  We show that two-bridge knots and alternating fibered knots admit no purely
cosmetic surgeries, i.e., no pair of distinct Dehn surgeries on such a knot
produce 3-manifolds that are homeomorphic as oriented manifolds. Our argument,
based on a recent result by Hanselman, uses several invariants of knots or
3-manifolds; for knots, we study the signature and some finite type invariants,
and for 3-manifolds, we deploy the $SL(2,\mathbb{C})$ Casson invariant.
