A recently introduced Dichelobacter nodosus strain caused an outbreak of footrot in Norway

BACKGROUND: In 2008, an outbreak of ovine footrot occurred in Norway. Dichelobacter nodosus isolates collected between 2008 and 2011 have been characterised. Isolates defined as virulent by the gelatin gel test (GG-test) were only found in sheep in Rogaland County, where the severe cases of footrot were registered. The majority (96%) of the virulent isolates belonged to serogroup A. It is suspected that they represent a newly introduced strain, and the aim of the present study was to investigate whether they are genetically similar. Sixty-one virulent isolates from sheep and 116 benign isolates from sheep, cattle and goats were included. Four GG-test virulent isolates from Danish sheep were also included. All isolates were genotyped by pulsed-field gel electrophoresis (PFGE) and by PCR for pgr variant determination. RESULTS: The Norwegian virulent isolates were assigned to 8 pulsotypes (PTs), while the benign isolates were assigned to 66 PTs. Thirty-seven (68.5%) of the 54, virulent, serogroup A isolates belonged to the same PT, and included isolates from 2008 through 2011. Isolates belonging to this PT were defined as the outbreak strain. The remaining virulent serogroup A isolates belonged to 4 PTs differing by ≤3 bands from the outbreak strain. Two virulent, Danish, serogroup A isolates differed by 2 bands from the Norwegian outbreak strain. All but 3 (95%) of the virulent isolates had the pgrA variant while 85% of the benign isolates had the pgrB variant. CONCLUSION: This study provides evidence that the footrot outbreak in Norway in 2008 most likely was caused by new introduction and local spread of one virulent D. nodosus strain

Additive Bayesian networks for antimicrobial resistance and potential risk factors in non-typhoidal Salmonella isolates from layer hens in Uganda

Background: Multi-drug resistant bacteria are seen increasingly and there are gaps in our understanding of the complexity of antimicrobial resistance, partially due to a lack of appropriate statistical tools. This hampers efficient treatment, precludes determining appropriate intervention points and renders prevention very difficult. Methods: We re-analysed data from a previous study using additive Bayesian networks. The data contained information on resistances against seven antimicrobials and seven potential risk factors from 86 non-typhoidal Salmonella isolates from laying hens in 46 farms in Uganda. Results: The final graph contained 22 links between risk factors and antimicrobial resistances. Solely ampicillin resistance was linked to the vaccinating person and disposal of dead birds. Systematic associations between ampicillin and sulfamethoxazole/trimethoprim and chloramphenicol, which was also linked to sulfamethoxazole/trimethoprim were detected. Sulfamethoxazole/trimethoprim was also directly linked to ciprofloxacin and trimethoprim. Trimethoprim was linked to sulfonamide and ciprofloxacin, which was also linked to sulfonamide. Tetracycline was solely linked to ciprofloxacin. Conclusions: Although the results needs to be interpreted with caution due to a small data set, additive Bayesian network analysis allowed a description of a number of associations between the risk factors and antimicrobial resistances investigated

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

The expression of <i>cheY</i> determined by qPCR in various conditions.

<p>The figure displays the relative expression of <i>cheY</i> when EHEC NIPH-11060424 is cultured in spent medium from <i>B</i>. <i>thetaiotaomicron</i>, <i>B</i>. <i>fragilis</i> and <i>C</i>. <i>perfringens</i> compared to growth in BHI. Boxes show the upper (75%) and the lower (25%) percentiles of the data. Whiskers indicate the highest and the lowest numbers.</p

Overview workflow for microarray experiment.

<p>Overview workflow for microarray experiment.</p

Adherence to HeLa cells, and expression of EspA in co-culture relative to pure culture.

<p>(A) Western blot of samples of total cell extracts from pure culture of <i>B</i>. <i>thetaiotaomicron</i> (lane 1), pure culture of EHEC NIPH-11060424 (lane 2), and <i>B</i>. <i>thetaiotaomicron</i> EHEC NIPH-11060424 co-culture (lane 3) using anti-EspA monoclonal antibodies. The arrow represents an unknown protein present in <i>B</i>. <i>thetaiotaomicron</i>. The results shown are representative of three independent biological and technical replicates. (B) The scatter plot shows the adherence of EHEC NIPH-11060424 in co-culture with <i>B</i>. <i>thetaiotaomicron</i> compared to pure culture of EHEC NIPH-11060424 to HeLa cells after 3 and 6 hours of incubation. The data are representative of three independent experiments with 3 technical replicates (n = 9). The vertical line illustrates the median of each group. The Mann-Whitney non-parametric test was used for comparison of groups. P< 0.05 was considered statistically significant.</p

The effect of co-culture on Stx2 production and release of bacteriophages.

<p>(A) Stx2 production by EHEC NIPH-11060424 was measured by reverse passive latex agglutination (RPLA) test. EHEC NIPH-11060424 was co-cultured with <i>B</i>. <i>thetaiotaomicron</i>, using different initial bacterial concentrations. The reciprocal of the highest twofold serial dilution causing latex agglutination was recorded as the titre. Data represent means ± standard errors of the mean (SEM) from three independent experiments. (B) Plaque assay demonstrating production of fewer bacteriophages when EHEC NIPH-11060424 was co-cultured with <i>B</i>. <i>thetaiotaomicron</i> compared to pure culture.</p

Bacterial strains used in this study.

<p>^aSynonym with NVH-734</p><p>^bAlso designated VPI-5482</p><p>Bacterial strains used in this study.</p