Maiko Watanabe

Virulence characteristics of Yersinia pseudotuberculosis isolated from breeding monkeys in Japan.

Between April 2001 and 2007, 18 Yersinia pseudotuberculosis outbreaks occurred in breeding monkeys at 12 zoological gardens in Japan, and 28 monkeys of 8 species died. A total of 18 Y. pseudotuberculosis strains from the dead monkeys, comprising one strain per outbreak, were examined for serotype and the presence of the virulence genes virF, inv, ypm (ypmA, ypmB and ypmC) and irp2. Of the 18 Y. pseudotuberculosis strains, 7 (38.9%) were serotype 4b, 7 (38.9%) were serotype 1b, and there was one each of serotypes 2b, 3, 6 and 7. All the 18 strains examined harbored virF and inv. Sixteen (88.9%) strains, including the strain of serotype 7, harbored ypmA. However, no strain harbored ypmB, ypmC and irp2. This study demonstrated that among other pathogenic factors, almost all the Y. pseudotuberculosis isolated from the outbreaks had the ypm gene encoding the superantigenic toxin, YPM. As most of the monkeys who died in those outbreaks originated from South America and other regions, where the presence of the ypm gene have not been reported, YPM might be the cause, or at least the most important factor for, the high mortality of the breeding monkeys infected by Y. pseudotuberculosis in Japan. This is also the first report of a fatal case due to Y. pseudotuberculosis serotype 7 infection in the world.

Fatal pneumonia caused by Penicillium digitatum: a case report

BackgroundPenicillium species are among the most common fungi present in the environment and are usually considered non-pathogenic to humans. However, in immunocompromised hosts they can be virulent pathogens and can cause death. Penicillium digitatum is a plant pathogen that commonly causes a postharvest fungal disease of citrus called green mould; it very rarely causes systemic mycosis in humans. Here, we report a case of fatal pneumonia due to P. digitatum infection, as confirmed by repeated examination of cultured sputum.Case presentationA cavity was found in the left upper lung on routine chest X-ray in a 78-year-old undernourished male who had been diagnosed at age 66 with bronchial asthma and pulmonary emphysema. No increased sputum production was present. The presence of antigen-specific precipitating antibodies to Aspergillus flavus and P. digitatum was confirmed in the patient’s serum and also later pleural fluid by using Ouchterlony double immunodiffusion testing with A. flavus and P. digitatum antigens. The patient was treated over a period of months with itraconazole, micafungin, voriconazole, amphotericin B, and antibacterials. However, the cavity enlarged, the pleural effusion increased, and the patient began producing purulent sputum. He died from progressive renal failure. From sputum culture only one fungus was isolated repeatedly on potato-dextrose agar in large quantities. This fungus was confirmed to be P. digitatum by molecular identification. Partial sequences of the beta-tubulin gene were determined by using the primers Bt2a and Bt2b for PCR amplification and sequencing and underwent a BLAST search at the National Centre for Biotechnology Information, these results confirmed that the isolated fungus was P. digitatum.ConclusionTo our knowledge, this is the first report of pulmonary infection with P. digitatum. Our patient had pulmonary emphysema and was elderly, and undernourished. These factors might have facilitated the infection. In his case, antimycotics were ineffective in treating the lung involvement. Although human infection with P. digitatum is considered rare, it appears that this organism can be very virulent and resistant to antimycotics.

New metabolic pathway for converting blasticidin S in Aspergillus flavus and inhibitory activity of aflatoxin production by blasticidin S metabolites.

Blasticidin S, a protein synthesis inhibitor, inhibits aflatoxin production of Aspergillus flavus without affecting fungal growth. Analysis of metabolites in blasticidin S-treated A. flavus using quadrupole time-of-flight liquid chromatography-mass spectrometry showed that blasticidin S was metabolized into a novel metabolite, N-acetyldeaminohydroxyblasticidin S. Conversion of blasticidin S to N-acetyldeaminohydroxyblasticidin S via deaminohydroxyblasticidin S or N-acetylblasticidin S was observed in in vivo and in vitro A. flavus systems. Blasticidin S and N-acetylblasticidin S inhibited the growth of Aspergillus niger strongly and weakly, respectively, but deaminohydroxyblasticidin S and N-acetyldeaminohydroxyblasticidin S did not inhibit its growth. On the other hand, deaminohydroxyblasticidin S sustained the inhibition of aflatoxin production whereas N-acetylblasticidin S and N-acetyldeaminohydroxyblasticidin S did not. These results suggest that the free amino group at C-13 of blasticidin S and deaminohydroxyblasticidin S may be important for the inhibitory activity of aflatoxin production.

