Genetic characteristics of archival noroviruses detected from the 1970s to the 1990s.

The genetic characterization of archival specimens is important for evaluating the evolutionary processes of noroviruses. Complete viral genome sequences, GVIII.1[GII.P28] and GIX.1[GII.P15], were determined from two archival specimens collected in Tokyo, Japan, in 1986 and 1995. In addition, complete VP1 and partial RdRp sequences of four samples collected between 1975 and 1983 were determined. Two viruses were classified as GI.5[P5] and GI.9[P9]; however, the viruses from the other two samples could not be assigned to any known genotypes using norovirus typing tools and phylogenetic analysis, suggesting that they might be untypable genotypes. Further evolutionary analysis of these viruses is warranted.

Whole genomic analysis of human G8P[14] group A rotavirus detected from community gastroenteritis outbreak.

Several suspected cases of zoonotic transmission of group A rotavirus (RVA)-related gastroenteritis were reported previously. In August 2012, G8P[14] RVA was detected in fecal specimens from a community gastroenteritis outbreak occurring during a school trip. In this study, additional analyses were performed and it was found that this strain had the G8-P[14]-I2-R2-C2-M2-A3-N2-T6-E2-H3 sequence, similar to bovine-like RVA strains. Some contamination by emesis and diarrheic feces was observed near a rest room in the lodging area. Contact history with animals was unknown in members of this school trip, and this case implied that the strain may have acquired the ability for person-to-person transmission.

Comparison between patients with norovirus-related gastroenteritis and asymptomatic carriers with respect to distribution of antibody-complexed viral particles and intestinal flora.

Asymptomatic carriers have a major influence on the spreading of norovirus infections. The objective of this study was to examine the characteristics of patients and asymptomatic carriers affected by norovirus-related community gastroenteritis outbreaks. No significant difference between the two groups was observed in terms of the number of norovirus-antibody complexes with respect to total numbers. Principal coordinates analysis of the intestinal flora based on ß-diversity analysis, revealed a different bacterial composition between patients and asymptomatic carriers, particularly regarding the genera Pseudomonas, Bacteroides, and Erwinia, as well as the Ruminococcaceae family. Although the proportional changes between these intestinal microorganisms were not sufficient to explain gastroenteritis symptoms, they represent possible markers shared by asymptomatic norovirus carriers.

[Molecular Epidemiological Analysis of Hepatitis A Viruses Circulating in Tokyo, 2016-2017].

Hepatitis A virus (HAV) is a common infectious agent that causes acute hepatitis worldwide. Since the incubation period of HAV infection is about one month, it is difficult to identify the source of infection based only on medical interviews. Molecular epidemiological analysis of HAV isolated from patients can help to reveal the infection route and to identify diffuse outbreaks caused by common food vehicles. In the present study, samples were collected from 108 cases notified to the active epidemiological investigation system in Tokyo between 2016 and 2017. Samples found to be HAV-positive by semi-nested RT-PCR were subjected to sequencing and phylogenetic analysis; the results were analyzed together with the epidemiological data. HAV was detected in 99 out of 108 cases. Phylogenetic analysis showed that the 99 HAV strains were divided into 91 of genotype IA, two of IB, and six of IIIA. The 91 HAV strains typed as IA were further divided into four main line-ages, IA-1, IA-2, IA-3, and IA-4, each with a unique epidemiological background. Our nucleotide sequence database of HAV and epidemiological background data will be helpful to investigate sources of infection and the epidemiology of hepatitis A cases in the future.

Genomic analysis of the evolutionary lineage of Norovirus GII.4 from archival specimens during 1975-1987 in Tokyo.

This study aimed to analyze NoV GII.4 sequences from archival specimens obtained during 1975-1987 by comparing them with reference sequences. The first NoV GII.P4_GII.4 sequence was identified in 1980. NoV GII.4 collected in 1970 had a GII.P1_GII.4 sequence. These results indicate that the GII.P4_GII.4 sequence may be the result of a recombination that might have occurred around 1980. Amino acid substitutions based on this replacement were mainly accumulated in the NTPase, p22, and RdRp regions. The emergence of GII.P4_GII.4 sequence is considered to have ended the major prevalence of NoV GII.4. J. Med. Virol. 89:363-367, 2017. © 2016 Wiley Periodicals, Inc.

Distribution of Staphylococcus aureus carriage among healthcare workers in a Japanese convalescent and rehabilitation hospital.

