Staphylococcus aureus Virulence Affected by an Alternative Nisin A Resistance Mechanism
Miki Kawada‐Matsuo, Atsuko Watanabe, Kaoru Arii, Yuichi Oogai, Kazuyuki Noguchi, Shouichi Miyawaki, Tetsuya Hayashi, Hitoshi Komatsuzawa
Abstract
Recently, the emergence of antibiotic-resistant bacteria has resulted in serious problems for chemotherapy. In addition, many antibacterial agents, such as disinfectants and food additives, are widely used. Therefore, there is a possibility that bacteria are becoming resistant to some antibacterial agents. In this study, we investigated whether Staphylococcus aureus can become resistant to nisin A, one of the bacteriocins applied as a food additive. We isolated a highly nisin A-resistant strain designated SAN2 that displayed increased expression of Pmt proteins, which are involved in the secretion of virulence factors called phenol-soluble modulins (PSMs). This strain also showed decreased susceptibility to human antimicrobial peptides and increased hemolytic activity. In addition, SAN2 showed increased lethal activity in a mouse bacteremia model. Our study provides new insights into the possibility that the acquisition of resistance against food preservatives may modulate virulence in S. aureus , suggesting that we need to pay more attention to the use of food preservatives together with antibiotics.