  Symmetry breaking induced by untwisted fermions in QED in a nonsimply
connected spacetime with topology $S^{1}\times R^{3}$ is investigated. It is
found that the discrete CPT symmetry of the theory is spontaneously broken by
the appearance of a constant vacuum expectation value of the electromagnetic
potential along the direction of space periodicity. The constant potential is
shown to be gauge nonequivalent to zero in the nonsimply connected spacetime
under consideration. Due to the symmetry breaking, one of the electromagnetic
modes of propagation is massive with a mass that depends on the inverse of the
compactification length. As a result, the system exhibits a sort of topological
directional superconductivity.
