Ct/Ng co-infections are common (Creighton et al., 2003), may be associated with increased Ng transmissibility (Stupiansky et al., 2011), could promote acquisition of Ng drug resistance (Unemo and Shafer, 2014), and interaction between the two organisms could cause a synergistic effect on infectivity and/or transmission (Althaus et al., 2014). The gene discussed is NRGN; the disease is coinfection.