Silva Lívia Christina Alves da, Leal-Balbino Tereza Cristina, Melo Beatriz Souza Toscano de, Mendes-Marques Carina Lucena, Rezende Antonio Mauro, Almeida Alzira Maria Paiva de, Leal Nilma Cintra
Instituto Aggeu Magalhães (IAM/Fiocruz PE), Avenida Professor Moraes Rego, s/n. Cidade Universitária, Recife, Pernambuco, 50740-465, Brazil.
BMC Microbiol. 2017 Aug 18;17(1):179. doi: 10.1186/s12866-017-1089-0.
Aeromonas spp. are gram-negative bacteria that can cause a variety of infections in both humans and animals and play a controversial role in diarrhea outbreaks. Our aim was to identify clinical and environmental Aeromonas isolates associated with a cholera outbreak in a northeast county of Brazil at the species level. We also aimed to determine the genetic structure of the bacterial population and the virulence potential of the Aeromonas isolates.
Analysis based on concatenated sequences of the 16S rRNA and gyrB genes suggested the classification of the 119 isolates studied into the following species: A. caviae (66.9%), A. veronii (15.3%), A. aquariorum (9.3%), A. trota (3.4%), A. hydrophila (3.4%) and A. jandaei (1.7%). One isolate did not fit any Aeromonas species assessed, which might indicate a new species. The haplotype network based on 16S rRNA gene sequences identified 59 groups among the 119 isolates and 26 reference strains, and it clustered almost all A. caviae isolates into the same group. The analysis of the frequency patterns of seven virulence-associated genes (alt, ast, hlyA, aerA, exu, lip, flaA/B) revealed 29 virulence patterns composed of one to seven genes. All the isolates harbored at least one gene, and three of them harbored all seven virulence genes.
The results emphasize the need to improve local water supply and maintain close monitoring of possible bacterial contamination in the drinking water.
气单胞菌属是革兰氏阴性菌，可在人类和动物中引起多种感染，并且在腹泻暴发中起着有争议的作用。我们的目的是在物种水平上鉴定与巴西东北部一个县的霍乱暴发相关的临床和气单胞菌环境分离株。我们还旨在确定细菌群体的遗传结构和气单胞菌分离株的毒力潜力。
基于16S rRNA和gyrB基因的串联序列分析表明，所研究的119株分离株可分类为以下物种：豚鼠气单胞菌（66.9%）、维罗纳气单胞菌（15.3%）、水族气单胞菌（9.3%）、温和气单胞菌（3.4%）、嗜水气单胞菌（3.4%）和詹氏气单胞菌（1.7%）。有一株分离株不符合所评估的任何气单胞菌物种，这可能表明是一个新物种。基于16S rRNA基因序列的单倍型网络在119株分离株和26株参考菌株中鉴定出59个组，并且几乎将所有豚鼠气单胞菌分离株聚类到同一组。对七个毒力相关基因（alt、ast、hlyA、aerA、exu、lip、flaA/B）的频率模式分析揭示了由一至七个基因组成的29种毒力模式。所有分离株至少携带一个基因，其中三株携带所有七个毒力基因。
结果强调需要改善当地供水并密切监测饮用水中可能的细菌污染。
