 These so-called persister cells  are insensitive to antibiotics treatment, and contribute to the serious problem of drug resistance.
<meaning-changed>  These so-called persister cells  are insensitive to antibiotics treatment, and contribute to the serious problem of drug resistance.
 These so-called persister cells keep themselves in a dormant state and thus are insensitive to antibiotics treatment, and contribute to the serious problem of drug resistance.