An evidence based ranking system for multiple studies designs for informing public policy. An example using interventions associated with Salmonella in swine.

Using the association between feed characteristics and Salmonella prevalence we will present an approach to combining data with multiple outcomes from multiple studies designs. The approach may be a method of informing policy makers in the area of food safety when a large amount of heterogeneous literature is available about a topic. The procedure for a systematic review of the literature was followed until the synthesis component. However, to combine the evidence we modified of the FDA Interim Evidence Ranking System for Scientific Information. Each study was characterized as one of 5 study design types based on evidentiary value. After classification by evidentiary value, the studies were considered collectively to rate the strength of the body of evidence based on quantity and consistency. The quantity ranking considered the number of studies, the number of individuals studied and generalizability to the target population. The consistency ranking considered whether studies with different designs reported similar findings. After ranking the body of evidence, an overall ranking was assigned for the strength of the evidence. The final ranking system had four levels. For example, the highest rank of scientific evidence, reflects a high level of comfort among qualified scientists that the association/relationship is scientifically valid. This level ranked relationship would be considered to have a very low probability of significant new data overturning the conclusion that the relationship is valid or significantly changing the nature of the relationship

Vaccination against Salmonella and the association with measures of Salmonella prevalence in live and slaughtered swine - A systematic review

A systematic review was conducted to evaluate the effectiveness of vaccination to reduce Salmonella prevalence in market weight finisher swine. To identify relevant studies, online databases and selected conference proceedings were searched. Two reviewers independently assessed the relevance screening and methodological quality of studies. Data of characteristics of study population, intervention, outcome, statistical analysis, and results were extracted. Four clinical trials and 21 challenge studies were identified for the final review as they described vaccination to reduce Salmonella in swine Present evidence suggests that vaccination is associated with reduced Salmonella prevalence in swine

Interventions associated with feeding management practices and feed characteristics, and measures of Salmonella prevalence in live and slaughtered swine: A systematic review and summation of evidence

The aim of this review is to evaluate and summarize the evidence for associations between feeding management practices and feed characteristics, and Salmonella prevalence in swine, which may represent opportunities for interventions. Salmonella prevalence in the reviewed literature was measured either by culture or by the presence of antibodies. A systematic review of the area was conducted, the goal being to minimize the impact of bias. Systematic reviews include an assessment of the quality of studies and exclusion of studies that fail to meet standards for published material. The review evaluated evidence for an association between feed withdrawal from swine prior to slaughter, acidification of feed, heat treatment of feed, pellet vs. mash, course vs fine grind, and wet vs. dry. A large number of intervention studies were excluded from the review because they failed to report design features designed to limit the introduction of bias such as randomization and blinding. The majority of studies included were cross sectional studies, however these failed to provide strong evidence of an association because of the potential for confounding and the failure to document a temporal association between exposure to the risk factor and the outcome. The review concluded that title strongest body of work was available for pelleted feed and dry feed, however there was still uncertainty about the situations were this association may be effective. The conclusion was that there should be a low level of comfort among qualified scientists that the claimed association/relationship is scientifically valid. This ranking is primarily based on moderate to low quality studies, or insufficient numbers of tested individuals or herds, resulting in a low degree of confidence that results could be extrapolated to the target population

Prevalence, antimicrobial susceptibility and risk factors associated with non-typhoidal Salmonella on Ugandan layer hen farms

