  We present results of optical spectroscopy of 35 H II regions from eight
dwarf galaxies in the Centaurus A group. [O III]4363 A is detected in
ESO272-G025 and ESO324-G024, and direct oxygen abundances of 12+log(O/H) = 7.76
+/- 0.09 and 7.94 +/- 0.11 are derived, respectively. For the remaining
galaxies, abundances are derived using common bright-line methods. To compare
the influence of group environments on dwarf galaxies, we have also gathered
data for additional dwarf irregular galaxies from the Cen A and the Sculptor
groups from the literature. We have examined possible relationships between
oxygen abundance, gas fraction, effective chemical yield, and tidal indices.
Despite large positive tidal indices for a number of Cen A dwarfs in the
present sample, there is no clear separation between galaxies with positive
tidal indices and galaxies with negative tidal indices in the
luminosity-metallicity, metallicity-gas fraction, and metallicity-tidal index
diagrams. The H I surface mass density decreases with increasing positive tidal
index, which is expected in strong tidal encounters. There are no strong trends
between oxygen abundances or yields and projected distances of galaxies within
their respective groups. We also present spectra for 13 H II regions in three
nearby dwarf irregular galaxies: DDO 47, NGC 3109, and Sextans B. For DDO 47,
the [O III]4363 oxygen abundance (7.92 +/- 0.06) for the H II region SHK91 No.
18 agrees with recently published values. For Sextans B, the [O III]4363 oxygen
abundance (7.80 +/- 0.13) for H II region SHK91 No. 5 agrees with published
work in which O^+ abundances were determined entirely from [O II]7320,7330
fluxes.
