English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Background  The objective of this study was to examine  Streptococcus pneumoniae  isolates collected from a longitudinal surveillance program in order to determine their susceptibility to currently used fluoroquinolones and of the frequency and type of mutations in the quinolone-resistant determining regions (QRDRs) of their  parC  and  gyrA  genes.    Methods  The Canadian Bacterial Surveillance Network has been collecting clinical isolates of  S. pneumoniae  from across Canada since 1988. Broth microdilution susceptibility testing was carried out according to the Clinical and Laboratory Standards Institute guidelines. The QRDRs of the  parC  and  gyrA  genes were sequenced for all isolates with ciprofloxacin MIC ≥ 4 mg/L, and a large representative sample of isolates (N = 4,243) with MIC ≤ 2 mg/L.    Results  A total of 4,798 out of 30,111 isolates collected from 1988, and 1993 to 2007 were studied. Of those isolates that were successfully sequenced, 184 out of 1,032 with mutations in  parC  only, 11 out of 30 with mutations in  gyrA  only, and 292 out of 298 with mutations in  parC  and  gyrA  were considered resistant to ciprofloxacin (MIC ≥ 4 mg/L). The most common substitutions in the  parC  were at positions 137 (n = 722), 79 (n = 209), and 83 (n = 56), of which substitutions at positions 79 and 83 were associated with 4-fold increase in MIC to ciprofloxacin, whereas substitutions at position 137 had minimal effect on the ciprofloxacin MIC. A total of 400 out of 622 isolates with Lys-137  parC  mutation belonged to serotypes 1, 12, 31, 7A, 9V, 9N and 9L, whereas only 49 out of 3064 isolates with no mutations belonged to these serotypes. Twenty-one out of 30 isolates with substitutions at position 81 of the  gyrA  gene had an increased MIC to ciprofloxacin. Finally, we found that isolates with mutations in both  parC  and  gyrA  were significantly associated with increased MIC to fluoroquinolones.    Conclusions  Not all mutations, most frequently Lys-137, found in the QRDRs of the  parC  gene of  S. pneumoniae  is associated with an increased MIC to fluoroquinolones. The high prevalence of Lys-137 appears to be due to its frequent occurrence in common serotypes.

Characterization of the quinolone resistant determining regions in clinical isolates of pneumococci collected in Canada