Pseudomonas aeruginosa is an opportunistic human pathogen that causes nosocomial, acute, and chronic infections in patients with conditions such as cystic fibrosis, severe burns, and cancer. P. aeruginosa is associated with increased patient morbidity, mortality, and healthcare costs and is known for its persistence of infections. P. aeruginosa is resistant to many antibiotics; however, most strains are susceptible to colistin. The World Health Organization has identified antimicrobial resistance as a major threat and Antimicrobial Stewardship Programs (ASP) have been initiated. ASP goals are to improve patient outcomes, optimize patient safety, reduce antimicrobial resistance, and control healthcare costs. Recommendations to reduce antimicrobial resistance include optimizing the use of antimicrobials and preventing the transmission of drug-resistant organisms. Using antimicrobic agents wisely leads to optimization of their use. For these reasons, we sought to adopt a model system for testing minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) levels for standardized strains of P. aeruginosa (ATCC strains 10145, 27853, 1744, CRM-9027, 9721) using standardized methods. This study sought to compare results of standardized analysis that used Mueller-Hinton Broth (MHB), the recommended and standardized growth medium, or tryptic soy broth (TSB), the growth medium used in many labs with published MIC and MBC reports. Given the ASP recommendations of optimizing use of antimicrobial agents, it is important to know the impact of variations in and deviations from standardized MIC and MBC methodologies in reporting of research results relevant to antimicrobic agents. This comparison study tested the assumption that MIC and MBC results are the same regardless of whether MHB or TSB is used as the growth medium. Preliminary results suggest that MIC and MBC values obtained by using TSB or MHB may display some degree of variability.
Financial support for AP was received from the DeNardo Education and Research Foundation awarded to RMH.
