Conventional Microbiological Techniques Identify Sphingomonas paucimobilis in a Urine Culture Isolate

Sphingomonas paucimobilis is a non-fermenting, Gram-negative bacterium, an emerging pathogen. It is associated with various clinical presentations, both healthcare-associated as well as community-acquired infections, especially in immunocompromised patients. On account of its rarity, it is seldom identified and reported by Microbiology laboratories. We report an unusual case of S. paucimobilis urinary tract infection (UTI) where a clinically significant pure isolate of non-lactose fermenting (NLF) was isolated from a patient with renal dysfunction. However, advanced automated systems such as Matrix-assisted laser desorption/ionisation time of flight mass spectroscopy (MALDI-TOF MS) failed to accurately identify the organism, prompting the use of biochemical tests, through which S. paucimobilis was ultimately identified. In the absence of standardised guidelines, antimicrobial susceptibility-guided, tailor-made treatment is warranted with prompt initiation for favourable outcomes in such cases. This case highlights the diagnostic challenges associated with such rare organisms and the importance of conventional microbiological techniques in the identification of these emerging pathogens.