The rise in the number of antibiotic-resistant bacteria, due in part to the widespread use of antibiotics, has spawned new technological approaches for identifying novel antimicrobials with narrow specificity. Current antibiotic treatment regimens and anti-tuberculosis drugs are not effective at treating Mycobacterium abscessus; therefore, antimicrobial peptides have gained prominence as alternative antimicrobials due to their specificity towards anionic bacterial membranes, rapid action, and inability for the bacteria to develop resistance by acting against the cell membrane. Our group has developed a high-density peptide microarray consisting of 125,000 random synthetic peptides for rapid screening of antimicrobial peptides against M. abscessus. From the array screening, the peptides that interacted with the mycobacterial cell surface were synthesized and subsequent inhibitory, bactericidal, and toxicity assays were performed. Additionally, minimum inhibitory concentration assays were performed with these peptides against Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli in order to determine if inhibitory activity was observed against Gram-positive and Gram-negative bacteria. Six peptides, out of the 125,000 peptides screened, had inhibitory activity against M. abscessus and low toxicity (< 10%) against human red blood cells. One peptide also exhibited inhibitory activity against S. aureus and E. coli. To determine combination effects, antimicrobial synergy assays will be performed with the six peptides and clarithromycin

Pyocyanin is a pigment produced by Pseudomonas aeruginosa that acts as a virulence factor in helping this pathogen to establish chronic infection in the lungs of persons with cystic fibrosis (CF). Then, as lung infections become chronic, P. aeruginosa tends to down-regulate pyocyanin production. The effects of environmental conditions, particularly temperature change, on pyocyanin production in P. aeruginosa has not been widely studied in the past. The goals of this project were twofold: First, we aim to identify how environmental conditions potentially present in the CF lungs affect pyocyanin pigment production in P. aeruginosa. Second, through the examination of effects of environmental changes, we aim to identify methods to modulate phenotypes of P. aeruginosa in order to identify putative biomarkers through metabolic analysis. This paper also identifies a newly derived pyocyanin culturing and extraction procedure that yields increased sensitivity for pyocyanin detection.
Through a liquid-liquid extraction procedure, pyocyanin was quantified in cultures that were incubated at 30°C, 37°C, and 40°C and in the presence of Staphylococcus aureus spent media. In addition, culturing methods for the measurement of pyocyanin under hypoxic conditions were analyzed. I hypothesized that environmental conditions such as temperature, co-infection with S. aureus, and oxygen depletion would influence pyocyanin production. It was found that overall, 30°C incubation produced statistically significant decrease in pyocyanin production compared with incubation at 37°C. These findings will help to determine how phenotypes are affected by conditions in the CF lung. In addition, these conclusions will help direct metabolic analysis and to identify volatile biomarkers of pyocyanin production for future use in breath-based diagnostics of CF lung infections.