Salmonella enterica serovar Typhi in Japan, 2001–2006: emergence of high-level fluoroquinolone-resistant strains

The phage types and antimicrobial susceptibilities of 226 isolates of Salmonella enterica serovar Typhi from imported cases in Japan between 2001 and 2006 were investigated. Most (93.8%) had travelled to Asian countries, particularly South East Asia. Twenty-one phage types were identified with E1 (30.5%), UVS (15.9%) and B1 (9.3%) being the most common. The frequency of multidrug-resistant strains reached 37.0% in 2006 with phage types E1 and E9 predominating. Almost half (48.2%) of the isolates were resistant to nalidixic acid and two isolates displayed high-level fluoroquinolone resistance. Three mutations, two in gyrA and one in parC, were identified in both isolates.