However, lipocalin 2, an innate immune protein produced by neutrophils and mucosal surfaces, specifically binds enterobactin and disrupts iron acquisition.58 Lipocalin 2 cannot bind to the siderophore yersiniabactin and thus yersiniabactin has been shown to promote respiratory tract infections.58 In this study, the ybt gene cluster was detected in approximately three-quarters of the isolates. This evidence concerns the gene LCN2 and Respiratory tract infection.