Department of Science, Roma Tre University, Viale G. Marconi 446, 00146, Rome, Italy.
Department of Medicine, Epidemiology, Workplace and Environmental Hygiene, Lamezia Terme Research Centre, INAIL - National Institute for Insurance against Accidents at Work, Lamezia Terme, Italy.
BMC Microbiol. 2019 Feb 26;19(1):51. doi: 10.1186/s12866-019-1422-x.
Colonization by livestock-associated MRSA (LA-MRSA) has increasingly been reported in the swine population worldwide. The aim of this study was to assess the prevalence of MRSA nasal carriage in healthy pigs, including the black (Calabrese) breed, from farms in the Calabria Region (Southern Italy). Between January and March 2018, a total of 475 healthy pigs reared in 32 farms were sampled by nasal swabbing. MRSA isolates were characterized by spa, MLST and SCCmec typing, and susceptibility testing to 17 antimicrobials.
22 of 32 (66.8%) pig farms resulted positive for MRSA. The prevalence of MRSA was 46.1% (219 MRSA culture-positive out of 475 samples). MRSA colonization was significantly higher in intensive farms and in pigs with a recent or ongoing antimicrobial treatment. All 219 MRSA isolates were assigned to ST398. The most common spa types were t011 (37.0%), t034 (22.4%) and t899 (15.1%). A novel spa type (t18290) was detected in one isolate. An insertion of IS256 in the ST398-specific A07 fragment of the SAPIG2195 gene was detected in 10 out of 81 t011 isolates. Nearly all isolates carried the SCCmec type V element, except 11 isolates that carried the SCCmec type IVc. None of the isolates was positive for the Panton-Valentine leukocidin. All isolates were resistant to tetracycline. High resistance rates were also found for clindamycin (93.1%), trimethoprim/sulfamethoxazole (68.4%), fluoroquinolones (47.9-65.3%) and erythromycin (46.1%). None of the isolates was resistant to vancomycin and fusidic acid. Overall, a multidrug resistant phenotype was observed in 88.6% of isolates.
We report a high prevalence of MRSA among healthy swine in Southern Italy farms, with higher isolation frequency associated with intensive farming. The epidemiological types identified in our study reflect those reported in other European countries. Our findings underscore the importance of monitoring the evolution of LA-MRSA in pig farms in order to implement control measures and reduce the risk of spread in the animal population.
家畜相关耐甲氧西林金黄色葡萄球菌（LA-MRSA）在全球范围内的猪群中的定植情况越来越多。本研究的目的是评估健康猪（包括卡拉布里亚（Calabria）地区的 Calabrese 品种）中 MRSA 鼻腔携带的流行率。 2018 年 1 月至 3 月期间，从卡拉布里亚地区的 32 个农场采集了 475 头健康猪的鼻腔拭子。对分离的 MRSA 进行 spa、MLST 和 SCCmec 分型，并对 17 种抗菌药物进行药敏试验。
32 个猪场均有 22 个（66.8%）为 MRSA 阳性。MRSA 的流行率为 46.1%（475 个样本中 219 个为 MRSA 培养阳性）。集约化农场和近期或正在接受抗菌药物治疗的猪的 MRSA 定植率明显更高。219 株 MRSA 分离株均被归为 ST398。最常见的 spa 类型为 t011（37.0%）、t034（22.4%）和 t899（15.1%）。在 1 株分离株中发现了一种新的 spa 类型（t18290）。在 81 株 t011 分离株中，有 10 株携带 SAPIG2195 基因中 ST398 特异性 A07 片段的 IS256 插入。几乎所有分离株均携带 SCCmec 类型 V 元件，只有 11 株携带 SCCmec 类型 IVc。所有分离株均未检测到 Panton-Valentine 白细胞毒素。所有分离株均对四环素耐药。克林霉素（93.1%）、甲氧苄啶/磺胺甲恶唑（68.4%）、氟喹诺酮类（47.9-65.3%）和红霉素（46.1%）的耐药率也很高。没有分离株对万古霉素和夫西地酸耐药。总的来说，88.6%的分离株表现出多重耐药表型。
我们报告了在意大利南部农场健康猪中存在高比例的 MRSA，集约化养殖与更高的分离频率相关。本研究中鉴定的流行类型反映了在其他欧洲国家报告的类型。我们的研究结果强调了监测猪农场中 LA-MRSA 演变的重要性，以实施控制措施并降低动物种群传播的风险。
