Analysis of Haemophilus influenzae serotype f isolated from three Japanese children with invasive H. influenzae infection

作者：Hoshino Tadashi^*; Hachisu Yushi; Kikuchi Takashi; Tokutake Shoko; Okui Hideyuki; Kutsuna Satoru; Fukasawa Chie; Murayama Kei; Ohara Asami; Shimizu Hiroyuki; Ito Midori; Takahashi Yoshiko; Ishiwada Naruhiko

来源：Journal of Medical Microbiology, 2015, 64(Pt_4): 355-358.

DOI：10.1099/jmm.0.000031

In Japan, publicly subsidized Haemophilus influenzae serotype b vaccines became available in 2011; consequently, the incidence of invasive H. influenzae infection in paediatric patients of less than 5 years of age decreased dramatically. In 2013, the first case of H. influenzae serotype f (Hip meningitis in a Japanese infant was reported, and another case of Hif meningitis in a Japanese infant was observed in 2013. We experienced a fatal paediatric case of Hif bacteraemia in 2004; therefore, we conducted an analysis of the three Hif strains isolated from these three Japanese children with invasive Hif infections. All three strains were beta-lactamase-non-producing, ampicillin-sensitive strains, with MICs of 1 mu g ml(-1) or less. However, one of the three strains showed slightly elevated MICs for ampicillin (1 mu g ml(-1)), cefotaxime (0.25 mu g ml(-1)) and meropenem (0.13 mu g ml(-1)). A molecular analysis by multilocus sequence typing identified all three strains as sequence type (ST) 124, which is a predominant invasive Hif strain in many countries. Smal-digested PFGE showed variable DNA fragmentation patterns among the strains, suggesting that some highly virulent strains have originated from a single ST124 clone and caused invasive Hif infections in Japan. Additional studies are needed to determine the factors that have led to the clonal expansion of virulent ST124 strains.

• 出版日期2015-4