1. Generation and Characterization of Stable Small Colony Variants of USA300 Staphylococcus aureus in RAW 264.7 Murine Macrophages
- Author
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Dalida Bivona, Carmelo Bonomo, Lorenzo Colombini, Paolo G. Bonacci, Grete F. Privitera, Giuseppe Caruso, Filippo Caraci, Francesco Santoro, Nicolò Musso, Dafne Bongiorno, Francesco Iannelli, and Stefania Stefani
- Subjects
persistence ,carnosine ,erythromycin ,macrophages ,USA300 ,methicillin-resistant S. aureus ,Therapeutics. Pharmacology ,RM1-950 - Abstract
Intracellular survival and immune evasion are typical features of staphylococcal infections. USA300 is a major clone of methicillin-resistant S. aureus (MRSA), a community- and hospital-acquired pathogen capable of disseminating throughout the body and evading the immune system. Carnosine is an endogenous dipeptide characterized by antioxidant and anti-inflammatory properties acting on the peripheral (macrophages) and tissue-resident (microglia) immune system. In this work, RAW 264.7 murine macrophages were infected with the USA300 ATCC BAA-1556 S. aureus strain and treated with 20 mM carnosine and/or 32 mg/L erythromycin. Stable small colony variant (SCV) formation on blood agar medium was obtained after 48 h of combined treatment. Whole genome sequencing of the BAA-1556 strain and its stable derivative SCVs when combining Illumina and nanopore technologies revealed three single nucleotide differences, including a nonsense mutation in the shikimate kinase gene aroK. Gene expression analysis showed a significant up-regulation of the uhpt and sdrE genes in the stable SCVs compared with the wild-type, likely involved in adaptation to the intracellular milieu.
- Published
- 2024
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