Department of Biology, Faculty of Sciences, University of Isfahan, Hezar Jarib Street, Isfahan, Iran.
Department of Pharmaceutical Biotechnology and Pharmaceutical Sciences Research Center, Faculty of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran.
Probiotics Antimicrob Proteins. 2018 Mar;10(1):34-42. doi: 10.1007/s12602-017-9267-9.
The emergence of antibiotic-resistant and food-spoilage microorganisms has renewed efforts to identify safe and natural alternative agents of antibiotics such as probiotics. The aim of this study was the isolation of lactobacilli as potential probiotics from local dairy products with broad antibacterial and anti-biofilm activities against antibiotic-resistant strains of Pseudomonas aeruginosa and determination of their inhibition mechanism. Antibiotic susceptibility and classification of acquired resistance profiles of 80 P. aeruginosa strains were determined based on Centers for Disease Control and Prevention (CDC) new definition as multidrug-resistant (MDR), extensively drug-resistant (XDR), and pan-drug-resistant (PDR) followed by antibacterial assessment of lactobacilli against them by different methods. Among the 80 P. aeruginosa strains, 1 (1.3%), 50 (62.5%), and 78 (97.5%) were PDR, XDR, and MDR, respectively, and effective antibiotics against them were fosfomycin and polymyxins. Among 57 isolated lactobacillus strains, two strains which were identified as Lactobacillus fermentum using biochemical and 16S rDNA methods showed broad inhibition/killing and anti-biofilm effects against all P. aeruginosa strains. They formed strong biofilms and had bile salts and low pH tolerance. Although investigation of inhibition mechanism of these strains showed no bacteriocin production, results obtained by high-performance liquid chromatography (HPLC) analysis indicated that their inhibitory effect was the result of production of three main organic acids including lactic acid, acetic acid, and formic acid. Considering the broad activity of these two L. fermentum strains, they can potentially be used in bio-control of drug-resistant strains of P. aeruginosa.
抗生素耐药和食物腐败微生物的出现促使人们重新努力寻找安全且天然的抗生素替代品，如益生菌。本研究的目的是从当地乳制品中分离出具有广谱抗菌和抗生物膜活性的乳酸菌，作为潜在的益生菌，针对铜绿假单胞菌的抗生素耐药菌株，并确定其抑制机制。根据疾病控制与预防中心（CDC）的新定义，即多药耐药（MDR）、广泛耐药（XDR）和全耐药（PDR），对 80 株铜绿假单胞菌的抗生素敏感性和获得性耐药谱进行分类，然后采用不同方法评估乳酸菌对它们的抗菌作用。在 80 株铜绿假单胞菌中，1 株（1.3%）、50 株（62.5%）和 78 株（97.5%）分别为 PDR、XDR 和 MDR，对它们有效的抗生素为磷霉素和多黏菌素。在分离出的 57 株乳酸菌中，有 2 株经生化和 16S rDNA 方法鉴定为发酵乳杆菌，对所有铜绿假单胞菌菌株均表现出广谱抑制/杀灭和抗生物膜作用。它们形成的生物膜较强，且能耐受胆盐和低 pH 值。虽然这些菌株的抑制机制研究表明它们不产生细菌素，但高效液相色谱（HPLC）分析结果表明，它们的抑制作用是产生三种主要有机酸（包括乳酸、乙酸和甲酸）的结果。鉴于这两株发酵乳杆菌的广泛活性，它们可能有潜力用于控制铜绿假单胞菌的耐药菌株。