Characteristics of bacterial and fungal growth in plastic bottled beverages under a consuming condition model

Microbial contamination in unfinished beverages can occur when drinking directly from the bottle. Various microorganisms, including foodborne pathogens, are able to grow in these beverages at room temperature or in a refrigerator. In this study, we elucidated the characteristics of microorganism growth in bottled beverages under consuming condition models. Furthermore, we provide insight into the safety of partially consumed bottled beverages with respect to food hygiene. We inoculated microorganisms, including foodborne pathogens, into various plastic bottled beverages and analysed the dynamic growth of microorganisms as well as bacterial toxin production in the beverages. Eight bottled beverage types were tested in this study, namely green tea, apple juice drink, tomato juice, carbonated drink, sport drink, coffee with milk, isotonic water and mineral water, and in these beverages several microorganism types were used: nine bacteria including three toxin producers, three yeasts, and five moulds. Following inoculation, the bottles were incubated at 35°C for 48 h for bacteria, 25°C for 48 h for yeasts, and 25°C for 28 days for moulds. During the incubation period, the number of bacteria and yeasts and visible changes in mould-growth were determined over time. Our results indicated that combinations of the beverage types and microorganism species correlated with the degree of growth. Regarding factors that affect the growth and toxin-productivity of microorganisms in beverages, it is speculated that the pH, static/shaking culture, temperature, additives, or ingredients, such as carbon dioxide or organic matter (especially of plant origin), may be important for microorganism growth in beverages. Our results suggest that various types of unfinished beverages have microorganism growth and can include food borne pathogens and bacterial toxins. Therefore, our results indicate that in terms of food hygiene it is necessary to consume beverages immediately after opening the bottle.

Spread and change in stress resistance of Shiga toxin‐producing Escherichia coli O157 on fungal colonies

To elucidate the effect of fungal hyphae on the behaviour of Shiga toxin‐producing Escherichia coli (STEC) O157, the spread and change in stress resistance of the bacterium were evaluated after coculture with 11 species of food‐related fungi including fermentation starters. Spread distances of STEC O157 varied depending on the co‐cultured fungal species, and the motile bacterial strain spread for longer distances than the non‐motile strain. The population of STEC O157 increased when co‐cultured on colonies of nine fungal species but decreased on colonies of Emericella nidulans and Aspergillus ochraceus. Confocal scanning microscopy visualization of green fluorescent protein‐tagged STEC O157 on fungal hyphae revealed that the bacterium colonized in the water film that existed on and between hyphae. To investigate the physiological changes in STEC O157 caused by co‐culturing with fungi, the bacterium was harvested after 7 days of co‐culturing and tested for acid resistance. After co‐culture with eight fungal species, STEC O157 showed greater acid resistance compared to those cultured without fungi. Our results indicate that fungal hyphae can spread the contamination of STEC O157 and can also enhance the stress resistance of the bacteria.

Microbial contamination associated with consumption and the growth in plastic bottled beverage

Plastic bottles enable the storage of unfinished beverages, and most of microbial contamination has occurred in the unfinished beverage that was left. Therefore, we investigated microorganisms in various beverages contaminated by pouring and drinking directly by mouth from the bottle, and analyzed the growth of microorganisms in the beverages at room temperature. In the pouring test, microbial growth was detected in 60 of 320 samples, and 13 bacterial strains, 49 mold strains, and 8 yeast strains were isolated. Molds including Cladosporium spp., Tramets spp., Bjerkandera spp., and Penicillium spp. accounted for the majority of isolated microorganisms. In the drinking test, microbial growth was detected in 181 of 352 samples, and 225 bacterial strains, 27 mold strains and 77 yeast strains were isolated. Bacteria including Streptococcus spp. such as S. salivarius and Staphylococcus spp. such as S. aureus accounted for the majority of isolated microorganisms. Enterotoxin-producing S. aureus and Bacillus cereus were also isolated. The pH of the beverage influenced the growth of bacteria. The Brix values of the beverage did not correlate with the growth of microorganisms. These results revealed that various microorganisms including foodborne pathogens were able to grow in numerous types of beverages and that the storage of unfinished beverage in inappropriate condition, such as the storage at room temperature led microorganism to grow easily in beverage. Therefore, it is necessary to consume beverages as soon as possible after opening the bottle.