Earlobes, nasal cavities, and fingers of 145 healthcare workers in convalescent and rehabilitation hospital (60 nurses and 85 rehabilitation healthcare workers) were sampled. Of the 3 sites sampled, Staphylococcus aureus was detected in one or more sites in 25 nurses and 27 rehabilitation workers. S. aureus was detected in all 3 sites in 2 (8.0%) nurses and 2 (7.4%) rehabilitation workers, and the S. aureus isolates in each case showed related PFGE pattern. S. aureus was detected in both the fingers and nasal cavities of 5 (18.5%) of the rehabilitation healthcare workers; in all 5 cases, the PFGE patterns of the S. aureus isolates from each site belonged to same cluster based on PFGE. Of the 2 cases in which methicillinresistant S. aureus (MRSA) was recovered from earlobes, fingers, and nasal cavities, in both cases, MRSA isolates from the 3 sites were the same clone according to PFGE analysis and SCCmec type IV. As S. aureus was detected in pierced earlobes of nurses, hand hygiene must be practiced after touching pierced earlobes and before patient contact. The same S. aureus clone in the nasal cavity and earlobes indicates that the route of transmission is through the fingers.

Cross-contamination of bacteria-colonized pierced earring holes and fingers in nurses is a potential source of health care-associated infections.

BACKGROUND: In recent years, the wearing of pierced earrings for personal adornment has increased among health care workers in Japan. However, the transmission dynamics between bacteria in pierced earring holes and fingers has not been clearly shown. METHODS: Earlobes and fingers of 200 nurses (128 nurses with pierced earlobes and 72 nurses with unpierced earlobes) working at a university hospital were sampled to determine whether cross-transmission of bacteria-colonized pierced earring holes and fingers in nurse is possible. RESULTS: Of 128 nurses who had pierced earring holes, Staphylococcus aureus was recovered from earlobes of 24 nurses (18.8%) compared with 7 of 72 nurses without pierced earring holes (9.7%) (P = .09). Of those 15 nurses yielding S aureus from both earlobes and fingers, 12 were from nurses who had pierced earring holes compared with 3 nurses without pierced earring holes. Excluding 1 nurse, antimicrobial susceptibility patterns and genotypes of S aureus from both earlobe and fingers of each nurse were identical. CONCLUSION: Pierced earlobes can be a source of health care-associated infection via cross-transmission of bacteria from earlobe holes to fingers.

Detection of Norovirus in Swab Specimens of Restrooms and Kitchens Collected for Investigation of Suspected Food Poisoning Outbreaks in Tokyo.

During 2015-2016, we examined norovirus (NoV) RNA in swab specimens collected for investigation of suspected food poisoning outbreaks in Tokyo by real-time RT-PCR. Of 1,726 swab samples, 65 (3.8%) were NoV-positive and all positive swab samples were derived from NoV-positive outbreaks. Swab specimens were positive in 41 of 181 (22.7%) NoV outbreaks, while no positive swabs were detected in NoV-negative outbreaks. PCR fragments amplified from 32 swabs were sequenced, and all of them displayed complete homology with sequences from clinical and food samples. Though the results of swabs may be useful for determining the causative agent and infection route in some outbreaks, there was no case in which the results of swabs alone could elucidate the cause of food poisoning. Swabs may be useful in food poisoning investigations, if the results are interpreted in conjunction with epidemiological findings and clinical data. Swab samples are often collected several days after an outbreak, and the influence of disinfection should be taken into consideration. In NoV outbreaks, 55 out of 640 (8.6%) restroom swab specimens were NoV-positive whereas six of 618 (1.0%) were positive among kitchen swab specimens. In the restroom, the toilet bowl (43.6%) showed the highest positive rate and next was the toilet seat (14.5%). Additionally, NoV was detected at various sites in the restroom, including doorknob and floor. Since NoV-positive swab specimens may suggest that sanitation management is not performed properly in the facility, swab results may be utilized as a basis for hygiene guidance.

Detection of Enteric Viruses in Fecal Specimens from Nonbacterial Foodborne Gastroenteritis Outbreaks in Tokyo, Japan between 1966 and 1983.

