Surprising uncovering of gram-negative diplococci from blood cultures: First identification of Pseudoroseomonas aerofrigidensis as probable bloodstream infection - clinical and laboratory approach towards an unknown pathogen.

Identification of pathogens has been accelerated by MALDI-TOF, including very rare bacteria, which can challenge routine diagnostics by uncommon features. Moreover, rare or only recently discovered microorganisms often lack experience or data on antibiotic sensitivity. A 67-year-old patient presented with a feverish clinical picture. Initial Gram-staining of bacteria in positive blood cultures showed gram-negative diplococci suggesting highly pathogenic bacteria. In further identification a 2017 newly discovered species, Pseudoroseomonas aerofrigidensis, was identified by MALDI. We present the interdisciplinary management of this first probable bloodstream infection. A close communication between clinicians and microbiological laboratory is crucial in managing patients with infectious pathogens, for which clinical experience is rare.