Development of an Analytical Method for Simultaneous Determination of the Modified Forms of 4,15-Diacetoxyscirpenol and their Occurrence in Japanese Retail Food

4,15-Diacetoxyscirpenol (4,15-DAS) is a type A trichothecene mycotoxin produced by Fusarium species. Four modified forms of 4,15-DAS including 7-hydroxydiacetoxyscirpenol, 7,8-dihydroxydiacetoxyscirpenol, 4β,8α,15-triacetoxy-3α,7α-dihydroxy-12,13-epoxytrichothec-9-ene and 4,15-diacetylnivalenol were purified from cultures of F. equiseti. An analytical method using a multifunctional column has been developed for the simultaneous determination of 4,15-DAS, its four modified forms, T-2 toxin, HT-2 toxin and neosolaniol in cereals. The performance of the current method was evaluated, and a total of 248 samples of five different commodities were analyzed for over two years by this method. 4,15-DAS was detected in Job’s tears products, corn flour and azuki bean, but it was not found in wheat flour or rye flour. The four modified forms of 4,15-DAS were detected in samples of Job’s tears products, contaminated by 4,15-DAS. This is the first report on quantification of the modified forms of 4,15-DAS in cereals.

Innate immune response reflects disease activity in eosinophilic granulomatosis with polyangiitis

Eosinophilic granulomatosis with polyangiitis (EGPA) is a disease characterized by allergic granulomatosis, necrotizing vasculitis, and peripheral blood eosinophilia. Interleukin (IL)‐33, thymic stromal lymphopoietin (TSLP), and type 2 innate lymphoid cells (ILC2) are involved in the innate and type 2 immune responses in EGPA. However, the relationships among these molecules and the mechanisms underlying the development of EGPA remain unknown.

Allergic Bronchopulmonary Mycosis due to Exposure to Eurotium herbariorum after the Great East Japan Earthquake

BACKGROUND Indoor mold levels typically increase after natural disasters, flooding, and water damage. Eurotium herbariorum is the sexual stage of Aspergillus glaucus. Case Presentation A 66-year-old, Japanese male, ex-smoker had been diagnosed with bronchial asthma when he was five years old; he achieved remission at the age of 13 years. He was displaced from his home during the Great East Japan Earthquake on March 11, 2011 and moved to temporary housing in Miyagi Prefecture in June 2011. He experienced the first episode of chest tightness, coughing, and wheezing in February 2012, when he again was diagnosed as having bronchial asthma. Mycofloral surveillance detected high counts of Eurotium in the air of his bedroom, kitchen, and living room, with a maximal fungal count of 163,200 colony-forming units per cubic meter (CFU/m3). Although Cladosporium and Penicillium typically predominate in the indoor air of residential dwellings, only low levels of these organisms were present in the patients home. Morphologic identification confirmed the isolates as E. herbariorum. The patient had positive reactions to E. herbariorum in skin prick testing and the presence of antigen-specific precipitating antibodies to E. herbariorum. Computed tomography of the chest in August 2013 revealed central bronchiectasis and bronchial wall thickening. The patient experienced late reactions after provocation testing with E. herbariorum. CONCLUSION This report presents the rare case of a patient who developed allergic bronchopulmonary mycosis (ABPM) due to exposure to E. herbariorum during temporary housing after the Great East Japan Earthquake. Oshikata C , Watanabe M , Saito A , Ishida M , Kobayashi S , Konuma R , Kamata Y , Terajima J , Cho J , Yanai M , Tsurikisawa N . Allergic bronchopulmonary mycosis due to exposure to eurotium herbariorum after the Great East Japan Earthquake. Prehosp Disaster Med. 2017;32(6):688-690.

Allergic bronchopulmonary mycosis caused by Penicillium luteum

A 65-year-old Japanese male had severe bronchial asthma had increased mold-containing sputum. Serum total IgE level had increased to 798 IU/mL and antigen-specific precipitating antibodies to P. luteum and P. notatum were present but not those reactive toward any species of Aspergillus. Chest computed tomography revealed central bronchiectasis and bronchial wall thickness. After antigen-specific provocation with 10 mg/mL of P. luteum, the patient developed asthma exacerbation, but not with A. fumigatus. We present a rare case of Penicillium-induced allergic bronchopulmonary mycosis caused by P. luteum.