scholarly journals Emergence of Reduced Susceptibility and Resistance to Fluoroquinolones in Escherichia coliin Taiwan and Contributions of Distinct Selective Pressures

2001 ◽  
Vol 45 (11) ◽  
pp. 3084-3091 ◽  
Author(s):  
L. Clifford McDonald ◽  
Feng-Jui Chen ◽  
Hsiu-Jung Lo ◽  
Hsiao-Chuan Yin ◽  
Po-Liang Lu ◽  
...  
Keyword(s):  
Single Point ◽  
Point Mutations ◽  
E Coli ◽  
Hospital Acquired Infections ◽  
Selective Pressures ◽  
Adult Inpatient ◽  
Resistant Strains ◽  
Single Point Mutations ◽  
Hospital Acquired ◽  
Susceptibility And Resistance

ABSTRACT A survey of 1,203 Escherichia coli isolates from 44 hospitals in Taiwan revealed that 136 (11.3%) isolates were resistant to fluoroquinolones and that another 261 (21.7%) isolates had reduced susceptibility. Resistance was more common in isolates responsible for hospital-acquired (mostly in intensive care units) infections (17.5%) than in other adult inpatient (11.4%; P = 0.08) and outpatient isolates (11.9%; P > 0.1). Similarly, reduced susceptibility was more common in isolates responsible for hospital-acquired infections (30.9%) than in other adult inpatient (21.0%; P = 0.04) and outpatient (21.4%; P = 0.06) isolates. Isolates from pediatric patients were less likely to be resistant (1.3 versus 12.0%; P < 0.01) but were nearly as likely to have reduced susceptibility (17.7 versus 21.9%;P > 0.1) as nonpediatric isolates. There was an inverse relationship in the proportion of isolates that were resistant versus the proportion that had reduced susceptibility among isolates from individual hospitals (R = 0.031; P < 0.05). In an analysis of isolates from two hospitals, all 9 resistant strains possessed double point mutations ingyrA and all 19 strains with reduced susceptibility strains had single point mutations; no mutations were found among fully susceptible strains. Risk factors for resistance included underlying cancer (odds ratio [OR], 83; 95% confidence interval [CI95], 7.3 to 2,241; P < 0.001), exposure to a quinolone (OR, undefined; P = 0.02), and exposure to a nonquinolone antibiotic (OR, 20; CI95, 2.2 to 482; P < 0.001); underlying cancer was the only independent risk factor (OR, 83; CI95, 8.6 to 807; P < 0.001). There were no significant associations between any of these factors and reduced susceptibility. Whereas acute and chronic quinolone use in cancer patients is a major selective pressure for resistance, other undetermined but distinct selective pressures appear to be more responsible for reduced susceptibility to fluoroquinolones in E. coli.

scholarly journals gyrA Mutations in Ciprofloxacin-Resistant Bartonella bacilliformis Strains Obtained In Vitro

2003 ◽  
Vol 47 (1) ◽  
pp. 383-386 ◽  
Author(s):  
Michael F. Minnick ◽  
Zachary R. Wilson ◽  
Laura S. Smitherman ◽  
D. Scott Samuels
Keyword(s):  
Single Point ◽  
Point Mutations ◽  
Dna Gyrase ◽  
Wild Type ◽  
Bartonella Bacilliformis ◽  
E Coli ◽  
A Subunit ◽  
Resistant Strains ◽  
Single Point Mutations

ABSTRACT We isolated and characterized mutants of Bartonella bacilliformis that are resistant to the fluoroquinolone antibiotic ciprofloxacin, which targets the A subunit of DNA gyrase. Mutants had single point mutations in the gyrA gene that changed either Asp-90 to Gly or Asp-95 to Asn and had 3- or 16-fold higher resistance, respectively, to ciprofloxacin than did wild-type B. bacilliformis. Asp-95 is homologous to Asp-87 of Escherichia coli GyrA and is a common residue mutated in fluoroquinolone-resistant strains of other bacteria. This is the first report of a mutation at an Asp-90 homologue, which corresponds to Asp-82 in E. coli GyrA.

scholarly journals First Characterization of Fluoroquinolone Resistance in Streptococcus suis

2006 ◽  
Vol 51 (2) ◽  
pp. 777-782 ◽  
Author(s):  
Jose Antonio Escudero ◽  
Alvaro San Millan ◽  
Ana Catalan ◽  
Adela G. de la Campa ◽  
Estefania Rivero ◽  
...  
Keyword(s):  
Horizontal Gene Transfer ◽  
Single Point ◽  
Point Mutations ◽  
Streptococcus Suis ◽  
Fluoroquinolone Resistance ◽  
Genes Encoding ◽  
Resistant Strains ◽  
Single Point Mutations ◽  
Clonal Spread

ABSTRACT We have identified and sequenced the genes encoding the quinolone-resistance determining region (QRDR) of ParC and GyrA in fluoroquinolone-susceptible and -resistant Streptococcus suis clinical isolates. Resistance is the consequence of single point mutations in the QRDRs of ParC and GyrA and is not due to clonal spread of resistant strains or horizontal gene transfer with other bacteria.

scholarly journals HIV recombination: what is the impact on antiretroviral therapy?

