投稿分類 微生物

主委發表種類: 壁報

投稿標題(中): RND外排幫浦基因在嗜水氣單胞菌環境分離株中的分佈

投稿標題(英): Distribution of RND efflux pump genes in Aeromonas hydrophila environmental isolates

投稿摘要: Abstract
Background & Objective: Aeromonas hydrophila is a gram-negative bacterium widely distributed in various aquatic ecosystems such as drinking water, natural water and soil. This pathogen is the major causative agent of infections in fish and occasionally responsible for human infections following contact with contaminated water or food. Clinical manifestations include gastroenteritis, cellulitis, soft tissue infections, septicemia and a series of clinical syndromes that appear in immunocompromised patients. Currently, the extensive use of antibiotics in clinical practice leads to the increase of prevalence of multidrug-resistant (MDR) Aeromonas isolates and results in a serious challenge in public health. The efflux system is a critical mechanism of antibiotic resistance in most Gram-negative bacteria, especially the resistance-nodulation-division (RND) efflux transporters.However, the role of RND efflux pumps in A. hydrophila is not fully understood. This study explored the different distribution of the RND efflux pump system between clinical and environmental strains, and the relationship between the efflux system and the characteristics of antibiotic resistance and bacterial virulence.
Method: The distribution of RND genes among Aeromonas hydrophila environmental strains was determined by PCR. The susceptibility of bacterial strains was evaluated by broth microdilution method using Vitek 2 system. The virulent characteristics including bacterial motility, exoenzyme secretion and biofilm formation were investigated in this study.
Results: Significant differences in motility and biofilm formation were found between environmental and clinical strains. Most environmental isolates displayed a susceptible phenotype compared with those of clinical isolates which were resistant to 2 or 3 classes of antibiotics. The secretion of exoenzyme by both strains characterized by protease activity was comparable. The PCR results indicated that the distribution of RND efflux pumps AHA0021, AHA1320 and AHA2963 widely found in clinical isolates (100%, 7 of 7 isolates) was higher than those of environmental strains (37.5%; 3 of 8 isolates, 0; 0 of 8 isolate, and 25%; 2 of 8 isolates).
Conclusion: The distribution of RND efflux pumps in clinical isolates was different from that of environmental strains; whether these genes are involved in the development of pathogenicity and antibiotic resistance of A. hydrophila clinical isolates remain to be proven.

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