Aerococcus viridans: A rare pathogen causing urinary tract infection

Abstract

Aerococci are Gram-positive cocci with colony morphology similar to viridans streptococci. Most often these isolates in clinical samples are misidentified and considered insignificant. However, with the use newer techniques like Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass-Spectrometry (MALDI-TOF MS), aerococci have been recognized as significant human pathogens capable of causing a diverse spectrum of infections. Among the different species of aerococci, Aerococcus urinae is the most common agent causing Urinary Tract Infection (UTI) followed by A. sanguinocola. Aerococcus viridans (A. viridans) have been reported rarely in urinary tract infections. The antimicrobial resistance in aerococci in terms of its intrinsic resistance and evolving resistance to penicillin and vancomycin has raised the concern for better understanding of this pathogen. We recently encountered two cases of nosocomial UTI caused by A. viridans which are being reported here.