Clinical Develops to Small Colony Variants to Promote Persistent Infection.

is a novel staphylococcal species (also considered as a part of complex) that is infrequently reported on, and clinical infections are largely unstudied. Here, we report a persistent and recurrent hip joint infection case in which a strain and its small colony variants (SCVs) strain were successively isolated. We present features of the two strains and case details of their pathogenicity, explore factors that induce SCVs formation in the course of anti-infection therapy, and reveal potential genetic mechanisms for SCVs formation. strains were identified using phenotypic and genotypic methods. The strain XNO62 and SCV strain XNO106 were characterized using different models. SCVs were induced by the administration of amikacin and by chronic infection course based on the clinical case details. The genomes of both strains were sequenced and aligned in a pair-wise fashion using Mauve. The case details gave us important insights on the characteristics and therapeutic strategies for infections caused by and its SCVs. We found that strain XNO62 and SCV strain XNO106 are genetically-related sequential clones, the SCV strain exhibits reduced virulence but enhanced intracellular persistence compared to strain XNO62, thus promoting persistent infection. The induction experiments for SCVs demonstrated that high concentrations of amikacin greatly induce XNO62 to form SCVs, while a chronic infection of XNO62 slightly induces SCVs formation. Potential genetic mechanisms for SCVs formation were revealed and discussed based on genomic alignments. In conclusion, we report the first case of infection caused by and its SCVs strain. More attention should be paid to infections caused by and its SCVs, as they constitute a challenge to current therapeutic strategies. The problem of SCVs should be noticed, in particular when amikacin is used or in the case of a chronic infection.