Microevolution during the emergence of a monophasic Salmonella Typhimurium epidemic in the United Kingdom

Microevolutionary events associated with the emergence and clonal expansion of new 27 epidemic clones of bacterial pathogens hold the key to understanding the drivers of 28 epidemiological success. We describe a comparative whole genome sequence and 29 phylogenomic analysis of monophasic Salmonella Typhimurium isolates from the UK 30 and Italy from 2005-2012. Monophasic isolates from this time formed a single clade 31 distinct from recent monophasic epidemic clones described previously from North 32 America and Spain. The current UK monophasic epidemic clones encode a novel 33 genomic island encoding resistance to heavy metals (SGI-3), and composite transposon 34 encoding antibiotic resistance genes not present in other Typhimurium isolates, that 35 may have contributed to the epidemiological success. We also report a remarkable 36 degree of genotypic variation that accumulated during clonal expansion of a UK 37 epidemic including multiple independent acquisitions of a novel prophage carrying the 38 sopE gene and multiple deletion events affecting the phase II flagellin locus

Review: Nutritional ecology of heavy metals

The aim of this review is to focus the attention on the nutrition ecology of the heavy metals and on the major criticisms related to the heavy metals content in animal feeds, manure, soil and animal-origin products. Heavy metals are metallic elements that have a high density that have progressively accumulated in the food chain with negative effects for human health. Some metals are essential (Fe, I, Co, Zn, Cu, Mn, Mo, Se) to maintain various physiological functions and are usually added as nutritional additives in animal feed. Other metals (As, Cd, F, Pb, Hg) have no established biological functions and are considered as contaminants/undesirable substances. The European Union adopted several measures in order to control their presence in the environment, as a result of human activities such as: farming, industry or food processing and storage contamination. The control of the animal input could be an effective strategy to reduce human health risks related to the consumption of animal-origin products and the environmental pollution by manure. Different management of raw materials and feed, animal species as well as different legal limits can influence the spread of heavy metals. To set up effective strategies against heavy metals the complex interrelationships in rural processes, the widely variability of farming practices, the soil and climatic conditions must be considered. Innovative and sustainable approaches have discussed for the heavy metal nutrition ecology to control the environmental pollution from livestock-related activities

Bovine tuberculosis and brucellosis in livestock at the Greater Ruaha Ecosystem

Tanzania Veterinary Journal Vol. 35 (1) 2020A cross-sectional study was conducted to determine the prevalence of bovine tuberculosis (BTB) and the seroprevalence of brucellosis in livestock at the Greater Ruaha Ecosystem in Tanzania. The study further characterized the Mycobacterium spp. from the slaughtered livestock. Survey conducted to assess potential herd-level risk factors for BTB and brucellosis revealed that the respondents’ ethnicity and herd mixing were the significant risk factors. Twenty-eight percent of 102 cattle herds had at least one positive or suspect BTB reactor. The overall prevalence of BTB infection in the cattle was 1.32% (18/1368). Forty-two percent of 93 flocks of the small ruminants had at least one brucellosis seropositive animal. The overall seroprevalence of brucellosis in the cattle and small ruminants was 6.6%. Although the prevalence of both diseases was relatively low for individual animals, herd-level prevalence was high, suggesting that infection is widespread in the study area and a significant number of households are at risk. Mycobacterium bovis strain identified via polymerase chain reaction (PCR) was confirmed by spoligotyping as spoligotype SB0133. This cattle strain of M. bovis was similar to previously reported involving wild animals in adjacent protected areas. Isolation of identical M. bovis from the wildlife and livestock and the demonstration of Brucella spp. seroprevalence in livestock in the same interface, strongly suggest livestock-wildlife interspecies sharing of these pathogens. Occurrence of the microorganisms poses a serious challenge to disease management strategies in pastoralist communities in the interface area

Citrobacter as a gastrointestinal pathogen, its prevalence and molecular characterization of antimicrobial resistant isolates in food-producing animals in Morogoro, Tanzania

Proceeding of the 35 scientific conference of the Tanzania Veterinary association, Volume 35: 133-139Citrobacter is a gastrointestinal commensal of man and animals. The zoonotic Citrobacter spp. infection can occur if food products of animal origin are not hygienically handled. Therefore, the prevalence, antimicrobial resistance profile and resistance transmission mechanism of Citrobacter spp. in food-producing animals in Tanzania needs to be understood. Citrobacter isolates were recovered from 2.4% of the total of 1099 samples from apparently healthy animals. Citrobacter isolates were detected in 3.0% and 1.9% of the swine and the cattle samples, respectively. Over 80% of food products contamination with Citrobacter isolates originated from slaughtered cattle carcasses just before meat is transported to retail stores. About 62% of the isolates detected were resistant to at least one antimicrobial, whereas, 38.5% of the resistant isolates were exhibiting resistance to three or more antibiotic classes. All 26 presumptive Citrobacter isolates were screened for invA, intI1 and 16S rRNA. None of the isolates carried invA. Nearly 19% of the MDR Citrobacter isolates were found to carry an intI1. All intI1-positive isolates contained resistance gene cassettes dfrA1, dfrA7 and dfrA15. Detection of resistance gene cassettes in the MDR Citrobacter isolates in animals and animal products represents a potential source for horizontal transfer of antimicrobial resistance genes and mobile genetic elements between pathogenic and non-pathogenic bacteria in the microbial population. The findings indicate that animal feces could one of the potential sources for contamination of animal products along the food production chain

