Massilia shenzhen sp. nov., isolated from blood of one premature infant, causing sepsis.

This study explores a premature infant with respiratory failure and pneumonia, suggestive of neonatal sepsis. Despite initially negative clinical specimens, blood testing revealed a pathogen. MALDI-TOF-MS and physiological tests initially failed to identify it accurately. Subsequent analysis of the 16S rRNA gene, housekeeping genes, and whole genome sequencing placed it in the genus Massilia. Average Nucleotide Identities (ANIs) indicated 88.47 % similarity with the type strain of Massilia norwichensis. Detailed characterization showed it as Gram-negative, aerobic, flagellated, measuring 0.45-0.55 × 1.75-2.40 μm. Major fatty acids included C16:0, C16:1ω7c, C18:1ω7c, and cyclo-C17:0. Minimum inhibitory concentrations to ceftazidime, penicillin, and meropenem were <0.032 μg/mL, ≤0.75 μg/mL, and <0.002 μg/mL respectively. Phylogenetic analysis, fatty acid composition, and physiological parameters confirmed it as Massilia shenzhen sp. nov., with strain GZ0329T. Given limited research on Massilia drug resistance, ceftazidime and imipenem show promise in treating Massilia infections.