  Let X be an arbitrary hyperbolic geodesic metric space and let G be a
countable non-elementary weakly acylindrical group of isometries of X. We show
that the second bounded cohomology group of G with real coefficients or with
coefficients in the regular representation is infinite dimensional. The result
holds for any subgroup of the mapping class group of a non-exceptional surface
of finite type not containing a normal subgroup which virtually split as a
direct product.
