Starvation- and antibiotics-induced formation of persister cells in Pseudomonas aeruginosa

Abstract

Background. Planktonic stationary and exponential cultures of Pseudomonas aeruginosa are highly resistant to killing by bactericidal antimicrobials because of the presence of persisters, cells that are multidrug tolerant and play a key role in the recalcitrance of biofilm infections. Aim. The aim of this study was to investigate the formation of persister cells in P. aeruginosa stationary vs. exponential cultures using different class antimicrobials. Methods. The susceptibilities of P. aeruginosa PAO1 wild-type and mutant strains to antimicrobials were determined by standard microtiter broth dilution method. In order to determine persister formation, dose-and time-dependent killing experiments were performed with antibiotics. Results. Ceftazidime (Cephalosporin) showed little efficacy against either culture. Stationary-phase cells were more tolerant to imipenem (Carbapenem) than exponential cells, leaving a small fraction of persisters at high imipenem concentration in both populations. Polymyxin B (Polymyxin) appeared to be ineffective at low concentrations against both cell populations. Very high polymyxin B concentration completely eradicated exponential cells and regrowth was seen in a stationary population. Stationary cells were more tolerant to tobramycin (Aminoglycoside) than exponential cells but a higher concentration of tobramycin completely eliminated survivors. Ciprofloxacin (Fluoroquinolone) at a low concentration resulted in killing of both cultures of P. aeruginosa, producing persisters that were invulnerable to killing. Conclusions. Stationary cells appear to be somewhat more tolerant than exponential cells in all of these assays. We also showed that nutrient deprivation (serine starvation) regulated by stringent and general stress response, contribute to the increased tolerance of P. aeruginosa exponential and stationary planktonic cells via production of persisters.

A Quantitative Survey of Bacterial Persistence in the Presence of Antibiotics: Towards Antipersister Antimicrobial Discovery

“…A selection of 847 primary publications deemed relevant to the theme of antibiotic bacterial persisters were manually surveyed for quantitative data from work carried out in planktonic cultures. Numerical data were finally extracted from 187 articles [ 3 , 4 , 7 , 8 , 11 , 12 , 36 , 39 , 40 , 49 , 51 , 52 , 55 , 56 , 57 , 58 , 61 , 66 , 67 , 68 , 89 , 115 , 116 , 117 , 119 , 121 , 122 , 126 , 133 , 141 , 142 , 143 , 150 , 163 , 173 , 177 , 184 , 185 , 186 , 187 , 188 , 189 , 190 , 191 , 192 , 193 , 194 , 195 , 196 , 197 , 198 ,…”

“…Cells better suited to surviving transient exposure to high concentrations of antibiotics are slow-growing cells, which are a minority when the environmental conditions are conducive to rapid cell multiplication (e.g., exponential phase in batch cultures) [ 7 , 8 , 36 ]. When the surrounding milieu has been exhausted of nutrients, cell growth stagnates, and the cell fraction that persists to antibiotics is somewhat higher (e.g., in the stationary phase in batch cultures) [ 37 , 38 , 39 , 40 ]. Any microorganism will find itself in cycles continuously oscillating between these two extremes of cell growth [ 41 , 42 ] and henceforth surviving exposure to antibiotics (or any other toxins) with different degrees of success.…”

Antibiofilm and antipersister activity of acetic acid against extensively drug resistant Pseudomonas aeruginosa PAW1

“…To the best of our knowledge there are no previous reports demonstrating P. aeruginosa persisters in presence of polymyxin B. Gentamicin has not been studied for persister formation in P. aeruginosa. However, Mlynarcik and Kolar (2017) have studied the formation of persister cells in P. aeruginosa PAO1 against various antibiotics including the aminoglycoside, tobramycin and polymyxin B [31]. They demonstrate that treatment of tobramycin (at 104 μg/mL, 80X MIC) resulted in complete killing of PAO1 at 24 h; while our study revealed that treatment of gentamicin (at 100 μg/mL, 100X MIC) resulted in relatively large population of PAW1 persisters at 24 h. Similarly, treatment of PAO1 with polymyxin B (at 64 μg/mL, 80X MIC) showed regrowth of the cells after 24 h, possibly due to mutation [31]; whereas our study showed a…”

Bactericidal Activity of Usnic Acid-Chitosan Nanoparticles against Persister Cells of Biofilm-Forming Pathogenic Bacteria

“…Antibiotic treatment also leads to the formation of persister cells [63][64][65][66]. There are several mechanisms involved in the formation of persister cells upon exposure to chemicals or antibiotics, as explained in detail in the aforementioned references.…”