Alexandre Tomomitsu Okatani

Contamination of Salmonella in retail meats and shrimps in the Mekong Delta, Vietnam.

From March 2000 to September 2001, 608 samples of retail meat (136 pork, 70 beef, 202 chicken, and 200 ducks) and 110 samples of retail shrimp from six provinces of the Mekong Delta in Vietnam were collected individually and examined for the prevalence of Salmonella. Of the 718 samples examined, 243 (33.8%) were Salmonella positive. Salmonella was isolated from 69.9% of the pork samples, 48.6% of the beef samples, 21.0% of the chicken meat samples, 22.3% of the duck meat samples, and 24.5% of the shrimp samples. From 261 Salmonella isolates, 24 different serovars were identified. The predominant serovars of the isolates were Salmonella Derby, Salmonella Weltevreden, and Salmonella London in pork; Salmonella Weltevreden, Salmonella London, and Salmonella Dessau in beef; Salmonella Emek, Salmonella Typhimurium, and Salmonella Dessau in chicken meat; Salmonella Lexington, Salmonella Derby, and Salmonella Dessau in duck meat; and Salmonella Weltevreden, Salmonella Tennessee, and Salmonella Dessau in shrimps. Salmonella Bovismorbificans, Salmonella Derby, Salmonella Dessau, and Salmonella Weltevreden were the most common serovars in all the samples examined. These results indicate a high rate of contamination by Salmonella in retail meats and shrimps in the Mekong Delta, Vietnam.

Sensitive and Specific Detection of Yersinia pseudotuberculosis by Loop-Mediated Isothermal Amplification

ABSTRACT We developed a loop-mediated isothermal amplification method able to detect Yersinia pseudotuberculosis strains in 30 min by using six primers designed by targeting the inv gene. This method is more sensitive than PCR and might be a useful tool for detecting and identifying Y. pseudotuberculosis.

Occurrence of Yersiniosis and Listeriosis in wild boars in Japan

From December 1994 to February 1995, 131 wild boars (Sus scrofa leucomysta) living in a mountainous area in Japan were examined for yersiniosis and listeriosis. Of 131 wild boars, 76 (58%) were males and 55 (42%) were females. Four Yersiniaspp. including Y. pseudotuberculosis, Y. enterocolitica, Y. frederiksenii,and Y. aldovei,were isolated from 49 (37%) of 131 wild boars. Yersinia pseudotuberculosiswas isolated from five (4%) of 131 wild boars. All Y. pseudotuberculosisisolates were serotype 4b and harbored virulence plasmids. Yersinia pseudotuberculosiswas isolated only from boars under 2-yr-old. No human pathogenic Y. enterocoliticawas isolated. Listeria monocytogeneswas isolated from two (1%) of the wild boars and both isolates were serotype 4b. These findings indicated that wild boar could be a reservoir of Y. pseudotuberculosisand L. monocytogenesin Japan.

Pulsed-Field Gel Electrophoresis in Differentiation of Erysipelothrix Species Strains

ABSTRACT We report here the first analysis of Erysipelothrixspp. using pulsed-field gel electrophoresis (PFGE). Seventy strains of Erysipelothrix spp. were analyzed.SmaI, AscI, and NotI were tested for the ability to cleave the DNA extracted from those strains, and among them, SmaI was the most reliable enzyme. Sixty-three distinct PFGE patterns were produced, and no DNA degradation was observed, allowing the identification of all of the strains. Based on these results and on those of a previous analysis using randomly amplified polymorphic DNA and ribotyping, PFGE withSmaI might be considered to be more sensitive than those methods and to be the best method for epidemiological studies of strains of this genus.

Genetic Characteristics of CTX-M-Type Extended-Spectrum-β-Lactamase (ESBL)-Producing Enterobacteriaceae Involved in Mastitis Cases on Japanese Dairy Farms, 2007 to 2011

ABSTRACT Sixty-five CTX-M-2/15/14 extended-spectrum-β-lactamase-producing Enterobacteriaceae were isolated from 258,888 mastitic milk samples from Japanese dairy farms between 2007 and 2011. CTX-M-2-producing Klebsiella pneumoniae and CTX-M-15-producing Escherichia coli were the predominant strains isolated. There was no predominant clonal type, and clonal diversity was found even in strains isolated from a single farm.

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.

Herd prevalence of Enterobacteriaceae producing CTX-M-type and CMY-2 β-lactamases among Japanese dairy farms.

To determine the herd prevalence of Enterobacteriaceae producing CTX‐M‐type extended‐spectrum β‐lactamases (ESBLs) among 381 dairy farms in Japan.

Contamination of Salmonella blockley in the environment of a poultry farm.

Cecal and environmental samples were collected and examined for the presence of Salmonella on a farm where a high prevalence of Salmonella blockley in chickens was observed. Of 895 cecal and 525 environmental samples examined, 242 (27.0%) and 202 (38.5%) samples, respectively, yielded S. blockley. From the analysis of plasmid profile patterns, 11 different plasmid profile patterns were found among 444 isolates, with plasmid patterns c and d the most frequent among the isolates from ceca and the environment. Salmonella blockley was isolated from environmental samples such as floor litter, walls, drinking water, waste water, dust, and soil collected when barns were occupied and was positive in drinking water, waste water, and soil when samples were collected from empty barns with occupied neighboring barns, but it was negative in all environmental samples with the exception of soil when the environmental samples were collected from empty barns with empty neighboring barns.

Differences in Heat Resistance among Pathogenic Yersinia enterocolitica Depended on Growth Temperature and Serotype

To gain a better understanding about the effect of growth temperature on heat resistance of Yersinia enterocolitica, we determined decimal reduction times at 60 degrees C (D60-values) for O:3; O:5,27; O:8; and O:9 strains harboring virulence plasmid coding for Yersinia outer membrane protein and experimentally virulence plasmid-deleted strains after they were grown to stationary phase at 7, 25, or 37 degrees C. Bacteria were inoculated into Trypticase soy broth and were incubated at several temperatures. D60-values of O:3; O:5,27; and O:8 strains were larger when they were grown at 37 degrees C than at 7 or 25 degrees C, despite the presence or absence of virulence plasmids. However, similar D60-values were observed in O:9 strains, despite growth at 7, 25, or 37 degrees C. The results indicate two types of Y. enterocolitica strains, growth temperature-dependent and -independent, and a Yersinia outer membrane protein that is not directly involved in growth temperature-dependent heat resistance.

MEASUREMENT OF CONCENTRATIONS OF POLYCYCLIC AROMATIC HYDROCARBONS (PAHS) IN SANDBOXES IN 51 JAPANESE PARKS

We investigated the concentrations of polycyclic aromatic hydrocarbons (PAHs) in the sand of sandboxes in 51 parks in Japan. We inspected the following 10 kinds of PAHs: fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1, 2, 3,-cd]pyrene, benzo [ghi]perylene, and dibenz[a,h]anthracene. The PAHs that showed relatively high concentrations were fluoranthene and pyrene, at 17.2 ng/g sand and 14.9 ng/g sand, respectively, on average. While the total concentration of PAHs in most samples ranged from 1 to 120 ng/g sand, some samples showed concentrations of 400, 600, and even nearly 1500 ng/g sand. The composition ratios of PAHs of most samples were comparable, but some samples had distinctive composition ratios, suggesting that various sources of pollution existed. The main problem is that the infants playing in sandboxes cannot distinguish between sandboxes polluted by PAH levels of several hundred ng/g sand or a thousand ng/g sand. Therefore, it is essential to investigate the causes of the pollution of PAH and to take countermeasures.