1Dipartimento di Medicina Veterinaria, Università degli Studi di Milano, Milan, Italy.
2Istituto Zooprofilattico Sperimentale delle Venezie, Vicenza, Italy.
Foodborne Pathog Dis. 2019 Aug;16(8):590-596. doi: 10.1089/fpd.2018.2598. Epub 2019 May 17.
causes a significant number of clinical mastitis cases in dairy cattle worldwide. The antimicrobial susceptibility of is important for both human and animal health. Surveillance reports recorded that the efficacy of most antibiotics is substantially preserved but detection of from clinical mastitis cases producing extended-spectrum beta-lactamases and plasmid-encoded AmpC beta-lactamases has been reported. These resistance determinants have frequently been associated with multidrug resistance. The aim of this study was to determine if a MacConkey agar medium supplemented with 8 mg/L of ceftiofur (MC-CEF) could be a useful tool to identify cephalosporin-resistant and multidrug-resistant (MDR) among bovine mastitis isolates. During the period 2010-2011, 773 were isolated from bovine clinical mastitis milk samples collected in 80 dairy farms in Northern Italy. A total of 105 were selected and assigned either to group randomly selected (RSEC; = 53), based on a random selection among the whole collection of 773 , or to group ceftiofur-resistant (CEFREC; = 52). CEFREC isolates were identified by spreading the 773 isolates on MC-CEF. Minimum inhibitory concentration (MIC) was used to test the phenotypic antimicrobial susceptibility to 16 antibiotics. The MIC results confirmed the ceftiofur resistance in 73.1% (38/52) of CEFREC isolates, whereas all RSEC isolates were susceptible to ceftiofur. The comparison of MIC values for each antibiotic tested between the two groups revealed significantly higher frequencies of resistance to antimicrobials other than ceftiofur in the CEFREC group. Resistance profiles highlighted a significantly higher frequency of MDR isolates among CEFREC (73.1%) than RSEC (17%) . The results showed that MC-CEF may be a useful selective medium to identify cephalosporin-resistant and MDR on dairy farms, without performing MIC on all the isolates.
在全世界范围内，都会引起大量的奶牛临床乳腺炎病例。 的抗菌药敏性对人类和动物健康都很重要。监测报告记录表明，大多数抗生素的疗效基本保持不变，但已发现从产生超广谱β-内酰胺酶和质粒编码的 AmpCβ-内酰胺酶的临床乳腺炎病例中分离出 。这些耐药决定因素经常与多药耐药性有关。本研究旨在确定是否可以使用补充有 8mg/L 头孢噻呋的麦康凯琼脂培养基（MC-CEF）作为一种有用的工具来鉴定牛乳腺炎分离株中的头孢菌素耐药和多药耐药（MDR） 。在 2010 年至 2011 年期间，从意大利北部 80 个奶牛场采集的牛临床乳腺炎奶样中分离出 773 株 。共选择了 105 株，并将其随机分配到组（RSEC；=53）或头孢噻呋耐药组（CEFREC；=52）。CEFREC 分离株通过在 MC-CEF 上扩散 773 株分离株进行鉴定。最低抑菌浓度（MIC）用于测试对 16 种抗生素的表型抗菌药敏性。MIC 结果证实，73.1%（38/52）的 CEFREC 分离株对头孢噻呋耐药，而所有 RSEC 分离株对头孢噻呋均敏感。对两组测试的每种抗生素的 MIC 值进行比较，结果显示在 CEFREC 组中，对除头孢噻呋以外的抗菌药物的耐药频率明显更高。耐药谱突出表明，CEFREC 组（73.1%）的 MDR 分离株的频率明显高于 RSEC 组（17%）。结果表明，MC-CEF 可能是一种有用的选择性培养基，可在奶牛场中鉴定头孢菌素耐药和 MDR ，而无需对所有分离株进行 MIC 测试。