Bovine tuberculosis and brucellosis in Livestock at the Greater Ruaha Ecosystem

A cross-sectional study was conducted to determine the prevalence of bovine tuberculosis (BTB) and the seroprevalence of brucellosis in livestock at the Greater Ruaha Ecosystem in Tanzania. The study further characterized the Mycobacterium spp. from the slaughtered livestock. A questionnaire survey conducted to assess potential herd-level risk factors for BTB and brucellosis revealed that the respondents’ ethnicity and herd mixing were the significant risk factors. Twenty-eight percent of 102 cattle herds had at least one positive or suspect BTB reactor. The overall prevalence of BTB infection in the cattle was 1.32% (18/1368). Forty-two percent of 93 flocks of the small ruminants had at least one brucellosis seropositive animal. The overall seroprevalence of brucellosis in the cattle and small ruminants was 6.6%. Although the prevalence of both diseases was relatively low for individual animals, herd-level prevalence was high suggesting that infection is widespread in the study area and a significant number of households are at risk. Mycobacterium bovis strain identified via polymerase chain reaction (PCR) was confirmed by spoligotyping as spoligotype SB0133. This cattle strain of M.bovis was similar to previously reported involving wild animals in adjacent protected areas. Isolation of identical M. bovis from wildlife and livestock and the demonstration of Brucella spp. seroprevalence in livestock in the same interface, strongly suggest livestock-wildlife interspecies sharing of these pathogens. Occurrence of the microorganisms poses a serious challenge to disease management strategies in pastoralist communities in the interface are

Citrobacter as a gastrointestinal pathogen, its prevalence and molecular characterization of antimicrobial resistant isolates in food-producing animals in Morogoro, Tanzania

Proceeding of the 35 scientific conference of the Tanzania Veterinary association, Volume 35: 133-139Citrobacter is a gastrointestinal commensal of man and animals. The zoonotic Citrobacter spp. infection can occur if food products of animal origin are not hygienically handled. Therefore, the prevalence, antimicrobial resistance profile and resistance transmission mechanism of Citrobacter spp. in food-producing animals in Tanzania needs to be understood. Citrobacter isolates were recovered from 2.4% of the total of 1099 samples from apparently healthy animals. Citrobacter isolates were detected in 3.0% and 1.9% of the swine and the cattle samples, respectively. Over 80% of food products contamination with Citrobacter isolates originated from slaughtered cattle carcasses just before meat is transported to retail stores. About 62% of the isolates detected were resistant to at least one antimicrobial, whereas, 38.5% of the resistant isolates were exhibiting resistance to three or more antibiotic classes. All 26 presumptive Citrobacter isolates were screened for invA, intI1 and 16S rRNA. None of the isolates carried invA. Nearly 19% of the MDR Citrobacter isolates were found to carry an intI1. All intI1-positive isolates contained resistance gene cassettes dfrA1, dfrA7 and dfrA15. Detection of resistance gene cassettes in the MDR Citrobacter isolates in animals and animal products represents a potential source for horizontal transfer of antimicrobial resistance genes and mobile genetic elements between pathogenic and non-pathogenic bacteria in the microbial population. The findings indicate that animal feces could one of the potential sources for contamination of animal products along the food production chain

Molecular Characterization of Multidrug Resistant Salmonella Isolates From Food Animals and Animal Products in Tanzania

Food animals are major sources of human salmonellosis. Animals raised for food play an important role in transmission of antimicrobial resistant Salmonella strains to humans. The aim of this study was to determine the antimicrobial resistance profile, the occurrence of class 1 integrons and the resistance gene cassettes mobilized in the class 1 integrons of Salmonella isolates. A cross-sectional design was carried out in pastoral regions of Tanzania with large population of livestock. Salmonella isolates were recovered from 4.2% of the total of 1540 samples from apparently healthy animals and the animal products. The results showed that Salmonella isolates were detected in 5.2%, 3.7% and 3.8% of the swine, cattle and chicken, respectively. Sixty-one Salmonella isolates belonged to Salmonella enterica subsp. enterica. Predominant serotypes were Salmonella I 8,20:i:- (32.8%), S. Hadar (10.9%), S. Colindale (6.3%), S. Anatum (6.3%) and S.  Heidelberg (6.3%). S.  I 8,20:i:- isolates were widespread in different samples from different food animals. Of 64 Salmonella isolates, about 35.9% were resistant to at least one antimicrobial, whereas, 82.6% were multi-drug resistant (MDR) Salmonella. About 8.7% of the MDR Salmonella isolates were found to also carry integrons (intI1) and 100% of intI1-positive isolates contained resistance gene cassettes known as aac(3)-Id-aadA7 showing high rate of MDR. The occurrence of clonal MDR Salmonella isolates in food animals and animal products from pastoral communities indicates the high significance of informal traditional sector as an important source of foodborne pathogens in the food chain and the entry of pathogens to the pastoralist communitie