Edgardo Soriano-Vargas

Isolation and Distribution of Bacterial Flora in Farmed Rainbow Trout from Mexico

Trout farming is a growing aquaculture industry in Mexico, with stock mainly supplied by the importation of eyed eggs. The aim of the present study was to determine the frequency of bacterial isolations in farmed rainbow trout Oncorhynchus mykiss from Mexico. Sixty-five farms distributed among seven states of Mexico were included in the study. Individual samples from gills, liver, spleen, intestine, and kidney were obtained from 563 apparently healthy fish. In total, 371 bacterial isolates were recovered from sampled fish; isolates of the genera Aeromonas, Edwardsiella, Enterobacter, Escherichia, Klebsiella, Plesiomonas, Pseudomonas, and Yersinia were identified. Aeromonads were the most frequently isolated bacteria. Renibacterium salmoninarum was not isolated from any of the sampled fish. Our results showed the presence of bacteria that are potential pathogens of both rainbow trout and humans.

ERIC-PCR Genotyping of Emergent Serovar C-1 Isolates of Avibacterium paragallinarum from Mexico

SUMMARY. Between 2008 and 2010, 14 isolates of Avibacterium paragallinarum were identified as serovar C-1 in Mexico. All isolates were obtained from commercial laying hens suffering infectious coryza despite a history of vaccination. The enterobacterial repetitive intergenic consensus-based PCR genotyping showed that all isolates had a common pattern. Until recently, serovars A-1, A-2, B-1, and C-2 were the serovars prevalent in Mexico. Serovar C-1 has been identified in Japan and recently in the Americas in Ecuador. Our current study suggests that Av. paragallinarum serovar C-1 is an emerging serovar in Mexico. Our results also indicate that the Mexican isolates of Av. paragallinarum serovar C-1 may have a clonal relationship. Knowledge of the genetic diversity of Av. paragallinarum may be of value in understanding vaccine performance and identifying the best combination to achieve broader protection.

Pathogenicity of Mexican isolates of Aeromonas sp. in immersion experimentally-infected rainbow trout (Oncorhynchus mykiss, Walbaum 1792)

Ten species of Aeromonas have been previously identified in farmed rainbow trout from Mexico. The aim of the current study was to investigate the pathogenicity of 10 Aeromonas isolates belonging to 10 different Aeromonas species in immersion experimentally-infected rainbow trout fry. Isolates of A. bestiarum, A. hydrophila, A. salmonicida, and A. veronii produced significant mortality (8.8%, 12.2%, 18.8%, and 8.8%, respectively). Isolates of A. caviae and A. sobria produced no significantly mortality (3.3% and 1.1%, respectively). No mortality was recorded in fish infected with A. allosaccharophila, A. lusitana, A. media, or A. popoffii. Microscopic lesions and bacterial reisolation were registered in liver of fish infected with the ten different Aeromonas isolates. Our results suggest that all Aeromonas species included in the study have the ability to colonize the liver. The results have confirmed that species A. bestiarum, A. hydrophila, A. salmonicida, and A. veronii affected fish as elsewhere reported. In conclusion, the variation in pathogenicity of Aeromonas isolates included in the study, emphasizes the importance of active, on-going monitoring of Aeromonas in the Mexican rainbow trout farming.

Hemagglutinin serotyping of Avibacterium paragallinarum isolates from Ecuador.

Avibacterium paragallinarum is the causative agent of infectious coryza, an acute respiratory disease of chickens. In this study, a total of 28 isolates of A. paragallinarum from Ecuador were serotyped by the hemagglutinin scheme which recognizes nine serovars. Out of 28 isolates, 17 isolates belonged to serovar A-3, and five isolates to each serovars B-1 and C-1, whereas one isolate was non-typeable. This is the first report of A. paragallinarum serovar A-3 outside Brazil and serovar C-1 outside Japan.

Outer membrane vesicles of Pasteurella multocida contain virulence factors.

Pasteurella multocida (Pm) is a gram‐negative bacterium able to infect different animal species, including human beings. This bacterium causes economic losses to the livestock industry because of its high morbidity and mortality in animals. In this work, we report the characterization of outer membrane vesicles (OMVs) released into the culture medium by different Pm serogroups. Purified OMVs in the range of 50–300 nm were observed by electron microscopy. Serum obtained from chickens infected with Pm recognized several proteins from Pm OMVs. Additionally, rabbit antiserum directed against a secreted protease from Actinobacillus pleuropneumoniae recognized a similar protein in the Pm OVMs, suggesting that OMVs from these bacterial species contain common immunogenic proteins. OmpA, a multifunctional protein, was identified in OMVs from different Pm serogroups, and its concentration was twofold higher in OMVs from Pm serogroups B and D than in OMVs from other serogroups. Three outer membrane proteins were also identified: OmpH, OmpW, and transferrin‐binding protein. Three bands of 65, 110, and 250 kDa with proteolytic activity were detected in Pm OMVs of serogroups A and E. Additionally, β‐lactamase activity was detected only in OMVs from Pm 12945 Ampr (serogroup A). Pm OMVs may be involved in different aspects of disease pathogenesis.

