Antibiotic resistance and virulence factors among Escherichia coli isolates from avian organic fertilizer

ABSTRACT: Brazilian poultry industry generates large amounts of organic waste, such as chicken litter, which is often used in agriculture. Among the bacteria present in organic fertilizer are members of the Enterobacteriaceae family, such as Escherichia coli. The aim of this study was to analyze the profile of virulence factors and antimicrobial resistance of E. coli isolates from avian organic fertilizer. A total of 47 E. coli strains were tested through Polymerase chain reaction to detect virulence genes (hlyF, iss, ompT, iutA and iroN). Fourteen antimicrobials were used to test antimicrobial susceptibility in the strains. Genes characteristic of Avian Pathogenic E. coli (APEC) were reported among the strains, with the hlyF, iss and ompT genes being the most prevalent. The isolates showed high resistance (˃50%) to tetracycline, gentamicin, cefotaxime, nitrofurantoin, trimethoprim-sulfamethoxazole and ampicillin. Multidrug resistance was reported in a great number of strains (>70%). The results showed the presence of APEC cells with virulence genes and antimicrobial resistance after 15 days of the windrowing process in poultry houses, it means this process should be improved to eliminate these cells.

摘要：巴西家禽养殖业会产生大量有机废弃物，例如鸡垫料（chicken litter），这类废弃物常被应用于农业生产。有机肥料中的细菌类群包含肠杆菌科（Enterobacteriaceae）成员，例如大肠埃希氏菌（Escherichia coli，以下简称大肠杆菌）。本研究旨在分析禽源有机肥料分离得到的大肠杆菌的毒力因子谱与抗菌耐药性。本研究共计对47株大肠杆菌菌株开展聚合酶链式反应（Polymerase chain reaction，以下简称PCR）检测，以鉴定其携带的毒力基因（hlyF、iss、ompT、iutA及iroN）；同时采用14种抗菌药物对菌株进行抗菌敏感性测试。菌株中检出了禽致病性大肠杆菌（Avian Pathogenic E. coli，以下简称APEC）的特征基因，其中hlyF、iss与ompT基因的检出率最高。分离菌株对四环素、庆大霉素、头孢噻肟、呋喃妥因、甲氧苄啶-磺胺甲恶唑及氨苄青霉素均表现出≥50%的高耐药率。超过70%的菌株呈现多重耐药性。研究结果显示，经禽舍内条垛式堆肥工艺处理15天后，仍存在携带毒力基因且具有抗菌耐药性的APEC菌株，这表明该堆肥工艺亟需优化以灭杀此类菌株。