RESUMO
Ticks are one of the main vectors of pathogens for humans and animals worldwide. However, they harbor non-pathogenic microorganisms that are important for their survival, facilitating both their nutrition and immunity. We investigated the bacterial communities associated with two neotropical tick species of human and veterinary potential health importance from Brazil: Amblyomma aureolatum and Ornithodoros brasiliensis. In A. aureolatum (adult ticks collected from wild canids from Southern Brazil), the predominant bacterial phyla were Proteobacteria (98.68%), Tenericutes (0.70%), Bacteroidetes (0.14%), Actinobacteria (0.13%), and Acidobacteria (0.05%). The predominant genera were Francisella (97.01%), Spiroplasma (0.70%), Wolbachia (0.51%), Candidatus Midichloria (0.25%), and Alkanindiges (0.13%). The predominant phyla in O. brasiliensis (adults, fed and unfed nymphs collected at the environment from Southern Brazil) were Proteobacteria (90.27%), Actinobacteria (7.38%), Firmicutes (0.77%), Bacteroidetes (0.44%), and Planctomycetes (0.22%). The predominant bacterial genera were Coxiella (87.71%), Nocardioides (1.73%), Saccharopolyspora (0.54%), Marmoricola (0.42%), and Staphylococcus (0.40%). Considering the genera with potential importance for human and animal health which can be transmitted by ticks, Coxiella sp. was found in all stages of O. brasiliensis, Francisella sp. in all stages of A. aureolatum and in unfed nymphs of O. brasiliensis, and Rickettsia sp. in females of A. aureolatum from Banhado dos Pachecos (BP) in Viamão municipality, Brazil, and in females and unfed nymphs of O. brasiliensis. These results deepen our understanding of the tick-microbiota relationship in Ixodidae and Argasidae, driving new studies with the focus on the manipulation of tick microbiota to prevent outbreaks of tick-borne diseases in South America.
Assuntos
Amblyomma/microbiologia , Microbiota , Ornithodoros/microbiologia , Animais , Bactérias/genética , Bactérias/isolamento & purificação , Coxiella/genética , Coxiella/isolamento & purificação , DNA Bacteriano/isolamento & purificação , Francisella/genética , Francisella/isolamento & purificação , Ixodidae/microbiologia , Metagenômica , RNA Ribossômico 16S/genética , Rickettsia/genética , Rickettsia/isolamento & purificaçãoRESUMO
Francisella noatunensis subsp. orientalis (FNO) is an important emerging pathogen associated with disease outbreaks in farm-raised Nile tilapia. FNO genetic diversity using PCR-based typing, no intra-species discrimination was achieved among isolates/strains from different countries, thus demonstrating a clonal behaviour pattern. In this study, we aimed to evaluate the population structure of FNO isolates by comparing whole-genome sequencing data. The analysis of recombination showed that Brazilian isolates group formed a clonal population; whereas other lineages are also supported by this analysis for isolates from foreign countries. The whole-genome multilocus sequence typing (wgMLST) analysis showed varying numbers of dissimilar alleles, suggesting that the Brazilian clonal population are in expansion. Each Brazilian isolate could be identified as a single node by high-resolution gene-by-gene approach, presenting slight genetic differences associated to mutational events. The common ancestry node suggests a single entry into the country before 2012, and the rapid dissemination of this infectious agent may be linked to market sales of infected fingerlings.
Assuntos
Francisella/genética , Sequenciamento Completo do Genoma , Técnicas de Tipagem Bacteriana , DNA Bacteriano , Francisella/classificação , Variação Genética , Genômica , Tipagem de Sequências MultilocusRESUMO
Historically, piscine francisellosis in various warm-, temperate-, and cold-water fish hosts has been attributed to Francisella noatunensis From 2015 to 2016, an undescribed Francisella sp. was recovered during mortality events in cultured spotted rose snapper (Lutjanus guttatus) off the Pacific coast of Central America. Despite high mortality and emaciation, limited gross findings were observed in affected fish. Histological examination revealed multifocal granulomatous lesions, with the presence of numerous small, pleomorphic coccobacilli, predominantly in the peritoneum, spleen, kidneys, liver, pancreas, heart, and intestine. Sequencing of an â¼1,400-bp fragment of the 16S rRNA gene demonstrated these isolates to be most similar (99.9% identity) to Francisella sp. isolate TX077308 cultured from seawater in the Gulf of Mexico, while sharing <99% similarity to other Fransicella spp. Biochemical analysis, multilocus sequence comparisons of select housekeeping genes, repetitive extragenic palindromic PCR fingerprinting, matrix-assisted laser desorption ionization-time of flight mass spectrometry, and fatty acid methyl ester analysis revealed marked differences between these isolates and other described members of the genus. Koch's postulates were fulfilled by experimental intracoelomic injection and immersion trials using Nile (Oreochromis niloticus) and blue (Oreochromis aureus) tilapia. Based on observed phenotypic and genotypic differences from recognized Francisella spp., the name Francisellamarina sp. nov. (NRRL B-65518) is proposed to accommodate these novel strains.IMPORTANCE Finfish aquaculture is the fastest growing global food production sector. Infectious disease, particularly emergent pathogens, pose a significant threat to established and nascent aquaculture industries worldwide. Herein, we characterize a novel pathogen isolated from mortality events in cultured spotted rose snapper in Central America. The bacteria recovered from these outbreaks were genetically and phenotypically dissimilar from other known Francisella spp. from fish, representing a previously unrecognized member of the genus Francisella, for which the name Francisella marina sp. nov. is proposed.
