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Please cite this paper as: Wada et al. (2010). An epidemiological analysis of severe cases of the influenza A (H1N1) 2009 virus infection in Japan. Influenza and Other Respiratory Viruses 4(4), 179–186. Background The age distribution of confirmed cases with influenza A (H1N1) 2009 has shifted toward children and young adults, in contrast to interpandemic influenza, because of the age specificities in immunological reactions and transmission characteristics. Objectives Descriptive epidemiological analysis of severe cases in Japan was carried out to characterize the pandemic’s impact and clinical features. Methods First, demographic characteristics of hospitalized cases ( n = 12 923), severe cases ( n = 894) and fatal cases ( n = 116) were examined. Second, individual records of the first 120 severe cases, including 23 deaths, were analyzed to examine potential associations of influenza death with demographic variables, medical treatment and underlying conditions. Among severe cases, we compared proportions of specific characteristics of survivors with those of fatal cases to identify predictors of death. Results Age distribution of hospitalized cases shifted toward those aged <20 years; this was also the case for deaths without underlying medical conditions. Deaths in adults were mainly seen among those with underlying medical conditions, resulting in an increased risk of death as a function of age. According to individual records, the time from onset to death in Japan appeared rather short compared with that in other countries. Conclusion The age specificity of severe cases and their underlying medical conditions were consistent with other countries. To identify predictors of death in influenza A (H1N1) 2009 patients, more detailed clinical characteristics need to be examined according to different age groups and types of manifestations, which should ideally include mild cases as subjects. [ABSTRACT FROM AUTHOR]

Acinetobacter baumannii is regarded as one of the most important pathogens in hospital outbreaks. To obtain an efficient and simple epidemiologic method of surveillance during outbreaks, we assessed the applicability of the polymerase chain reaction–based open reading frames typing (POT) method and compared it with pulsed-field gel electrophoresis. The POT method was found to have sufficient discriminatory power to identify the strains and would be widely applicable to epidemiologic surveillance during hospital outbreaks. [ABSTRACT FROM AUTHOR]

Acinetobacter calcoaceticus–Acinetobacter baumannii complex, especially A. baumannii , Acinetobacter pittii and Acinetobacter nosocomialis , constitutes an important group of nosocomial pathogens; however, epidemiological or clinical characteristics and prognosis is limited in Japan. From 2009 to 2013, 47 blood stream infection cases resulting from A. baumannii group were reviewed at the National Defense Medical College, an 800-bed tertiary hospital. To determine the genospecies, further comparative nucleotide sequence analyses of the RNA polymerase b-subunit ( rpoB ) gene were performed. Sequence analysis of rpoB gene showed that 25 (49.0%), 17 (33.3%) and 5 (9.8%) cases were caused by A. baumannii , A. pittii and A. nosocomialis , respectively. The 30-day and in-hospital mortality rates of A. baumannii were 8.5% and 25.5%, respectively, and there were no significant differences between Acinetobacter species. Clinical characteristics were statistically insignificant. Multidrug-resistant Acinetobacter species were detected in 3 cases (5.9%) with same pulsed-field gel electrophoresis (PFGE) pattern and A. baumannii was less susceptible to amikacin and levofloxacin. In this study, the mortality and clinical characteristics were similar among A. baumannii group isolate cases despite some showing drug resistance. However, identification of Acinetobacter species helps to initiate appropriate antibiotic therapy in earlier treatment phase, because A. baumannii shows some drug resistance. [ABSTRACT FROM AUTHOR]