title: Phloretin derived from apple can reduce alpha-hemolysin expression in methicillin-resistant Staphylococcus aureus USA300.
abstract: Methicillin-resistant Staphylococcus aureus (MRSA) has become increasingly important because it is the most common cause of hospital-acquired infections, which have become globally epidemic. Our study specifically focused on the MRSA strain USA300, which was shown in 2014 to be responsible for the most current pandemic of highly virulent MRSA in the United States. We aimed to evaluate the in vitro effect of phloretin on USA300. Susceptibility testing, western blotting assays, hemolysis assays and real-time RT-PCR were employed to examine the in vitro effects of phloretin on alpha-hemolysin (Hla) production when the bacterium was co-cultured with phloretin. The protective effect of phloretin against the USA300-mediated injury of human alveolar epithelial cells (A549) was tested using the live/dead analysis and cytotoxicity assays. We showed that sub-inhibitory concentrations of phloretin have no effect on bacterial viability; however, they can markedly inhibit the production of Hla in culture supernatants and the transcriptional levels of hla (the gene encoding Hla) and agrA (the accessory gene regulator). Phloretin, at a final concentration of 16 µg/ml, could protect A549 cells from injury caused by USA300 in the co-culture system. Our study suggests that phloretin might have a potential application in the development of treatment for MRSA infections.
authors.affiliation: Department of Respiratory Medicine, The First Hospital of Jilin University, College of Veterinary Medicine, Jilin University, Changchun, China.
authors.forename: Xuan
authors.initials: X
authors.lastname: Zhou
authors.forename: Shui
authors.initials: S
authors.lastname: Liu
authors.forename: Wenhua
authors.initials: W
authors.lastname: Li
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
authors.forename: Bowen
authors.initials: B
authors.lastname: Liu
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: Xuming
authors.initials: X
authors.lastname: Deng
authors.forename: Liping
authors.initials: L
authors.lastname: Peng
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001427:Bacterial Toxins / Q000235:genetics* / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D006460:Hemolysin Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D027845:Malus / Q000737:chemistry*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D010693:Phloretin / Q000494:pharmacology*; D010936:Plant Extracts / Q000494:pharmacology*; D013203:Staphylococcal Infections / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D001427:Bacterial Toxins; D006460:Hemolysin Proteins; D010936:Plant Extracts; C021091:staphylococcal alpha-toxin; D010693:Phloretin