INS and empyema: Wei et al. (2019) reported that insulin therapy promoted the formation of P. aeruginosa biofilm by increasing intracellular c-di-GMP levels as detected by PNA-FISH and led to chronic wound infection and delayed wound healing. Furthermore, Zhang et al. (2020) reported that the amount of biofilm formation of P. aeruginosa strains with different intracellular c-di-GMP levels could be compared using PNA-FISH in the rabbit empyema model. Similar PNA-FISH images of biofilms on wound tissues and on the surface of the pleura have been described (Wei et al., 2019; Zhang et al., 2020).