Molecular Identification and Virulence Potential of the Genus Aeromonas Isolated from Wild Rainbow Trout (Oncorhynchus mykiss) in Mexico.

The members of the Aeromonas genus are important foodborne pathogens, with a worldwide distribution. Wild rainbow trout, from the national protected area Santuario del Agua State Park, Corral de Piedra, were analyzed. Species of Aeromonas were isolated from the trout, and their pathogenic potential was analyzed based on different pathogenicity and virulence factors. The isolates were identified as A. allosaccharophila (n = 15), A. sobria (n = 8), A. veronii (n = 3), A. rivipollensis (n = 2), A. piscicola (n = 2), and A. popoffii (n = 1), by RNA polymerase sigma factor (rpoD) gene sequencing. Sequence similarity with the type strain was 92.2 to 99.6% for A. sobria isolates, 97.8 to 98.0% for A. allosaccharophila isolates, 99.2% for the A. popoffii isolate, 99.2 to 100% for A. piscicola isolates, and 98.2 to 99.2% for A. veronii isolates. Notably, isolates A30T2-gills and A30T2-spleen showed sequence similarity of 98.0% with strain A. media CECT 4232T and 99.0% with strain A. rivipollensis P2G1T. Virulence genes were detected by PCR at the following frequencies: fla and serine protease, 96.77%; aerA, 93.54%; aexT, 87.09%; lipases, 74.19%; ascV and ahyB, 67.74%; exu, 61.29%; act, 41.93%; ascF-G, 38.70%; lafA, 32.26%; alt, 6.46%; aopP, 9.67%; and ast, 3.23%. These results indicate that several Aeromonas species had the potential pathogenicity to infect wild rainbow trout in the waterway created by the Corral de Piedra dam, suggesting they could be an emerging zoonotic pathogen.

Eimeria atlapetesi nom. nov., a replacement name for Eimeria pileata Soriano-Vargas et al., 2015 (Apicomplexa: Eimeriidae), preoccupied by Eimeria pileata Straneva and Kelley, 1979 (Apicomplexa: Eimeriidae), with observations on histopathology and phylogenetic analysis.

Eimeria pileata Soriano-Vargas, Medina, Salgado-Miranda, García-Conejo, Galindo-Sánchez, Janczur, Berto and Lopes, 2015 is a junior homonym of Eimeria pileata Straneva and Kelley, 1979 and needs to be replaced. This coccidium was described from a rufous-capped brush finch Atlapetes pileatus Wagler in the Nevado de Toluca Natural Protected Area, Mexico. Thus, to maintain the original intent of the specific epithet derived from the scientific name of the type-host, the name Eimeria atlapetesi nom. nov. is proposed as a replacement name. Additionally, the current work reports another rufous-capped brush finch A. pileatus parasitized by E. atlapetesi in co-infection with an Isospora sp., providing observations of histopathology and phylogenetic analysis of 18S ribosomal RNA (rRNA) gene from E. atlapetesi. Endogenous forms of E. atlapetesi and Isospora sp. were observed in intestinal sections. Few oocysts of Isospora sp. were observed; therefore they were not morphologically or molecularly identified. In return, E. atlapetesi was identified and it was phylogenetically close to Eimeria dispersa Tyzzer, 1929 from the domestic turkey Meleagris gallopavo Linnaeus.