  Coupled channels model of meson-baryon interactions based on the effective
chiral Lagrangian is extended to account explicitly for the $\Sigma(1385)$
resonance that dominates the $P$-wave $\bar{K}N$ and $\pi\Sigma$ interactions
at energies below the $\bar{K}N$ threshold. The presented model aims at a
uniform treatment of the $\Lambda(1405)$ and $\Sigma(1385)$ dynamics in the
nuclear medium. We demonstrate the applicability of the model by confronting
its predictions with the vacuum scattering data, then we follow with discussing
the impact of nuclear matter on the $\pi\Sigma$ mass spectrum and on the energy
dependence of the $K^{-}p$ branching ratios.
