As pili are necessary for infection by the lytic caulophage CbK (φCbK) (Skerker and Shapiro, 2000), we specifically sought mutants in pilus assembly factors encoded outside of the major pilus assembly cpa gene locus (pilA-cpaA-K) (Christen et al., 2016; Skerker and Shapiro, 2000). The gene discussed is CPA1; the disease is infection.