Braun Sascha D, Ahmed Marwa F E, El-Adawy Hosny, Hotzel Helmut, Engelmann Ines, Weiß Daniel, Monecke Stefan, Ehricht Ralf
Alere Technologies GmbHJena, Germany; InfectoGnostics Research CampusJena, Germany.
Department of Animal Hygiene and Zoonoses, Faculty of Veterinary Medicine, Mansoura University Mansoura, Egypt.
Front Microbiol. 2016 Jul 4;7:1020. doi: 10.3389/fmicb.2016.01020. eCollection 2016.
Industrial livestock farming is a possible source of multi-resistant Gram-negative bacteria, including producers of extended spectrum beta-lactamases (ESBLs) conferring resistance to 3rd generation cephalosporins. Limited information is currently available on the situation of ESBL producers in livestock farming outside of Western Europe. A surveillance study was conducted from January to May in 2014 in four dairy cattle farms in different areas of the Nile delta, Egypt.
In total, 266 samples were collected from 4 dairy farms including rectal swabs from clinically healthy cattle (n = 210), and environmental samples from the stalls (n = 56). After 24 h pre-enrichment in buffered peptone water, all samples were screened for 3rd generation cephalosporin-resistant Escherichia coli using Brilliance™ ESBL agar. Suspected colonies of putatively ESBL-producing E. coli were sub-cultured and subsequently genotypically and phenotypically characterized. Susceptibility testing using the VITEK-2 system was performed. All suspect isolates were genotypically analyzed using two DNA-microarray based assays: CarbDetect AS-1 and E. coli PanType AS-2 kit (ALERE). These tests allow detection of a multitude of genes and their alleles associated with resistance toward carbapenems, cephalosporins, and other frequently used antibiotics. Serotypes were determined using the E. coli SeroGenotyping AS-1 kit (ALERE).
Out of 266 samples tested, 114 (42.8%) ESBL-producing E. coli were geno- and phenotypically identified. 113 of 114 phenotypically 3rd generation cephalosporin-resistant isolates harbored at least one of the ESBL resistance genes covered by the applied assays [blaCTX-M15 (n = 105), blaCTX-M9 (n = 1), blaTEM (n = 90), blaSHV (n = 1)]. Alarmingly, the carbapenemase genes blaOXA-48 (n = 5) and blaOXA-181 (n = 1) were found in isolates that also were phenotypically resistant to imipenem and meropenem. Using the array-based serogenotyping method, 66 of the 118 isolates (55%) could be genotypically assigned to O-types.
This study is considered to be a first report of the high prevalence of ESBL-producing E. coli in dairy farms in Egypt. ESBL-producing E. coli isolates with different underlying resistance mechanisms are common in investigated dairy cattle farms in Egypt. The global rise of ESBL- and carbapenemase-producing Gram-negative bacteria is a big concern, and demands intensified surveillance.
工业化畜牧业养殖是多重耐药革兰氏阴性菌的一个潜在来源，其中包括能产生超广谱β-内酰胺酶（ESBLs）的细菌，这类酶可使细菌对第三代头孢菌素产生耐药性。目前关于西欧以外地区畜牧业养殖中ESBLs产生菌情况的信息有限。2014年1月至5月在埃及尼罗河三角洲不同地区的四个奶牛场进行了一项监测研究。
总共从4个奶牛场采集了266份样本，包括临床健康奶牛的直肠拭子（n = 210）和牛舍环境样本（n = 56）。在缓冲蛋白胨水中进行24小时预富集后，使用Brilliance™ ESBL琼脂对所有样本进行第三代头孢菌素耐药大肠杆菌的筛查。疑似产ESBLs大肠杆菌的菌落进行传代培养，随后进行基因型和表型鉴定。使用VITEK-2系统进行药敏试验。所有疑似分离株使用两种基于DNA微阵列的检测方法进行基因型分析：CarbDetect AS-1和大肠杆菌全型AS-2试剂盒（ALERE）。这些检测可检测与对碳青霉烯类、头孢菌素类和其他常用抗生素耐药相关的多种基因及其等位基因。使用大肠杆菌血清学分型AS-1试剂盒（ALERE）确定血清型。
在检测的266份样本中，通过基因型和表型鉴定出114株（42.8%）产ESBLs大肠杆菌。在114株表型上对第三代头孢菌素耐药的分离株中，有113株携带至少一种所应用检测方法涵盖的ESBL耐药基因[blaCTX-M15（n = 105）、blaCTX-M9（n = 1）、blaTEM（n = 90）、blaSHV（n = 1）]。令人担忧的是，在对亚胺培南和美罗培南也表现出表型耐药的分离株中发现了碳青霉烯酶基因blaOXA-48（n = 5）和blaOXA-181（n = 1）。使用基于阵列的血清学分型方法，118株分离株中有66株（55%）可通过基因型确定为O型。
本研究被认为是埃及奶牛场中产ESBLs大肠杆菌高流行率的首次报告。具有不同潜在耐药机制的产ESBLs大肠杆菌分离株在埃及受调查的奶牛场中很常见。产ESBLs和碳青霉烯酶的革兰氏阴性菌在全球范围内的增加是一个重大问题，需要加强监测。
