Compositions and methods of the present invention prevent,inhibit or reduce the toxic effects of proteins and toxinssecreted from microbes. A method for neutralizingmicrobial protein products in a subject comprisesadministering a composition to the subject, saidcomposition comprising plasma-derived IgM and optionallyone or more excipients in a pharmaceutical carrier,wherein the composition is administered in an amounteffective to neutralize the microbial protein products.