We investigated the prevalence of 5 enteric viruses (norovirus [NoV], sapovirus, rotavirus, astrovirus, and adenovirus) in archived stool specimens collected from 70 foodborne gastroenteritis outbreaks in Tokyo, Japan, which occurred from 1966 to 1983, and genetically characterized these viruses. NoV was detected in 48 (68.6%) outbreaks, while SaV, group C rotavirus (RVC), and astrovirus were detected in 1 (1.4%) outbreak each. Based on the partial capsid sequences, the detected NoVs were classified into the following genotypes: 9 in genogroup I (GI; GI.1-6, GI.8, GI.9, and GI.NA), 13 GII (GII.1-9, GII.13, GII.16, GII.17, and GII.22), and one in GIV. The oldest NoV outbreaks occurred in 1966. No predominant genotype was found. One strain, classified as GI. NA based on the N/S region sequence, was subsequently classified as GI.8 based on the complete VP1 sequence. Nine types of recombinant NoV sequences, including 7 unreported combinations, were identified. Further genetic characterization of NoV GII.17 and GII.4 demonstrated that the NoV GII.17 strains detected from 1970 to 1982 clustered independently from previously reported NoV GII.17 strains. Phylogenetic analysis, using the complete VP1 region and the P2 domain, demonstrated that NoV GII.4 strains collected between 1975 and 1980 clustered with archival strains collected in the USA in the mid-1970s. In contrast, a NoV GII.4 strain collected in 1983 formed an independent branch from reference strains collected in the mid-1970s to 2012.

Multiplex real-time PCR assays for the detection of group C rotavirus, astrovirus, and Subgenus F adenovirus in stool specimens.

Group C rotavirus (GCRV), astrovirus (AstV), and adenovirus (subgenus F AdenoV) are etiologic agents of acute nonbacterial gastroenteritis, which often represents community outbreaks. For the efficient detection of GCRV, AstV, and subgenus F AdenoV in stool specimens, a multiplex real-time PCR assay was developed to detect these three viruses simultaneously, with high sensitivity and specificity. In total, 8404 clinical specimens were collected between April 2008 and March 2011 and tested for GCRV, AstV, and subgenus F AdenoV by the multiplex real-time PCR, as well as for norovirus (NoV), sapovirus (SaV), and group A rotavirus (GARV) by non-multiplex real-time PCR. Forty-one specimens were positive for GCRV, AstV, or subgenus F AdenoV, including 15 specimens that were also positive for NoV, SaV, or GARV. Multiple viruses were detected simultaneously in 29 out of 4596 (0.63%) specimens infected with at least one virus. The association rates of AstV and subgenus F AdenoV with other viruses were significantly higher than those of NoV, SaV, GARV, or GCRV.

[Detection of norovirus RNA in bivalve molluscs by using bacteria-culture-employed method (A3T method)].

Norovirus (NV) RNA has rarely been detected in foods despite the use of highly sensitive methods such as RT-PCR and real-time RT-PCR. In the modified method (A3T method) reported previously, a bacterial culture process was introduced into the standard protocol for NV detection to remove some inhibitor(s) present in food ingredients. To confirm the efficiency of the A3T method and to examine NV contamination in bivalve molluscs, we tried to detect NV RNA in bivalve molluscs on the market and in oyster samples associated with foodborne outbreaks by using the standard method and the A3T method. NV RNAs were detected in 20 samples (18.0%) of 111 bivalve molluscs, including oysters, on the market by use of the A3T method, while only one sample (0.9%) was positive according to the standard method. NV RNA was also detected in 10 of 35 oyster samples related to foodborne outbreaks by the A3T method. Those results show that the A3T method is suitable for the detection of NV in bivalve molluscs in general laboratories.

[Enhancement of norovirus detection rates in oysters and other food samples by using bacterial treatment].

Factors such as low recovery rate and food contaminants may be responsible for the difficulty of detecting Norovirus (NV) by PCR in foodborne outbreaks. To detect NV more efficiently, we introduced a bacterial treatment, in which concentrated samples were incubated overnight with Klebsiella oxytoca at 35 degrees C before RNA extraction using the standard protocol. Recovery rates of NVs (G I/8 or G II/13) added to food suspensions in the modified method were compared with those in the standard method by quantification of NV RNAs using real-time PCR. Recovery rates in the modified method were 8.6% for G I/8 and 11.6% for G II/13 in 18 oyster samples and 13.9% for G I/8 and 19.6% for G II/13 in 15 other food samples, while those in the standard method were 0.3% for G I/8 and 0.5% for G II/13 in the oyster samples and 1.9% for G I/8 and 7.9% for G II/13 in the other food samples. These results indicate that the bacterial treatment increase the recovery of NV from foods such as oysters, suggesting that the modified method will be useful for NV detection in food samples.