic acid expressed by the Gly81Asp mutant was dominant, while that expressed by the Asp82Gly mutant was recessive. From these results, we hypothesize that some amino acids within the quinolone resistance-determining region of gyrase A are more important for the association of subunits rather than for the activity of the holoenzyme.

scholarly journals Adaptation of Esherichia coli to Antiobiotic Cycling via Single Nucleotide Polymorphisms

2017 ◽  
Vol 14 (1) ◽  
Author(s):  
Samuel Hager ◽  
Ellen Jensen ◽  
Timothy Johnson ◽  
David Mitchell
Keyword(s):  
Escherichia Coli ◽  
Minimum Inhibitory Concentration ◽  
Nalidixic Acid ◽  
Inhibitory Concentration ◽  
Acid Resistance ◽  
Penicillin G ◽  
Single Nucleotide ◽  
E Coli ◽  
Esherichia Coli ◽  
Nalidixic Acid Resistance

Bacteria are quick to adapt and evolve, especially under the effects of selective pressures from chemical antibiotics. In addition, bacteria may develop resistance to antibiotics from multiple classes simultaneously, making their eradication from the human body particularly challenging. This study aims to demonstrate that bacterial multiple-drug resistance can be developed and retained in a laboratory setting. Escherichia coli B was grown in tryptic soy broth in the presence of a small, increasing concentration of streptomycin. This exposure resulted in a strain of E. coli, which had an increased minimum inhibitory concentration (MIC) towards streptomycin, or “resistance.” This resistant strain was then grown in like manner in nalidixic acid and then penicillin G. The result was a strain that became resistant to streptomycin and nalidixic acid, and increasingly resistant to nalidixic acid after penicillin G exposure. Additionally, the bacteria retained resistance to streptomycin and nalidixic acid even after exposure to those chemicals ceased. Genome sequencing and comparison to E. coli B reference strain REL606 revealed the emergence of point mutations with each exposure to an antibiotic. Of particular interest is a mutation associated with the appearance of nalidixic acid resistance. Base pair 4,553,488 was changed from adenine to guanine, resulting in a change from aspartate to glycine in the protein helicase. Previous studies have not indicated mutations to this locus as nalidixic acid resistance conferring. Thus, this mutation may be a novel mutation conferring E. coli B nalidixic acid resistance. Since the region of the mutated helicase is functionally undefined, a mechanism is not apparent. Further research needs to be done to confirm this hypothesis and illuminate a mechanism. KEYWORDS: Bacteria; Escherichia coli; Evolution; Antibiotic Resistance; Nalidixic Acid; Streptomycin; Point Mutation; Single-nucleotide Polymorphism; Helicase; Minimum Inhibitory Concentration

scholarly journals Transferable high-level trimethoprim resistance among isolates ofEscherichia colifrom urinary tract infections in Ontario, Canada

1992 ◽  
Vol 109 (3) ◽  
pp. 473-481 ◽  
Author(s):  
N. Harnett
Keyword(s):  
Nalidixic Acid ◽  
Antimicrobial Agents ◽  
Acid Resistance ◽  
The Public ◽  
E Coli ◽  
High Level ◽  
Tract Infections ◽  
K 12 ◽  
Level Resistance ◽  
Nalidixic Acid Resistance

SUMMARYOf 1171 isolates ofEscherichia coliisolated from urine samples at the Public Health Laboratory, Toronto, Ontario, Canada, between May 1990 and December 1991, 120 (10·3%) were resistant to trimethoprim (TMP), cotrimoxazole (TMP/SMX), sulfamethoxazole (SMX) and other antimicrobial agents; 110 of the 120 isolates (91·7%) were resistant to four or more agents. The majority of resistant isolates (91·7%) exhibited high-level resistance (MIC > 1000 mg/L) to TMP. The MIC of TMP/SMX for all 120 isolates was > 2·0/38·0 mg/L and for SMX > 1024 mg/L. High-level resistances were also present among the β-lactam antimicrobials with MICs ranging from 16- > 256 mg/L. Forty-three of 120 TMP-resistant (35·8%) isolates conjugally transferred TMP-resistance toE. coliK-12. Co-transfer of several other resistances was observed. SMX cotransferred from 86% of the 43 donors and β-lactams together with SMX cotransferred from 70%. Nalidixic acid resistance was present among 22 (18·3%) of the 120 resistant isolates, however, nalidixic acid resistance was not transferred toE. coliK-12.

scholarly journals Escherichia coli from community-acquired urinary tract infections resistant to fluoroquinolones and extended-spectrum beta-lactams

2007 ◽  
Vol 1 (03) ◽  
pp. 257-262 ◽  
Author(s):  
Samuel Kariuki ◽  
Gunturu Revathi ◽  
John Corkill ◽  
John Kiiru ◽  
Joyce Mwituria ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Nalidixic Acid ◽  
Urinary Tract Infections ◽  
Acid Resistance ◽  
Beta Lactam ◽  
E Coli ◽  
Extended Spectrum ◽  
Tract Infections ◽  
Multiple Drugs

