Colimetric index and virulence genes iss and iutA in Escherichia coli isolates in cellulitis of poultry carcasses under sanitary inspection

SUMMARY Current study determines the population of total coliforms and Escherichia coli and identifies iss and iutA virulence genes in Escherichia coli strains isolated from cellulitis in poultry carcasses retrieved from a slaughterhouse. One hundred cellulitis lesions were collected between August 2013 and January 2014. The population of total coliforms and Escherichia coli was verified by Petrifilm™ rapid counting method (AOAC 998.8). Escherichia coli samples were analyzed for iss and iutA genes by Polymerase Chain Reaction (PCR) technique. Total coliforms were present in 96.0% (96/100) of the analyzed samples, with a population between 3.4 and 9.5 log CFU/g. Escherichia coli was present in 82.0% (82/100) of cellulitis samples and the population ranged between <1.0 and 9.0 log CFU/g. The iss gene was found in 89.0% of isolates and the iutA gene in 97.6%. High populations of total coliforms and Escherichiacoli in cellulitis samples indicate that hygienic-sanitary failures may have occurred in the production of broilers. When high prevalence of virulence genes under analysis, characteristic of Avian Pathogenic Escherichia coli (APEC) and possible zoonotic character of the pathotype are taken into account, it is important to highlight the need to adopt Good Manufacturing Practices, Standard Procedures of Operational Hygiene and Hazard Analysis and Critical Control Points in poultry slaughterhouses to ensure the safety of the final product.

研究概述
本研究旨在检测某屠宰场采集的家禽屠体蜂窝织炎病灶中分离得到的大肠杆菌（Escherichia coli）菌株的总大肠菌群（total coliforms）与大肠杆菌菌落数，并鉴定其iss和iutA毒力基因。本研究于2013年8月至2014年1月期间，共采集100份蜂窝织炎病灶样本。
采用Petrifilm™快速计数法（AOAC 998.8）对总大肠菌群与大肠杆菌的菌落数进行检测；采用聚合酶链式反应（Polymerase Chain Reaction，PCR）技术对大肠杆菌样本的iss和iutA基因进行分析。
本次检测的样本中，96.0%（96/100）检出总大肠菌群，菌落数范围为3.4至9.5 log CFU/g；82.0%（82/100）的蜂窝织炎样本检出大肠杆菌，菌落数范围为小于1.0至9.0 log CFU/g。分离菌株中，89.0%携带iss基因，97.6%携带iutA基因。
蜂窝织炎样本中高浓度的总大肠菌群与大肠杆菌，提示肉鸡生产过程中可能存在卫生管控失误。结合本次检测的毒力基因高检出率——这符合禽致病性大肠杆菌（Avian Pathogenic Escherichia coli，APEC）的特征，且该致病菌型可能具备人畜共患特性——需着重强调：家禽屠宰场应采用良好生产规范（Good Manufacturing Practices，GMP）、作业卫生标准操作规程以及危害分析与关键控制点（Hazard Analysis and Critical Control Points，HACCP）体系，以保障最终产品的安全性。