Phenotypical characteristics, genetic identification, and antimicrobial sensitivity of Aeromonas species isolated from farmed rainbow trout (Onchorynchus mykiss) in Mexico

In the present study, Aeromonas isolates from diseased and healthy farmed rainbow trout (Oncorhynchus mykiss) in Mexico, were characterized phenotypically and identified to species level by using 16S rDNA RFLP-PCR. A total of 50 isolates were included in the study and 10 Aeromonas species identified. The species A. veronii biovar sobria (22%), A. hydrophila (20%) and A. bestiarum (20%) were the most predominant. All isolates (100%) were resistant to cephalothin.

Identification of Avibacterium paragallinarum Serovar B-1 from Severe Infectious Coryza Outbreaks in Panama

Abstract The isolation and identification of Avibacterium paragallinarum serovar B-1 from severe infectious coryza outbreaks in broiler breeders in Panama is reported for the first time. Infectious coryza was absent for over a decade in the breeder farms area. Disease outbreaks were characterized by an up to 45% drop in egg production and increased mortality. Use of a commercial trivalent bacterin and a strengthened biosecurity program prevented outbreaks in susceptible flocks in the farm.

An evaluation of serotyping of Avibacterium paragallinarum by use of a multiplex polymerase chain reaction

In the present study, the ability of a recently proposed multiplex polymerase chain reaction (mPCR) to determine the serogroups (A, B, and C) of Avibacterium paragallinarum was evaluated. A total of 12 reference strains and 69 field isolates of Av. paragallinarum from Ecuador, Mexico, Panama, and Peru were included in the study. With some exceptions (which were serotyped in the current study), all of the isolates and strains had been previously examined by 2 serotyping schemes (Page and Kume) or were the formal reference strains for the schemes. Three of 6 (50%) reference strains of serogroup A, 2 (100%) of serogroup B, and 1 of 4 (25%) reference strains of serogroup C were correctly serotyped by the mPCR. With the field isolates, the mPCR correctly recognized 16 of the 17 serogroup A isolates, 10 of the 12 serogroup B isolates, and 18 of the 37 serogroup C isolates. Overall, the specificity and sensitivity of the PCR test was as follows: 82.6% and 87.3% (serogroup A), 85.7% and 71.9% (serogroup B), and 46.3% and 100% (serogroup C). The poor performance of the mPCR in terms of recognition of serogroup C isolates (low sensitivity of 46.3%) and the relatively high level of uncertainty about the accuracy of the serogroup A and B results (specificity of 87.3% and 71.9%, respectively) means that the assay cannot be recommended as a replacement for conventional serotyping.

Identification of Pasteurella multocida capsular types isolated from rabbits and other domestic animals in Mexico with respiratory diseases

Pasteurella multocida is the causative agent of pasteurellosis, a major disease in most domestic animals and livestock. In this study, a total of 34 isolates of P. multocida from rabbits and other domestic animals from Mexico with respiratory diseases underwent polymerase chain reaction-based capsular typing. One sheep isolate was found to belong to capsular serogroup D, whereas the rest of the rabbit, sheep, cattle, pig, goat, and duck isolates belonged to capsular serogroup A of P. multocida. This is the first report of capsular type A in P. multocida isolates from rabbits and duck origin in Mexico.

Phylogenetic Relationship of Serovar C-1 Isolates of Avibacterium paragallinarum

SUMMARY The bacterium Avibacterium paragallinarum is the etiologic agent of infectious coryza of chickens. Serovar C-1 has emerged in infectious coryza outbreaks in layer hens of Ecuador and Mexico. In the current study, genotyping and phylogenetic analyses of five Ecuadorian and 10 Mexican isolates of Av. paragallinarum serovar C-1 were performed. All 15 isolates share a unique enterobacterial repetitive intergenic consensus-based-PCR fingerprint and have identical 16S ribosomal RNA and hemagglutinin antigen gene sequences. Results indicate that Ecuadorian and Mexican isolates of serovar C-1 of Av. paragallinarum have a clonal relationship. RESUMEN Nota de Investigación—Relación filogenética de aislamientos de Avibacterium paragallinarum serovar C-1. La bacteria Avibacterium paragallinarum es el agente etiológico de la coriza infecciosa de los pollos. El serovar C-1 se ha presentado en brotes de coriza infecciosa en gallinas ponedoras de Ecuador y de México. En el presente estudio, se llevó a cabo la genotipificación y análisis filogenéticos de cinco aislamientos ecuatorianos y de diez aislamientos mexicanos de Av. paragallinarum serovar C-1. Los 15 aislamientos compartieron una huella genética intergénica, consensuada y repetitiva única de enterobacterias, que fue detectada por PCR y también mostraron secuencias idénticas de los genes ribosomal 16S y del antígeno de la hemaglutinina. Los resultados indican que los aislamientos ecuatorianos y mexicanos de serovar C-1 de Av. paragallinarum tienen una relación clonal.