Mohammadi Barzelighi Hajar, Bakhshi Bita, Daraei Bahram, Fazeli Hossein, Nasr Esfahani Bahram
Department of Microbiology, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran.
Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
Infect Drug Resist. 2020 Jul 13;13:2261-2275. doi: 10.2147/IDR.S248043. eCollection 2020.
The purpose of this study was to analyze the sequence of gene in relation to its expression in strains isolated from different clinical specimens of burn patients. Moreover, in silico sequence analysis of gene using globally reported sequences was intended.
Fifty-nine multidrug-resistant isolates were selected from different clinical specimens of patients suffering from burn wound infections in two university hospitals and subjected to antibacterial susceptibility testing. The frequency and genetic diversity of the gene was determined by polymerase chain reaction (PCR) and Sanger sequencing. The gene sequences were compared with the sequence data from other countries. The expression level of gene in isolates with different sequences from different clinical specimens was evaluated by real-time PCR.
About 98%-100% of the isolates were resistant to gentamicin, tobramycin, cefoxitin, ciprofloxacin, amikacin, and imipenem, while 100% and 23.9% of the isolates were susceptible to colistin and ceftazidime, respectively. Only eight point mutations were detected with amino acid substitutions in only two positions (81 and 102). In global analysis, 93% of strains showed missense mutation at positions 81 (alanine to threonine). The majority (81%) of Iranian strains were allocated to two major clusters distinct from the rest of world, which may suggest that strains from Iran have made a distinct genetic stockpile through point mutations which has established them separate from the other counties. However, 19% were distributed in different clusters together with the strains from different countries of North and South America, Europe, South and East Asia. The expression level of the gene was statistically higher in the isolates collected from the blood of burns patients with systemic infection compared to the isolates collected from other specimens (wound, catheter and tissue), which shows a positive correlation between gene expression and increased pathogenicity and capability for dissemination. This study may open new insight about genetic variation and significance in pathogenesis.
本研究旨在分析从烧伤患者不同临床标本中分离出的菌株中某基因的序列及其表达情况。此外，还打算利用全球公布的序列对该基因进行计算机序列分析。
从两家大学医院烧伤创面感染患者的不同临床标本中选取59株多重耐药菌株，进行抗菌药敏试验。通过聚合酶链反应（PCR）和桑格测序法确定该基因的频率和遗传多样性。将该基因序列与其他国家的序列数据进行比较。通过实时PCR评估来自不同临床标本、具有不同该基因序列的菌株中该基因的表达水平。
约98%-100%的菌株对庆大霉素、妥布霉素、头孢西丁、环丙沙星、阿米卡星和亚胺培南耐药，而100%和23.9%的菌株分别对黏菌素和头孢他啶敏感。仅检测到8个点突变，且仅在两个位置（81和102）发生氨基酸替换。在全球分析中，93%的菌株在81位（丙氨酸到苏氨酸）出现错义突变。大多数（81%）伊朗菌株被归入两个主要簇，与世界其他地区不同，这可能表明伊朗的菌株通过点突变形成了独特的基因库，使其与其他国家的菌株区分开来。然而，19%分布在不同簇中，与来自北美、南美、欧洲、南亚和东亚不同国家的菌株在一起。与从其他标本（伤口、导管和组织）收集的菌株相比，从患有全身感染的烧伤患者血液中收集的菌株中该基因的表达水平在统计学上更高，这表明该基因表达与致病性增加和传播能力之间存在正相关。本研究可能为该基因在发病机制中的遗传变异和意义提供新的见解。
