High-Level Antibiotic Tolerance of a Clinically Isolated Enterococcus faecalis Strain

Eradication of Pseudomonas aeruginosa Persister Cells by Eravacycline

Pseudomonas aeruginosa is a leading bacterial pathogen that causes persistent infections. One major reason that antibiotics fail to clear such infections is the presence of a dormant subpopulation called persister cells. To eradicate persister cells, it is important to change drug development from traditional strategies that focus on growth inhibition to the search for new leads that can kill dormant cells. In this study, we demonstrate that eravacycline can effectively accumulate in P. aeruginosa persister cells, leading to strong killing during wakeup, including persister cells in both planktonic cultures and biofilms of the wild-type strain and its mucoid mutant. The effects of eravacycline on persister control were further validated in vivo using a lung infection model in mice. Collectively, these results demonstrate the possibility to control persister cells of bacterial pathogens by targeting dormancy.

Antibiotic heteroresistance and persistence: an additional aid in hospital acquired infections by Enterococcus spp.?

Enterococcus, particularly E. faecium and E. faecalis, are responsible for many hospital-acquired infections. With their intrinsic antibiotic resistance and ability to form biofilms, enterococcal infections are already challenging to manage. However, when heterogenous populations are present, such as those exhibiting heteroresistance and persistence, the complexity of these infections increases exponentially not only due to their treatment but also due to their difficult diagnosis. In this study, we provide a summary of the current understanding of both heteroresistance and persistence in terms of mechanisms, diagnosis and treatment and subsequently review recent literature pertaining to these susceptibility types specifically in enterococci.

Antimicrobial tolerance and its role in the development of resistance: Lessons from enterococci

Bacteria have developed resistance against every antimicrobial in clinical use at an alarming rate. There is a critical need for more effective use of antimicrobials to both extend their shelf life and prevent resistance from arising. Significantly, antimicrobial tolerance, i.e., the ability to survive but not proliferate during antimicrobial exposure, has been shown to precede the development of bona fide antimicrobial resistance (AMR), sparking a renewed and rapidly increasing interest in this field. As a consequence, problematic infections for the first time are now being investigated for antimicrobial tolerance, with increasing reports demonstrating in-host evolution of antimicrobial tolerance. Tolerance has been identified in a wide array of bacterial species to all bactericidal antimicrobials. Of particular interest are enterococci, which contain the opportunistic bacterial pathogens Enterococcus faecalis and Enterococcus faecium. Enterococci are one of the leading causes of hospital-acquired infection and possess intrinsic tolerance to a number of antimicrobial classes. Persistence of these infections in the clinic is of growing concern, particularly for the immunocompromised. Here, we review current known mechanisms of antimicrobial tolerance, and include an in-depth analysis of those identified in enterococci with implications for both the development and prevention of AMR.