Mycolyltransferase is important for biofilm formation and pathogenesis of <i>Tsukamurella</i> keratitis

<i>Tsukamurella</i>, a group of multi-drug resistant, Gram-positive, aerobic, and partially acid-fast bacteria, are emerging causes of bacterial conjunctivitis and keratitis. However, the pathogenesis of <i>Tsukamurella</i> keratitis is largely unknown. To address this, we used New Zealand White rabbits to develop the first eye infection model and conducted <i>in vitro</i> tests to study the pathogenesis mechanisms of <i>Tsukamurella</i>. There is increasing evidence that biofilms play a significant role in ocular infections, leading us to hypothesize that biofilm formation is crucial for effective <i>Tsukamurella</i> infection. In order to look for potential candidate genes which are important in biofilm formation and <i>Tsukamurella</i> keratitis. We performed genome sequencing of two ocular isolates, <i>T. pulmonis</i>-PW1004 and <i>T. tyrosinosolvens</i>-PW899, to identify potential virulence factors. Through <i>in vitro</i> and <i>in vivo</i> studies, we characterized their biological roles in mediating <i>Tsukamurella</i> keratitis. Our findings confirmed that <i>Tsukamurella</i> is an ocular pathogen by fulfilling Koch's postulates, and using genome sequence data, we identified <i>tmytC,</i> encoding a mycolyltransferase, as a crucial gene in biofilm formation and causing <i>Tsukamurella</i> keratitis in the rabbit model. This is the first report demonstrating the novel role of mycolyltransferase in causing ocular infections. Overall, our findings contribute to a better understanding of <i>Tsukamurella</i> pathogenesis and provide a potential target for treatment. Specific inhibitors targeting TmytC could serve as an effective treatment option for <i>Tsukamurella</i> infections.