Identification of serotype e strains missing the gene in clinical isolates from Japan.

. Certain nontypeable cannot be assigned a sequence type (ST) by Multilocus Sequence Typing (MLST) due to the lack of the gene, one of seven MLST loci in , which encodes a fucose-operon enzyme.. To confirm whether the loss of is also found in the encapsulated strains, we analysed clinical isolates of serotype e (Hie).. We conducted MLST, PFGE, and antimicrobial susceptibility tests of 45 Hie strains; the majority (=43) were derived from respiratory samples of pediatric patients at Chiba Children's Hospital between 2000 and 2016. The two remaining strains were obtained from the blood of elderly patients with invasive diseases (IHiDs) between 2015 and 2016 at general hospitals. For the -negative strains, PCR analysis for fucose operon was also performed.. Four STs (ST18, 122, 621 and 1758) were assigned to 13 strains, and remaining 32 (including one associated with IHiD) were -negative, completely missing the fucose operon. The allelic profiles of six other loci were identical among 31 strains and to that of ST18, 122 and 621, and these strains were genetically closely related. Forty of 45 isolates were ampicillin-sensitive.. The loss of was frequently observed in clinical isolates of Hie from children. Moreover, -negative Hie may be the cause of IHiD in adult patients. The majority of Hie, including -negative strains, were shown to be clonally related and were ampicillin sensitive. This represents the first report examining losses in encapsulated .