2005 ◽  
Vol 2 (5) ◽  
pp. 489-503 ◽  
Author(s):  
Christophe Fraser
Keyword(s):  
Antiretroviral Therapy ◽  
Single Point ◽  
Point Mutations ◽  
Wild Type Virus ◽  
Wild Type ◽  
Genetic Barrier ◽  
Resistant Strains ◽  
Single Point Mutations ◽  
The Impact ◽  
Retroviral Recombination

Retroviral recombination is a potential mechanism for the development of multiply drug resistant viral strains but the impact on the clinical outcomes of antiretroviral therapy in HIV-infected patients is unclear. Recombination can favour resistance by combining single-point mutations into a multiply resistant genome but can also hinder resistance by breaking up associations between mutations. Previous analyses, based on population genetic models, have suggested that whether recombination is favoured or hindered depends on the fitness interactions between loci, or epistasis. In this paper, a mathematical model is developed that includes viral dynamics during therapy and shows that population dynamics interact non-trivially with population genetics. The outcome of therapy depends critically on the changes to the frequency of cell co-infection and I review the evidence available. Where recombination does have an effect on therapy, it is always to slow or even halt the emergence of multiply resistant strains. I also find that for patients newly infected with multiply resistant strains, recombination can act to prevent reversion to wild-type virus. The analysis suggests that treatment targeted at multiple parts of the viral life-cycle may be less prone to drug resistance due to the genetic barrier caused by recombination but that, once selected, mutants resistant to such regimens may be better able to persist in the population.

Isolation of post operative hospital acquired infections in a private hospital of Bangladesh and identification of clonal relatedness of E. coli by using Pulse filed gel electrophoresis

2012 ◽  
Vol 6 (2) ◽  
pp. 7-10
Author(s):  
Mohammad Murshed ◽  
Sabeena Shahnaz ◽  
Md. Abdul Malek
Keyword(s):  
Private Hospital ◽  
Isolation And Identification ◽  
College Hospital ◽  
Hospital Acquired Infection ◽  
E Coli ◽  
Hospital Acquired Infections ◽  
Medical College ◽  
Clonal Relatedness ◽  
Hospital Acquired ◽  
Dressing Materials

Isolation and identification of post operative hospital acquired infection was carried out from July 2008 to December 2008 in Holy Family Red Crescent Medical College Hospital (private hospital). The major pathogen of wound infection was E. coli. A total; of 120 samples were collected from the surrounding environment of post operative room like floor, bed sheets, instruments, dressing materials, catheter, nasogastric and endotracheal tube. E. coli (40%) was the predominant organism followed by S. aureus (24%). DNA fingerprinting analysis using pulsed field gel electreopheresis of XbaI restriction digested genomic DNA showed that clonal relatedness between the two clinical nd environmental isolates were 100%.DOI: http://dx.doi.org/10.3329/bjmm.v6i2.19369 Bangladesh J Med Microbiol 2012; 06(02): 7-10

Cupin Variants as Macromolecular Ligand Library for Stereoselective Michael Addition of Nitroalkanes

2019 ◽  
Author(s):  
Nobutaka Fujieda ◽  
Miho Yuasa ◽  
Yosuke Nishikawa ◽  
Genji Kurisu ◽  
Shinobu Itoh ◽  
...  
Keyword(s):  
Michael Addition ◽  
In Silico ◽  
Addition Reaction ◽  
Single Point ◽  
Point Mutations ◽  
Unsaturated Ketone ◽  
Michael Addition Reaction ◽  
Beta Barrel ◽  
Cupin Superfamily ◽  
Single Point Mutations

Cupin superfamily proteins (TM1459) work as a macromolecular ligand framework with a double-stranded beta-barrel structure ligating to a Cu ion through histidine side chains. Variegating the first coordination sphere of TM1459 revealed that H52A and H54A/H58A mutants effectively catalyzed the diastereo- and enantio-selective Michael addition reaction of nitroalkanes to an α,β-unsaturated ketone. Moreover, in silico substrate docking signified C106N and F104W single-point mutations, which inverted the diastereoselectivity of H52A and further improved the stereoselectivity of H54A/H58A, respectively.

Single-Point Mutations in Qβ Virus-like Particles Change Binding to Cells

2021 ◽  
Author(s):  
Marisa L. Martino ◽  
Stephen N. Crooke ◽  
Marianne Manchester ◽  
M.G. Finn
Keyword(s):  
Single Point ◽  
Point Mutations ◽  
Virus Like Particles ◽  
Single Point Mutations

MinD directly interacting with FtsZ at the H10 helix suggests a model for robust activation of MinC to destabilize FtsZ polymers

2017 ◽  
Vol 474 (18) ◽  
pp. 3189-3205 ◽  
Author(s):  
Ashoka Chary Taviti ◽  
Tushar Kant Beuria
Keyword(s):  
Cell Division ◽  
Single Point ◽  
Point Mutations ◽  
Direct Interaction ◽  
Ring Formation ◽  
Z Ring ◽  
Single Point Mutations ◽  
Biochemical Analyses ◽  
Ftsz Assembly ◽  
The Mind

Cell division in bacteria is a highly controlled and regulated process. FtsZ, a bacterial cytoskeletal protein, forms a ring-like structure known as the Z-ring and recruits more than a dozen other cell division proteins. The Min system oscillates between the poles and inhibits the Z-ring formation at the poles by perturbing FtsZ assembly. This leads to an increase in the FtsZ concentration at the mid-cell and helps in Z-ring positioning. MinC, the effector protein, interferes with Z-ring formation through two different mechanisms mediated by its two domains with the help of MinD. However, the mechanism by which MinD triggers MinC activity is not yet known. We showed that MinD directly interacts with FtsZ with an affinity stronger than the reported MinC–FtsZ interaction. We determined the MinD-binding site of FtsZ using computational, mutational and biochemical analyses. Our study showed that MinD binds to the H10 helix of FtsZ. Single-point mutations at the charged residues in the H10 helix resulted in a decrease in the FtsZ affinity towards MinD. Based on our findings, we propose a novel model for MinCD–FtsZ interaction, where MinD through its direct interaction with FtsZ would trigger MinC activity to inhibit FtsZ functions.

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