IJAA Editor's Choice

The following articles have been selected as 'Editor's Choice' for the February issue of IJAA:

All editor's choice articles are free to access for a limited time.

1. RamA upregulates multidrug resistance efflux pumps AcrAB and OqxAB in Klebsiella pneumoniae

Editor's comment:

Efflux pumps are an important and complex mechanism for antimicrobial resistance in bacteria. Among them, Resistance-nodulation-cell division family (RND) efflux pumps are widely found in enterobacteria and play a role in antibiotic resistance. The most well-known efflux pump in Klebsiella pneumoniae is AcrAB that is upregulated by the ramA transcription regulator gene and downregulated by the repressor acrR. In this work, authors interested in another efflux pump, OqxAB, and focused on the role of ramA in the regulation of this pump. They confirmed that ramA gene is overexpressed after inhibition of its repressor ramR and up-regulate both AcrAB and OqxAB efflux pumps. These efflux pumps were able to efflux tigecycline, cefepime, piperacillin-tazobactam, ciprofloxacin, chloramphenicol and nitrofurantoin for AcrAB and tetracycline, ciprofloxacin and nitrofurantoin for OqxAB. These results emphasize the role of ramA in regulation of multidrug resistance efflux pumps in K. pneumoniae.
 
2. Confronting Ceftolozane-tazobactam Susceptibility in Multi-Drug Resistant Enterobacterales Isolates and Whole Genome Sequencing Results (STEP Study)

Editor's comment:

Ceftolozane-tazobactam is a novel β-lactam / β-lactamase inhibitor active on multidrug resistant enterobacteria, especially Extended-Spectrum-Beta-Lactamase (ESBL) ones. In this work, Hernandez-Garcia et al. evaluated the concordance between the phenotypic susceptibility of ceftolozane-tazobactam in 426 enterobacteria (mostly Escherichia coli and Klebsiella pneumoniae) isolated in intensive care unit from patients hospitalized between 2017 and 2018 in Portugal with the Resistome of these isolates by whole genome sequencing. They also characterized the clones found in ICU during this period. Interestingly, the most prevalent clones were the international well-known clones ST131 for E. coli and ST307 for K. pneumoniae and the major resistance genes were blaCTX-M-15 for ESBL phenotype and blaKPC-3 for carbapenemase. Surprisingly, the presence of carbapenemase did not correlate with ceftolozane-tazobactam resistance in E. coli, unlike in K. pneumoniae. These results suggest other mechanisms involved in the resistance to ceftolozane-tazobactam in E. coli.