Aims: To clarify the epidemiological relationship between Lactococcus garvieae isolates from the Seriola in Japan and isolates from other animals. Methods and Results: A total of 32 isolates obtained from aquatic (the genus Seriola and trout) and terrestrial animals (cow, pig, cat, dog and horse) was used to evaluate its pathogenicity to yellowtail and mouse, phenotype (KG+ and KG)), its susceptibility to three bacteriophages and the pattern of pulsed field gel electrophoresis (PFGE). Lactococcus garvieae isolated from Seriola showed strong pathogenicity to yellowtail, while isolates from trout showed weak pathogenicity and those obtained from terrestrial animals showed no distinct pathogenicity. Only, the isolates from the genus Seriola in Japan showed susceptibility to the bacteriophages. The results of PFGE pattern indicate that the isolates obtained from the Seriola predict homogeneity, while there is no similarity among the isolates obtained from different animals. Conclusion: This experiment indicates that L. garvieae isolated from Seriola in Japan appears to be very different from the isolates obtained from other animals, and the isolates prevalent among the genus Seriola in Japan might be homogeneous. Significance and Impact of the Study: This study suggests that a particular genetic group that has specially adapted and acquired virulence toward yellowtail were prevalent among the genus Seriola in Japan.

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Aims:  To investigate the existing antimicrobial susceptibility and genetic characteristics of Lactococcus garvieae isolates from cultured Seriola in Japan. Methods and Results:  Minimum inhibitory concentrations (MICs) of 14 antimicrobial agents for 170 isolates were determined using the agar dilution method. Seventy‐five isolates (44·1%) were simultaneously resistant to erythromycin (EM) (MIC ≥ 2 μg ml−1), lincomycin (LCM) (MIC ≥ 128 μg ml−1) and oxytetracycline (OTC) (MIC ≥4 μg ml−1). Resistance to EM was grouped as intermediate‐ and high‐level resistant by MIC values. All resistant isolates possessed ermB and tet(S) genes. The number of different bands between pulsed‐field gel electrophoresis patterns of 25 isolates and two ATCC strains (isolated in 1974), determined using two enzymes (ApaI and SmaI), did not exceed 3. Conclusions:  The present resistance pattern observed with ermB and tet(S) is similar to that observed in previous reports. Moreover, the genetic characteristics of L. garvieae isolates from a wide area in Japan in 2002 and ATCC strains were closely related. Significance and Impact of the Study:  This study suggests that EM‐, LCM‐ and OTC‐resistant isolates have been present for 15 years and that L. garvieae strains with same origin have spread among Seriola spp. in Japan since 1974.

We screened mcr-1 and mcr-2 genes in 9,306 Escherichia coli strains isolated from healthy animals in the Japanese Veterinary Antimicrobial Resistance Monitoring (JVARM) system. mcr-1 was detected in 39 strains (5, 20, and 14 strains isolated from cattle, swine, and broilers, respectively), whereas mcr-2 was not detected. mcr-2 was also not detected with the investigation sequence homology search against our curated GenEpid-J database.

Aims:  To identify Lactococcus garvieae isolates from radish and broccoli sprouts and compare them with virulent and less virulent mutant strains obtained from yellowtails with regard to KG phenotype, presence of a capsule and virulence towards yellowtails and mice. Methods and Results:  Comparative 16S rRNA gene sequence analysis of six isolates obtained from radish and broccoli sprouts indicated that they were L. garvieae (similarity >99%). They were compared with KG9502, Lg2 and ATCC49156 strains obtained from yellowtails. A less virulent mutant strain Lg2‐S was obtained by Lg2 subculture. Biochemical characterization of the six strains resembled that of KG9502, Lg2, ATCC49156 and Lg2‐S, except for saccharose and tagatose acidification and the presence of hippuricase. These six strains were nonpathogenic towards yellowtails and mice, nonsusceptible to bacteriophages and demonstrated heterogeneity on pulsed‐field gel electrophoresis analysis. Using transmission electron microscopy, a capsule was observed in KG9502 and Lg2 but not in ATCC49156 and Lg2‐S. Conclusions:  We isolated L. garvieae strains that lacked pathogenicity towards yellowtails and mice from radish and broccoli sprouts; these were noncapsulated and exhibited KG+ phenotype. Significance and Impact of the Study:  This is the first documentation of L. garvieae isolated from terrestrial plants. These isolates exhibited genetic diversity; however, they were noncapsulated and nonpathogenic towards yellowtails and mice.