Arsenicicoccus bolidensis, an Unusual Cause for Early-Onset Sepsis in a Term Neonate

Abstract Arsenicicoccus is a gram-positive, non–spore-forming facultatively anaerobic coccus growing in clusters, named after its ability to reduce arsenic from As (V) to As (III). The geographical distribution of Arsenicicoccus isolates is globally diverse and includes soil, avian, and marine sources. No adult cases and only 1 pediatric case of Arsenicicoccus bacteremia have so far been reported. We describe a term neonate with early-onset sepsis and positive blood culture for gram-positive cocci in clusters and the final identification of Arsenicicoccus bolidensis. This is the first described case of Arsenicicoccus causing early-onset sepsis in a neonate. The case illustrates the importance of performing genetic sequencing studies to detect taxonomic misclassification of microorganisms of slow growth and of equivocal identity in the setting of clinical illness when antibiotic susceptibility testing is needed.