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

Understanding the impact of antimicrobial use on the emergence of resistant bacteria is imperative to prevent its emergence. For instance, activation of the AcrAB efflux pumps is responsible for the emergence of antimicrobial-resistant  Salmonella  strains. Here, we examined the expression levels of  acrB  and its multiple regulator genes (RamA, SoxS, MarA, and Rob) in 17 field isolates of  S . Choleraesuis by using quantitative PCR methods. The expression of  acrB  increased in eight of the field isolates ( P  < 0.05). The expression of  acrB  was associated with that of  ramA  in one isolate,  soxS  in one isolate, and both these genes in six isolates. Thereafter, to examine the effect of selected antimicrobials (enrofloxacin, ampicillin, oxytetracycline, kanamycin, and spectinomycin) on the expression of  acrB  and its regulator genes, mutants derived from five isolates of  S . Choleraesuis were selected by culture on antimicrobial-containing plates. The expression of  acrB  and  ramA  was higher in the mutants selected using enrofloxacin (3.3–6.3- and 24.5–37.7-fold, respectively), ampicillin (1.8–7.7- and 16.1–55.9-fold, respectively), oxytetracycline (1.7–3.3- and 3.2–31.1-fold, respectively), and kanamycin (1.6–2.2- and 5.6–26.4-fold, respectively), which are AcrAB substrates, than in each of the parental strains ( P  < 0.05). In contrast, in AcrAB substrate-selected mutants, the expression of  soxS ,  marA , and  rob  remained similar to that in parental strains. Of the four antimicrobials, the level of  ramA  expression was significantly higher in the enrofloxacin- and ampicillin-selected mutants than in the oxytetracycline- and kanamycin-selected mutants ( P  < 0.05), whereas the expression levels of  acrB  and multiple regulator genes in spectinomycin-selected mutants were similar to those in each parental strain. These data suggest that exposure to antimicrobials that are AcrAB substrates enhance the activation of the AcrAB efflux pump  via  RamA, but not  via  SoxS, MarA, or Rob in  S . Choleraesuis.

Effect of Antimicrobial Exposure on AcrAB Expression in Salmonella enterica Subspecies enterica Serovar Choleraesuis