不同介质间采用矩阵量化气单胞菌的交叉污染

为定量描述气单胞菌在不同介质间的转移及变化过程,基于单个细菌在每次转移过程中只能被转移到一个介质表面的假设,采用矩阵方式将气单胞菌的转移路径及被转移的可能性集中于一个二维的数据表格之中,并对不同场景下气单胞菌在不同介质表面的交叉污染水平进行分析。结果表明,采用矩阵方式不仅可用于探究交叉污染对细菌受体表面带菌量的变化,同时可定量分析细菌供体表面带菌量的变化,如在分割冷却猪肉前、后,猪肉中气单胞菌的带菌量平均值分别为3.02 lg CFU/g、1.82 lg CFU/g。对不同场景下各介质带菌量的量化结果证实:分割冷却猪肉后,若及时对被污染的案板、刀具等介质进行清洗或更换,可有效降低交叉污染水平并可预防二次交叉污染的发生。     

Spatial analysis of bovine spongiform encephalopathy in Galicia, Spain (2000-2005)

In Spain, the first bovine spongiform encephalopathy (BSE) case was detected in 2000 in a cow born in the Galicia region (Northwestern Spain). From then and until October 2005, 590 cases were detected, 223 of them in Galicia.

In 1994, meat and bone meal (MBM) was banned on ruminant feed and, in 1996, an EU decision mandating an overall change in MBM processing was implemented. This decision was gradually applied in the territory and not enforced before July 1998. The objective of this study was to explore clustering of BSE cases and estimate the standard incidence ratio (SIR) of BSE in Galicia. Our study was based on the BSE cases detected during the surveillance period 2000–2005 in the Galicia region. These cases were divided, based on birth date, into two periods: animals born from 1994 to July 1998, and those born after July 1998. We tested the role of cross-contamination on the geographical SIR distribution for both periods. Hierarchical Bayesian models were used to model the overdispersion and lack of independence of the SIR estimates. The geographical distribution of the standard incidence ratio of BSE between both periods was different. In the second period, the SIR was reduced in some areas. The reduction in these areas could be attributable to the changes in the processing of MBM. We did not find any statistical link between the poultry population and the standard incidence ratio, but pig population had a positive effect.