Seeking an Alternative to Antibiotics

Antibiotics remain our primary therapeutic for the treatment of bacterial infections. However, overuse of these lifesaving drugs has created intense selective pressures for the emergence of multi-drug resistant pathogens. The result is that antibiotic resistance is predicted to be the greatest human health challenge by 2050. There are currently no alternatives to antibiotics approved for human use. One promising avenue in the drug discovery pipeline is the diverse family of bacteriocins; antimicrobial proteins and peptides naturally produced by most bacteria that inhibit the growth of closely related bacterial strains and species. The bacteriocin nisin serves as a prime example of the benefits of this alternative. Recently there has been a push to present nisin as a treatment option for a variety of different pathogens affecting humans, animals, and plants! The studies backing this effort have shown that against Gram-positive bacterial pathogens, nisin's killing activity is comparable, or better, than most common antibiotics. Unfortunately, the same is not true for Gram-negative species, and a common belief asserted in the literature is that nisin has a low effectiveness against Gram-negative bacteria. However, there have been little to no studies actually confirming this. In addition, previous data collected in the Riley lab shows that nisin is able to inhibit many different species of Gram-negative bacteria. Why is that the case if all of these species contain an outer membrane that should prevent nisin from functioning? Is there a relationship between these sensitive strains? This study seeks to answer these questions, and more.