Isothermal Microcalorimetry Detects the Presence of Persister Cells in a Staphylococcus aureus Biofilm After Vancomycin Treatment

• Published in: Frontiers in microbiology Vol. 10; p. 332
• Main Authors: Butini, Maria Eugenia, Abbandonato, Gerardo, Di Rienzo, Carmine, Trampuz, Andrej, Di Luca, Mariagrazia
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 25.02.2019
• Subjects: antibiotic activity; biofilm; isothermal microcalorimetry; Microbiology; persister cells; Staphylococcus aureus; vancomycin; biofilm-associated infection; biofilm; isothermal microcalorimetry; vancomycin; antibiotic activity; Staphylococcus aureus; persister cells
• ISSN: 1664-302X; 1664-302X
• DOI: 10.3389/fmicb.2019.00332

biofilm plays a major role in implant-associated infections. Here, the susceptibility of biofilm to daptomycin, fosfomycin, vancomycin, trimethoprim/sulfamethoxazole, linezolid, and rifampicin was investigated by isothermal microcalorimetry (IMC). Moreover, the persister status of cells isolated from biofilm after treatment with vancomycin was also analyzed. biofilm was tolerant to all the antibiotics tested [minimum biofilm bactericidal concentration (MBBC) > 256 μg/ml], except to daptomycin [MBBC and minimum biofilm eradicating concentration (MBEC) = 32 μg/ml] and rifampin (MBBC and MBEC = 128 μg/ml). After the treatment of MRSA biofilm with 1024 μg/ml vancomycin, ∼5% cells survived, although metabolically inactive (persisters). Interestingly, IMC revealed that persister bacteria reverted to a normal-growing phenotype when inoculated into fresh medium without antibiotics. A staggered treatment of MRSA biofilm with vancomycin to kill all the metabolically active cells and daptomycin to kill persister cells eradicated the whole bacterial population. These results support the use in the clinical practice of a therapeutic regimen based on the use of two antibiotics to kill persister cells and eradicate MRSA biofilms. IMC represents a suitable technique to characterize in real-time the reversion from persister to metabolically-active cells.