Polyethylene glycol (PEG) and polyethylene glycol-polylactic acid (PEG-PLA) have an organic structure and no negative effect on human health. The present study compares the antimicrobial effectiveness of PEG and PEG-PLA on microbial growth. The following pathogens and fungi were examined: seven bacteria strains and 10 fungi (four yeasts and six molds). PEG, a non-modified polymer, exhibited no inhibition effect on all test microorganisms. However, the antimicrobial effect increased with the concentration of PEG-PLA. Bacteria showed more sensitivity to PEG-PLA compared with the other microorganisms used in this study. Enterobacter ATCC 19434 was found to be the most resistant bacteria. Molds and yeasts were more resistant than bacteria against PEG-PLA. MIC and MFC could not be determined on the tested fungi owing to the level of concentrations used, with the exception of the yeast Candida albicans and the molds Penicillium expansum and Aspergillus parasiticus.