Aerococcus urinae, Alloscardovia omnicolens, and Actinotignum schaalii: the AAA Minor League Team of Urinary Tract Infection Pathogens

In clinical microbiology laboratories, advancements in the methods used for routine organism identification have facilitated more accurate species level resolution. This, along with increasing knowledge regarding “new” pathogens, has provided new insights into biology and has revealed clinical associations not previously known. Aerococcus urinae, Alloscardovia omnicolens, and Actinotignum schaalii are Gram-positive bacteria associated with urinary tract infections but can also be members of the urinary tract microbiota. In addition, invasive infections have been reported for the three bacteria, usually with a urinary tract source. Importantly, the use of routine biochemical testing methods for identification of these bacteria can result in misidentification or the incorrect determination that they are not clinically significant. Of these bacteria, only A. urinae has antimicrobial susceptibility testing criteria and interpretative breakpoints. Microbiologists and clinicians need to be aware of these urinary tract pathogens and how to correctly identify them.