33 research outputs found

    Time–kill curves showing effects of proton pump inhibitors (PPIs) on the activity of tigecycline.

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    <p>MIC<sub>T</sub>, MIC for tigecycline alone; MIC<sub>L5</sub> and MIC<sub>L50</sub>, MIC for tigecycline in combination with 5 mg/L and 50 mg/L lansoprazole; MIC<sub>A5</sub> and MIC<sub>A50</sub>, MIC for tigecycline in combination with 5 mg/L and 50 mg/L omeprazole; MIC<sub>P5</sub> and MIC<sub>P50</sub>, MIC for tigecycline in combination with 5 mg/L and 50 mg/L pantoprazole. •, Control; ▴, 50 mg/L lansoprazole; ▾, 50 mg/L omeprazole; ▪, 50 mg/L pantoprazole; Δ, 5 mg/L lansoprazole; ▽, 5 mg/L omeprazole; □, 5 mg/L pantoprazole; ○, tigecycline alone. The <i>in vitro</i> time-kill experiments were duplicated; mean values are plotted. In all duplicate experiments, similar time-kill results were obtained.</p

    Dendrogram displaying the PFGE profiles of the 43 isolates.

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    <p>The strain number, origin, source, sequence type (ST), and H<sub>2</sub>S phenotype are shown for each strain. +, H<sub>2</sub>S-producing isolate; −, non-H<sub>2</sub>S-producing isolate.</p

    Sequence alignment of the <i>phs</i> gene and the protein.

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    <p>A nonsense mutation at position 208 of the <i>phsA</i> gene results in the replacement of a sense codon (CAG) with a termination codon (UAG) leading to the premature termination of <i>phsA</i>. The first sequence, <i>phsA</i>, is based on <i>S</i>. enterica serotype Typhimurium strain LT2 (GenBank AE006468). *, termination codon; +, H<sub>2</sub>S-producing isolate; −, non-H<sub>2</sub>S-producing isolate.</p

    Dominant serotype distribution and antimicrobial resistance profile of <i>Shigella</i> spp. in Xinjiang, China

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    <div><p><i>Shigella</i> represents one of the major diarrhea-inducing pathogens threatening public health, but its prevalence and antimicrobial resistance profile in Xinjiang Uygur Autonomous region, China, remains unclear. We conducted comprehensive investigation of <i>Shigella</i> serotype distribution and antimicrobial resistance pattern in Xinjiang, identifying 458 <i>Shigella</i> isolates between 2008 to 2014. <i>Shigella flexneri</i> was identified as predominant species, and several <i>S</i>. <i>flexneri</i> serotypes were isolated, including atypical serotypes 1c, 2c, and 4s. Dominant <i>S</i>. <i>flexneri</i> serotypes were 2a, 1b, 2b, and Xv, different from those generally dominant in China. A hybrid serotype pattern was observed, which included the major Chinese serotypes (2a, Xv) and those predominant in Pakistan (1b, 2b). <i>Shigella sonnei</i> was shown to have a lower frequency compared with that generally observed in China, but an increasing trend of infections associated with this pathogen was observed. Furthermore, a high frequency of drug resistance and different <i>Shigella</i> antimicrobial resistance patterns were demonstrated as well, including very severe resistance phenotypes, such as multidrug resistance and resistance to frontline antibiotics. Seventy-five cephalosporin-resistant <i>Shigella</i> isolates were frequently identified with the resistance determinants that can undergo horizontal transfer, such as <i>bla</i><sub>OXA</sub>, <i>bla</i><sub>TEM</sub>, <i>bla</i><sub>CTX-M</sub>, and integrons, facilitating the development of cephalosporin resistance among <i>Shigella</i> subtypes. Additionally, genetic analyses demonstrated that all 86 quinolone-resistant <i>S</i>. <i>flexneri</i> isolates possess 3–4 mutation sites in quinolone resistance-determining regions, primarily contributing to their resistance to quinolone. However, <i>S</i>. <i>sonnei</i> isolates were not shown to be quinolone resistant. Co-resistance to cephalosporins and quinolones was detected in 17 <i>S</i>. <i>flexneri</i> isolates, and these isolates were additionally multidrug resistant and carried β-lactamase genes and quinolone-resistance determinants. As is demonstrated in this study, dominant serotypes of <i>Shigella</i> were distributed in unique trend with dangerous drug resistance patterns. Novel strategies are urgently required to prevent the development of drug resistance among diarrhea-inducing pathogens.</p></div

    Mutations detected in the <i>gyrA</i> and <i>parC</i> gene of H<sub>2</sub>S-negative <i>S</i>. Choleraesuis isolates.

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    <p>Ser, serine. Gly, glycine. Ala, alanine. Tyr, tyrosine. Cys, cysteine. Arg, arginine. Pro, proline.</p><p>Mutations detected in the <i>gyrA</i> and <i>parC</i> gene of H<sub>2</sub>S-negative <i>S</i>. Choleraesuis isolates.</p

    Antimicrobial Resistance and Molecular Investigation of H<sub>2</sub>S-Negative <i>Salmonella enterica</i> subsp. <i>enterica</i> serovar Choleraesuis Isolates in China

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    <div><p><i>Salmonella enterica</i> subsp. <i>enterica</i> serovar Choleraesuis is a highly invasive pathogen of swine that frequently causes serious outbreaks, in particular in Asia, and can also cause severe invasive disease in humans. In this study, 21 <i>S</i>. Choleraesuis isolates, detected from 21 patients with diarrhea in China between 2010 and 2011, were found to include 19 H<sub>2</sub>S-negative <i>S</i>. Choleraesuis isolates and two H<sub>2</sub>S-positive isolates. This is the first report of H<sub>2</sub>S-negative <i>S</i>. Choleraesuis isolated from humans. The majority of H<sub>2</sub>S-negative isolates exhibited high resistance to ampicillin, chloramphenicol, gentamicin, tetracycline, ticarcillin, and trimethoprim-sulfamethoxazole, but only six isolates were resistant to norfloxacin. In contrast, all of the isolates were sensitive to cephalosporins. Fifteen isolates were found to be multidrug resistant. In norfloxacin-resistant isolates, we detected mutations in the <i>gyrA</i> and <i>parC</i> genes and identified two new mutations in the <i>parC</i> gene. Pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and clustered regularly interspaced short palindromic repeat (CRISPR) analysis were employed to investigate the genetic relatedness of H<sub>2</sub>S-negative and H<sub>2</sub>S-positive <i>S</i>. Choleraesuis isolates. PFGE revealed two groups, with all 19 H<sub>2</sub>S-negative <i>S</i>. Choleraesuis isolates belonging to Group I and H<sub>2</sub>S-positive isolates belonging to Group II. By MLST analysis, the H<sub>2</sub>S-negative isolates were all found to belong to ST68 and H<sub>2</sub>S-positive isolates belong to ST145. By CRISPR analysis, no significant differences in CRISPR 1 were detected; however, one H<sub>2</sub>S-negative isolate was found to contain three new spacers in CRISPR 2. All 19 H<sub>2</sub>S-negative isolates also possessed a frame-shift mutation at position 760 of <i>phsA</i> gene compared with H<sub>2</sub>S-positive isolates, which may be responsible for the H<sub>2</sub>S-negative phenotype. Moreover, the 19 H<sub>2</sub>S-negative isolates have similar PFGE patterns and same mutation site in the <i>phs</i>A gene, these results indicated that these H<sub>2</sub>S-negative isolates may have been prevalent in China. These findings suggested that surveillance should be increased of H<sub>2</sub>S-negative <i>S</i>. Choleraesuis in China.</p></div