Inter‐laboratory validation of a rapid assay for the detection and quantification of Legionella spp. in water samples

Aims: To compare the standard culture method with a new, rapid test (ScanVIT‐Legionella?) using fluorescently labelled gene probes for the detection and enumeration of Legionella spp. The new technique was validated through experiments conducted on both artificially and naturally contaminated water and through an inter‐laboratory comparison. Methods and Results: All samples were processed by the ScanVIT test according to the manufacturer’s instructions and by a culture method (ISO 11731). ScanVIT detected significantly more positive samples, although concentrations were similar and a strong positive correlation between the two methods was observed (r = 0·888, P < 0·001). The new test was more accurate in identifying the co‐presence of Legionella pneumophila and Leg. non‐pneumophila. ScanVIT showed a slightly higher Legionella recovery from water samples artificially contaminated with Leg. pneumophila alone or together with Pseudomonas aeruginosa. Lastly, the inter‐laboratory comparison revealed that the ScanVIT test exhibits a lower variability than the traditional culture test (mean coefficient of variation 8·7 vs 16·1%). Conclusions: The results confirmed that the ScanVIT largely overlaps the reference method and offers advantages in terms of sensitivity, quantitative reliability and reduced assay time. Significance and Impact of the Study: The proposed method may represent a useful validated alternative to traditional culture for the rapid detection and quantification of Legionella spp. in water.     

内陆湖泊水体固有光学特性的典型季节差异

固有光学特性是水体光学性质的重要内容,是水色反演分析模型建立的基础.本研究利用定量滤膜技术（QFT）和后向散射测量仪BB9,对太湖梅梁湾夏、冬季水体的有色可溶性有机物(CDOM)吸收系数、总悬浮物吸收系数和总悬浮物后向散射系数进行了观测.在分别对两季节水体组分吸收系数、后向散射系数光谱特征分析的基础上,阐明其季节差异性,并结合水质参数的变化,揭示导致两季节水体固有光学特性不同的原因,达到通过固有光学量反映水环境状态的目的.初步建立了后向散射系数与悬浮物浓度的关系模型,为分析模型的构建提供了参数保障.     

Inhibition of crossed caudal interneurons by lateral interneurons in lamprey spinal cord during fictive locomotion

Templates of the membrane potential profiles from lateral (LI) interneurons and motoneurons during glutamate- and N-methyl-D-aspartate (NMDA)-induced fictive locomotion showed pronounced plateau phases. In contrast, crossed caudal (CC) interneurons had a less obvious and steeper plateau region that was followed by a clear notch coinciding with the end of the lateral interneuron plateau phase. These results indicate a significant inhibitory input from LI to CC interneurons.     

Prevalence in Bulk Tank Milk and Epidemiology of Campylobacter jejuni in Dairy Herds in Northern Italy

Thermotolerant Campylobacter spp. are frequently the cause of human gastroenteritis and have assumed more importance in Italy following the increased consumption of raw milk. Our objectives were to determine the prevalence and genotypes of Campylobacter spp. in dairy herds and to investigate the possible sources of bulk milk contamination. Bulk milk from dairy herds (n = 282) was cultured for Campylobacter spp. and Enterobacteriaceae. At three Campylobacter jejuni-positive farms, bovine feces, pigeon intestines, milk, and water points were also investigated. Isolates were identified by PCR and genotyped using multilocus sequence typing (MLST). C. jejuni was detected in 34 (12%) bulk milk samples. The strains belonged to 14 sequence types, and the most common clonal complexes were CC-21, CC-48, and CC-403. No association was demonstrated between the presence of C. jejuni and high levels of Enterobacteriaceae in bulk milk. At the three farms examined, C. jejuni was isolated from bovine feces (25/82 [30.5%]), pigeon intestines (13/60 [21.7%]), bulk milk (10/24 [41.7%]), and water points (4/16 [25%]). MLST revealed lineages that were common between milk and bovine feces but distinct between cattle and pigeons. In one herd, C. jejuni with the same genotype was isolated repeatedly from bulk milk and a cow with an udder infection. Our results showed a high prevalence of C. jejuni in bulk milk and suggested that udder excretion, in addition to fecal matter, may be a route of bulk milk contamination. MLST analysis indicated that pigeons are probably not relevant for the transmission of C. jejuni to cattle and for milk contamination.