Mercyhurst University, Erie, Pennsylvania, USA.
Appl Environ Microbiol. 2013 Aug;79(16):4821-8. doi: 10.1128/AEM.01281-13. Epub 2013 Jun 7.
Water is a major route for infection of humans by exotoxin-producing bacteria, including Shiga toxin-producing Escherichia coli (STEC). While STEC has the potential to be present in nearly every type of water source, its distribution is sporadic, and an understanding of factors that govern its emergence and persistence within water is lacking. In this study, we examined the influence of microbe content on STEC persistence in freshwater. We found that depletion of microbes in the water leads to a considerable increase in the persistence of STEC, an effect that can be mitigated by adding grazing protists to the water. STEC strains appear to be more resistant to the impact of grazing protists than E. coli strains that lack the Shiga toxin (stx) gene. Our results demonstrate that the microcosm can dramatically influence the persistence of STEC in aquatic ecosystems and that the overall impact by microbes on STEC strains is fundamentally different from that of non-STEC strains of bacteria. Overall, these results provide insight into why STEC and possibly other exotoxin-producing bacterial pathogens display such variability in abundance, distribution, and persistence in aquatic ecosystems.
水是人类感染产肠毒素细菌（包括产志贺毒素大肠杆菌（STEC））的主要途径。虽然 STEC 有可能存在于几乎每一种水源中，但它的分布是零星的，并且对于控制其在水中出现和持续存在的因素缺乏了解。在这项研究中，我们研究了微生物含量对淡水 STEC 持续存在的影响。我们发现，水中微生物的耗尽会导致 STEC 的持续存在显著增加，而通过向水中添加放牧原生动物可以减轻这种影响。STEC 菌株似乎比缺乏志贺毒素（stx）基因的大肠杆菌菌株更能抵抗放牧原生动物的影响。我们的结果表明，微观环境可以极大地影响水生生态系统中 STEC 的持续存在，并且微生物对 STEC 菌株的整体影响与非 STEC 菌株的细菌根本不同。总的来说，这些结果提供了一些见解，说明为什么 STEC 以及可能其他产肠毒素细菌病原体在水生生态系统中的丰度、分布和持续存在方面表现出如此大的可变性。
