In this study, we numerically investigate the effect of Kerr-comb-generated breather soliton pulses on optical communication systems. The breather soliton pulse amplitude and spectrum envelope oscillate periodically in time. Simulations show that the spectrum of each comb line in the breather soliton state has multiple sub-teeth due to the periodic oscillation of the comb spectrum. In the simulation, the comb output is modulated with different formats. We find that the sub-teeth distort quadrature phase-shift-keyed signals but have less of an effect on on-off-keyed signals.