Abstract Background Non-typhoidal Salmonella (NTS) are among the leading global foodborne pathogens and a significant public health threat. Their occurrence in animal reservoirs and their susceptibilities to commonly used antimicrobials are poorly understood in developing countries. The aim of this study was to estimate the prevalence, determine antimicrobial susceptibility and identify risk factors associated with NTS presence in laying hen farms in Uganda through a cross-sectional study. Results Pooled faecal samples were collected from 237 laying hen farms and these were analysed for NTS following standard laboratory procedures. In total, 49 farms (20.7%; 95% Confidence interval (CI): 15.6–25.6%) were positive for NTS presence. Altogether, ten Salmonella serotypes were identified among the confirmed 78 isolates, and the predominant serotypes were Salmonella Newport (30.8%), S. Hadar (14.1%), S. Aberdeen (12.8%), S. Heidelberg (12.8%), and S. Bolton (12.8%). Phenotypic antimicrobial resistance was detected in 45(57.7%) of the isolates and the highest resistance was against ciprofloxacin (50.0%) followed by sulphonamides (26.9%) and sulphamethoxazole/trimethoprim (7.7%). Resistance was significantly associated with sampled districts (p = 0.034). Resistance to three or more drugs, multi-drug resistance (MDR) was detected in 12 (15.4%) of the isolates, 9 (75%) of these were from Wakiso district. A multivariable logistic model identified large farm size (OR = 7.0; 95% CI: 2.5–19.8) and the presence of other animal species on the farm (OR = 5.9; 95% CI: 2.1–16.1) as risk factors for NTS prevalence on farms. Having a separate house for birds newly brought to the farms was found to be protective (OR = 0,4; 95% CI: 0.2–0.8). Conclusion This study has highlighted a high prevalence and diversity of NTS species in laying hen farms in Uganda and identified associated risk factors. In addition, it has demonstrated high levels of antimicrobial resistance in isolates of NTS. This could be because of overuse or misuse of antimicrobials in poultry production. Also importantly, the insights provided in this study justifies a strong case for strengthening One Health practices and this will contribute to the development of NTS control strategies at local, national and international levels

An evidence based ranking system for multiple studies designs for informing public policy. An example using interventions associated with Salmonella in swine.

Using the association between feed characteristics and Salmonella prevalence we will present an approach to combining data with multiple outcomes from multiple studies designs. The approach may be a method of informing policy makers in the area of food safety when a large amount of heterogeneous literature is available about a topic. The procedure for a systematic review of the literature was followed until the synthesis component. However, to combine the evidence we modified of the FDA Interim Evidence Ranking System for Scientific Information. Each study was characterized as one of 5 study design types based on evidentiary value. After classification by evidentiary value, the studies were considered collectively to rate the strength of the body of evidence based on quantity and consistency. The quantity ranking considered the number of studies, the number of individuals studied and generalizability to the target population. The consistency ranking considered whether studies with different designs reported similar findings. After ranking the body of evidence, an overall ranking was assigned for the strength of the evidence. The final ranking system had four levels. For example, the highest rank of scientific evidence, reflects a high level of comfort among qualified scientists that the association/relationship is scientifically valid. This level ranked relationship would be considered to have a very low probability of significant new data overturning the conclusion that the relationship is valid or significantly changing the nature of the relationship.</p

Interventions associated with feeding management practices and feed characteristics, and measures of Salmonella prevalence in live and slaughtered swine: A systematic review and summation of evidence

The aim of this review is to evaluate and summarize the evidence for associations between feeding management practices and feed characteristics, and Salmonella prevalence in swine, which may represent opportunities for interventions. Salmonella prevalence in the reviewed literature was measured either by culture or by the presence of antibodies. A systematic review of the area was conducted, the goal being to minimize the impact of bias. Systematic reviews include an assessment of the quality of studies and exclusion of studies that fail to meet standards for published material. The review evaluated evidence for an association between feed withdrawal from swine prior to slaughter, acidification of feed, heat treatment of feed, pellet vs. mash, course vs fine grind, and wet vs. dry. A large number of intervention studies were excluded from the review because they failed to report design features designed to limit the introduction of bias such as randomization and blinding. The majority of studies included were cross sectional studies, however these failed to provide strong evidence of an association because of the potential for confounding and the failure to document a temporal association between exposure to the risk factor and the outcome. The review concluded that title strongest body of work was available for pelleted feed and dry feed, however there was still uncertainty about the situations were this association may be effective. The conclusion was that there should be a low level of comfort among qualified scientists that the claimed association/relationship is scientifically valid. This ranking is primarily based on moderate to low quality studies, or insufficient numbers of tested individuals or herds, resulting in a low degree of confidence that results could be extrapolated to the target population.</p

Vaccination against Salmonella and the association with measures of Salmonella prevalence in live and slaughtered swine - A systematic review

A systematic review was conducted to evaluate the effectiveness of vaccination to reduce Salmonella prevalence in market weight finisher swine. To identify relevant studies, online databases and selected conference proceedings were searched. Two reviewers independently assessed the relevance screening and methodological quality of studies. Data of characteristics of study population, intervention, outcome, statistical analysis, and results were extracted. Four clinical trials and 21 challenge studies were identified for the final review as they described vaccination to reduce Salmonella in swine Present evidence suggests that vaccination is associated with reduced Salmonella prevalence in swine.</p