  We critically examine the $\bar{K}N$ coupled-channel approach presented in
[1] and demonstrate that it violates constraints imposed by chiral symmetry of
QCD. The origin of this violation can be traced back to the off-shell treatment
of the chiral-effective vertices, in combination with the use of
non-relativistic approximations and the chosen regularization scheme. We
propose an improved version of the approach, which is directly given by a
resummation of relativistic Feynman graphs of baryon chiral perturbation
theory, and is in accord with the chiral symmetry constraint. Within this
improved model, two poles are generated dynamically in the isoscalar $\pi\Sigma
- \bar{K}N$ coupled channels sector, in contrast with the non-relativistic
model of [1] in which only one such pole was reported.
