Related Experiment Video
Updated: Jun 3, 2026
Time-Lapse Epifluorescence Microscopy Imaging of Pseudomonas aeruginosa and Staphylococcus aureus Heterogeneous Phenotypes
Published on: February 14, 2025
Evidence for persisters in Staphylococcus epidermidis RP62a planktonic cultures and biofilms
Julie A Shapiro1, Valerie L Nguyen1, Neal R Chamberlain1
1Department of Microbiology and Immunology, Kirksville College of Osteopathic Medicine, A. T. Still University of Health Sciences, 800 West Jefferson Street, Kirksville, MO 63501, USA.
Abstract:
The pathogenesis of Staphylococcus epidermidis in foreign device-related infections is attributed primarily to its ability to form biofilms on a polymer surface. One mechanism proposed for the survival of organisms in a biofilm is the presence of persister cells. Persister cells survive antibiotic treatment without acquiring heritable antibiotic resistance. This study was conducted to determine if S. epidermidis RP62a growing in planktonic cultures and biofilms could survive as persister cells following treatment with levofloxacin and vancomycin. S. epidermidis RP62a produced a small percentage of persisters (levofloxacin, 3.09×10⁻⁷%; vancomycin, 8.21×10⁻⁵ %) when grown to exponential phase, whereas biofilms contained 28 and 94 % persisters, following exposure to levofloxacin and vancomycin, respectively. The highest percentages of persisters were obtained during stationary phase in planktonic cultures and the lowest percentages of persisters were obtained during mid-exponential phase. An increase in persister number was not due to activation of quorum-sensing regulons. Confocal laser scanning microscopy images of biofilms exposed to levofloxacin demonstrated that the antibiotic was able to kill bacteria throughout the biofilm. Our results suggest that antibiotic tolerance in biofilms and in planktonic cultures of S. epidermidis RP62a is due in part to the presence of persister cells.
Insights
Staphylococcus epidermidis forms biofilms that protect persister cells from antibiotics. Biofilms significantly increase persister cell survival compared to planktonic cultures, contributing to antibiotic tolerance.
Area of Science:
- Microbiology
- Infectious Diseases
- Biomedical Engineering
Background:
- Staphylococcus epidermidis is a major cause of foreign device-related infections.
- Biofilm formation is key to S. epidermidis pathogenesis.
- Persister cells are a subpopulation of bacteria that survive antibiotic treatment without genetic resistance.
Purpose of the Study:
- To investigate the presence and frequency of persister cells in planktonic and biofilm cultures of S. epidermidis RP62a.
- To determine the impact of antibiotic treatment (levofloxacin and vancomycin) on persister cell survival.
- To explore the role of persister cells in antibiotic tolerance of S. epidermidis.
Main Methods:
- Culturing S. epidermidis RP62a in both planktonic and biofilm states.
- Treating cultures with levofloxacin and vancomycin at different growth phases.
- Quantifying persister cell percentages post-antibiotic exposure.
- Utilizing confocal laser scanning microscopy to visualize antibiotic effects within biofilms.
Main Results:
- Planktonic cultures showed very low persister percentages (levofloxacin: 3.09×10⁻⁷%, vancomycin: 8.21×10⁻⁵%).
- Biofilms exhibited significantly higher persister percentages (levofloxacin: 28%, vancomycin: 94%).
- Persister cell numbers were highest in stationary phase planktonic cultures and lowest in mid-exponential phase.
Conclusions:
- Persister cells contribute significantly to antibiotic tolerance in both planktonic and biofilm cultures of S. epidermidis.
- Biofilm formation dramatically enhances the survival rate of persister cells.
- Understanding persister cells is crucial for developing effective treatments against device-related S. epidermidis infections.
Related Concept Videos
01:29Biofilms
01:25Clinical Significance of Antibiotic Resistance
01:29Staphylococcal Skin Infections