Assuntos
Ciclídeos/microbiologia , Doenças dos Peixes/microbiologia , Francisella/isolamento & purificação , Infecções por Bactérias Gram-Negativas/veterinária , Animais , Aquicultura , América Central , DNA Bacteriano/genética , Doenças dos Peixes/mortalidade , Francisella/genética , Infecções por Bactérias Gram-Negativas/mortalidade , Filogenia , RNA Ribossômico 16S/genéticaAssuntos
Ciclídeos , Doenças dos Peixes/microbiologia , Francisella/isolamento & purificação , Infecções por Bactérias Gram-Negativas/veterinária , Animais , Aquicultura , Brasil/epidemiologia , Doenças dos Peixes/diagnóstico , Francisella/genética , Infecções por Bactérias Gram-Negativas/diagnóstico , Infecções por Bactérias Gram-Negativas/epidemiologia , Reação em Cadeia da Polimerase em Tempo Real/veterináriaRESUMO
Streptococcus agalactiae and Francisella noatunensis subsp. orientalis (Fno) are important pathogens for farm-raised tilapia worldwide. There are no reports of coinfection caused by S. agalactiae and Fno in fish. This study aimed to determine the aetiology of atypical mortalities in a cage farm of Nile tilapia and to characterize the genetic diversity of the isolates. Fifty-two fish were sampled and subjected to parasitological and bacteriological examination. The S. agalactiae and Fno isolates were genotyped using MLST and REP-PCR, respectively. Whole-genome sequencing was performed to confirm the MLST results. Seven fish were shown coinfected by S. agalactiae and Fno. Chronic hypoxia and a reduction in the water temperature were determined as risk factors for coinfection. Fno isolates were shown clonally related in REP-PCR. The MLST analysis revealed that the S. agalactiae isolates from seven coinfected fish were negative for the glcK gene; however, these were determined to be members of clonal complex CC-552. This is the first description of coinfection by S. agalactiae and Fno in farm-raised Nile tilapia. The coinfection was predisposed by chronic hypoxia and was caused by the main genotypes of S. agalactiae and Fno reported in Brazil. Finally, a new S. agalactiae genotype with glcK gene partially deleted was described.
Assuntos
Ciclídeos , Doenças dos Peixes/mortalidade , Francisella/fisiologia , Variação Genética , Infecções por Bactérias Gram-Negativas/veterinária , Infecções Estreptocócicas/veterinária , Streptococcus agalactiae/fisiologia , Animais , Aquicultura , Coinfecção/microbiologia , Coinfecção/mortalidade , Coinfecção/veterinária , Doenças dos Peixes/microbiologia , Francisella/genética , Infecções por Bactérias Gram-Negativas/microbiologia , Infecções por Bactérias Gram-Negativas/mortalidade , Sequências Repetitivas Dispersas , Sequências Repetidas Invertidas , Tipagem de Sequências Multilocus/veterinária , Reação em Cadeia da Polimerase/veterinária , Infecções Estreptocócicas/microbiologia , Infecções Estreptocócicas/mortalidade , Streptococcus agalactiae/genéticaRESUMO
Despite the worldwide occurrence of Francisella noatunensis subsp. orientalis (Fno) infection in farmed tilapia, sensitivity and specificity estimates of commonly used diagnostic tests have not been reported. This study aimed to estimate the sensitivity and specificity of bacteriological culture and qPCR to detect Fno infection. We tested 559 fish, sampled from four farms with different epidemiological scenarios: (i) healthy fish in a hatchery free of Fno; (ii) targeted sampling of diseased fish with suggestive external clinical signs of francisellosis during an outbreak; (iii) convenience sampling of diseased and clinically healthy fish during an outbreak; and (iv) sampling of healthy fish in a cage farm without a history of outbreaks, but with francisellosis reported in other farms in the same reservoir. The qPCR had higher median sensitivity (range, 48.8-99.5%) than culture (range, 1.6-74.4%). Culture had a substantially lower median sensitivity (1.6%) than qPCR (48.8%) to detect Fno in carrier tilapia (farm 4). Median specificity estimates for both tests were >99.2%. The qPCR is the superior test for use in surveillance and monitoring programmes for francisellosis in farmed Nile tilapia, but both tests have high sensitivity and specificity which make them fit for use in the diagnosis of Fno outbreaks.
