High-Throughput Screening Identifies Synthetic Peptides with Antibacterial Activity against and Serum Stability.

The rise in antibiotic resistance in bacteria has spawned new technological approaches for identifying novel antimicrobials with narrow specificity. Current antibiotic treatment regimens and antituberculosis drugs are not effective in treating . Meanwhile, antimicrobial peptides are gaining prominence as alternative antimicrobials due to their specificity toward anionic bacterial membranes, rapid action, and limited development of resistance. To rapidly identify antimicrobial peptide candidates, our group has developed a high-density peptide microarray consisting of 125,000 random synthetic peptides screened for interaction with the mycobacterial cell surface of morphotypes. From the array screening, peptides positive for interaction were synthesized and their antimicrobial activity was validated. Overall, six peptides inhibited the smooth morphotype (IC = 1.7 μM for all peptides) and had reduced activity against the rough morphotype (IC range: 13-82 μM). Peptides ASU2056 and ASU2060 had minimum inhibitory concentration values of 32 and 8 μM, respectively, against the smooth morphotype. Additionally, ASU2060 (8 μM) was active against , including multidrug-resistant clinical isolates, , and methicillin-resistant . ASU2056 and ASU2060 exhibited no significant hemolytic activity at biologically relevant concentrations, further supporting these peptides as promising therapeutic candidates. Moreover, ASU2060 retained antibacterial activity after preincubation in human serum for 24 h. With antimicrobial resistance on the rise, methods such as those presented here will streamline the peptide discovery process for targeted antimicrobial peptides.