The present invention is a genetically engineered version of a lysozyme protein wherein the engineered enzyme exhibits enhanced antimicrodial activity, relative to the wild type enzyme, as a result of a reduced overall electrostatic charge. Such an enzyme is an attractive therapeutic candidate for treating microbial or viral infections, particularly in cases where the infection results in an accumulation of polyanion inhibitors at the site of infection. Respiratory tract infections are one example of an infection where such an enzyme might be a particularly useful drug.