Multidrug-resistant bacteria (MDR bacteria) are bacteria that are resistant to three or more classes of antimicrobial drugs.[1] MDR bacteria have seen an increase in prevalence in recent years[clarification needed][2] and pose serious risks to public health. MDR bacteria can be broken into 3 main categories: Gram-positive, Gram-negative, and other (acid-stain). These bacteria employ various adaptations to avoid or mitigate the damage done by antimicrobials. With increased access to modern medicine there has been a sharp increase in the amount of antibiotics consumed.[3] Given the abundant use of antibiotics there has been a considerable increase in the evolution of antimicrobial resistance factors, now outpacing the development of new antibiotics.[4]
Examples of MDR bacteria identified as serious threats to public health include:[5]
MDR bacteria employ a plurality of adaptations to overcome the environmental insults caused by antibiotics. Bacteria are capable of sharing these resistance factors in a process called horizontal gene transfer where resistant bacteria share genetic information that encodes resistance to the naive population.[6]
Bacteriophage therapy, commonly known as 'phage therapy,' uses bacteria-specific viruses to kill antibiotic resistant bacteria. Phage therapy offers considerably higher specificity as the phage can be engineered to only infect a certain bacteria species.[9] Phage therapy also allows for the possibility of biofilm penetration in cases where antibiotics are ineffective due to the increased resistance of biofilm-forming pathogens.[9] One major drawback to phage therapy is the evolution of phage-resistant microbes which was seen in a majority of phage therapy experiments aimed to treat sepsis and intestinal infection.[10] Recent studies suggest that development of phage resistance comes as a trade-off for antibiotic resistance and can be used to create antibiotic-sensitive populations.[10][11]