Background: Uropathogenic Escherichia coli are increasingly becoming resistant to flouroquinolones and to other commonly available antimicrobials. We sought to investigate the genetic basis for fluoroquinolone and extended spectrum beta-lactam (ESBL) resistance in 17 fluoroquinolone-resistant (MIC of levofloxacin and ciprofloxacin >32 μg/ml) E. coli isolated from patients with urinary tract infections (UTIs). Methods: We applied PCR and Pulsed Field Gel Electrophoresis (PFGE) to characterize resistance genes and to determine clonal relatedness of strains, respectively. Results: Twelve of the 17 E. coli were resistant to multiple drugs, including ampicillin, co-amoxyclav, cefotaxime, ceftriaxone, ceftazidime and gentamicin and nalidixic acid and produced plasmid-mediated CTX-M-15 type ESBLs and CMY-2 AmpC type enzymes. The other 5 E. coli that were non-ESBL-producing were multiply resistant to ampicillin, nitrofurantoin, cefoxitin, nalidixic acid. Resistance to fluoroquinolones resulted from a combination of the presence of qnrA, qnrB, ciprofloxacin acetylating enzyme designated aac(6’)-1b-cr, and mutations in the two amino acid substitutions; 83 Serine (TCG) to Leucine (TTG) and 87 Aspartic acid (GAC) to Asparagine (AAC). Conclusion: Antibiogram patterns and PFGE of E. coli showed that these were community acquired UTI caused by pockets of clonally-related and some discreet strain types. Plasmid-mediated CTX-M-15 beta-lactamases and CMY-2 AmpC enzymes and fluoroquinolone resistant E. coli are becoming increasingly prevalent in hospitals in Kenya, posing a major challenge in the management of UTIs.

Determination of Ciprofloxacin and Nalidixic Acid Resistance in Campylobacter jejuni with a Fluorogenic Polymerase Chain Reaction Assay

2003 ◽  
Vol 66 (2) ◽  
pp. 319-323 ◽  
Author(s):  
PAWIN PADUNGTOD ◽  
JOHN B. KANEENE ◽  
DAVID L. WILSON ◽  
JULIA BELL ◽  
JOHN E. LINZ
Keyword(s):  
Polymerase Chain Reaction ◽  
Nalidixic Acid ◽  
Campylobacter Jejuni ◽  
Polymerase Chain Reaction Assay ◽  
Acid Resistance ◽  
Chain Reaction ◽  
Gyra Gene ◽  
In Vitro Susceptibility ◽  
Polymerase Chain ◽  
Nalidixic Acid Resistance

A fluorogenic polymerase chain reaction assay for the gyrA gene was used to determine the frequency of a Thr-86 mutation in Campylobacter jejuni isolates from food animals and humans in northern Thailand and to investigate the correlation between this mutation and bacterial resistance to fluoroquinolones. Eighty-four isolates of C. jejuni were used: 65 from healthy chickens on farms, 16 from chickens at the slaughterhouse, 1 from chicken meat at the market, and 1 from a healthy farm worker. The microbroth dilution technique was used for in vitro susceptibility testing. MIC breakpoints established by the National Antimicrobial Resistance Monitoring System were used to categorize the resistance of C. jejuni to ciprofloxacin and nalidixic acid. Sixty of the 84 C. jejuni isolates tested carried the Thr-86 mutation in the gyrA gene. All isolates with ciprofloxacin MICs of ≥ 2 mg/liter carried the mutation, and no isolates with nalidixic acid MICs of ≤16 mg/liter carried the Thr-86–to–Ile mutation. There was a very strong association between ciprofloxacin resistance and the presence of the mutation (kappa = 0.971, P < 0.01). The association between the presence of the Thr-86–to–Ile mutation and nalidixic acid resistance was weaker (kappa = 0.859; P ≤ 0.01).

scholarly journals Fluctuation analysis of mutations to nalidixic acid resistance in Escherichia coli.

1994 ◽  
Vol 176 (10) ◽  
pp. 2781-2787 ◽  
Author(s):  
L Boe ◽  
T Tolker-Nielsen ◽  
K M Eegholm ◽  
H Spliid ◽  
A Vrang
Keyword(s):  
Escherichia Coli ◽  
Nalidixic Acid ◽  
Acid Resistance ◽  
Fluctuation Analysis ◽  
Nalidixic Acid Resistance

Phenotypic and genetic characterization of multidrug-resistant Salmonella Infantis strains isolated from broiler chicken meats in Turkey

Biologia ◽  
2011 ◽  
Vol 66 (3) ◽  
Author(s):  
Duygu Abbasoglu ◽  
Mustafa Akcelık
Keyword(s):  
Nalidixic Acid ◽  
Acid Resistance ◽  
Molecular Size ◽  
Multidrug Resistant ◽  
Chromosomal Dna ◽  
Gyra Gene ◽  
Class I Integrons ◽  
Phenotypic And Genetic Characterization ◽  
Nalidixic Acid Resistance

AbstractTwenty Salmonella Infantis strains resistant against kanamycin, tetracycline, neomycin, spectinomycin, sulphonamide, nalidixic acid and trimethoprim were selected for this study out of 103 Salmonella strains isolated from broiler samples collected from several markets in the Bolu and Ankara regions of Turkey. The resistance genes aadA1, aphA1, sul1, tet(A), dfrA5/dfrA14 and gyrA were determined for these multidrug-resistant S. Infantis strains. S. Infantis strains contained a mega plasmid with the molecular size of 206 kb. The strains were divided into three groups according to the pulsed field gel electrophoresis patterns of XbaI digested chromosomal DNA. A Ser83→Tyr83 point mutation was found in the gyrA gene of all quinolone-resistant isolates. Filter mating experiments showed that 206 kb plasmid transferred nalidixic acid resistance associated with class I integrons.

Sign in / Sign up

Export Citation Format

Share Document