Binding of highly branched poly(N-isopropylacrylamide) with vancomycin end groups to Staphylococcus aureus induced a coil-to-globule phase transition. The polymers aggregated this Gram-positive bacteria (but not Gram-negative bacteria) over a wide range of temperatures, but cooling to 24-26 degrees C progressed the polymer-bound bacteria through a globule-to-coil phase transition, after which the bacteria were released.