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.

We report here the first analysis of Erysipelothrix spp. 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 with SmaI might be considered to be more sensitive than those methods and to be the best method for epidemiological studies of strains of this genus.Erysipelothrix rhusiopathiae is a gram-positive, slender, and straight or slightly curved rod that causes a wide spectrum of diseases in animals, birds, and humans (14,49). This bacterium has been isolated in most parts of the world, not only from sick and healthy animals but even from pork, seafood, retail game meat, and chicken meat (11,19,26,27,38,40,44). Human infections with this bacterium are usually related to occupational exposure (33). However, infection after consumption of undercooked pork and infections of patients with no history of contact with animals or skin lesions have been reported, and in many cases, the source of infection has not been identified (6,13,20,28,37). Moreover, potential errors in the recognition of this organism isolated from human infections due to unusual clinical presentations and the possibility of underdiagnosed infections have been reported (3, 10, 34). PCR-based assays for the rapid diagnosis of Erysipelothrix species have been described (22, 39, 42). However, to proceed with an epidemiological study and identify the source of infection, it is necessary to be able to identify each strain isolated from a case or outbreak, as well as the relatedness among the strains isolated from the possible source.During the last few years, molecular biological methods such as randomly amplified polymorphic DNA (RAPD), ribotyping, and pulsed-field gel electrophoresis (PFGE) have been demonstrated to be reliable tools for the differentiation of species and strains of one genus and for use in epidemiological studies of several pathogenic bacteria (9,15,16,24,32,(46)(47)(48). Although PFGE has been considered to be the "gold standard" among these methods (30), studies have shown that this method can be less sensitive than ribotyping and PCR-based methods with regard to the ability to differentiate between bacterial strains of some species (5,36,45). Moreover, there is no standard and universal PFGE protocol for all species of bacteria and it is necessary to adapt the procedures and choose a suitable enzyme for each genus or species. However, the use of this method for strains of the genus Erysipelothrix has not been reported. Therefore, we describe herein the first analysis of a large collection of Erysipelothrix species strains by PFGE. MATERIALS AND METHODSBacterial strains. Seventy strai...

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In the period from December 2002 to January 2003, 5 of 50 squirrel monkeys (Saimiri sciureus) housed at a Zoological Garden in the Kanto region of Japan died following a few days' history of diarrhea. After this outbreak had ended in the squirrel monkeys, 1 of 2 dark-handed gibbons (Hylobates agilis) died in April of 2003, showing similar clinical signs. We examined the organs of 3 of the dead squirrel monkeys and of the dark-handed gibbon, and Yersinia enterocolitica serovar O:8, which is the most pathogenic serovar of Y. enterocolitica, was isolated. In order to determine the source and the transmission route of infection, 98 fecal samples (45 from squirrel monkeys, 20 from other monkeys of 18 different species, and 33 from black rats captured around the monkey houses) and 7 water samples were collected in the Zoological Garden, and were examined for the prevalence of Y. enterocolitica serovar O:8. Serovar O:8 was isolated from 21 of 65 monkeys (32.3%) and 5 of 33 (15.2%) black rats (Rattus rattus). Furthermore, we examined the 30 isolates using molecular typing methods, pulsed field gel electrophoresis (PFGE), ribotyping using the RiboPrinter system, and restriction endonuclease analysis of virulence plasmid DNA (REAP), and compared the isolates in this outbreak with Japanese O:8 isolates previously identified. Genotyping showed that almost all the isolates were identical, and the genotype of the isolates was highly similar to that from wild rodents captured in Niigata Prefecture. This is the first report of fatal cases of Y. enterocolitica serovar O:8 infection in monkeys anywhere in the world.