Does P-AST more accurately determine susceptibility for polymicrobial samples?

Antimicrobial sensitivity protocols are standardized for monomicrobial infections; however, the standard methods do not consider bacterial interactions that impact susceptibility results. In this study, antibiotic susceptibility patterns were evaluated using a novel Pooled Antibiotic Susceptibility Test to identify the impact of bacterial interactions on susceptibility results. Antibiotic resistance rates in polymicrobial specimens were compared to those in monomicrobial infections. Utilizing two different logistic models, resistance rates were compared. The study found that bacterial interactions in polymicrobial samples result in antimicrobial resistance rate changes that are not detected when microbial isolates are evaluated independently. As a result, those with polymicrobial infections may depend upon precise identification of organisms and susceptibility patterns identified by Pooled Antibiotic Susceptibility Testing.