Summary
In this study, a 4-year-old girl presented with a case of septic
arthritis and fever. Salmonella was isolated from her knee
effusion and feces; isolates were confirmed to be a novel S.Virchow monophasic variant (Salmonella 6,7,14 :r:-) based
on core genome MLST (cgMLST), CRISPR typing combined with analysis of
the fljAB operon. Whole-genome sequencing analysis revealed that
replacement of the fljAB operon by a 4.8 kb cassette fromE. coli caused the nonexpression of phase-2 flagellar antigen inS. Virchow monophasic variant. Additionally, the acquisition ofSalmonella genomic island 2 (SGI2) with an antimicrobial
resistance gene cassette enabled the isolates to be multidrug-resistant
(MDR) to chloramphenicol, tetracycline, trimethoprim, and
sulfamethoxazole. The emerging of MDR S. Virchow monophasic
variant causing human infection should be concerned in the nationalSalmonella surveillance system.