RESUMO
Salmonella enterica serovar Heidelberg is isolated from poultry-producing regions around the world. In Brazil, S. Heidelberg has been frequently detected in poultry flocks, slaughterhouses, and chicken meat. The goal of the present study was to assess the population structure, recent temporal evolution, and some important genetic characteristics of S. Heidelberg isolated from Brazilian poultry farms. Phylogenetic analysis of 68 S. Heidelberg genomes sequenced here and additional whole-genome data from NCBI demonstrated that all isolates from the Brazilian poultry production chain clustered into a monophyletic group, here called S. Heidelberg Brazilian poultry lineage (SH-BPL). Bayesian analysis defined the time of the most recent common ancestor (tMRCA) as 2004, and the overall population size (Ne) was constant until 2008, when an â¼10-fold Ne increase was observed until circa 2013. SH-BPL presented at least two plasmids with replicons ColpVC (n = 68; 100%), IncX1 (n = 66; 97%), IncA/C2 (n = 65; 95.5%), ColRNAI (n = 43; 63.2%), IncI1 (n = 32; 47%), ColMG828, Col156, IncHI2A, IncHI2, IncQ1, IncX4, IncY, and TrfA (each with n < 4; <4% each). Antibiotic resistance genes were found, with high frequencies of fosA7 (n = 68; 100%), mdf(A) (n = 68; 100%), tet(34) (n = 68; 100%), sul2 (n = 64; 94.1%), and blaCMY-2 (n = 56; 82.3%), along with an overall multidrug resistance (MDR) profile. Ten Salmonella pathogenicity islands (SPI1 to SPI5, SPI9, and SPI11 to SPI14) and 139 virulence genes were also detected. The SH-BPL profile was like those of other previous S. Heidelberg isolates from poultry around the world in the 1990s. In conclusion, the present study demonstrates the recent introduction (2004) and high level of dissemination of an MDR S. Heidelberg lineage in Brazilian poultry operations. IMPORTANCES. Heidelberg is the most frequent serovar in several broiler farms from the main Brazilian poultry-producing regions. Therefore, avian-source foods (mainly chicken carcasses) commercialized in the country and exported to other continents are contaminated with this foodborne pathogen, generating several national and international economic losses. In addition, isolates of this serovar are usually resistant to antibiotics and can cause human invasive and septicemic infection, representing a public health concern. This study demonstrates the use of whole-genome sequencing (WGS) to obtain epidemiological information for one S. Heidelberg lineage highly spread among Brazilian poultry farms. This information will help to define biosecurity measures to control this important Salmonella serovar in Brazilian and worldwide poultry operations.
Assuntos
Galinhas/microbiologia , Genoma Bacteriano , Aves Domésticas , Salmonella , Animais , Teorema de Bayes , Brasil , Fazendas , Genômica , Filogenia , Aves Domésticas/microbiologia , Salmonella/genética , Sorogrupo , Sequenciamento Completo do GenomaRESUMO
Foodborne pathogens cause an important public health burden, which is estimated in 600 million cases and more than 400,000 deaths, globally every year. The most susceptible populations, such as children under the age of five, the elderly and immunocompromised, account for the majority of the deaths. Food safety incidents, outbreaks, sporadic cases, and recalls have recognized economic impact, estimated at 7 billion every year in the US. Food safety has become a priority, and the implementation of preventive controls and monitoring systems has raised the development of new tools to detect and prevent pathogens in the food chain. Detection tools have evolved quickly, from rapid testing methods to application of genomics and metagenomics. Importantly, to reduce food safety hazards at food processing, the food chain needs to be seen from farm to fork. This review summarized the main findings discussed during the 2016 OECD-sponsored symposium on food safety. These include i) trends in food safety that embrace the need to implement new tools in detection and prevention, ii) the very rapid evolution of technologies to detect foodborne pathogens, iii) holistic approaches to prevent pathogens require a whole chain approach, and iv) key pillars to facilitate global implementations of new tools in food safety.
Assuntos
Contaminação de Alimentos/prevenção & controle , Manipulação de Alimentos/métodos , Doenças Transmitidas por Alimentos/prevenção & controle , Animais , Bactérias/classificação , Bactérias/genética , Bactérias/crescimento & desenvolvimento , Bactérias/isolamento & purificação , Contaminação de Alimentos/legislação & jurisprudência , Manipulação de Alimentos/legislação & jurisprudência , Manipulação de Alimentos/normas , Doenças Transmitidas por Alimentos/microbiologia , Humanos , MetagenômicaRESUMO
The genus Salmonella has more than 2,600 serovars, and this trait is important when considering interventions for Salmonella control. Bacteriophages that are used for biocontrol must have an exclusively lytic cycle and the ability to lyse several Salmonella serovars under a wide range of environmental conditions. Salmonella phages were isolated and characterized from 34 backyard production systems (BPSs) with a history of Salmonella infections. BPSs were visited once, and cloacal or fecal samples were processed for phage isolation. Four hosts, Salmonella serovars Enteritidis, Heidelberg, Infantis, and Typhimurium, were used for phage isolation. The host range of the phages was later characterized with a panel of 23 Salmonella serovars (serovar diversity set) and 31 isolates obtained from the same farms (native set). Genetic relatedness for 10 phages with a wide host range was characterized by restriction fragment length polymorphism, and phages clustered based on the host range. We purified 63 phages, and 36 phage isolates were obtained on Salmonella Enteritidis, 16 on Salmonella Heidelberg, and 11 on Salmonella Infantis. Phages were classified in three clusters: (i) phages with a wide host range (cluster I), (ii) phages that lysed the most susceptible Salmonella serovars (serogroup D) and other isolates (cluster II), and (iii) phages that lysed only isolates of serogroup D (cluster III). The most susceptible Salmonella serovars were Enteritidis, Javiana, and Dublin. Seven of 34 farms yielded phages with a wide host range, and these phages had low levels of genetic relatedness. Our study showed an adaptation of the phages in the sampled BPSs to serogroup D Salmonella isolates and indicated that isolation of Salmonella phages with wide host range differs by farm. A better understanding of the factors driving the Salmonella phage host range could be useful when designing risk-based sampling strategies to obtain phages with a wide lytic host range for biocontrol purposes.
Assuntos
Fezes/microbiologia , Fagos de Salmonella/genética , Salmonella/virologia , Animais , Fazendas , Especificidade de Hospedeiro , Salmonelose Animal , SorogrupoRESUMO
Since this book was originally published in 2007 there has been a significant increase in the number of Salmonella bacteriophages, particularly lytic virus, and Salmonella strains which have been fully sequenced. In addition, new insights into phage taxonomy have resulted in new phage genera, some of which have been recognized by the International Committee of Taxonomy of Viruses (ICTV). The properties of each of these genera are discussed, along with the role of phage as agents of genetic exchange, as therapeutic agents, and their involvement in phage typing.