Malissiova Eleni, Papadopoulos Theofilos, Kyriazi Aikaterini, Mparda Maria, Sakorafa Christina, Katsioulis Antonios, Katsiaflaka Anna, Kyritsi Maria, Zdragas Antonios, Hadjichristodoulou Christos
Dairy Laboratory,Food Technology Faculty,Technological Educational Institute of Thessaly,Greece.
Veterinary Research Institute of Thessaloniki,National Agricultural Foundation,Thermi,Greece.
J Dairy Res. 2017 May;84(2):206-213. doi: 10.1017/S0022029917000103. Epub 2017 Mar 15.
The aim of this study was to examine differences in the microbiological profile and antimicrobial resistance of bacteria isolated from milk from organic and conventional sheep and goat farms. Twenty-five organic and 25 conventional sheep and goat farms in the region of Thessaly, Greece participated in this study. A standardised detailed questionnaire was used to describe farming practices. A total of 50 samples were collected and analysed for total viable count (TVC), total coliform count (TCC) and somatic cell count (SCC), while Staphylococcus aureus and Escherichia coli were isolated using standard methods. Isolates were identified at species level by Api-test and Matrix-Assisted Laser Desorption/Ionisation-Time of Flight Mass Spectrometry (MALDI-TOF MS). Susceptibility to a panel of 20 for E. coli and 16 for S. aureus antimicrobials was determined by the agar dilution method. Pulsed Field Gel Electrophoresis (PFGE) was performed for S. aureus and E. coli isolates to determine predominant clones. Lower counts of TVC, TCC and SCC were identified in milk from the organic farms, possibly due to differences in the hygienic farming practices found on those farms. API-tests and MALDI-TOF MS showed no significant differences in the S. aureus and E. coli isolates. Overall, antimicrobial resistance rates were low, while a statistically higher percentage was estimated among strains originating from conventional farms in comparison with organic farms, possibly due to the restriction of antibiotic use in organic farming. PFGE revealed diversity among S. aureus and E. coli populations in both organic and conventional farms indicating circulation of 2-3 main clones changing slightly during their evolution. Consequently, there is evidence that milk from the organic farms presents a better microbiological profile when compared with milk from conventional farms.
本研究的目的是检测从有机和传统绵羊及山羊养殖场采集的牛奶中分离出的细菌在微生物特征和抗菌药物耐药性方面的差异。希腊色萨利地区的25个有机和25个传统绵羊及山羊养殖场参与了本研究。使用标准化的详细问卷来描述养殖方式。总共采集了50份样本，分析其总活菌数（TVC）、总大肠菌群数（TCC）和体细胞数（SCC），同时采用标准方法分离金黄色葡萄球菌和大肠杆菌。通过Api测试和基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF MS）在种水平上鉴定分离株。采用琼脂稀释法测定一组20种针对大肠杆菌和16种针对金黄色葡萄球菌的抗菌药物的敏感性。对金黄色葡萄球菌和大肠杆菌分离株进行脉冲场凝胶电泳（PFGE）以确定主要克隆。在有机养殖场的牛奶中检测到较低的TVC、TCC和SCC计数，这可能是由于这些养殖场卫生养殖方式存在差异。Api测试和MALDI-TOF MS显示金黄色葡萄球菌和大肠杆菌分离株无显著差异。总体而言，抗菌药物耐药率较低，与有机养殖场相比，传统养殖场来源的菌株中估计有统计学上更高的百分比，这可能是由于有机养殖中抗生素使用受到限制。PFGE揭示了有机和传统养殖场中金黄色葡萄球菌和大肠杆菌群体的多样性，表明2-3个主要克隆在进化过程中略有变化地循环。因此，有证据表明与传统养殖场的牛奶相比，有机养殖场的牛奶呈现出更好的微生物特征。
