Typing of Pseudomonas aeruginosa from hemorrhagic pneumonia in mink (Neovison vison).

Hemorrhagic pneumonia in mink (Neovison vison) is caused by Pseudomonas aeruginosa and is an acute and fatal disease in farmed mink. Earlier work has demonstrated that some outbreaks of hemorrhagic pneumonia are caused by pathogenic strains while most outbreaks are caused by local strains. The objective of this study was to determine the genetic and geographical relationship among outbreaks of hemorrhagic pneumonia by pulsed-field gel electrophoresis typing of P. aeruginosa isolates. Furthermore, chosen isolates were typed by a commercial genotyping method based on single nucleotide polymorphisms (SNPs) and compared to a larger dataset of human and environmental origin. The bacterial isolates were obtained from diagnostic samples from 2002 to 2009 and contained 164 isolates from 95 outbreaks on 90 farms. Our results show that most outbreaks of hemorrhagic pneumonia in mink are caused by distinct strains of P. aeruginosa. We also identified related P. aeruginosa strains which, together with two prevalent but unrelated clones, caused one third of the outbreaks of hemorrhagic pneumonia supporting the sparse literature on this subject. None of the SNP typed strains were identified in a large dataset of human and environmental origin.

Spatio-temporal patterns of Campylobacter colonization in Danish broilers.

Despite a number of risk-factor studies in different countries, the epidemiology of Campylobacter colonization in broilers, particularly spatial dependencies, is still not well understood. A series of analyses (visualization and exploratory) were therefore conducted in order to obtain a better understanding of the spatial and temporal distribution of Campylobacter in the Danish broiler population. In this study, we observed a non-random temporal occurrence of Campylobacter, with high prevalence during summer and low during winter. Significant spatio-temporal clusters were identified in the same areas in the summer months from 2007 to 2009. Range of influence between broiler farms were estimated at distances of 9.6 km and 13.5 km in different years. Identification of areas and time with greater risk indicates variable presence of risk factors with space and time. Implementation of safety measures on farms within high-risk clusters during summer could have an impact in reducing prevalence.

Risk factors for Campylobacter infection in Danish broiler chickens.

Data from the Quality Assurance System in Danish Broiler Production (KIK system) were analyzed to identify within farm biosecurity- and management-related risk factors for Campylobacter infection in Danish broiler flocks. In the study, data from 2,835 flocks originating from 187 farms in the time period of December 2009 to November 2010 were included. The PCR test results of fecal samples collected on socks revealed that 14% of the Danish broiler flocks were positive to Campylobacter during the study period. Of the positive flocks, 55% were positive during summer time and the positive flocks during summer time were related to areas where clustering of infected farms was identified in previous conducted studies. The median number of people working in or entering broiler houses was 2 (from 1 to 7). The median slaughter age of Danish broiler flocks was 35 d (from 31-61 d). A multivariable logistic regression model with a random effect of farm was performed. The analysis revealed that flocks had a higher risk of acquiring positive infection status during summer time: odds ratio = 12.59 (95% CI: 6.79-23.36) and when more than one person entered the broiler house: odds ratio = 2.03 (95% CI: 1.19-3.84). Furthermore, there was a higher risk of a positive infection status if the test result of the farm for the previous flock was positive: odds ratio = 1.80 (95% CI: 1.22-2.63), if the broiler houses were built before and during 1990: odds ratio = 1.60 (95% CI: 1.17-2.18), and if the average slaughter age of the birds was more than 35 d: odds ratio = 1.33 (95% CI: 1.02-1.76).