Institute of Farm Animal Genetics, Friedrich-Loeffler-Institut, Neustadt-Mariensee, Germany.
J Antimicrob Chemother. 2010 Apr;65(4):619-25. doi: 10.1093/jac/dkq021. Epub 2010 Feb 17.
Twenty-five MRSA ST398 isolates from cases of bovine clinical mastitis and two isolates from farm personnel collected from 17 dairy farms in Germany were investigated for genetic relatedness, antimicrobial resistance and virulence properties.
Genomic relationships were determined by ApaI PFGE, spa typing, SCCmec typing and dru typing. Antimicrobial resistance phenotypes were determined by broth microdilution. Resistance and virulence genes were detected via a diagnostic DNA microarray and specific PCRs.
Nine major ApaI PFGE patterns were detected. Three spa types (t011, t034 and t2576) and two SCCmec types (IV and V) were identified. Five different dru types were seen with dt11a being predominant. All isolates were negative for Panton-Valentine leucocidin, enterotoxin and exfoliative toxin genes. Ten resistance patterns were observed with 11 (40.7%) isolates being resistant to only beta-lactam antibiotics and tetracyclines. Several resistance genes were detected: blaZ (penicillin resistance); tet(M), tet(K) and tet(L) (tetracycline resistance); erm(A), erm(B), erm(C) and erm(T) (macrolide/lincosamide/streptogramin B resistance); aacA-aphD, aphA3, aadD and spc (aminoglycoside or aminocyclitol resistance); fexA (phenicol resistance); dfrK (trimethoprim resistance); and vga(A) and vga(C) (pleuromutilin/lincosamide/streptogramin A resistance). The two human isolates were indistinguishable in their genotypic and phenotypic characteristics from the mastitis isolates of the same farm.
As previously described for ST398 from swine, isolates of this sequence type from cases of bovine mastitis also demonstrated a high degree of variability when ApaI PFGE profiles and other genotypic and phenotypic characteristics were compared. A uniform virulence gene pattern appeared to be conserved between ST398 isolates from both animal species.
从德国 17 个奶牛场的 25 株奶牛临床乳腺炎分离的耐甲氧西林金黄色葡萄球菌（MRSA）ST398 株和 2 株来自农场工作人员的分离株进行遗传相关性、抗菌药物耐药性和毒力特性的研究。
通过 ApaI PFGE、spa 分型、SCCmec 分型和 dru 分型来确定基因组关系。通过肉汤微量稀释法确定抗菌药物耐药表型。通过诊断性 DNA 微阵列和特定 PCR 检测耐药和毒力基因。
检测到 9 种主要的 ApaI PFGE 模式。鉴定出 3 种 spa 型（t011、t034 和 t2576）和 2 种 SCCmec 型（IV 和 V）。有 5 种不同的 dru 型，其中 dt11a 最为常见。所有分离株均未检出杀白细胞素、肠毒素和表皮剥脱毒素基因。观察到 10 种耐药模式，其中 11 株（40.7%）分离株仅对β-内酰胺类抗生素和四环素类药物耐药。检测到多个耐药基因：blaZ（青霉素耐药）；tet（M）、tet（K）和 tet（L）（四环素耐药）；erm（A）、erm（B）、erm（C）和 erm（T）（大环内酯类/林可酰胺类/链阳性菌素 B 耐药）；aacA-aphD、aphA3、aadD 和 spc（氨基糖苷类或氨基环醇类耐药）；fexA（氯霉素耐药）；dfrK（甲氧苄啶耐药）；以及 vga（A）和 vga（C）（截短侧耳素/林可酰胺类/链阳性菌素 A 耐药）。这两个来自人的分离株在与来自同一农场乳腺炎分离株的遗传和表型特征方面完全相同。
与之前报道的猪源 ST398 相同，来自奶牛乳腺炎的这些序列型的分离株在比较 ApaI PFGE 图谱和其他遗传和表型特征时，表现出高度的可变性。两种动物来源的 ST398 分离株之间似乎保持了一致的毒力基因模式。