Assuntos
Ciclídeos , Doenças dos Peixes/microbiologia , Francisella/classificação , Infecções por Bactérias Gram-Negativas/veterinária , Animais , Aquicultura , Brasil , DNA Bacteriano/genética , Surtos de Doenças/veterinária , Doenças dos Peixes/patologia , Francisella/genética , Francisella/isolamento & purificação , Infecções por Bactérias Gram-Negativas/microbiologia , Infecções por Bactérias Gram-Negativas/patologia , Reação em Cadeia da Polimerase em Tempo Real , Sensibilidade e EspecificidadeRESUMO
Francisellosis, an emerging disease in tilapia Oreochromis spp., is caused by the facultative, intracellular bacterium Francisella noatunensis subsp. orientalis, which is present in various countries where tilapia farming is commercially important. We confirmed the presence of francisellosis in Mexican tilapia cultures in association with an outbreak during the second semester of 2012. Broodstock fish presented a mortality rate of approximately 40%, and disease was characterized by histologically classified granulomas, or whitish nodules, in different organs, mainly the spleen and kidney. Through DNA obtained from infected tissue and pure cultures in a cysteine heart medium supplemented with hemoglobin, F. noatunensis subsp. orientalis was initially confirmed through the amplification and analysis of the 16S rRNA gene and the internal transcribed spacer region. Phylogenetic analysis of these genes demonstrated close similarity with previously reported F. noatunensis subsp. orientalis sequences obtained from infected tilapia from various countries. The identification of this subspecies as the causative agent of the outbreak was confirmed using the iglC gene as a target sequence, which showed 99.5% identity to 2 F. noatunensis subsp. orientalis strains (Ethime-1 and Toba04). These findings represent the first documented occurrence of francisellosis in Mexican tilapia cultures, which highlights the importance of establishing preventative measures to minimize the spread of this disease within the Mexican aquaculture industry.
Assuntos
Doenças dos Peixes/microbiologia , Francisella/isolamento & purificação , Infecções por Bactérias Gram-Negativas/veterinária , Tilápia , Animais , Aquicultura , DNA Bacteriano/genética , DNA Espaçador Ribossômico/genética , Doenças dos Peixes/epidemiologia , Francisella/classificação , Francisella/genética , Infecções por Bactérias Gram-Negativas/epidemiologia , Infecções por Bactérias Gram-Negativas/microbiologia , México/epidemiologia , Filogenia , RNA Bacteriano/genética , RNA Ribossômico 16S/genéticaRESUMO
Strains of Francisella spp. were isolated from cooling water from an air conditioning system in Guangzhou, China. These strains are Gram negative, coccobacilli, non-motile, oxidase negative, catalase negative, esterase and lipid esterase positive. In addition, these bacteria grow on cysteine-supplemented media at 20 °C to 40 °C with an optimal growth temperature of 30 °C. Analysis of 16S rRNA gene sequences revealed that these strains belong to the genus Francisella. Biochemical tests and phylogenetic and BLAST analyses of 16S rRNA, rpoB and sdhA genes indicated that one strain was very similar to Francisella philomiragia and that the other strains were identical or highly similar to the Francisella guangzhouensis sp. nov. strain 08HL01032 we previously described. Biochemical and molecular characteristics of these strains demonstrated that multiple Francisella species exist in air conditioning systems.
Assuntos
Ar Condicionado , Proteínas de Bactérias/genética , RNA Polimerases Dirigidas por DNA/genética , Flavoproteínas/genética , Francisella , Microbiologia da Água , Sequência de Bases , China , DNA Bacteriano/genética , DNA Ribossômico/genética , Francisella/classificação , Francisella/genética , Francisella/isolamento & purificação , Dados de Sequência Molecular , Tipagem Molecular , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNARESUMO
Strains of
Assuntos
Ar Condicionado , Proteínas de Bactérias/genética , RNA Polimerases Dirigidas por DNA/genética , Francisella , Flavoproteínas/genética , Microbiologia da Água , Sequência de Bases , China , DNA Bacteriano/genética , DNA Ribossômico/genética , Francisella/classificação , Francisella/genética , Francisella/isolamento & purificação , Dados de Sequência Molecular , Tipagem Molecular , Filogenia , /genética , Análise de Sequência de DNARESUMO
Strains of