Istituto Zooprofilattico Sperimentale delle Regioni Lazio e Toscana, Via Appia Nuova 1411, 00178 Rome, Italy.
J Antimicrob Chemother. 2011 Jun;66(6):1231-5. doi: 10.1093/jac/dkr115. Epub 2011 Mar 29.
The aim of this study was to provide molecular characterization of methicillin-resistant Staphylococcus aureus (MRSA) spa type t127, sequence type (ST) 1 isolates, detected in a European baseline survey in holdings of breeding pigs, to determine phenotypic and genotypic drug resistance and to compare the results with those obtained from a collection of t127, ST1 MRSA and methicillin-susceptible S. aureus (MSSA) clinical isolates.
Twenty-four t127, ST1 MRSA from dust sampled in different breeding holdings in Italy, Spain and Cyprus were studied, along with 2 t127, ST1 MRSA from fattening pigs and 11 human t127, ST1 MRSA and MSSA. Genotyping was performed using multilocus sequence typing (MLST), spa typing and PFGE. SCCmec elements were characterized by multiplex-PCR and resistance and pathogenicity genes by PCR and microarray.
PFGE patterns separated a porcine cluster (PC) from a human cluster (HC), with 75% similarity. The PC carried SCCmec cassette type V, while all isolates of the HC carried SCCmec cassette type IVa. Kanamycin resistance mediated by aadD, fluoroquinolone and erm(A)-mediated macrolide resistance and the absence of the sakA gene were features of the PC only. All isolates of both clusters were positive for LukE-LukD and LuF-LukS-HlgA leukotoxin genes and one human MSSA harboured Panton-Valentine leucocidin genes.
Despite differences in the host-specific genetic features, the possibility of PC transmission to humans cannot be excluded. MRSA spa type t127, ST1 from pigs possesses several virulence and resistance genes towards major classes of antimicrobials and may represent a serious therapeutic challenge in case of invasive infections in humans.
本研究旨在对在养猪场进行的欧洲基线调查中发现的耐甲氧西林金黄色葡萄球菌（MRSA）spa 型 t127、序列型（ST）1 分离株进行分子特征分析，确定其表型和基因型耐药性，并将结果与 t127、ST1 MRSA 和甲氧西林敏感金黄色葡萄球菌（MSSA）临床分离株的结果进行比较。
研究了来自意大利、西班牙和塞浦路斯不同养猪场灰尘样本中的 24 株 t127、ST1 MRSA，以及 2 株 t127、ST1 MRSA 肥育猪和 11 株人源 t127、ST1 MRSA 和 MSSA。采用多位点序列分型（MLST）、spa 分型和 PFGE 进行基因分型。通过多重 PCR 对 SCCmec 元件进行特征分析，通过 PCR 和微阵列对耐药性和毒力基因进行分析。
PFGE 图谱将猪源分离株（PC）与人间分离株（HC）分开，相似度为 75%。PC 携带 SCCmec 盒型 V，而 HC 中的所有分离株均携带 SCCmec 盒型 IVa。PC 中仅存在 aadD 介导的卡那霉素耐药、氟喹诺酮和 erm(A)介导的大环内酯耐药以及 sakA 基因缺失。两群均携带 LukE-LukD 和 LuF-LukS-HlgA 白细胞毒素基因，且 1 株人源 MSSA 携带 Panton-Valentine 白细胞毒素基因。
尽管宿主特异性遗传特征存在差异，但不能排除 PC 向人类传播的可能性。来自猪的 MRSA spa 型 t127、ST1 携带多种针对主要类别的抗生素的毒力和耐药基因，可能对人类侵袭性感染构成严重的治疗挑战。
