Fusar Poli Sara, Locatelli Clara, Monistero Valentina, Freu Gustavo, Cremonesi Paola, Castiglioni Bianca, Lecchi Cristina, Longheu Carla Maria, Tola Sebastiana, Guaraglia Alessandro, Allievi Carolina, Villa Luca, Manfredi Maria Teresa, Addis Maria Filippa
Dipartimento di Medicina Veterinaria e Scienze Animali - DIVAS, Università degli Studi di Milano, 26900 Lodi, Italy; Laboratorio di Malattie Infettive degli Animali (MiLab), Università degli Studi di Milano, 26900 Lodi, Italy.
Dipartimento di Medicina Veterinaria e Scienze Animali - DIVAS, Università degli Studi di Milano, 26900 Lodi, Italy.
Res Vet Sci. 2025 Jan;182:105482. doi: 10.1016/j.rvsc.2024.105482. Epub 2024 Nov 26.
Staphylococcus aureus is the main etiologic agent of contagious dairy cow mastitis, while non-aureus staphylococci and mammaliicocci (NASM) are the bacteria most frequently isolated from milk. Beyond their impact on animal health, NASM can harbor antimicrobial resistance (AMR) genes with potential for bidirectional transfer with S. aureus, and methicillin-resistant (MR) staphylococci (MRS) can raise significant One Health concerns. In our study, we evaluated the prevalence and characteristics of MRS in the bulk tank milk (BTM) of 88 dairy farms in the livestock-dense province of Lodi, Lombardy, northern Italy. S. aureus was isolated from 32.95 % of BTM samples, with the Ribosomal Spacer PCR (RS-PCR) genotype B being the most prevalent, identified in 37.93 % of S. aureus positive farms. All isolates carried the ica genes (icaA, icaB, icaC, icaD) indicating the potential to produce biofilm. MRS were isolated in 56.81 % of farms. According to MALDI-TOF MS analysis, the most prevalent MR species included S. epidermidis (MRSE, 35.59 %) followed by S. aureus (MRSA, 18.64 %), M. sciuri (15.25 %), S. saprophyticus (11.86 %), S. borealis (6.78 %), S. haemolyticus (5.08 %), M. fleurettii, (3.39 %), S. cohnii, and S. pettenkoferi (1.70 % each). Most MR isolates carried the mecA gene, while none carried mecC. The staphylococcal cassette chromosome mec (SCCmec) was predominantly type V in MRSA (45.45 %) and type IV in MRSE (61.90 %). Given their relevance to One Health, monitoring AMR in all staphylococci and mammaliicocci isolated from milk is essential for understanding the prevalence, characteristics, and transmission dynamics of MR gene pools within dairy herds.
金黄色葡萄球菌是传染性奶牛乳腺炎的主要病原体，而非金黄色葡萄球菌和哺乳动物葡萄球菌（NASM）是最常从牛奶中分离出的细菌。除了对动物健康产生影响外，NASM可能携带抗菌药物耐药性（AMR）基因，具有与金黄色葡萄球菌双向转移的可能性，耐甲氧西林（MR）葡萄球菌（MRS）可能引发重大的“同一个健康”问题。在我们的研究中，我们评估了意大利北部伦巴第大区洛迪省这个畜牧密集省份88个奶牛场的散装罐牛奶（BTM）中MRS的流行情况和特征。从32.95%的BTM样本中分离出了金黄色葡萄球菌，核糖体间隔区PCR（RS-PCR）基因型B最为常见，在37.93%的金黄色葡萄球菌阳性农场中被鉴定出来。所有分离株都携带ica基因（icaA、icaB、icaC、icaD），表明其具有产生生物膜的潜力。在56.81%的农场中分离出了MRS。根据基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）分析，最常见的MR菌种包括表皮葡萄球菌（MRSE，35.59%），其次是金黄色葡萄球菌（MRSA，18.64%）、松鼠葡萄球菌（15.25%）、腐生葡萄球菌（11.86%）、北方葡萄球菌（6.78%）、溶血葡萄球菌（5.08%）、弗勒氏葡萄球菌（3.39%）、科氏葡萄球菌和佩氏葡萄球菌（各1.70%）。大多数MR分离株携带mecA基因，而无一携带mecC基因。葡萄球菌盒式染色体mec（SCCmec）在MRSA中主要为V型（45.45%），在MRSE中主要为IV型（61.90%）。鉴于它们与“同一个健康”的相关性，监测从牛奶中分离出的所有葡萄球菌和哺乳动物葡萄球菌中的AMR对于了解奶牛群中MR基因库的流行情况、特征和传播动态至关重要。
