Sediment, water, and fish gut samples taken at three sites near the headwaters of the San Marcos River, Texas, were analyzed for salmonellae Salmonella spp. by culture and molecular techniques. While enrichment cultures from sediment and water samples from the two uppermost sites were negative for salmonellae in polymerase chain reaction analyses, both sediment and water samples were positive at the downstream site. At all sites, salmonellae were present in the guts of different fishes (e.g., largemouth bass Micropterus salmoides, channel catfish Ictalurus punctatus, common carp Cyprinus carpio, and suckermouth catfish Hypostomus plecostomus). The highest percentage of detection (33% of analyzed fish) occurred at the downstream site, whereas detection percentages at the upper two sites were 18% and 17%. Detection of salmonellae was usually limited to one segment of the gut (i.e., upper or lower part). Serovars were highly variable among individuals and differed between the upper and lower gut in the only individual (a common carp) that had salmonellae in both gut segments. In situ hybridization demonstrated that salmonellae were normally associated with particulate material in the gut and occurred in highly variable numbers ranging from an occasional organism to a majority of the gut microbe population. These results demonstrate the presence of different serovars of potentially human pathogenic salmonellae among four ecologically distinct fishes within natural environments. They also suggest that salmonellae are not components of the indigenous microbial community in fish intestines but rather are ingested with particulate material.

中文翻译：

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检测天然河流系统中鱼类的沙门氏菌

在德克萨斯州圣马科斯河源头附近的三个地点采集的沉积物、水和鱼肠样本进行了沙门氏菌沙门氏菌分析。通过培养和分子技术。虽然在聚合酶链反应分析中，来自两个最上方地点的沉积物和水样的富集培养物对沙门氏菌呈阴性，但下游地点的沉积物和水样均呈阳性。在所有地点，沙门氏菌都存在于不同鱼类（例如，大口黑鲈 Micropterus salmoides、沟鲶 Ictalurus punctatus、鲤鱼 Cyprinus carpio 和鲇鱼 Hypostomus plecostomus）的肠道中。下游站点的检测百分比最高（33% 的分析鱼），而上面两个站点的检测百分比分别为 18% 和 17%。沙门氏菌的检测通常仅限于肠道的一个部分（即上部或下部）。血清型在个体之间差异很大，并且在唯一一个在两个肠道段都含有沙门氏菌的个体（鲤鱼）的上消化道和下消化道之间存在差异。原位杂交表明，沙门氏菌通常与肠道中的颗粒物质有关，并且其数量变化很大，从偶尔出现的微生物到大多数肠道微生物群不等。这些结果表明，在自然环境中，四种生态不同的鱼类存在潜在人类致病沙门氏菌的不同血清型。他们还表明，沙门氏菌不是鱼肠中本地微生物群落的组成部分，而是与颗粒物质一起摄入。