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Fate of Methicillin‐resistant Staphylococcus aureus (MRSA) under simulated acidic conditions of the human stomach
Food Science & Nutrition ( IF 3.5 ) Pub Date : 2020-07-31 , DOI: 10.1002/fsn3.1698
Elisa Spinelli 1 , Teresa Requena 2 , Marta Caruso 3 , Antonio Parisi 4 , Loredana Capozzi 4 , Laura Difato 3 , Giovanni Normanno 1
Affiliation  

A known amount (107 cfu/ml) of animal origin Methicillin‐resistant Staphylococcus aureus (MRSA) ST398/t011/V and of human origin MRSA ST1/t127/IVa strains were individually inoculated into ricotta cheese and hamburger samples. The pH of each food matrix was gradually decreased from 6.0 down to 2.0 during a period of about 2 hr, under conditions simulating the mechanical digestion of the human stomach. Afterward, the MRSA strains were recovered by using a MRSA‐specific plating medium. Although both strains showed a certain acidic resistance, they showed different responses at low pH values during the experiment: ST398 survived unharmed during the course of the experiments to the last stage at pH 2 where counts of 6.4 cfu/g for the hamburger and 7.5 log cfu/g for ricotta cheese assays were obtained. In contrast, the ST1 population was no longer detectable at pH 3 in the hamburger and at pH 2 in the ricotta cheese assays. To the best of our knowledge, this is the first study that investigates the ability of MRSA to overcome the acidic conditions of the human stomach and that adds new evidence that might contribute to expand the scientific knowledge on the significance of MRSA in the food safety debate.

中文翻译:


模拟人胃酸性条件下耐甲氧西林金黄色葡萄球菌 (MRSA) 的命运



将已知量(10 7 cfu/ml)的动物源耐甲氧西林金黄色葡萄球菌(MRSA) ST398/t011/V 和人源 MRSA ST1/t127/IVa 菌株分别接种到乳清干酪和汉堡样品中。在模拟人胃机械消化的条件下,每种食物基质的 pH 在约 2 小时内逐渐从 6.0 降至 2.0。随后,使用 MRSA 特异性平板培养基回收 MRSA 菌株。虽然两种菌株都表现出一定的耐酸性,但在实验过程中它们在低 pH 值下表现出不同的反应:ST398 在实验过程中毫发无伤地存活下来,直到 pH 2 的最后阶段,其中汉堡计数为 6.4 cfu/g,计数为 7.5 log获得了用于乳清干酪测定的cfu/g。相比之下,在汉堡的 pH 3 和乳清干酪的 pH 2 下,ST1 群体不再可检测到。据我们所知,这是第一项调查 MRSA 克服人胃酸性条件的能力的研究,并增加了新的证据,可能有助于扩大关于 MRSA 在食品安全辩论中的重要性的科学知识。
更新日期:2020-09-20
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