Haruo Kuroki

Neonatal Legionnaires’Disease

A neonatal case of legionnaires’disease (LD) is reported. A male neonate was admitted to our hospital with high fever and dyspnea, which had started 5 days after birth, and died due to severe pneumonia at 10 days old. An autopsy revealed small areas of granular consolidation scattered diffusely in the bilateral lungs. Microscopic examination of the lungs showed mainly lobularly distributed pneumonia. Extensive exudation of macrophages and neutrophils was observed in the terminal respiratory tract and alveolar spaces. Warthin‐Starry and Gimenez staining and electron microscopy detected many coccobacilli in the cytoplasm of exudated macrophages and neutrophils. Immunofluorescence staining using antiserum against Legionella pneumophila, serogroup 1, showed a positive reaction. Bacteriological examinations of aspirate from the respiratory tract and autopsied lung tissue confirmed the presence of Legionella pneumophila, serogroup 1. Extrapulmonary LD was not detected. LD usually affects aged or immunocompromised hosts, but there was no evidence of immune deficiency in this case. Pediatric cases of LD have rarely been reported, and a survey of the literature revealed few neonatal cases. The present case may alert neonatologists and other medical personnel to the possibility of neonatal LD infection.

Changes in rotavirus genotypes before and after vaccine introduction: a multicenter, prospective observational study in three areas of Japan

In Japan, monovalent and pentavalent rotavirus (RV) vaccines were approved in 2011 and 2012, respectively. To monitor changes in the RV genotypes before and after vaccine introduction, we performed a prospective observational study among children (＜ 5 years) with gastroenteritis who tested RV-positive on antigen rapid tests. Stool samples were collected from 3 different sites in Japan: Tsu City, Mie Prefecture; Kurashiki City, Okayama Prefecture; and Isumi City, Chiba Prefecture. RV genotypes were determined using reverse transcription-polymerase chain reaction. In Tsu City, G3P[8] was dominant (61.0-77.1%) before vaccine introduction, but decreased after introduction. Meanwhile, in an inverse proportion to the decrease in G3P[8], G1P[8] increased until the 2013/14 season, when a sudden predominance of G2P[4] (100%) occurred. A similar trend was observed in Kurashiki City in terms of the extent of reduction in G3P[8] and the emergence of G2P[4]. In Isumi City, G1P[8] was dominant (70.3%) before vaccine introduction, and G9P[8] became predominant (83.3%) in the 2013/14 season. To determine whether the genotype changes are attributable to vaccines or natural epidemiological changes, ongoing continuous monitoring of the RV genotypes is required.

Characterization of unusual DS-1-like G3P[8] rotavirus strains in children with diarrhea in Japan

The emergence and rapid spread of novel DS‐1‐like intergenogroup reassortant rotaviruses having the equine‐like G3 genotype (DS‐1‐like G3P[8] strains) have been recently reported from several countries. During rotavirus surveillance in Japan in 2015–2016, three DS‐1‐like G3P[8] strains were identified from children with severe diarrhea. In the present study, we sequenced and characterized the full genomes of these three strains. On full‐genomic analysis, all three strains showed a unique genotype constellation including both genogroup 1 and 2 genes: G3‐P[8]‐I2‐R2‐C2‐M2‐A2‐N2‐T2‐E2‐H2. Phylogenetic analysis revealed that each of the 11 genes of the three strains was closely related to that of Japanese DS‐1‐like G1P[8] and/or Japanese equine‐like G3P[4] human strains. Thus, the three study strains were suggested to be reassortants that acquired the G3‐VP7 gene from equine G3 rotaviruses on the genetic background of DS‐1‐like G1P[8] strains. Our observations will provide important insights into the evolutionary dynamics of emerging DS‐1‐like G3P[8] strains.