Iweriebor Benson C, Iwu Chinwe J, Obi Larry C, Nwodo Uchechukwu U, Okoh Anthony I
SA-MRC Microbial Water Quality Monitoring Centre, University of Fort Hare, Alice, 5700, South Africa.
Applied and Environmental Microbiology Research Group, Department of Biochemistry and Microbiology, University of Fort Hare, Alice, 5700, South Africa.
BMC Microbiol. 2015 Oct 16;15:213. doi: 10.1186/s12866-015-0553-y.
Shiga toxin-producing Escherichia coli (STEC) O157:H7 is a well-recognized cause of bloody diarrhea and hemolytic-uremic syndrome (HUS). The ability of STEC strains to cause human disease is due to the production of Shiga toxins. The objectives of this study were to determinate the prevalence, serotypes, antibiotic susceptibility patterns and the genetic capability for Shiga toxin production in Escherichia coli (STEC) strains isolated from dairy cattle farms in two rural communities in the Eastern Cape Province of South Africa.
Fecal samples were collected between March and May 2014, from individual cattle (n=400) in two commercial dairy farms having 800 and 120 cattle each. Three hundred presumptive isolates obtained were subjected to polymerase chain reactions (PCR) for identification of O157 serogroup and Shiga toxin producing genes (stx1, stx2) on genomic DNA extracted by boiling method. Susceptibility of the isolates to 17 antibiotics was carried out in vitro by the standardized agar disc-diffusion method.
Based on direct PCR detection, 95 (31.7%) isolates were identified as O157 serogroup. The genetic repertoire for Shiga toxin production was present in 84 (88.42%) isolates distributed as stx1 (37), stx2 (38) and stx1/2 (9) respectively while 11 of the isolates did not harbor Shiga toxin producing genes. Multiple antibiotic resistances were observed among the isolates and genetic profiling of resistance genes identified bla ampC 90%, blaCMY 70%, blaCTX-M 65%, blaTEM 27% and tetA 70% and strA 80% genes among the antimicrobial resistance determinants examined.
We conclude that dairy cattle farms in the Eastern Cape Province are potential reservoirs of antibiotic resistance determinants in the province.
产志贺毒素大肠杆菌（STEC）O157:H7是血性腹泻和溶血尿毒综合征（HUS）的一个公认病因。STEC菌株导致人类疾病的能力归因于志贺毒素的产生。本研究的目的是确定从南非东开普省两个农村社区的奶牛场分离出的大肠杆菌（STEC）菌株中，志贺毒素产生的流行率、血清型、抗生素敏感性模式及遗传能力。
2014年3月至5月间，从两个商业化奶牛场的个体牛（n = 400）采集粪便样本，这两个奶牛场分别有800头和120头牛。对获得的300株疑似分离株进行聚合酶链反应（PCR），以鉴定通过煮沸法提取的基因组DNA上的O157血清群和产志贺毒素基因（stx1、stx2）。通过标准化琼脂纸片扩散法在体外检测分离株对17种抗生素的敏感性。
基于直接PCR检测，95株（31.7%）分离株被鉴定为O157血清群。产志贺毒素的基因库存在于84株（88.42%）分离株中，分别为stx1（37株）、stx2（38株）和stx1/2（9株），而11株分离株未携带产志贺毒素基因。在分离株中观察到多重抗生素耐药性，在所检测的抗菌耐药决定因素中，耐药基因的基因分型鉴定出bla ampC 90%、blaCMY 70%、blaCTX-M 65%、blaTEM 27%以及tetA 70%和strA 80%基因。
我们得出结论，东开普省的奶牛场是该省抗生素耐药决定因素的潜在储存库。
