Masashi Nakamatsu

Emergence of a colistin-resistant Escherichia coli clinical isolate harboring mcr-1 in Japan

The mcr-1 is a gene encoding a phosphoethanolamine transferase, which confers resistance to colistin by transferring phosphoethanolamine to lipid A. We describe here the emergence of a colistin-resistant Escherichia coli clinical isolate harboring plasmid-mediated mcr-1 in Japan. The isolate belonged to ST5702 and is suspected to come from livestock and transmitted to human. This is the first report of a clinical isolate harboring mcr-1 in Japan.

The clinical and phylogenetic investigation for a nosocomial outbreak of respiratory syncytial virus infection in an adult hemato-oncology unit

Although many reports have already shown RSV outbreaks among hemato‐oncology patients, genomic studies detecting similar RSV strains prior to an outbreak in the hospital are rare. In 2014, the University of the Ryukyus hospital hemato‐oncology unit experienced, and successfully managed, a respiratory syncytial virus (RSV) nosocomial outbreak. During the outbreak investigation, genotyping and phylogenetic analysis was used to identify a potential source for the outbreak. Nasopharyngeal swabs were tested for RSV using three tests: (1) rapid antigen test (RAT); (2) reverse transcriptase polymerase chain reaction (PCR); or (3) quantitative PCR (RT‐qPCR); a positive PCR reaction was considered a confirmed case of RSV. Phylogenetic analysis of the G protein was performed for outbreak and reference samples from non‐outbreak periods of the same year. In total, 12 confirmed cases were identified, including 8 hemato‐oncology patients. Patient samples were collected weekly, until all confirmed RSV cases returned RSV negative test results. Median time of suspected viral shedding was 16 days (n = 5, range: 8‐37 days). Sensitivity and specificity of the RAT compared with RT‐qPCR were 30% and 91% (n = 42). Phylogenetic analysis revealed nine genetically identical strains; eight occurring during the outbreak time period and one strain was detected 1 month prior. A genetically similar RSV detected 1 month before is considered one potential source of this outbreak. As such, healthcare providers should always enforce standard precautions, especially in the hemato‐oncology unit.

Emergence of IncX4 plasmids encoding mcr-1 in a clinical isolate of Klebsiella pneumoniae in Japan

The mcr-1 gene encodes a phosphoethanolamine transferase that confers resistance to colistin by transferring phosphoethanolamine to lipid A. A 33-kb IncX4 plasmid harboring mcr-1 was detected in a Klebsiella pneumoniae isolate and two Escherichia coli isolates, and a 66-kb IncI2 plasmid was detected in three E. coli isolates in hospitals in Okinawa, Japan.

Prevention of a Nosocomial Infection Caused by Influenza Virus A Using Prophylactic Administration of Oseltamivir : An Observational Study with Review of the Literature

Influenza virus infection in hospitals is a very important clinical issue. The objective of this study was to describe the effect of oseltamivir in controlling a nosocomial influenza virus infection with an observational study and case report. Intervention was carried out in a ward of the University of the Ryukyus Hospital. Symptomatic staff members were sent home for one week, and the infected inpatients were isolated. In addition, in an episode of influenza infection among the staff members and inpatients, oseltamivir (75 mg once a day for 7 days) was administered to all staff members as well as inpatients who had had close contact with the influenza patients. In the hospital ward, eight staff members (nurses and doctors) and ten hospitalized patients were definitively diagnosed with influenza A viral infection based on results of a rapid diagnostic test. Although a relatively large number of the staff members and inpatients had an influenza virus infection, it was possible that the use of oseltamivir efficiently minimized a nosocomial outbreak. It was very difficult to diagnose influenza A virus infection based on clinical symptoms. It was possible to minimize and end the outbreak immediately by using oseltamivir prophylaxis. With a review of the literature, it is considered that prophylaxis with anti‐influenza drugs are highly recommended in hospital settings.