The burden of rotavirus gastroenteritis and hospital-acquired rotavirus gastroenteritis among children aged less than 6 years in Japan: a retrospective, multicenter epidemiological survey.

BACKGROUND: Rotavirus is a leading worldwide cause of acute gastroenteritis in young children. This retrospective hospital-based study assessed the burden of rotavirus gastroenteritis in children younger than 6 years in Japan. METHODS: Children admitted to eight hospitals for acute gastroenteritis between 2008 and 2009 were identified from hospital admission databases. Diagnosis of acute gastroenteritis/rotavirus gastroenteritis and hospital-acquired rotavirus gastroenteritis was confirmed based on either the International Classification of Diseases and Related Health Problems 10th revision (ICD10) codes (intestinal infectious diseases [AA00-AA09] and rotavirus gastroenteritis [A08.0]) or from rapid rotavirus diagnostic test results. RESULTS: Of 13,767 hospitalized children, 11.9% (1,644), 4.8% (665) and 0.6% (81) were diagnosed with acute gastroenteritis, rotavirus gastroenteritis and hospital-acquired rotavirus gastroenteritis, respectively. Among acute gastroenteritis hospitalizations, 40.5% (665/1,644; ICD10 and rapid test) and 57.7% (645/1,118; rapid test only) were confirmed as rotavirus positive. Of 1,563 children with community-acquired acute gastroenteritis, 584 (37.4%) cases were confirmed as rotavirus positive. The median durations of hospitalization for all and community-acquired rotavirus gastroenteritis were 5.0 days (range: 2.0-133.0 days) and 5.0 days (range: 2.0-34.0 days), respectively. Among rotavirus gastroenteritis hospitalizations, 12.2% (81/665) of cases were hospital-acquired and the median duration of hospitalization was 10.0 days (range: 2.0-133.0 days). The median duration of additional hospitalization due to hospital-acquired rotavirus gastroenteritis was 3.0 days (range: 0-14 days). The overall incidence rate of hospital-acquired rotavirus gastroenteritis was 1.0 per 1,000 children hospital-days. The number of rotavirus gastroenteritis cases peaked between February and May in both 2008 and 2009, and the highest number of cases was reported in March 2008 (21.8%; 145/665). The highest number of rotavirus gastroenteritis hospitalizations (24.1%; 160/665) was observed in children aged 12-18 months. The proportion of hospital-acquired rotavirus gastroenteritis was higher in children aged below 18 months as compared to children at least 18 months of age (0.94 [95% CI: 0.71-1.21] vs. 0.39 [95% CI: 0.25-0.58]) and for children hospitalized for at least 5 days compared to those hospitalized for less than 5 days (0.91 [95% CI: 0.72-1.14] vs. 0.15 [95% CI: 0.05-0.32]). CONCLUSIONS: Both community- and hospital-acquired rotavirus gastroenteritis are significant public health problems in Japan. Data from this study justify the need for the introduction and implementation of rotavirus vaccination in the Japanese national immunization program. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01202201.

Role of the carboxy-terminal region of the outer membrane protein AatA in the export of dispersin from enteroaggregative Escherichia coli.

Enteroaggregative Escherichia coli (EAEC) is an emerging enteric pathogen in both developing and industrialized countries. AatA, an outer-membrane protein that is a homolog of E. coli TolC, facilitates the export of the dispersin protein Aap across the outer membrane in EAEC. To identify which amino acids are important for this export activity, site-directed mutagenesis of the carboxy terminus was performed. An insertional mutant of aatA was complemented with each of several deletion mutants, and was examined for Aap secretion. The results showed that three nonpolar amino acids at positions 381-383 (Phe-Leu-Leu) were required for the activity, and these residues were located at the base of carboxy-terminal elongation in the equatorial domain of AatA.

Biofilm formation by and accessory gene regulator typing of methicillin-resistant Staphylococcus aureus strains recovered from patients with nosocomial infections.

The association between biofilm formation and the accessory gene regulator (agr) types of methicillin-resistant Staphylococcus aureus (MRSA) strains in our hospital were investigated. The biofilm index and the incidence of MRSA strains carrying agr-2 in the infection group (n=91) were significantly higher than were those in the carrier group (n=225), suggesting that biofilm formation and agr type are associated with nosocomial MRSA infections.

Increased interleukin-18 expression in bone marrow of a patient with systemic juvenile idiopathic arthritis and unrecognized macrophage-activation syndrome.

The aberrant induction of proinflammatory cytokines is considered to be crucial in the pathogenesis of systemic juvenile idiopathic arthritis and adult-onset Still's disease. Interleukin-18 (IL-18) in particular has been reported to be a candidate for the key cytokine in both diseases; however, the origin of IL-18 is unclear. To clarify the origin, we investigated specimens from various organs obtained during autopsy of a child with systemic JIA and macrophage activation syndrome, using immunohistochemical staining. Our results showed a high number of cells expressing IL-18 in the bone marrow but not in the other organs. This finding suggests that bone marrow is the origin of increased serum IL-18 and raises the possibility that other proinflammatory cytokines are also induced by IL-18 in bone marrow in this disease. Bone marrow may be an essential organ in the pathogenesis of systemic JIA.

Effects of supplemental L-methionine on E-64 [trans-epoxysuccinyl-1-leucyl-amido (4-guanido) butane]-induced dysmorphology in rat embryos cultured in vitro.

E-64 [trans-epoxysuccinyl-1-leucyl-amido (4-guanido) butane] is teratogenic, inducing a spec-trum of malformations in vivo and producing similar effects in vitro. Numerous studies support the concept that E-64-induced malformations result from embryonic nutritionaldeficiency, without affecting the maternal nutritional status. This has provided a useful model with which to investigate the nutritional requirements of the early embryo, as well as the role of various nutrients in the etiology of congenital defects. In the current investigation, we examined effects of L-methionine on E-64-induced embryotoxicity in vitro. For these experiments, we cultured rat embryos 9.5 days postconception (p.c.) for 48 hours with E-64 and/or L-methionine. We found that the addition of L-methionine to E-64-exposed cultures reduced optic abnormality and increased embryo protein. These results suggest that embryopathy largely results from a deficiency of L-methionine although E-64 limits the supply of all amino acids to the embryo. Furthermore, although endocytosis and degradation of proteins by the visceral yolk sac (VYS) supply most amino acids to the embryo, free amino acids may be compensatory when this source is reduced. These results support those of previous investigations that suggest L-methionine is a limiting nutrient for embryonic development.